Falcon 500 WCD Gearbox

Compact and light enough that I could make a case for using it over a COTS gearbox, simple enough that I’d actually be comfortable using it over a COTS gearbox.


It’s so beautiful…


That looks impressively compact. Any chance you’re willing to share the cad model.


I feel like given how compact it is we dont often see gearing on both sides of the tube. Does anyone know if there is a good reason for that?

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I’ll gladly share the CAD model for the next rev. Going to make a few tweaks and add in details before the gearbox is final.

Also, my gear ratios are mostly guesswork because I don’t have the Falcon 500 specs in my JVN Calc. Also, my pinions are cim pinions because I don’t have Falcon 500 pinions in my MKcad.

If CAD is up for the pinions or anyone has a JVN Calc version with the Falcon 500 specs, I’d appreciate your help dialing in this gearbox.


I’ll chime in as well and say that that is a very nice looking gearbox. It’s amazing how you got it so compact. However, have you considered the ground clearance for the gear on the motor side? It looks pretty low to me, so I’d be concerned using this gearbox for games like this last season, where you have angled platforms.

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you can edit and add motors to the JVN calculator its the last tab “Data”…


VexPro has the CAD for the falcon gears up on their website https://www.vexrobotics.com/20dp-motorpinions.html under the cad files tab

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If the gears are all outside the box, is it still a gearbox? :thinking:


This has been addressed in the other thread :wink:

But - anecdotally outside of FRC, we plan for an offseason parade demo that runs on city streets, so we don’t use our gears as a wheel with extra grip, and now aim for ~0.75" nominal ground clearance (~0.50" under bolt heads) after one particularly scrape-filled year at ~0.25" under our bolts. YMMV.

The CAD looks like 1/8" tube and 1/4" plate - I think that the rail could go to 0.0625" and the plates to 3/16" or 1/8".

At current thickness, it looks like you’ll be locating by the four through bolts rather than by a bearing bore in the tube, which has its own benefits, but my preference is to use the bearing hole in the tube to locate the output shaft. That’s easiest to do with 3/16" plates rather than counterboring 1/4".

At current thickness, it looks like you need extra spacers to center the 17t sprocket - maybe tweaking some details will let you take those out.

It might be worth sticking to 1/8" tube for this design so that you can crank down on those mounting bolts without worrying about crushing the tube.


I like your design, but wonder how you are planning to attach blue gearbox plates to tube…if rivets, would they hit chain?

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973 intentionally just locates with bolts on similar gearboxes such that the tubes don’t need any precision bores.


I’m a few days late, but in this case probably better late than never. Attached is my edited version of JVN’s Design Calculator. It has NEOs, Falcon 500s, and I added a few more rows in the DATA tab (as EricLeifermann mentioned) for other motors you might use at some point. Hope this helps. Good luck with the gearbox, it looks amazing.

JVN-DesignCalc.20170214.xlsx (845.6 KB)


Thanks everyone for the kind words, advice, and resources! Keep an eye out for another revision and full drivetrain model soon!!

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So I might be missing something but how are you actually fastening the gearbox to the tubing (Other than the shafts themselves). Are there other bolts and standoffs that arent in view? Also if you were planning on using the holes that are drilled on the face of the 2x1 wouldn’t it interfere with the Chain inside the tube?

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