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Re: pic: 2851 2014 off-season design: Bottom view with electronics
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#2
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
I'll see if our guys can post a CAD. We have two center cross members about where yours are, with the piano hinges attached there by rivets. Our electronics hinges down from the center cross members, accessible from the bottom, with the rivet nuts on the extreme ends of the chassis to hold the hinges closed. We will have a shear plate welded between the two center cross members, and we'll mount our compressor on that. We are also putting small gussets at the corners of the chassis for shear (I think that's more of a concern than torsional rigidity with regards to a belly pan). Also the battery will go in a "cage" and that cage will be mounted in a location tbd depending on access and the mechanisms above the electronics. Our chassis is welded tubular 1x2 for the most part. It's our first time with a west-coast style drive...
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#3
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
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#4
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
It looks like you have a sheet metal frame. We do not have sheet metal sponsors, so we've never ventured into that scary place. My first concern for you would be parallelogramming (shear) for the chassis when you get a violent hit on the corner. The welded tubular frame does pretty well against those corner hits, but it still definitely needs a shear plate. Other teams would speak with more authority on how to achieve the same thing with sheet metal, but I would start with lots of rivets on your shear plate or gussets. I see you have basically created box cross sections for the sides and end members. That's great; you just need to figure out how to connect them and resist shear.
As for the advantages: the biggest advantage of tubular is simplicity. From my point of view, the easiest chassis is an off-the-shelf chassis, the next easiest is one the sorta off the shelf (like ours: we're using versablocks), the next is a custom one using plates or tubes (what we usually do), and the most difficult is sheet metal. Just so you know, we routinely find 1/8" wall 1" square tubing bending dramatically because of hits to our front and rear bumpers . |
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#5
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
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I do have a piece in the center on the bottom of the chassis to prevent shear, and the shooter bolted on top should help some. You don't think that would be enough? Also, the reason I did sheet metal was because I wanted to be able to do this with minimal hand fabrication at our build site. Another goal was for it to be easy to build, and as soon as we get the parts back from Accu-Rite, we can basically just assemble it. |
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#6
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
That's a nice looking chassis. I don't have the experience with sheet metal to say whether it's enough or not, but i like your T-shaped bottom plate, and if that's a piece of lexan on top, it could help a lot too. Box structures are good, and box structures made out of box structures are really good. Nice chassis! Can't see what you're doing for gearboxes...
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
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#8
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
![]() ![]() Here is a simple CAD of our West Coast Chassis with the drop down e-plates cfair was talking about. We have two e-plates on this robot, and both are able to be dropped. However, in this CAD I only dropped down one to show what one e-plate would look like when it is not dropped. wyrzykowskij1 also asked what the dimensions of this robot are. Currently we are at 29.5 inches x 26.25 inches. |
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#9
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
That chassis looks really good. Do you think the corner supports on the inside are enough to counteract forces from corner hits and shear? Also, What made you go with (almost) square?
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#10
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
Is it strong enough? Time will tell. The chassis is inspired by (blatant ripoff of) team 3256, the warriorborgs. That's where we got the idea for the upper level that supports bumpers and provides an interface to the game-piece manipulator. That upper level doesn't have any gussets, but it's welded, and we expect our game-specific device (we call it an EVOM) to provide some stiffness once it's installed. We have 0.75" square cross members in our pocket for the upper center (same function the AM churros provided on one of their chassis) depending on what happens with the EVOM. We are also looking forward to much nicer bumper fasteners: quick-release pins!
If it's going to fail, I would expect the welds for the corner verticals to go first. |
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#11
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
I see. There is definitely a lot of room in this design for peripheral mechanisms, and I would imagine this could be converted to other shapes if needed depending on the game. I like it.
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#12
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Re: pic: 2851 2014 off-season design: Bottom view with electronics
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