FRC Belly Pan CAD Tutorial


After learning how to CAD a belly pan a few years ago I felt there was a need for more information on how to CAD a belly pan as for me it was one of the hardest parts to figure out how to CAD efficiently. With this I felt there was a need for a tutorial that walks through the entire process. There were numerous other tutorials that inspired me to do this namely @PatrickW and @gurish_sharma . Although I felt that to teach the rest of my team the steps we take in designing our belly pans a more concise and consolidated tutorial was needed and felt the rest of the FRC community could benefit as well.
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Nice tutorial. One thing I would recommend is to just leave the material underneath any components intact (don’t cut any diamond) unless you are reallllllly close on weight. Save some time and wear on your cutter. Cables aren’t going to be routed underneath components anyways.

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Awesome tutorial! Certainly more complete than mine.

Here is my belly pan tutorial for reference for people who want to see something similar in Solidworks.

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wow! thanks! you have done the frc community a great service

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Hmm not a bad idea makes CAD and Machining take a little less time with almost negligible weight penalty and helps with mounting things like spark max with tape. Might thinking about doing this next season or well whenever the next new game is.

Nice technique. But, we’ve also gone with a solid belly pan because then we can add any additional mounting holes we need in it. IIRC .09 aluminum is about 1.3 lbs/sq ft, so this might save about 5lbs. Which if you need it, I guess this is a decent place to find it, but our initial CAD is probably not good enough that we would know exactly how our pan is going to need to turn out. YMMV.

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This year we actually did two sheets for our pan. The first had mounting slots everywhere and was about 1/16" think (don’t remember exact dim, but less than what typically gets recommended here) the second was a full sheet at about 1/32". We riveted the two together with our base.

Looked early on that the bottom of pans were going to rip up the PCs.

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I agree pocketed belly pan is definitely not essential and most teams probably should use those machining resources elsewhere. But why not use one of the other options like Baltic Burch and save the 3-5 pounds. Unless you want ballast in which case belly pan is probably a great place to add weight.

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Oh, we’re far too ‘metal’ to have any wood on our robot!
metalfist

:wink:

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If you’re not pocketing your structural belly pan (which, I agree, is a waste of time unless you’re getting it jetted / lasered and there is little cost to you in time / money), it should probably be wood or garolite. You’ll get more rigidity for the weight that way.

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Isn’t that insanely expensive?

Yeah, I’d recommend a good plywood for most robotics teams. Garolite is kind of the high-performance, low machining option for those with like $75 per robot to spare (typically used in 1/16" or so)

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If it really needs to be metal I know teams have used expanded metal with success in the past. Although Baltic birch is still probably the better option.

(Mod edit: Corrected an unfortunate typo)

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Why is it a waste of time if you’re traditionally milling it out? We used our velox 5050 to make two lightened .09” belly pans this year and it took us between 3-4 hours per part. I would argue that the weight savings from the belly pan is one of the most if not the most efficient way to lose weight.

Our belly pan went from ~5.7 lbs to ~2.7 lbs.

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Apologies for derailing the thread a bit but are you using one of the Spacemouse CAD mice? If you are how are you liking it? Has it made you more efficient? I have been considering getting one for a while now but am still on the fence about it.

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Yes I have had the space mouse wireless for a little over 2 years now and love it and it saves so much time. Some people say its not worth it and to just use orbit but i find it much more precise and amazing at getting the right angle to click something buried inside a robot. Their a bit expensive but they have an education discount on their website that saves you about $50.

And here is mine in Autodesk Inventor :slight_smile:
https://www.youtube.com/watch?v=KOtjQcImxBc

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Pocketing aluminum belly pans is definitely worth it to save the 3-5 pounds as well as has some advantages over other materials. Its just for some teams spending 3-4 hours can be a very significant amount of machining resources when baltic birch will weight the same as a pocket belly pan. We find that for our team with our build schedule and machining resources aluminum belly pans work well for us.

For mounting motor drives - SPARKMAX, TalonSRX, Victor - to robot surfaces we have been using a block (or sketch) pattern. Last year, we found that zip ties weren’t sufficient to restrain longitudinal motion of the SPARKMAX. This year, we created a 3D printed block; when used in pairs the block locks in the longitudinal position of the SPARKMAX. The 3D printed part, and the associated sketch and block files, can be found here:
https://grabcad.com/library/spark-mounting-block-1

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Do you happen to have an image of them in use?

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