Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: Don & Tys on January 11, 2012, 07:52:01 pm
Title: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 11, 2012, 07:52:01 pm
Today I was cutting and fitting some of the new square tubing and new angle iron sill. Took a few pics to document the process and thought I would share because if you are like me, you will find it interesting to see what our coaches are like under the skin. Seeing the frame work this way makes it clear why some frame members are doubled up and most are not. My belief is that they used (at least in these years) the same basic framework across models and even perhaps, lengths as well. In the lower left of the pic that shows the entire width of the utility compartment, you can see the opening where the hook-ups pass through. To the right of that just to the left of the divder that seperates (and supports the weight of) the waste tanks and the FW tank, is another potential hook-up opening where the piece of angle iron that spans that gap would be cut out in a coach with a different layout. In our 99' U270, the grey and black tank are on the left side of the compartment divider and the fresh on the right. I have seen pictures of 320's and 295's where the waste and fresh tanks are reversed and the divider is moved toward the front of the coach accordingly. This way they can build the subframe according to one plan and adjust it to fit the floor plan of whichever model is on the build list. So, in other words, I don't believe that the strange seeming doubled up frame members are for particular structural purposes other than to facilitate the building process and have sub assemblies ready to use over a range of models and floor plans. Just my thoughts, I welcome any observations you might want to share... Cheers! Don
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 11, 2012, 08:08:53 pm
Don...
Are you welding those new pieces back into the frame? And, if so, are there any special precautions needed when doing that? I have some frame members around the generator (which is right under the driver's seat position where it gets spray from the front left tire) that I am thinking about replacing and wondering about the welding process.
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 11, 2012, 09:46:17 pm
Hi Craig, Yes we (my son and I) are welding in the new metal, and yes, according to Foretravel, there is a whole host of items to turn off and disconnect. Such as the batteries, the Allison ECU, the ABS brains, etc. I believe it would be okay if you clamp the ground quite close to where you are working (my understanding of what happens at the mothership), and you aren't using an old school AC Arc welder (so my son believs), or of course, a gas welder. However, I am going to do the reccomended disconnects before starting the major work.. We did tack weld some nuts to the broken Roloks that were to ate up to use the double nut method, but so far no indication that there was any deterimental effect from that, and the ground clamp was right there where we were working. His welder uses DC at 24 volts... Don
Are you welding those new pieces back into the frame? And, if so, are there any special precautions needed when doing that? I have some frame members around the generator (which is right under the driver's seat position where it gets spray from the front left tire) that I am thinking about replacing and wondering about the welding process.
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 11, 2012, 09:50:30 pm
Don... thanks.... I had thought there were some precautions. I don't have ABS (I'm pretty sure) or an ECU on a U225 with the 4-speed Allison. Maybe someone can set me straight on that. In 1993 there was not a lot of computer operated systems on the coaches.
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Barry Beam on January 11, 2012, 09:52:36 pm
Hi Craig, Yes we (my son and I) are welding in the new metal, and yes, according to Foretravel, there is a whole host of items to turn off and disconnect. Such as the batteries, the Allison ECU, the ABS brains, etc. I believe it would be okay if you clamp the ground quite close to where you are working (my understanding of what happens at the mothership), and you aren't using an old school AC Arc welder (so my son believs), or of course, a gas welder. However, I am going to do the reccomended disconnects before starting the major work.. We did tack weld some nuts to the broken Roloks that were to ate up to use the double nut method, but so far no indication that there was any deterimental effect from that, and the ground clamp was right there where we were working. His welder uses DC at 24 volts... Don
Don, Here is the Foretravel Welding Checklist Welding Checklist (https://wiki.foreforums.com/doku.php?id=technical:chassis:welding)
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: JohnFitz on January 11, 2012, 10:49:54 pm
Don, Thank you for posting photos and the progress. Please continue to do so as the project moves along. It looks like you and your son are doing very nice work.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: jor on January 12, 2012, 09:43:01 am
Let me second John's thanks on your postings, Don. The descriptions and the photos are fascinating. jor
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Kent Speers on January 12, 2012, 09:56:49 am
Don, you have been so thorough in this process I am guessing that you talked to Foretravel about removing the fiberglass clear across the bottom of the chassis. I would be concerned that removal might compromise the monocoque structure of the Foretravel chassis. Am I correct that you discussed this with the factory and found that it was OK to remove all of the glass. Do you have to do anything special when re-glassing to insure the new fiberglass will withstand the stress on chassis at this critical point?
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: John Haygarth on January 12, 2012, 11:32:20 am
Kent, regarding your comment on the fibreglass skin below floor frame on Don's coach, do you think the thin skin of it is a part of the strength in the frame? Seems to me to be too thin to help in any way, other than a weather stop!! I am not an engineer so may be way off. John
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 12, 2012, 12:01:27 pm
Kent, To answer your question, no I didn't talk to Foretravel about removing the skin. I did it simply because it was necessary to access the rusted subframe. The bottom skin, as well as the skin on the floor of the storage/utility bays, is a sheet of FRP (fiberglass reinforced plastic) less than .090" thick, and as John surmised, is a weather cover with perhaps a tiny bit of "R" value thrown in. I will be replacing the bottom skin with a new sheet of FRP. The wall structure on the sides of the coach, on the other hand, surely does provide some of the strength as they have actual fiberglass bonded to luan. Even there though, I am sure that it is the welded steel that does most of the work. The metal which I will be welding in along with some extra gussets will make our particular U270 much more structurally sound and integral than it has been in a number of years. I will document the process as I go for the community's entertainment... Regards, Don
Don, you have been so thorough in this process I am guessing that you talked to Foretravel about removing the fiberglass clear across the bottom of the chassis. I would be concerned that removal might compromise the monocoque structure of the Foretravel chassis. Am I correct that you discussed this with the factory and found that it was OK to remove all of the glass. Do you have to do anything special when re-glassing to insure the new fiberglass will withstand the stress on chassis at this critical point?
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 12, 2012, 12:44:03 pm
Don... are the beams you are welding back into place the same as those you have removed? What is the wall thickness? I'm probably going to use a flux welder unless I run into lots more of a problem than I anticipate; then I'll invest in a better welding unit. (Or maybe keep an eye on craigslist... some serious bargains on there lately.)
You aren't just doing a repair... more of a structural restoration. I'm glad I stumbled in to this forum in time to be here while you document it. I really appreciate the postings!!
Right now I figure I can stabilize the rust on the steel in the generator compartment by removing the scale and then spraying it down with a stabilization spray (rust converter) then repaint with a durable paint. If I discover any seriously debilitated structure my first choice would have been to sister it but I'm thinking that what you're doing is probably a much better solution.
Thanks... and keep 'em coming. :)
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Barry Beam on January 12, 2012, 01:07:26 pm
Kent, To answer your question, no I didn't talk to Foretravel about removing the skin. I did it simply because it was necessary to access the rusted subframe. The bottom skin, as well as the skin on the floor of the storage/utility bays, is a sheet of FRP (fiberglass reinforced plastic) less than .090" thick, and as John surmised, is a weather cover with perhaps a tiny bit of "R" value thrown in. I will be replacing the bottom skin with a new sheet of FRP. The wall structure on the sides of the coach, on the other hand, surely do provide some of the strength as they have actual fiberglass bonded to luan. Even there though, I am sure that it is the welded steel that does most of the work. The metal which I will be welding in along with some extra gussets will make our particular U270 much more structurally sound and rigid than it has been in a number of years. I will document the process as I go for the community's entertainment... Regards, Don
Don, Here are a couple of photos of what foretravel did to reconstruct mine for comparison.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Kent Speers on January 12, 2012, 01:24:54 pm
I am not an engineer but I spent many years working with Polymers and Polymer Structural Members. We used to make hundreds of structural polymer members by bonding fiberglass under pressure to both rigid urethane insulation board, plywood and even phenolic board and honeycomb. Some of these polymer sandwiches were used in the RV industry.
I was under the assumption that the outer skin of the Unicoach was part of the structural monocoque frame. I have never opened up a bay floor or the underskin like you did to see what the makeup was. I always thought the bottom of the coach would be a sandwich of a fiberglass outer skin, approx 100 mils, bonded to rigid urethane insulation board and a steel structural skeleton, bonded to either another layer of fiberglass or plywood with an upper skin of fiberglass. The 1" box metal frame would be embedded in the middle of the sandwich. If the fiberglass skin was not bonded to either the plywood or rigid insulation board then the fiberglass skin is probably inconsequential and not part of the monocoque structure. If, however the plywood or insulation board was bonded to the skin, you may want to talk to the engineers at FOT.
I have a very high regard for the expert knowledge and experience of many of our forum members so I am probably wrong about my assumption, but just in case the bottom of your 1999 U270 is part of the structural integrity of the chassis, I thought I should explain my thoughts further. Making an error in this regard could be catastrophic.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 12, 2012, 01:37:27 pm
I have a very high regard for the expert knowledge and experience of many of our forum members so I am probably wrong about my assumption, but just in case the bottom of your 1999 U270 is part of the structural integrity of the chassis, I thought I should explain my thoughts further. Making an error in this regard could be catastrophic.
I don't think you're wrong on this, Kent. I think it would depend on how (or whether) the FRP "skin" is bonded to the structure. Even though the skin is extremely thin it still would offer resistance to compression (as a result of the movement of the structure in torsion) and could contribute significantly to the strength of the member. Certainly worth talking to the people who had a hand in the design.
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: John Haygarth on January 12, 2012, 02:10:51 pm
Kent, my fg panel looks like it is held to base by a row of Rolocks (or such) across the width every few feet and is not glued to underside. Would that constitute some rigidity for frame? I feel that if this does not then the meer fact of all those bolts actually depletes the strength of each of these cross tubes by having so many holes in them. Surely another way to hold the FG sheet up would be better/ as I said I am not an Eng'r but figure if you drill a whole bunch of holes in the underside of a beam or box tube some strength is lost. Maybe the Mexican sun has got to me too much!!!
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Kent Speers on January 12, 2012, 02:18:44 pm
John, I really don't know the answer to that question. Your assumption sounds logical. I just find it hard to believe that the fiberglass skin is not part of the monocoque structure. The 1" steel grid would not appear to have enough strength to hold the whole thing together. I think it is supplemental rather than the foundation of the frame structure.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 12, 2012, 02:25:16 pm
if you drill a whole bunch of holes in the underside of a beam or box tube some strength is lost. Maybe the Mexican sun has got to me too much!!!
I can see how you might think this but it's not necessarily true. In some cases you can put holes in the web of a structure and have very little loss of strength (at least in the direction you want). Consider a truss versus a girder, for instance. A girder, with a solid web, is a common structural component. But if you make much of that web empty space it becomes a truss and is almost as strong and a LOT lighter. Turn the truss sideways and much of that strength is lost, of course... so you have to understand the direction of the force(s) you want to withstand.
In the case of the thin fiberglass covering on the bottom of the FT unicoaches (and unihomes) you can easily create a model to see how this can aid the resistance to torsion of the structure. Set up some popsicle sticks on edge and glue them together in a flat box shape (like the steel in the bottom of the coach). Once it's dry pick it up and try to torque (twist) it in various directions.
Now glue some paper to the top and bottom of the structure and try to torque that. I bet it will a lot stiffer.
This would be because the twisting of the box structure is converted into tension and compression on the paper... and this is exactly what the paper will resist the best. Of course, if the paper weren't well glued to the box structure then it would add nothing to the strength of hte structure and would just slip around.
Bolting the fiberglass to the steel frame of the coach may not be the best way to secure the material... but it's probably the best practical way. And while the holes for the bolts probably do weaken the beams a little, they don't weaken it enough for a failure.... if they did then all those 1987 Unicoaches would be failing all over the place and we'd hear about it.
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 12, 2012, 02:41:58 pm
Kent, I appreciate your concern, but in any case, the structure of our coach was already compromised by the damaged metal and there is only one way to get at it. I would have been happy to let Foretravel do the work to repair and replace the rusted framework, but in our case, it was not an option. Next best scenario, figure out what to do and how to do it myself. I was all set just to do the standard bulkhead fix, but I saw signs I couldn't ignore. Upon peeling back the skin on the floor of the compartment, my worst fears were revealed and you can bet I was devasted. Our dream RV had become a nightmare.
Had I just done the standard fix, I am quite sure that it would have held for awhile, but the stresses and contnuing rusting would have eventually (probably sooner rather than later) broke the welds around the rust thinned metal and left the rear 1/8" box tubing firmly bolted to the angle iron but seperated from the forward going longitudinal frame members leaving us with an even worst case scenario. I am not an engineer by trade, nor do I play one on TV, but I do trust my sense of how things work in the world enough to be confident in a good outcome. Hopefully the documentation of the process will provide convincing evidence that my fix will provide a permanent soloution to my problem. True, the FRP was bonded to the styrofoam, the four small areas of plywood. However, the wood, for the most part, had turned to mush, and the rust on the metal had all but released the fiberglass skin, and the bond to sthe styrofoam was negligible. That said, I intend to bond the new skin in place, but I don't believe that it contributes significantly to the structural integrity other than to protect the metal from moisture and corrosive elements. All the metal will also be coated with POR-15 after the welding is done with the overlaping parts painted beforehand with high zinc weld-through primer prior to welding.
The plywood, which by staying wet and holding moisture next to the steel frame, is being replace with 3/16" sheet aluminum in the areas where fixtures like the water pump and the like were screwed to (the screws likely contributing to letting water get to the wood). The aluminum will be mechanically fastent to steel gussets similar to what you see in the photos posted by Barry, which by the way, were not a feature in the original construction of the subframe on our coach.
Thanks for the replies, thoughts, concerns, and observations, keep em' coming! Don
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 12, 2012, 02:47:35 pm
Kent, the structure is 1 1/2" box tubing, for the most part 16ga or thinner, but 1/8" thick at the bulkhead joint. There is also 1 1/2"X1 1/2"X1/8" longitudinal angle iron on the sides.under the alumin
John, I really don't know the answer to that question. Your assumption sounds logical. I just find it hard to believe that the fiberglass skin is not part of the monocoque structure. The 1" steel grid would not appear to have enough strength to hold the whole thing together. I think it is supplemental rather than the foundation of the frame structure.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 12, 2012, 02:58:15 pm
John, I believe the primary purpose of those Roloks is to tie the subframe to the vertical compartment walls, which are in turn bolted to the floor above, thus supplying support and cutting down the span of the box tubing of the subframe. Don
Kent, my fg panel looks like it is held to base by a row of Rolocks (or such) across the width every few feet and is not glued to underside. Would that constitute some rigidity for frame? I feel that if this does not then the meer fact of all those bolts actually depletes the strength of each of these cross tubes by having so many holes in them. Surely another way to hold the FG sheet up would be better/ as I said I am not an Eng'r but figure if you drill a whole bunch of holes in the underside of a beam or box tube some strength is lost. Maybe the Mexican sun has got to me too much!!!
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Paul Smith on January 12, 2012, 03:04:39 pm
Quote
The plywood, which by staying wet and holding moisture next to the steel frame, is being replace with 3/16" sheet aluminum in the areas where fixtures like the water pump and the like were screwed to (the screws likely contributing to letting water get to the wood). The aluminum will be mechanically fastent to steel gussets similar to what you see in the photos posted by Barry, which by the way, were not a feature in the original construction of the subframe on our coach.
Aluminum connected to steel. Have you given any thought to galvanic corrosion?
And which one, steel or aluminum, would be corroded?
best, paul
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 12, 2012, 03:21:40 pm
Aluminum connected to steel. Have you given any thought to galvanic corrosion?
And which one, steel or aluminum, would be corroded?
Excellent point! I think the corrosion could be mitigated by using some sort of insulation. Fasteners could still be a problem, however. Teflon washers, maybe?
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Dave Head on January 12, 2012, 03:27:29 pm
A quick call to James or Rance at Xtreme would provide the answers...
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 12, 2012, 03:28:40 pm
I have thought of that Paul... not being enough of a chemist or materials scientist to say with certainty, but I figure that have both materials coated with POR-15 should help with that, but mostly prevent future moisture coming in contact which could provide the electrolyte need for that process to take place. In any case, I feel fairly certain that removing the wet wood sponge from the equation will be beneficial in the long run. I have considerd using some composite material like Starboard in place of the wood, but the 3/16" aluminum will actually let me add about an inch and a quarter of rigid foam insulation below it.
Also, the original configuration had a thin strip of aluminum inserted between the bulkhead joint that wrapped around the edge of the fiberglass reinforced plactic botoom skin. With the addition of road salt and water, perhaps that was a contributing factor to the failure of the Roloks... Interestingly enough, the structure of the top of our coaches is also aluminum, while the sides are steel. My guess is that the persistant presence of moisture to act as an electrolyte would be required to create the ion exchange required to create a galvanic reaction. Don
Aluminum connected to steel. Have you given any thought to galvanic corrosion?
And which one, steel or aluminum, would be corroded?
best, paul
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Kent Speers on January 12, 2012, 03:37:53 pm
Don, my only point was that if the area being repaired is an integral part of the monocoque structure, I would check with engineering at Foretravel to see if you need to tie the glass, insulation, metal framing and bay flooring glass together. If you use the POR 15 on the steel structure, you may not be able to get an adequate bond between the metal, the skin, and the foam. You also need to know the structural rating or density of the foam and the specs of the resin used to attach all of the components. You will need to match the fiberglass specs, flexural strength and compressive strength of the resin to that of the original resins used and total thickness of the skin to insure uniformity of the system.
I'm not trying to be an alarmist and I hope I am wrong and things are very simple for you but if I am correct about the importance of that section of the chassis and you don't get it right, you could have an unrepairable catastrophic chassis failure. I'm just suggesting that you ask the questions before you start putting everything back together. I would start with Mark Harvey and FOT. If it is part of the chassis integrity, it won't be much harder to do it the right way. You will just need to make sure you get the correct components. You have already done most of the hard work.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: John Haygarth on January 12, 2012, 03:38:42 pm
Maybe a thin coating of the paste used in electrical connection of alum and copper wires would provide protection after all the prep work and painting is done in final installation. I also use pure copper sulphate on many connections on the coach-elec/frame/bolts etc and have found so far this works well. Anyway, very interesting reading and thought process by all, and I am sure FOT are reading and stealing some ideas from you all.I personally think Don is right in that keep any moisture away from joints and you have it beat (as best as humanly possible) John
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Paul Smith on January 12, 2012, 03:39:33 pm
Quote
Excellent point! I think the corrosion could be mitigated by using some sort of insulation. Fasteners could still be a problem, however. Teflon washers, maybe?
Teflon could mitigate 99% of the potential problem. But that leaves the most critical part vulnerable: the shank of the bolt. Us anal engineers might try some silicon in the donut made because the hole is a bit larger than the diameter of the bolt....
best, paul
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 12, 2012, 04:48:54 pm
Don, my only point was that if the area being repaired is an integral part of the monocoque structure, I would check with engineering at Foretravel to see if you need to tie the glass, insulation, metal framing and bay flooring glass together. If you use the POR 15 on the steel structure, you may not be able to get an adequate bond between the metal, the skin, and the foam.
I think that the Roloks were there for the express purpose of tying these parts together; why else use them? If the design engineer didn't envision strain on this joint then they would have simply used screws. So if they worked before then they (or something similar) would still work. I do agree that there does need to be a good mechanical bonding between all those bits but I think that fasteners would do the job. In fact, at least from a corrosion standpoint, the POR 15 will help.
However, as far as Don's theory about keeping moisture out of the area... I don't think it's possible to keep moisture out given the environment (wet roads, salt, humidity, sand and gravel, etc.). I think I'd try to mitigate galvanic corrosion as much as possible by insulating the dissimilar metals from each other. I would make sure that the aluminum bits and the steel bits never touch. Whatever you do, do not "bond" aluminum and steel together!
Teflon washers and silicon would be an easy and cheap solution.
But I also agree that a phone call to FOT or MOT would be a good idea.
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: travelite on January 12, 2012, 05:57:59 pm
Craig,
I really like your popsickle stick and paper model idea. I once did a finite element analysis (FEA) of a space-frame touring bus (Prevost like). It used frame elements with a similar section to what Don has found in his Foretravel. The structure was plenty strong but wasn't very stiff. Then I added the fiberglass outer skin and the stiffness was dramatically improved. As you know, the skin adds stiffness and the fasteners used to adhere it add damping. The net effect was a much higher resonant frequency. What you say about girders versus trusses where the strength can be maintained in the direction needed while greatly lightening the structure also rings (so to speak:)). If it's stiff and light, then it resonates at a higher frequency and will be that much more insulated from road inputs. The net effect is better ride and handling and metal fatigue resistance. An alternative to the fiberglass skin is to add diagonals to adjacent corners; i.e., turn all those rectangles into triangles. I'm with everyone on the dissimilar metals idea too, and on the idea that you can't keep water out. This is why if it were me I'd add some diagonal 1.5" members, or some sheetmetal skin (14 gauge), or some gussetting as in Barry's coach, and I'd leave ample room for water to escape. Don, you're doing excellent work. Looks really good. Please forgive me for my eng'r ways. I simply can't resist commenting on a project of this nature. Excellent work and thanks for the photos!
David Brady '02 Blue Bird, Wanderlodge LXi NC
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Paul Smith on January 12, 2012, 06:15:49 pm
Quote
I once did a finite element analysis (FEA) of a space-frame touring bus (Prevost like).
"Finite element analysis" sure brings back memories of my 4 years at UCB. In fact, we just returned from the funeral of Jerry Goudreau who headed a group at LLNL developing FEA code that was used for nonlinear FEA of car crashes - thereby saving auto manufacturers big $$$ (it reduced the number of actual test needed - the code was actually developed for weapons purposes). Professors Bob Taylor and Karl Pister and others were there.
best, paul
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Gary Bouland (RIP) on January 12, 2012, 06:42:20 pm
From all this engineer talk maybe FT needs to let contracts to some Real professionals that have real world experience. :) Gary B
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 12, 2012, 08:12:53 pm
Don... travelite's suggestion of improving stiffness with corner bracing sounds like it might be a great idea. It would add very little weight and cost almost nothing (probably just use scraps from what you've cut for the frame members). Even if you just installed two in opposite corners of each rectangle.
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: PatC on January 13, 2012, 11:16:01 am
Don... travelite's suggestion of improving stiffness with corner bracing sounds like it might be a great idea. It would add very little weight and cost almost nothing (probably just use scraps from what you've cut for the frame members). Even if you just installed two in opposite corners of each rectangle.
Craig
Good point and one that Kenworth failed at. Fishtails are very important in adding strength to to anything your welding on. My old Kenworth had a cracked frame because the Kenworth engineers forgot that stuff. But some good old southern engineering and welding fixed things up.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Paul Smith on January 13, 2012, 11:43:49 am
Quote
Don... travelite's suggestion of improving stiffness with corner bracing sounds like it might be a great idea. It would add very little weight and cost almost nothing (probably just use scraps from what you've cut for the frame members). Even if you just installed two in opposite corners of each rectangle.
If I understand the proposed construction, the aluminum plates would do a great job of increasing lateral shear stiffness parallel to and below the plane of the FT's frame, if attached with enough bolts - say every 6 inches. This also means the length of the aluminum plates should be a least a long in the direction perpendicular to the length of the FT as their length in the long direction of the FT.
This assumes the lower tubular framing is well-connected to the FTs frame above. Such as vertical steel-framed shear panels up to the frame.
best, paul
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Jerry Whiteaker on January 13, 2012, 04:59:47 pm
I think Don is doing the right thing by replacing the rusty metal and doing it properly. I think the fiberglass skins no matter how thin add strength to the structure if properly bonded. If one steps back from the coach and looks at the cargo compartments with the doors open, they are a lot like a cardboard box without any ends, and a box like that folds up flat very easily. The coach does have a rigid metal structure at the ends near the wheels that prevents that from happening. The basement floor is fastened in place at the front and rear with horizontal bolts, and it is held up in the middle with vertical bolts into the bulkheads. I have never checked, but the top of the middle bulkheads are probably bolted to the main cabin floor from above. All the rectangular tanks once in place will add some resistance to the cargo floor moving fore and aft. There is also one fore and aft vertical bulkhead in my coach that forms the back of the battery compartment that should add rigidity to these compartments. One should be able to bond the skins to the metal frame by using epoxy. Epoxy bonds to metal much better than polyester resin will and also will bond to the polyester resin skin. On the top skin one could just place bags of sand to apply pressure until it cures. The bottom skin presents more of a problem and should be done first, but an old or cheap air mattress or two should be able to lift the skin into place and apply enough pressure until it cures. One could paint the tubing and sand to bare metal for the epoxy, or sand blast and coat all the metal with epoxy, maybe a bit of overkill though. Definitely put the foam back in place as it insulates the tanks.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Jerry Whiteaker on January 13, 2012, 05:11:48 pm
I should add something. The foam should also be bonded to the skins. Do a test on a scrap piece to make sure the foam is not dissolved by the uncured epoxy. I don't think epoxy will do that, but uncured polyester resin will dissolve some foams.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Kent Speers on January 13, 2012, 07:10:23 pm
I should add something. The foam should also be bonded to the skins. Do a test on a scrap piece to make sure the foam is not dissolved by the uncured epoxy. I don't think epoxy will do that, but uncured polyester resin will dissolve some foams.
Jerry, you are correct, epoxy should be used and any 100% solids (no solvent) epoxy should not melt the urethane foam. If the skin is polyester, then go ahead and glass with polyester resin but try to use one with similar physical properties. I hope that Foretravel used epoxy resin but maybe not.
Rather than using the POR 15 for rust proofing, a good application of epoxy resin will be more effective and allow for a better bond to the skin and the foam. Remember, epoxy is the coating of choice for coated rebar in bridge construction.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 14, 2012, 04:28:05 pm
Craig et al., Regarding the question of galvanic corrision: I do think I will be able to keep moisture out of this area, but the talk of galvanic corrosion got me thinking about some things, so I did some research... just in case. It appears that the chances for corrosive damage to the steel is almost nil in this configuration. First of all, it is the aluminum that would be the annode in this scenario and the corrosion would be mostly limited to the point of contact. Secondly, since the Aluminum is right next to mild steel in the Galvanic series, there isn't much difference in voltage potential, meaning the galvanic action would be very slow, but in any case would be protective of the steel. Also, the aluminum plate which I plan to use is 3/16" thick and any corrosion will be a long way down the road, even if moisture was persistently present (but I am determined to mkae sure that doesn't happen!).
Finally, if it is likely to be a problem, why would Foretravel use a piece of aluminum trim "inside" the bulkhead joint? You might say so that it would be the sacrificial anode and protect the steel exposed to road salts and the like, and that does make sense to me... but that doesn't explain the substantial 1/8" thick extruded anodized aluminum bottom sill trim which runs in direct contact with the steel frame along both bottom edges of the coach, electrically connected by many screws, as well as all of the bay door trim that holds the struts and weatherstriping, all screwed into the steel framework. Could be that Foretravel missed that one, but I don't think so. I have been too busy working the project to post more, but I will in the near future. In the mean time, I appreciate all the comments- which I take in the spirit in which they have been given. That is to say, out of concern for the wellbeing of one of our beloved Foretravel coaches :D Don
I think that the Roloks were there for the express purpose of tying these parts together; why else use them? If the design engineer didn't envision strain on this joint then they would have simply used screws. So if they worked before then they (or something similar) would still work. I do agree that there does need to be a good mechanical bonding between all those bits but I think that fasteners would do the job. In fact, at least from a corrosion standpoint, the POR 15 will help.
However, as far as Don's theory about keeping moisture out of the area... I don't think it's possible to keep moisture out given the environment (wet roads, salt, humidity, sand and gravel, etc.). I think I'd try to mitigate galvanic corrosion as much as possible by insulating the dissimilar metals from each other. I would make sure that the aluminum bits and the steel bits never touch. Whatever you do, do not "bond" aluminum and steel together!
Teflon washers and silicon would be an easy and cheap solution.
But I also agree that a phone call to FOT or MOT would be a good idea.
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: John Haygarth on January 14, 2012, 04:48:25 pm
Don, good job and interesting topic. Hope you are taking lots of pics for a later-show and tell!! Have you got any of the bulkhead area you had to fix that we can see now? Glad I do not have any of these issues as mine is tight and dry. John H
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on January 14, 2012, 05:50:45 pm
Craig et al., Regarding the question of galvanic corrision: I do think I will be able to keep moisture out of this area, but the talk of galvanic corrosion got me thinking about some things, so I did some research... just in case. It appears that the chances for corrosive damage to the steel is almost nil in this configuration.
I thought aluminum and steel were farther apart but hadn't look at the chart in years. At any rate, the aluminum plate is a much better idea than wood.
Mostly we were all just talking through potential problems and, like engineers everywhere, thinking about the worst case scenario and how to avoid it. You have a good handle on what you're doing so don't mind us. :D
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: travelite on January 14, 2012, 08:41:12 pm
Don, there's another material you might consider instead of 3/16" aluminum panels. Blue Bird (BB) Wanderlodge uses this material on the inside of walls to add structural stiffness. It's a urethane fiberglass composite panel: Coosa Composites, LLC - Manufacture of high-density, fiberglass-reinforced (http://www.coosacomposites.com/) I'm sure other manufacturers make similar products. You won't have the galvanic issues, it doesn't rot, it's light, and it provides structural stiffness. BB bonds it with structural adhesive (Sikaflex 221) and Tek screws.
Craig's right as usual, us engineer types are looking for Penn State Altoona, STURAA, (Surface Transportation and Uniform Relocation Assistance Act), 12 year/500,000 mile toughness. :) The kind of service most motorhomes will never see!
David Brady '02 Blue Bird Wanderlodge LXi NC
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Dwayne on January 15, 2012, 01:46:09 am
What's the deal with STURAA? Just curious...I'm from Altoona. As a boy I used to ice skate on the campus pond. I'm sure they don't allow that these days.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: travelite on January 16, 2012, 10:59:56 am
What's the deal with STURAA? Just curious...I'm from Altoona. As a boy I used to ice skate on the campus pond. I'm sure they don't allow that these days.
Not sure Dwayne, I don't have any involvement. I think Altoona Sturaa testing is going strong, testing buses for anyone who wants to listen, and for municipalities and government agencies that are required to buy buses that pass the testing. There's a lot of info on their website. They do a good job, nothing emerges unscathed, a lot of failures of the suspension control arm pick up joints, as we're describing in this thread.
David Brady '02 Blue Bird, Wanderlodge LXi NC
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 29, 2012, 05:44:28 pm
Hi all, I have been busy grinding rust and prepping for the replacement of some of the metal subframe parts and am close to being ready to tack weld some new pieces in prior to finalizing the welds when my son has the time. Today I have a few questions regarding the welding disconnect list and the location of some of the components... to start with, here is the list that pertains to our coach;
Disconnect the following before welding on completed coaches:
U270/U280/U295 - B-21 - Alternator ground at alternator C-2 - Transmission ground at breakerboard Allison ECU - Under dash / driver's side / both plugs ABS - 3 plugs in brake ECU - Power in / Front axle / Rear axle HWH -All grounds on coach and engine batteries
Here is the list with followed my comments/questions in parenthesis; U270/U280/U295 - B-21 - Alternator ground at alternator (self explanatory) C-2 - Transmission ground at breaker board (Does this refer to the electrical panel just inside the entry door next to the steps? It is difficult to see all of the connector labels because many are obscured by wires, but I don't find a "C-2" upon my initial examination.) Allison ECU - Under dash / driver's side / both plugs (See picture, but my ECU seems to be mounted street side on the rear wall of the cargo compartment, not under the dash; and it has three large plugs- a grey, a black, and a blue. I am wondering if earlier coaches had just two plugs and the under dash location....) ABS - 3 plugs in brake ECU - Power in / Front axle / Rear axle (I believe this refers to the black box mounted to the ceiling of the cargo compartment curb side near the center that says Midland-Grau ABS on it) HWH -All grounds on coach and engine batteries (not sure what this refers to... the ground wires on the outside of the silver HWH Aluminum box just forward of the ABS ECU? As well as the starting battery grounds?
Any insight to the location of these components will be appreciated! Don
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Dave Katsuki on January 29, 2012, 10:52:14 pm
U270/U280/U295 - B-21 - Alternator ground at alternator (self explanatory) C-2 - Transmission ground at breaker board (Does this refer to the electrical panel just inside the entry door next to the steps? It is difficult to see all of the connector labels because many are obscured by wires, but I don't find a "C-2" upon my initial examination.) Allison ECU - Under dash / driver's side / both plugs (See picture, but my ECU seems to be mounted street side on the rear wall of the cargo compartment, not under the dash; and it has three large plugs- a grey, a black, and a blue. I am wondering if earlier coaches had just two plugs and the under dash location....) ABS - 3 plugs in brake ECU - Power in / Front axle / Rear axle (I believe this refers to the black box mounted to the ceiling of the cargo compartment curb side near the center that says Midland-Grau ABS on it) HWH -All grounds on coach and engine batteries (not sure what this refers to... the ground wires on the outside of the silver HWH Aluminum box just forward of the ABS ECU? As well as the starting battery grounds?
Any insight to the location of these components will be appreciated! Don
Don,
Not sure what C-2 is, but also check the main DC distribution board at the front of the street side center compartment (behind the white fiberglass cover).
Our Allison TCU is where yours is, as is the ABS controller. I would just disconnect all cables from all controllers you can reach, and then pull the grounds from the coach and engine batteries. I think you can pull the cables from the HWH controller (silver box on the ceiling of the bay) if you unscrew the cover. I would also disconnect the cable from the HWH control panel in the dash, and if you really want to play it safe, maybe lift the Allison control panel (one with the joystick) and disconnect the cables from it.
I think if your welding ground clip is very close to the work area there shouldn't be much problem with induced current in the wiring. Where you could get into trouble would be if you clipped the welding ground to the frame at the engine and then welded far away.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on January 30, 2012, 01:51:11 pm
Thanks Dave, That is helpful info... I was puzzled by the instructions to disconnect both plugs under the dash when the Allison ECU has three, but perhaps earlier years had just two and were located under the dash. Your thinking about the ground clamp location and disconnecting the various "brains" and battery grounds makes sense to me, so that is how I will proceed. Don
Not sure what C-2 is, but also check the main DC distribution board at the front of the street side center compartment (behind the white fiberglass cover).
Our Allison TCU is where yours is, as is the ABS controller. I would just disconnect all cables from all controllers you can reach, and then pull the grounds from the coach and engine batteries. I think you can pull the cables from the HWH controller (silver box on the ceiling of the bay) if you unscrew the cover. I would also disconnect the cable from the HWH control panel in the dash, and if you really want to play it safe, maybe lift the Allison control panel (one with the joystick) and disconnect the cables from it.
I think if your welding ground clip is very close to the work area there shouldn't be much problem with induced current in the wiring. Where you could get into trouble would be if you clipped the welding ground to the frame at the engine and then welded far away.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Chuck Pearson on February 09, 2012, 10:56:11 am
Don,
I was thinking about your project, and installing the aluminum panels. I'd recommend the use of 3M VHB tape. There are many varieties of it, some costing several hundred dollars a roll, but the stuff you can buy at any auto paint place is incredibly strong. The 1/2" X 20' long drive rack on my cnc router is attached with this stuff, no bolts. I had to remove a section of it and it took a 3' crowbar and some bent metal to do it. This drive rack engages pinion gears that hurtle the gantry and spindle, some 300 lbs of it, back and forth at high speeds, sometimes changing direction several times a second. VHB tape is what semi trailers are put together with, the skins and framing, skyscraper facades, aircraft. No muss, no fuss, no screws, permanent and it insulates the alum from steel.
I was thinking about your project, and installing the aluminum panels. I'd recommend the use of 3M VHB tape. There are many varieties of it, some costing several hundred dollars a roll, but the stuff you can buy at any auto paint place is incredibly strong. The 1/2" X 20' long drive rack on my cnc router is attached with this stuff, no bolts. I had to remove a section of it and it took a 3' crowbar and some bent metal to do it. This drive rack engages pinion gears that hurtle the gantry and spindle, some 300 lbs of it, back and forth at high speeds, sometimes changing direction several times a second. VHB tape is what semi trailers are put together with, the skins and framing, skyscraper facades, aircraft. No muss, no fuss, no screws, permanent and it insulates the alum from steel.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on February 24, 2012, 05:32:28 pm
I have been making some progress- slow progress, but progress nonetheless! I thought I would post a few some pictures for your entertainment... some are from earlier in the process, the latest from today. Light at the end of the tunnel? You decide. For me, I am seeing it! Don
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Pierce & Gaylie Stewart on February 24, 2012, 09:56:55 pm
Looks like you are just about at the end of the tunnel. Nice work and clear photos! I close my eyes when I look at my compartments and bulkheads now.
Hip, Hip
Pierce
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Benjie Zeller on February 24, 2012, 09:57:16 pm
Awesome! So when should I schedule to drop mine off? :P
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: John Haygarth on February 24, 2012, 10:12:09 pm
Don, congratulations on a first class job you are doing. I have been in steel fabrication for many years earlier on and that is a nice job. Please make a file of the job as you proceeded and with photos as you whent and let barry include it in the Mods section of his FT website as that would be great info for future people (should they ever consider doing what you have almost done). You may get a call from FT to work in their shop!!!! John haygarth
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on February 25, 2012, 12:43:59 am
Great job... breathtaking, in fact. I'm glad you're doing it and documenting it so I know that it can be done. I don't think I would have even considered it before seeing what you've done.
Thanks, Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on February 25, 2012, 01:23:43 am
Thanks for the nice comments guys... every little bit of encouragement helps! I do plan on organizing my photos with some commentarty when I get the chance and put it in an album of some kind. I hope that it will be of use to those who find themselves in similar situations. This forum has been a source of great information and inspiration! Thanks to all who have generously shared their knowledge. I am looking forward to contributing a few tidbits of hardwon wisdom myself... More later! Good night all! Don :D
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Merle Hench on February 25, 2012, 08:21:38 pm
Looks excellent Don. Very nice work. ^.^d
It feels good when you can see the plan coming together.
Steve
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on February 26, 2012, 01:05:26 am
Thanks Steve! :D It sure does feel good to be in the phase of the project where the progress is more noticeable, especially as opposed to the demolition phase when you aren't even sure how far to take it. At some point it felt like I was on a trajectory to demo the entire basement, since I originally was just going to do the standard bulkhead fix. Now I am glad I explored further because now I know the coach will be strong down there, not to mention all that I have learned while doing this project. I will have much to write about the subject, but that will have to wait awhile... Don P.S.here are a few more pics of some of today's progress. The previous set was the street side and this is the curb side, except the last pic which is an action shot ;D . On this side, I was able to leave the outside angle iron in place and I cut out the outermost 1&1/2" longitudinal square tube which was originally 16 gauge and thinned out by contact with the soaked plywood. I replaced it with new 13 gauge. That is what is in the pictures. I welded a nut to the square tubing for the outermost bolt on both sides. This nut is inside the outermost square tube on both sides. I am also using caged weld nuts where clearance allows on all the rest of the bulkhead bolts. There are a couple of places where I welded unistrut clip nuts. This will allow removal and replacement of all of the bulkhead bolts in the future without needing a wrench on the back side or a hole in the fiberglass to access them. The caged weld nuts are nice because they are easier to get started without risking cross threading.
It feels good when you can see the plan coming together.
Steve
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on March 28, 2012, 01:05:23 pm
Still progressing... Slowly, but surely! Here is a few more current pics...
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on March 28, 2012, 01:12:22 pm
I am thinking that my little $99 wire-feed welder I bought from Harbor Freight might not be up to that kind of job.
Frankly, until I saw what you're doing, I would not have believed that it would be possible to completely rebuild these portions of a motorhome. I wonder if the Unicoach/Unihome construction methods are the only ones that you could do this sort of work on.
As usual, awesome! Just awesome!!!
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wolfe10 on March 28, 2012, 01:20:09 pm
Beautiful work-- almost a shame to cover it up.
Brett
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Peter & Beth on March 28, 2012, 01:27:37 pm
Dang!!! That's A+ work as my dear, departed father-in-law would say, as a RIP high school shop teacher, now in heaven doing the greatest camping trip of all. Peter
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Steve & Kathy B on March 28, 2012, 02:34:31 pm
Wow. You effort is much appreciated by an ex shipfitter and welder :)
Now, that I see how you do this all I need is a welder, someplace to do it, about $10,000 more in tools, a couple of lifts.... never mind - I couldn't do that!
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on March 28, 2012, 04:59:26 pm
Thanks Guys! Brett, I briefly considered a transparent cover.... not for vanities sake, just so you could see if there was any moisture and rust creeping back in. Unfortuantely, all such material that I know of is somewhat brittle, and there for not suitable. If there was such a material one could use for the bottom skin, structural function not widthstanding, it would be a sure way to know what was going on down there! Don
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Raymond Jordan on March 28, 2012, 05:06:38 pm
Hi Don, I agree with Brett. That work is just to nice to cover. Thanks for letting us follow along. Raymond
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Peter & Beth on March 28, 2012, 05:35:51 pm
Thanks Guys! Brett, I briefly considered a transparent cover.... not for vanities sake, just so you could see if there was any moisture and rust creeping back in. Unfortuantely, all such material that I know of is somewhat brittle, and there for not suitable. If there was such a material one could use for the bottom skin, structural function not widthstanding, it would be a sure way to know what was going on down there! Don
Don, All it takes is lots of money. I'm sure there are automotive aftermarket companies that bullet-proof cars (mostly Suburbans, Rolls Royce, Cadillac and the like) that utilize advanced materials you can see through that can withstand the rigors.
Oh Yeah!
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Michelle on March 28, 2012, 05:45:01 pm
Thanks Guys! Brett, I briefly considered a transparent cover.... not for vanities sake, just so you could see if there was any moisture and rust creeping back in. Unfortuantely, all such material that I know of is somewhat brittle, and there for not suitable. If there was such a material one could use for the bottom skin, structural function not widthstanding, it would be a sure way to know what was going on down there!
You mean Transparent Aluminum?
Star Trek really IS a good guide to the future... Scientists now able to produce (http://www.dailymail.co.uk/sciencetech/article-2088257/Star-Trek-really-IS-good-guide-future--Scientists-able-produce-transparent-aluminium.html?ITO=1490)
Live long and prosper, Don!
Michelle
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: ARdave on March 28, 2012, 11:54:12 pm
What about inspection plates such as are on airplanes? Well at least 40 years or so ago when I was a student pilot. From other posts that might not be necessary, as the bulkhead issue does not seem to be universal, as many owners have never experienced problems.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wolfe10 on March 29, 2012, 12:13:24 am
I agree, no reason to ever have to go back and inspect the bulkhead UNLESS he decide to let a water leak in the wet bay go unchecked for a long time or drive it through salt and then park it for months at a time. Since he will not do those kind of things, the only reason I hate to see him cover it up is the work of art he is creating.
Very rare to see bulkhead failure without long-term causes, and then they fail one bolt at a time. Just not a big deal unless just totally ignored.
Brett
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Pierce & Gaylie Stewart on March 29, 2012, 10:38:03 am
You could just drill a 3/4" inch hole between the existing bolts and then use a digital inspection camera probe to take a look inside. They are available stand alone or probes that plug into a USB port on a Mac or PC laptop. They have 7 to 10MM diameter heads with LEDs so they supply their own light for the job. See at: inspection camera digital | eBay (http://www.ebay.com/sch/i.html?_from=R40&_trksid=p5197.m570.l1313&_nkw=inspection+camera+digital&_sacat=See-All-Categories)
Not all will work on all three computer operating systems so check the fine print before ordering. Mine only cost $50 delivered and plugs into my Mac laptop.
Naturally, you would want to have a plug for the hole. I almost have my service pit done so will be installing a new set of Hollo-Bolts between the OEM bolts. Will photo the job and post in the next couple of months.
Pierce
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on March 29, 2012, 11:55:18 am
Transparent Aluminum, that's the ticket! So far, I haven't been able to source transparent aluminum in large enough sheets, but I will keep looking... LOL! Seriously though, I am not worried about it because I know that I will be vigilant about water leaks and moisture intrusion of any kind. Every penetration into the framework will be be sealed and all seams caulked with the best materials available. And then there is a fact that all the steel down there, including the sheet metal bulkhead will be coated with Por-15. The idea that it would be nice to put a transparent skin over it was just one of many that I briefly considered and discarded as I stared down at the exposed rusty metal in front of me, too tired after a long day of working to move and start putting everything away... Pierce, I do have an inspection Camera and found it very useful when I was trying to route the washer drain pan tubing down alongside the water heater... Don
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: John Haygarth on March 29, 2012, 12:35:01 pm
Don, great work and I was just wondering if you have considered using cold galvanizing paint for the steel coating or a 2 part commercial epoxy paint that is used for bridge construction? John H
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on March 29, 2012, 12:49:28 pm
Nope, not familiar with those... Anyway, I have already invested a fair amount of money in the Por-15 product line. I feel confident that it will do the job as well as it can be done. I did a few test pieces and it has performed well being left out in the rain and elements over the course of a few months. Don
Don, great work and I was just wondering if you have considered using cold galvanizing paint for the steel coating or a 2 part commercial epoxy paint that is used for bridge construction? John H
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on March 29, 2012, 12:59:03 pm
Don's work is extensive and meticulous but what sorts of options are there for those of us who have some rust (and maybe a little scale) but not enough to warrant a complete rebuild? There are some products (mostly with tannin) that claim to "convert" rust and are paintable; I used one on a wheelchair lift before my knee surgery and it seemed to be very effective. I simply wire-brushed the rusty spots, applied the "converter" which served as a primer when dry and then painted the entire assembly with black rustoleum.
I have planned to do the same thing with the steel support structure around the generator on the U225. It's rusty with some scale but nothing that looks serious enough to require re-welding. Even though I'd re-weld it at the drop of a hat if I thought it was necessary; mostly because I love to weld... especially with my new auto-darkening helmet and the wire-feed. ;D
Anyone have any alternative suggestions?
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Pierce & Gaylie Stewart on March 29, 2012, 01:34:17 pm
Craig,
Those auto darkening helmets are great aren't they? How can you go wrong for $50 or less?
Would suggest drilling a hole in any suspect tubing and injecting several ounces of boiled linseed oil in each large rectangular/square tube, less in the small ones. It will climb up the walls and coat all interior surfaces. Stay away from the new synthetics as they don't work as well in the real world as their claims would have you believe.
Pierce
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on March 29, 2012, 02:21:23 pm
I added boiled linseed oil to some tubing and it does wick its way around... However, I would do any welding you want to do first, or it can create a bit of excitement! Don't ask me how I know that ;D Don
Those auto darkening helmets are great aren't they? How can you go wrong for $50 or less?
Would suggest drilling a hole in any suspect tubing and injecting several ounces of boiled linseed oil in each large rectangular/square tube, less in the small ones. It will climb up the walls and coat all interior surfaces. Stay away from the new synthetics as they don't work as well in the real world as their claims would have you believe.
Pierce
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: wa_desert_rat on March 29, 2012, 03:25:52 pm
I added boiled linseed oil to some tubing and it does wick its way around... However, I would do any welding you want to do first, or it can create a bit of excitement! Don't ask me how I know that ;D
Don... I scared the cat by bursting out laughing at your comment. LOL. I'll keep it in mind.
Pierce... yes those helmets are great. One of my problems stick welding was that by the time I got my helmet down my hand had jerked and moved. The auto-dark feature makes it a piece of cake. And they look sooooooo cool!!!
I think that, unless someone comes up with a super idea, I'll stick with the "brush scale off, hit with the coverter and paint" method that worked for me before.
I have to find something to weld on though... now. :P
Craig
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on April 06, 2012, 01:26:51 am
A couple of pics... fabricated some of the aluminum shelves with Angle Iron supports welded to the framing. The 3/16"X1.5" angle iron, along with the gussets, also beefs up the slightly thinned out original frame members creating a very strong rectangle. That will run from one edge go the utility compartment (front to back on both street side and curb side) to the other when it is finished ::)
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Chuck Pearson on April 07, 2012, 12:00:23 pm
Hmmm. I'd rethink screwing that aluminum directly to steel, would insulate it somehow. If you do, don't make the mistake of using stainless screws, galvanized is far less reactive. Personally, I would tape it down with VHB or bed it in a caulk type adhesive with no fasteners. Years of owning an alloy fab shop, building alloy boats, things like this give me pause. That said, it's not a huge deal and you've really done a fine job of reconstruction.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on April 07, 2012, 08:26:25 pm
Thanks for the compliment Chuck... I have given it some thought and research... while I wouldn't want to do this in a boat or marine environment, I don't believe that in my application it will be an issue in the life span of our Foretravel. A couple of points, the aluminum and the steel are both 3/16" thick, will be coated with Por-15 and the threads with Loctite (These plates are not designed to be easily removable). Acouple of the aluminum plates are warped in one direction (I got them in the remanants pile: :D ), so I don't think the tape is a viable option for those. One thing I know, I am going to war against water intrusion into this area! Also, compared to the plywood sponges that were in this area before the rebuild, the aluminum plates will be less destructive to the steel framework. Another point that I mentioned previously in this thread is that Foretravel frequently joins Aluminum to steel in the coach, i.e., the auminum eztrusion that forms the sill along the bottom. Not to mention the aluminum superstructure joined to the steel side wall framing, and certainly even the Alcoa wheels held to the steel hubs by steel studs and nuts. One other small point, I will have rigid styrofoam insulation below the aluminum plates that should provide a bit more R-Value than the 1.5" of plywood previously there. I am contemplating using a continuos sheet of 18gage stainless steel sheet in place of the FRP on the bottom of the compartment, or perhaps a much thinner gage (say 24) over FRP. I notice that many of the newer Foretravels and other hi-line coaches using stainless in that area these days... bad idea? I don't know if they are using FRP under the stainless, but I suspect so, and that the Stainless Steel is just a thin decoritive finish... well still a ways to go, back to work!
Hmmm. I'd rethink screwing that aluminum directly to steel, would insulate it somehow. If you do, don't make the mistake of using stainless screws, galvanized is far less reactive. Personally, I would tape it down with VHB or bed it in a caulk type adhesive with no fasteners. Years of owning an alloy fab shop, building alloy boats, things like this give me pause. That said, it's not a huge deal and you've really done a fine job of reconstruction.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Bob Thomas on April 10, 2012, 11:41:52 pm
Don, et.al., Thank you all for a very informational and inspirational thread. I enjoy following this. I just hope I don't need this information. But I now feel compelled to do a really careful inspection.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on May 06, 2012, 06:24:17 pm
Your welcome! I hope your inspection reveals nothing but a sound bulkhead joint... Sorry for the delay in my reply, I guess I missed this post somehow. Don
Don, et.al., Thank you all for a very informational and inspirational thread. I enjoy following this. I just hope I don't need this information. But I now feel compelled to do a really careful inspection.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on May 06, 2012, 06:52:59 pm
The actual reconstruction is now close to finished and I thought I would post picture or two to update this thread (because I know that there are many out there holding their breath waiting for the next installment ;D Almost ready to do the POR-15 coating... just some clean up from underneath to do and then I will open up the bulkhead joint so I can treat the space between. I will have more to say about how that is accomplished because a compromised bulkhead joint also causes some collateral damage similar to what is described in the "Calamity Jane strikes again" thread, and I have plans to reinforce the framing that attaches the suspension carriage to the bulkhead angle iron. Here are a few before and after pictures of the framing work I have done. As I said, it is mostly complete now. Unfortunately, I don't have any equivalent single before picture because I didn't set out to rebuild the whole thing from the start... just gradually came to the awareness that I wouldn't feel happy about the integrity of the utility compartment framing without going all the way.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: John Cooper on May 15, 2012, 04:08:42 pm
As is so typical you start out to replace a missing screw and end up rebuilding the whole coach! I too, can attest to the downside of water soaked wood against steel. Lucky for me my repairs are quite minor compared to yours. I ended up using wood hardener to permanently seal the wood that I replaced.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on May 15, 2012, 07:51:30 pm
LOL! Or maybe COL... wondering if you made that analogy from just reading this thread or if you were referencing my latest hijinks in the thread about the Fiberglass fuel tank cover on Unicoach (http://www.foreforums.com/index.php?topic=15375.msg93161#msg93161) covers on the unicoaches where I discovered more basement mysteries... I guess I should have posted that stuff in this thread since it really is just a continuation of same, though so far no welding has been involved! Don
As is so typical you start out to replace a missing screw and end up rebuilding the whole coach! I too, can attest to the downside of water soaked wood against steel. Lucky for me my repairs are quite minor compared to yours. I ended up using wood hardener to permanently seal the wood that I replaced.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: John Cooper on May 15, 2012, 10:41:11 pm
Don,
Personal experience with "old" stuff, especially my Prowler TT (the reason I now own a Foretravel), and the mention of no pictures in the beginning. I have not seen your thread yet.
Title: Re: Chassis construction photos from Don and welding on your FT
Post by: Don & Tys on May 17, 2012, 06:53:56 pm
Such has been my experience with old stuff as well. Irrationally, I had hoped this one would be different just his once! :o
Personal experience with "old" stuff, especially my Prowler TT (the reason I now own a Foretravel), and the mention of no pictures in the beginning. I have not seen your thread yet.