Self-centering tapered-thread Z-axis coupling [v2]

by loco, published

Self-centering tapered-thread Z-axis coupling [v2] by loco Dec 20, 2014

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This is a remake of my self-centering z-coupler (http://www.thingiverse.com/thing:396781)

The thread is now optimized for 3D printing and the overall length is way smaller. It's also a parametric design, so i can easily generate different sizes.

I made 4 different sizes for 5mm motor shaft and 5, 6, 8 or 10mm threaded rod.
You can just ask me, if you need different sizes.

12/24/14: Added coupler_5_12, coupler_6_12 and nut_12

10/17/15: Added [V2.5] coupler 6.35/8mm + nuts

12/16/15: Added [V2.5] coupler 5/3, 5/4, 5/7 + nuts

02/04/16: Added [V2.5] coupler 5/6.35

03/12/16: Added [V2.5] coupler 5/5

05/26/16: Added [V2.5] coupler 5/8

Print Settings


Doesn't Matter








Print the coupler with brim or raft if it doesn't stick to your printbed.


If you need a lot of force to push it on the shafts print it 1% or 2% bigger. Otherwise it may not center the shafts correctly.

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Hei I love idea and want to try but filenames is big confusion ;) I have Tevo tarantula - 18mm coupler + 8mm rod . Which cupler file and nuts do I need to print? Thanks

I see my issue. I didnt relize you can use it only without original coupler. And Im assuming it is only work if z motor at bottom . Mine is from top - if i use it is it going to hold enough pressure? Thanks

Hi I am using anet a6 anybody can advice me which file should i be using. Thank you

I am using it on my cr-10. I was suspicious about the design but It made my Z axis really good. No banding anymore!

Thank you so much!

Great job! The printer works great. 0 vibration.
Can I ask for the 8x11.8mm version.
I will be very grateful.

hey that's lenton thread.
that's what i make for a living. except it's rebarb couplers. you can screw the nut on tight in only 4 rotations.

anyway. it WAS a patented thread design. (although the cuts and clamping ability would circomvent that patent)

When I built bridges, these come in handy. Very Good design, I was skeptical at first, but Tested under loads. The rebar would break first, not the Lenton Threads.

ps: what material would you print this out of. super hard or more flexible filaments (like taulman 645 nylon)

i second that question. Will PLA be too brittle? ABS too "flexi"? Can anyone share some experience?
thanks in advance

Cool model. I just made two for my Anet A8, works great. Could you upload the Inventor file?, because I want to attach drill bits two a motor and need multiple versions of it.

Excuse me but I have a bad time understanding the magic behind this. Are the threaded rods and the stepper shaft supposed to be against each other when installing this or should I leave some room between them? Do I tighten the nuts as hard as I can?

Sorry if the questions look dumb but I'd rather prefer to use this one correctly. :)

Thanks for the help!


Hi Chris,
there's absolutely no magic behind it. Just leave a small gap between the shafts and tighten the nuts with some force.

would it be possible to have 5mm to 3.175mm?

Can you put together an 8mm to 8mm one?
the Malyan M150 uses an 8mm Motor Shaft.
and a 5mm to 16mm for a ball screw?

Exactly. Green tube from the aquarium works great but that one is better. I replaced coupling in Vellman Vertex K8400. One of linear Z barrings moves not smooth and sometime hangs up. This stuff not only drive trapezoidal screw perfectly but it solve barring issue.

Works incredibly well, thanks!
Is there a chance to add an hex part to the middle of the coupler? (to hold it with a wrench)

Great job, i printed the v2.5 of 5 to 8 mm and work ok!, Could you do a 5mm to 6mm coupler v2.5?, Thanks at advance!

This worked ok but the nuts broke easily and it's a bit bulky. Works in a jam though if necessary

Could you do a 5mm to 20mm coupler, please?

LOVE This.. I was skeptical that it would auto adjust.. I had a lot of wobble at first.. then I ran the axis the entire length of the Z rod and it was all gone.. . NICE

Hey there,
could you make 2 or 3 mm versions, please? Cant even find a 2 mm coupling to buy, so it would be really appreciated =D
I use your bigger ones on my printer, they work just great.

Any chance you could make a 3mm to 8mm adapter for me please?

ive printed the v2.5 5mm-8mm a few times now and the 8mm side doesnt tighten enough to stop the leadscrew turning easily
should i try the other version or am i missing soemthing?

Are there any blobs or other imperfections on your prints?

You could try to print it a few percents smaller.

Its like the nut is to big so when you screw it down it can't tighten enough before it stops
I'll print the originals and see if its any better
My prints come out spot on except that

I'll have a look at that.

Its like the nut is to big so when you screw it down it can't tighten enough before it stops
I'll print the originals and see if its any better
My prints come out spot on except that

it's how tapered thread works. just a few turns for it to fully tighten.

if this does not happen then both the coupler and the nut are slightly oversized for the nut. (it would clamp too much and then the angle of the taper would be off. same thing the other way around only then the nut would seem undersized)

anyway play with the scale to get it to fit right

Comments deleted.

I didn't think these would work, but thought I'd try them whilst waiting for some metal connectors to ship to join the acme rods that have replaced my 5mm rods.

I don't know how long they will last but the fist couple of prints with them on have been great :) [ Prusa i3]


Sorry for the silly question but: what would it be the proper way of adjustment?

hey Loco,

Could you please design a 5mm to 6mm v2.5 coupler ans nuts?

Thanks, it works fantastic the 5-8 adapter.

This is a good idea you should be working for space x.

first thank you for the design!
it works great for my PPrusa i3.
is it possible to make a different sice for 3mm threaded rod?

A wonderfull design and idea. It solved wobble on my prusa i3.

hey Loco,

Could you Post a 6mm to 5mm v2.5 coupler, please?



Works very well! I thank you for this THING and your good idea. Solved my Z-Axis-wobble-problem, but I had to stick the rods not to deep in the coupling. I hope this is the right way to use :)

Nice design!
I need a 9mm to 8mm coupler. Could you help me wit this?
Kind regards,

Looks awesome!
Could you Post a 10mm to 5mm v2.5 coupler, please?
I woul use them for 10/2 Trapezoid leadscrews meeting an NEMA17!

Wow fantastic! I just found this, but I think it is going to solve my problem beautifully!

Made, it works well! Haven't attached to my machine yet but I've been testing the threads and boy does it work! Really nicely.
However, just a design suggestion, how about putting a hex around the mid-collar between the two tightening nuts to make it easier to remove and tighten them?
Awesome work, thank you very much for uploading :)

Is there a way to reduce the outer size of the nuts, other than sanding it down? I need the 5x8, but it seems that the 8mm nut will hit my smooth rod on my Graber i3.

Actually I tested it, and it just clears with about 0.3mm of clearance. :)

Really curious to give there a try.
I was looking for 5mm/8mm but I couldn't find for v2.5 are those missing?

Second that. Also what plastic this should be printed of? Will PLA work or shaft would slide in it like in bushing.

I just made one of these, I used ABS for the nuts but I used PLA for the inside part, as I couldn't get it to print cleanly enough in ABS. Unfortunately the heat from the stepper motor soften the PLA enough when operating to cause it to slip and drop the gantry. I would recommend ABS or PETG. I did have the nuts very tight as well.

You guys are right, there was no 5/8mm coupler. I just uploaded it.
PLA works fine, just make sure you tighten the nuts properly.

Thank you!

I made the older version and used PLA so far it's working great.

Could you post a 8mm to 8mm coupler, please?

Very good design...

Could you post a 3mm shorter version of this adapter for 5mm to 8mm please? I am using a leadscrew and if you make a shorter one I will have enough clearance.

Thanks in advance

Great design! Please add one for 5mm->6.35mm.

Thanks! I just uploaded the 5mm / 6.35mm version.

one more: could you post a 5mm->6.5mm coupler/nut combo?

It's uploaded, please use the 5mm and 6mm nuts.

How about a 8 mm to 12.7 mm?

Done. It's big... :p

can you make a 5mm to 7mm coupler? :D

I just uploaded both :)

would you be able to upload the openscad (i'm assuming) file that you're using to generate the nuts/coupler? i'm super interested in how you pulled off some of this.


Sorry, this isn't an openscad design. I use Autodesk Inventor for my models.
I tried to recreate this model in Autodesk Fusion360 (its free for private use), but it's missing a function i need for this design.

This helped me a lot, thanks!
Is it possible to also have 5_3 and 5_4?

Take a look at the files-tab :)

Dankeschön :-)

Thanks very much for sharing this fantastic design.

Thanks for making this, great fix for my wobbling Z axis.

You are welcome :)
I'm glad it fixed your problem.

Simple and elegant. Nice job.

Hey, would you be able to make one for 3/8" z rods. Should be around 9.5mm. I'm not sure if 10mm would be too big for my z rod.

They are so simple and so usefull. Thanks for sharing

Hi, you can make a square 3mm to 8mm round shaft?

Any chance you could make me a 4.5mm to 5mm and 4.5mm to 6.35mm coupler? Also would it be possible to edit the length to make them 25mm long?

I think this is no problem, come back again later :)

I just uploaded both, Nut_5 and Nut_6 should fit.

Awesome, thank you. I will give them a print and test them out.

Sorry to bother you again, but i did remember wrong (though i can also use the 12mm) but the one i was thinking about is, 5x16 5x17 6x16 6x17 and if you like and it is easy, 4x12 4x16 4x17.

Thanks a lot! Iam starting to have my printer redialed in with simplify3d. So one od the comming days, i will print alle the couplers i need.
Thanks again!

Although it is parametric, i can't generate any size from it.
4-12mm should be possible, but 16 or 17mm is way to much for this design.
Why would you need all these different sizes?

I made a coupler the other day. it came out fantastic, thank you!

They looks very nice, looking forward to printing them, but i would LOVE to have 5-12mm and 6-12mm if you can upload those please? :)

I just uploaded them :)

i think the nut_12 is missing. could you upload that please?

You're correct, it was missing. I'll upload it now.
Thank you.