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Unread 20-01-2006, 16:22
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Peter Matteson Peter Matteson is offline
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FRC #0177 (Bobcat Robotics)
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Re: bolting square aluminum without crushing walls

Quote:
Originally Posted by Max Lobovsky
Please, don't spare the explanation. I'm interested. I assumed if you sufficiently supported the tube or used washers, bolting through would be fine.
Short version:
If properly supported no it is not a problem. The issue is the compressive stress on the box makes it a weak point and the probable location of a structural failure. This combined with overtorqued fasteners, because even if you calculate the proper bolting torque for the necessary pre-load people rarely use a torque wrench to assemble this type of setup. Also the grade 8 bolts we usually use on the robots are stronger than the box aluminum. In theory you want the bolt to fail before the box deforms so that you don't do any structural dammage to the frame. I hope that helps.