HDZ Install Issue: Z-motor won't fit with the coupler

Hi, I have hit a snag on the install of the HDZ 4.0 on my Shapeoko XXL circa Feb 2018. There is not enough axial space to fit the coupler in between the Z-axis motor shaft and the shaft of the lead screw on the HDZ. I have removed both screws from the coupler so that it can fully seat on the shaft ends, but both shafts bottom out on the elastomeric part of the coupler way before the motor is seated on the mount.

I could try to force this together, but it will take a lot of force to get the motor to seat and I am afraid that I will damage the motor.

For now, I will buy some washers or spacers from the big box store to put a gap in between the motor mount and the face of the stepper, but this puts the alignment of the Z-axis motor into question.

Any other ideas???

There’s a problem with the coupler — please write in to support@carbide3d.com and we’ll get this swapped out.

Hmm, where have I see this before… =)

The red plastic part in the middle of the coupler needs a hole through it to accommodate the motor shaft (not the ball screw shaft). Luke posted a good cross-sectional mechanical diagram in the other thread.

Support will certainly get you sorted out with a replacement, but if you’re impatient like me, you can drill a 6 mm hole through it. Just make sure you’re centered and vertical; the coupler itself makes a decent drill guide. I also cleaned up and slightly chamfered the edges with an x-acto blade. 6 mm is large enough to press-fit the coupler on the 6.35 mm motor shaft.

Use your judgment, though… if the hole isn’t centered, straight, and big enough, don’t force it and bend your motor shaft or put a radial load on the ball screw’s upper bearing.

I’m not planning to run any serious jobs with this hack, and I certainly don’t suggest you to do so, but it’s sufficient to let you get on with setting up the HDZ until Carbide3D sends a replacement coupler.


I have this same issue and just emailed support about it.

I’m not one to complain online, but 6 days later and I’m still waiting on the replacement coupler and have not been able to get tracking number or any other info on when it might arrive. In the meantime my cnc is unusable unless I reinstall my old z. And this is after having to wait for a shipment of parts that were missing from the initial package. I like Carbide3D and want them to be successful, but the quality control issues you hear so much about are real.

Bear with us, we identified a batch of couplings that were not to spec. Support should be in touch today!


Sounds good, thank you. I’ll keep an eye out.

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New coupler arrived this morning, thanks!

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