3/8" Shaft

Curious if any other teams still use 3/8" hex shaft on their robot for motion. I saw the Rev Ion standoff stock and that pretty much had the same dimensions as 3/8" thunderhex stock but is $8 cheaper. Do people just use them as standoffs or for actual motion?

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One thing to keep in mind is the REV #10-32 standoffs are 6061, 3/8" thunderhex and other 3/8" hex shaft is typically 7075.

But yes other than the material difference, dimensionally it would work. Of course the standoffs also just have blind tapped holes in either end, whereas thunderhex has a 0.159" thru hole so you could cut to a different length and the hole will still be there to tap.

Also worth noting REV is not selling any other hardware to support 3/8 shaft (no bearings, spacers, collars, etc).


Dunno about using the ION standoffs but our FTC teams use 3/8 hex for most of the power transmission after the motors.

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Ah okay my FTC team uses the 5mm hex not 3/8" so that’s pretty interesting

Yeah I was mainly comparing the 36" stock for both of them (so you can make any length shaft), which do not have the tapped holes. My team personally has never used 3/8" hex shaft for motion as it makes it easier parts wise to have everything 1/2", but I was more curious if any team actively uses a mix on their FRC robot.

We still use a fair bit of 3/8" thunderhex from Vex. It works well for first stage shafts in a gearbox (with 32DP gears especially) and also as strong-yet-small standoffs, tapped for #10-32.


We used 3/8 shaft to power our hood rotation this year, and had issues with 3d printed gears rounding out (this should have been obvious that it would be an issue), but swapped to metal gears and had no issues. We also used 3/8 shaft on the shafts that reversed our hood rollers, and that held up great. We used to use it for standoffs, but switch to 3/8 round because it was cheaper.

We use 3/8" thunderhex in our updated turret design, it works really well for single stage reductions where the torsional strength is still acceptable.

It’s important to note that 3/8" hex in 6061 will be significantly weaker. Also we specifically don’t use shaft like “Churro” for torsion because the profile is very weak and also less stiff.

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I’ve generally recommended Thunderhex for its strength (7075) and dimensional control (double extruded).

If you don’t need strong or precise, then cheaper stuff will do.

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