Z-axis spiral coupler

I've had my machine running for a little over a month now and have done a lot of upgrades to it. Most of the changes are based on models pulled off of github, but I couldn't help myself and modded them to my liking.

so far I've converted to lm8uu and added flexible spiral cut z-axis couplers.

I know, I know... end play, right? I fixed that with a cheap thrust bearing, but really, I'm sure a washer would do. The key to making it work is to captivate the coupler and put a slight preload on it to ever so slightly compress the spiral. Gravity will do the rest.

It's been running on my machine for over a week now and is super stable.

I have models up on thingiverse [www.thingiverse.com] with details and illustrations if anybody is interested.

Here's a screen shot of my cad file (SW) with some notes.





I know it's more elaborate than some other solutions, but it is truly wobble free.

Edited 4 time(s). Last edit at 01/29/2012 01:35PM by Skypuppet.

Nice, do you constrain the lead screw at the bottom as well? I've had no issues with wobble myself with a vanilla setup, but I'm going to try a m5 lead screw on my next reprap.

Have you seen rotorits variant eliminating the 5$ coupling? [www.thingiverse.com]

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-Nudel
Blog with RepRap Comic

Thanks for looking

No, no need to constrain at the bottom that I can see. It really has no wobble even during high speed jogs. I was careful to make the leadscrew parallel with the smooth rod tho.


Rotorits is definitely interesting. I hadn't seen it, but one would guess that I had, haha!

What is a vanilla setup? I'm new...

Edited 1 time(s). Last edit at 01/29/2012 01:34PM by Skypuppet.

Skypuppet Wrote:
> What is a vanilla setup? I'm new...

No extra flavouring , meaning I use the variant on prusajr's github without modifications. [github.com]

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-Nudel
Blog with RepRap Comic

I've seen posts where people complain about printed couplers failing.

Does this idea get around having to use a printed coupling? or do you feel the sprial helps out somehow?

its a cool look and could help with any slight missalignment between the screw the stepper

I use these spiral couplers as well but I haven't seen any kind of axis bounce or other drawbacks from their flexible nature. Here's a 50-micron print done at 50/100 speed, with no visible layer misalignment or layer height inconsistency:



Edited 1 time(s). Last edit at 01/29/2012 02:06PM by Pointedstick.

I think they are a really good option to the plastic couplers for a lot of people like me who may be using these machines to produce prototypes for job related needs.

I know that many people can get good accuracy out of printed ones and I feel like I could too. But I know that nicely machined aluminum parts will give me that accuracy, reliably and without fail.

The spiral cut allows for axial misalignment for sure, but it's best to also minimize that in the first place by taking a little extra time during assembly getting things parallel/square.

Pointedstick Wrote:
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> I use these spiral couplers as well but I haven't
> seen any kind of axis bounce or other drawbacks
> from their flexible nature.

I thought they would be stable even without endplay constraint, but I needed to be printing some lasting for footwear (job) and wanted to go straight to something that made sense to me.

Your print is testimony Very nice.