Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Helical Cut Flex Coupling

by phineasjw Feb 27, 2012
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5mm motor shaft, 8mm screw (for my CNC3018)....would that be the Flex_Coupling_25mm_Long_25mm_Wide_5mm_AND_9pt5255bore_1pt5_turns one correct?
The blue aluminum solid one sucks rocks

Just printing a pair of these now at 0.1mm layers 100% fill. i want them strong. will let you know how it turns out

Thanks a ton, Good Sir!

Will try printing both the original and 1.5 turn versions later tongiht and report back!


I tried this out in both ABS and PLA. They printed very well once I went to .3 mm layer height, with 50% fill and 2 shells.

Both have far too much angular flex to be useful, however, unless your load is close to zero. Might I suggest a helix of 1.5 times around, rather than 3.5 times around? I
think this might work pretty well in PLA.


Thanks for the feedback on printing this thing.

I added the 1.5 turn version of the 5mm bore. Still getting the hang of doing this so it takes awhile to redo these. Seems like it should be easier till I start making the changes.

Soory, on my PLA part, it looked like the helix went 3.5 times around, but it is translucent, and tough to make out. I see from the model that it goes 5X around. I suggest trying 2X.


The last file in the list is a modified coupling 25mm diameter, 5mm bore on one end and 3/8" on other end for NM-Buzzard. It was more of a tear up than I expected due to the large bore on one end.

Yes would love to have a generic CAD file for editing - would like to try 10mm bore at one end to a metric acme rod...

I added a .stp 3D CAD file exported from Alibre. I opened it in Inventor and it seems fine. Let me know if it works for you.

Got the STEP import repaired and printed one out on a Dimension uPrint. It seems to be OK but I'm going to mount it in a Sumpod machine and see how it works. I'll let you know, pictures included! :)

If it works out click on the I made one button here so I can see it!

It works but maybe not long term. If it had a thicker spiral wtih the same number of turns, I think it would be fine (even as that would make it longer). Obviously ABS is less stiff than metal of any kind.

Fantastic! I can't wait to see and here how it turns out.

Thanks! Got it. I was able to import into Inventor 2012 but had it crash just after, though I don't think it is your file (Autodesk is taking a look at my installation for issues). I'll let you know how it goes after we get the software bug squashed!

Very good man! Excellent part. I wish I still had the mill I could install this on...

Precisely, my boy! 8-)