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

by loco Dec 20, 2014
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Hey man do you perhaps have a 3mm to 8mm

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Hi Marco,

thank you for the great job! My Ender 3 runs much smoother now. For my next project i need a 5x14 coupler - could you add it to thing or just give it to me?
Thanx in advance.

Hey Marco!

Anyway you can send me an .STL file or 3D CAD file for the self centering coupler? I was looking for a 8mm/8mm but couldn't find one.


I cannot than you enough for this file. i made huge improvements on my Geeetech printer.

Here du you see the same file before and after the coupling.

Comments deleted.

Great it works very well, finally my rods turn smoothly.

Hi Marco!
Great design, I have been using them on all my printers.
Now I'm going to mount a belt on my CR10 to mechanically connect the two Z lead screws on top and need to raise the leads screws a bit.
Is it easy for you to model a 5/8mm coupler that is 15mm taller?
Thanks man.

Hi guys, i need the 5-8 coupler, but did not know which one to use. whats the difference between the 5-8 coupler and the v2.5 5-8 coupler?
also any chance this might be better printed using ABS? i have spider jaw coupler but that one failed, the top part always decouple on one rod.

What sizes are for a tevo tornado thanks

I just printed for my Tevo tornado and it works perfectly :-)

what you need is V2.5nut_5, V2.5nut_8 and V2.5coupler_5_8.

is there a chance of a 6/6,35 coupling ?


3-6 or 3-6.35 mm coupler is missing;-)(

Hi, @loko. Great design, thanks.
Can you replace the plain central cone (threadless area) to standard hexagonal prism for wrench?
Or provide please the source files for remix.

Thanks a lot for your design!

It basically works on an Anet A6 (5 mm to 8 mm), but I still have some issues and suggestions:

  • It's been hard to fix the threaded rod (spindle). I had to use pliers and a good amount of force. It would have helped, if the center part had flat sides to hold them with tools. Also I think the compression starts too late: the nut can be screwed all the way down until it starts pressing the sides together.
  • The spindle is still moving in X/Y-direction just above the coupling. This might be due to the fact that I had to apply a lot of force to tighten the nuts. Another reason might be, that the motor's axis has a single flat side (-0.5 mm for the grub screw). Would it be possible to provide a variant that case?

Those are amazing observations!
This might be the reason why i stopped using these to begin with!
I'll make those changes as a remix and test it out later today!

hi which do i need for geetech pro b prusa I3 clone please?

Great design. As it is paramteric, can you also add a 2.5 version of the nut for 12mm? I want to use it for my 1203 ball screw.

The coupler working great at firs day. After a few day the 5mm from stepper is loose. I go and thighten everything. Printed with PLA. I THINK need to used fix coupler

look promising, but the shafts on my motors are partialy cut for a grub screw.. due to that flat spot, the couplers are not centered when tightened..

I am so impressed with this coupler. Just replaced my stock cr-10 coupler and the quality of my prints have gone way up. I think I'm going to re print this in nylon foot long term use.

Printed perfectly, installed smoothly.

The attached file is the edited version (I cut some material out from the outer side ) of [V2.5] number 8 nut and it now fits the anycubic i3 mega without bumping the z stop switch screw. It can even tighten more with its current shape. Again thank you for sharing, wobbling action is gone.

Edit: Prints are way better than before! No more irregular shifting of lines. 3D printer manufacturers must pay attention to the kind of mechanism they put on the z axis coupling.

hi, i plan to use this on chiron, which one should i use, the v2.5 5-8 coupler or the 5-8 coupler stl? how was it going right now printed using ABS? i tried to use spider jaw coupler but the top part always decouple when move down on one rod. thanks! :D

I printed using ABS, the 5mm to 8mm coupler is a snug fit on the anycubic i3 mega except for the V2.5nut_8.stl that hits the screw on the z stop switch which makes the whole thing not usable at all. It is either I'll file out some material from the printed part or print another nut that is already modified to fit. Thank you for sharing, I have to find a way to make the nut thinner on the corners so that the rod can freely rotate.

Do you think that PET-G is a valid material for these couplers? Thank you for your answer.

Should be fine. I printed on with PLA at 100% infill and have not had an issue.

Can you share the inventor files please?

Hi mate, since it's parametric, can you do a 6 to 6 and a 5.8 to 6 mm ?? These one are not for a printer but extention couplers for potmeters in a DIY amplifier.

I'll redo the nuts to knurled ones, did this one which works perfect on my printer ! https://www.thingiverse.com/thing:2798293

Thanks !!

knurled nuts Z coupler 8 - 5 mm
by reddo

These definitely need flats in the middle to get a wrench/pliers onto, and the 5-to-8 mm coupler does not grab strongly onto TR8 lead screws, without putting some kind of "interface material" between the coupler and the screw, or perhaps cutting slots or something into the screw. These WILL slip over time otherwise, no matter how tight they are.

Great design!
Is it possible to make a 5-10 coupler?

Awesome! But i think you can make central part square or hexagonal. Then you can tighten nuts easier.

Hi, I am looking to extend my Z height. Would you be able to make these 38mm longer? I don't want to buy longer screws, and a longer Z coupler would do the trick.


Thank you so much! These incredibly reduced the banding on my printer (Hictop 3dp-11). I printed them out first to fit them on, and then I printed another pair to have them perfect. I can't believe that these work so well, and it makes me wonder why don't starter 3d printer companies print these out like they do many other parts, and not use metal couplings. I had one problem that others may run into: the file names start with an unusual character and they never showed up on my printer. I had to remove the bracket from the file name to get my printer to read it. Thanks!

I'd just like to say I think these are brilliant. Thanks for the effort you put into making these. Can't believe they're better than the metal couplings that came with my printer. (I have a geeetech prusa i3 pro b). I've changed my m8 threaded rods to t8 lead screws and along with these couplings they seem to be producing pretty good results.

Amazing! The original ones went to trash. Now Z axis is moving clear without any "not round move" and I have much more better print results! I built-in them in my AM8. Thank you very much dude!

I have printed these to test, just curious if there was any way to make the centre of coupler shaped for a spanner to help tighten the nuts that little bit more

I search for a 8/8mm coupler for two T8 lead screw, can you create one?

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

Sorry I'm a month late, but I printed these for my Hictop 3dp-11 printer in Hatchbox PLA and they seem to be working fine. I have so far only printed a few things but there are no major problems. Hope that helps!

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.