Lola53
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1953 Westfield Westerner
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Post by Lola53 on Apr 6, 2016 23:57:12 GMT -8
While repairing Lola’s sides, I had the opportunity to inspect the metal substructure (frame) where the sides connect to the metal “outrigger” supports. Not surprisingly, after 60+ years of use, about half of the outriggers have some damage. In most cases the damage consists of flattened "L" angles – normally 90°, now something like 170°. The worst damage is to the angle behind the right wheel, where the angle is twisted and pulled forward about 3 inches – most likely from a blown tire. My plan is to ‘sister” in four new lateral members next to the four existing supports. Instead of angles, I’ve tentatively selected 1 1/2″ x 2″ rectangular 14 gauge steel tubing (although Aluminum tubing is still an option). I plan on bolting the new laterals to the “C” channels instead of welding - bolting will facilitate future repairs, if necessary. Depending on the extent of each outriggers damage, I may selectively cut it off outside the “C” channel, leaving the welded portion between the “C” channels. below is an illustration showing left rear frame. Details and more illustrations on Lola's blog: www.kivas.com/wp/2016/04/07/frame-repair-ideas/. Please let me know what you think. Mark  |
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Post by danrhodes on Apr 7, 2016 6:00:48 GMT -8
I think you better have a good isolation barrier between the steel and aluminum to prevent galvanic corrosion. I would still with steel angle iron... It worked fine for decades.
Are you bolting to save money on a welder?
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Lola53
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1953 Westfield Westerner
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Post by Lola53 on Apr 7, 2016 7:00:09 GMT -8
I think you better have a good isolation barrier between the steel and aluminum to prevent galvanic corrosion. I would still with steel angle iron... It worked fine for decades. Are you bolting to save money on a welder? Hello Dan, Good point about the galvanic corrosion. Probably not a big issue in Northern California where it is fairlly dry, but certainly a design factor. Only advantage of AL would be a little weight saving. Steel members will add approximately 50 pounds. AL would save about 40%. So far leaning toward steel - strong and relatively inexpensive. No to welder cost savings. I have a Lincoln 120V wire feed welder and a Miller Big D2 (3 cylinder Perkins diesel welder / generator). Since the welded angles between the longitudinal channels are not going to be removed, the frame should maintain its rigidity. New members are to help carry the weight of the walls and bolted joint's seem like a good option. Easy to install. Easy to remove if future damage occurs. However welding is still an option. What are your concerns with bolted joints in this application? Thanks for the thoughts. I approciate the comments. Want to make sure I have not missed something critical. Mark |
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Post by danrhodes on Apr 7, 2016 7:49:08 GMT -8
You seem to know your metal, so I will defer to your knowledge. I know the c-channel in the Westerner is not particularly robust, so drilling just gives me a gut negative reaction. I'm sure you've gone over every inch of the frame for warping or cracks, but it does make some sense to bolt it if you may want to make an adjustment layer.
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Post by vintagebruce on Apr 7, 2016 11:57:14 GMT -8
I am wondering if something as basic as a strip of old inner tube could be layered between the two pieces of dissimilar metal at the bolting points. Seems like I have seen something like this done while working in both Yemen and Indonesia.
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Lola53
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1953 Westfield Westerner
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Post by Lola53 on Apr 7, 2016 18:05:31 GMT -8
I am wondering if something as basic as a strip of old inner tube could be layered between the two pieces of dissimilar metal at the bolting points. Seems like I have seen something like this done while working in both Yemen and Indonesia. An insulator might make a difference, but the bolt itself would need to be insulated from the metals as well. Galvanic reactions are most problematic in wet environments, especially when salt and chlorine are present (like by the ocean). I don't think it is a real concern in the dry climate of CA's Central Valley. Based on the Hehr window screws I recently removed while fixing several broken glass panes, it does not look like an issue. The steel fasteners were corroded, rusted, but there was not any evidence of galvanic corrosion between the steel and aluminum. If serious galvanic reactions were occurring the aluminum would be eaten away - not the case with Lola's windows. Could the rubber have been placed in the joint to reduce squeeks? Mark |
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Lola53
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1953 Westfield Westerner
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Post by Lola53 on Apr 7, 2016 19:06:31 GMT -8
You seem to know your metal, so I will defer to your knowledge. I know the c-channel in the Westerner is not particularly robust, so drilling just gives me a gut negative reaction. I'm sure you've gone over every inch of the frame for warping or cracks, but it does make some sense to bolt it if you may want to make an adjustment layer. I have not had the opportunity to survey the frame in detail, but the casual inspections so far have not identified any significant issues. I've viewed Teachndad's excellent pictures and posts about his Westerner's frame problems and do not see nearly the problems he had. A thorough inspection is on the list of things to do - a long list. Bolt holes in the frame should not be a problem. As long as the bolts are properly torqued, the joints will withstand the loads. Just for fun, I ran a Finite Element Analysis on a 6 ft "C" channel using the dimensions from the smallest / thinnest 3" C Channel Reyerson lists. I placed 1/4" and 3/8" holes along the channel and loaded it with 500 lb distributed along the channel. One end was fixed and the channel constrained so that it could not twist. This would be analogous to a 1,000 lb 12 foot beam supported in the center (like a teeter totter). As illustrated below, the stress around the holes in the highest stress area (center of the teeter totter) is not significantly higher than in the surrounding region. As shown in the middle picture, there may be localized stress around the hole edges reaching close to yield levels, but in reality, stress in this area would be relieved by localized yielding and would not result in failure. Note: the displacements shown in the pictures are 10X actual.   Mark |
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Post by danrhodes on Apr 7, 2016 19:19:52 GMT -8
Just for fun, I ran a Finite Element Analysis on a 6 ft "C" channel using the dimensions from the smallest / thinnest 3" C Channel Reyerson lists. I placed 1/4" and 3/8" holes along the channel and loaded it with 500 lb distributed along the channel. One end was fixed and the channel constrained so that it could not twist. This would be analogous to a 1,000 lb 12 foot beam supported in the center (like a teeter totter). Mark That does sound like fun. :eek: Seriously, very interesting stuff. Do you have a feel for what small holes in the vertical portion of a channel do? These are often added for electrical grounds, wiring paths or safety chains. |
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Lola53
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1953 Westfield Westerner
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Post by Lola53 on Apr 7, 2016 20:07:31 GMT -8
Just for fun, I ran a Finite Element Analysis on a 6 ft "C" channel using the dimensions from the smallest / thinnest 3" C Channel Reyerson lists. I placed 1/4" and 3/8" holes along the channel and loaded it with 500 lb distributed along the channel. One end was fixed and the channel constrained so that it could not twist. This would be analogous to a 1,000 lb 12 foot beam supported in the center (like a teeter totter). Mark That does sound like fun. :eek: Seriously, very interesting stuff. Do you have a feel for what small holes in the vertical portion of a channel do? These are often added for electrical grounds, wiring paths or safety chains. As shown in the illustration, the vertical sections have very low stress (dark blue) and a small round hole will not have any negative effects on the beam. In fact, you could put fairly substantial round holes along the vertical section to reduce weight without any problems. I'll add holes in the vertical region of the model and rerun the analysis for you next week. The problem to watch out for is areas where stress concentrations can occur - such as holes with square corners, notches, or distinct joint connections (such as where the tongue "C" channel is welded to the longitudinal "C" channel). Fatigue loading, which can be fairly small in magnitude, can result in crack formation at the stress concentration. Depending on loading condtitions, the cracks can grow and eventually result in structural failure. Mark |
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Post by danrhodes on Apr 7, 2016 20:15:15 GMT -8
Thanks mark... Just that is enough to alleviate my concerns.
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Lola53
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1953 Westfield Westerner
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Post by Lola53 on Apr 7, 2016 20:25:49 GMT -8
Thanks mark... Just that is enough to alleviate my concerns. Glad to help. Thanks again for your comments. Mark |
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Post by danrhodes on Apr 7, 2016 20:43:12 GMT -8
Thanks mark... Just that is enough to alleviate my concerns. Glad to help. Thanks again for your comments. Mark My ME co-worker enjoyed your analysis. |
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Lola53
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Post by Lola53 on Apr 7, 2016 20:51:19 GMT -8
My ME co-worker enjoyed your analysis. Takes one to know one. |
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Post by Teachndad on Apr 9, 2016 18:23:46 GMT -8
Hi Friends,
What a cool thread. I like the mix of modern technology and skills, combined and implemented with the restoration of old.
Great stuff, Mark!
keep it comin.
Rod
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