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Unread 22-12-2015, 08:54
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Ty Tremblay Ty Tremblay is offline
Robotics Engineer
FRC #0319 (Big Bad Bob)
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Re: 610's Preseason Drive

Quote:
Originally Posted by GeeTwo View Post
That's what's holding the two sides of the robot together. They aren't using any gussets or other brackets that attach to both the cross-tubing and the wheel tubes*. If they used nut & bolt at each end, the cross tubing would slide right off of the milled piece linked from post #3.

Edit:
* except the belly pan.
If they used a nut and bolt on each end, yeah. But that wouldn't make much sense...

My question was why not modify the milled piece such that machine screws can be used.

Quote:
Originally Posted by Nate Laverdure View Post
This is clearer when you consider the 2013 design. There was no machined inner block** that could have accepted any shorter fasteners. In that design, you use the whole end face of the ladder bar as a bearing surface to take any bending loads.

The ladder bar is a preloaded spacer. Because the threaded rod is so long, the spring rate is very low, which makes it possible to maintain big preloads on the rod, and therefore big clamping forces on the assembly.

**The opposite approach is taken in the 221 SimpleTube chassis... they use machined inner blocks to connect the ladder bars to the chassis rails.
Thanks. I understand how it works.

I'm asking why that method was chosen mostly because there IS an inner block in this chassis that could have been designed to accept shorter fasteners. Granted, would have taken an additional setup or two in the mill.
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Last edited by Ty Tremblay : 22-12-2015 at 09:06.