Re: Welding tubes on AMC20 - question
I'll jump in on this one. I am still of the opinion that it is not good to weld your tubes to the housing. OzarkJeep and I went back and forth on this a little bit, and I was going to build a finite element model on my computer to see what kind of stresses develop, but I haven't had time to do it yet[img]/wwwthreads_images/icons/frown.gif[/img](Ozark, if you are reading this, I haven't forgotten). Ozark was going to take a 10-bolt and weld it and do some abuse testing, but I haven't heard the results yet. The reason I don't think that it is a good idea, is because of the differences in the materials between the housing and the tube. The tube is probably not a real high alloy steel, and the housing is probably a maleable cast. The housing is a lot more rigid that the tube, and has to be to keep gears in tolerance. Even though the housing is maleable cast, it is still more brittle than the tube. With the tubes pressed into the housing and plug welded, it allows the tube to flex, and even move a little in the housing (we are talking maybe less than a thousanth of an inch, nothing big). Also, by welding on the top and bottom of the tube you create what is called a stress concentration in the tube. A stress concentration is a spot of weakness. Think about taking a paper clip, and putting it in a pair of side cuts and just denting the clip. When you bend this paper clip it will fail at the notch just created. A weld can have the same effect. The problem will be more pronounced in the welds on the bottom. A good way to illustrate this is with a block eraser (like the pink ones used in grade school). Draw a box on the top and bottom of the eraser and then bend it. You will notice that one box gets shorter and the other gets longer. The longer box would be on the bottom of the axle, which means that in essence your axle tubes actually stretch a little on the bottom and compress on the top. The weld against the housing will limit some of this bending and transfer the load into the housing. This would be fine, but the housing is designed to not bend. Plus, the cast does not behave as well when it is loaded in tension. With the tubes welded either the housing or the tube will fail prematurely, even if it is a series of short welds. I would bet that the housing will crack around the weld. If you are looking for a stronger axle, I would recommend a truss. Just my two cents, actually as long as this was, I guess it is probably closer to $2.50[img]/wwwthreads_images/icons/wink.gif[/img].
Cage Up, Wheels Down
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