Twisting 5mm rev steel hex

Have you guys ever made such a monstrosity (by accident)?


This is… interesting. How’d this end up happening?

That is a gorgeously even twist. A smith would need some real experience to do that on purpose.


its an art piece

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It wasn’t as beautiful, but 188 at the 2006 Finger Lakes Regional did something similar. The lesson we learned was that even though it machines cleanly,1 12L14 steel has plenty of ductility, but not enough yield strength. The expeditious fix was to pull out the custom gearboxes with multiple motors feeding a Nothing But DeWalts planetary gearbox, and swap in the cast-aluminum-bodied kitbot transmissions. They had neither the torque, nor the reduced double-D shaft profile to harm us any further.

1 Apart from the lead contamination.


this is why i like to use 1/2" hex whenever possible

nice churro tho

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This is what you show to people when they tell you “you can’t see torque”


The way our claw works means that we use ultrapnetary 90 degrees, so we need to use it lol. It has uktrahex around the top half of it to rngage with sprockets and gears used to rotate the wheels

yea it kinda sucks that the ultraplanetary has a half inch hex adapter, but the 90° adapter doesn’t

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We managed to do this to 0.5 in steel shaft at FMA DCMP


I can’t find a photo of it, but we did a very similar twist in 1/2" hex 7075 one year–almost a perfect 60 degree twist in less than half an inch of length.

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We may have snapped a few hex shafts this year (lightened steel ones included) but this is a very nice twist.

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Holy moly


Woah how?

We were using the hex shaft to transfer torque from a gearbox to an arm and accidentally drove the arm into its hard stop. The shaft twisted in the small gap between the gear and the arm assembly.

Thats scary lol

It’s all fun and games until you twist 0.5” steel hex shaft…


lmao thats amazing
what are the gear ratios of those stages on the maxplanetary?

also we’re both in curie :slight_smile:

The design has long since been changed, mainly because we kept breaking MAXPlanetary shaft adapters at OCR, but before that happened the reduction was 240:1

Now it’s 100:1 with a sprocket reduction, much better!

Broken MAXPlanetary adapter (1 of 3 lol):

And yep, will be great to see you guys again, Beach Blitz reunion. See you in Curie!

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We, too, have made the forbidden candy cane out of moly steel hex.