HDM Coupler Upgrade

So I had issues with slipping couplers on my HDM, and am now paranoid about them. I tightened them a bunch and it seems fine for now. But the mention of upgraded couplers on the SO5 definitely caught my eye.

I know this was asked on the main SO5 thread (Introducing the Shapeoko 5 Pro - #8 by robgrz) and it’s being looked into. But figured I’d start a separate thread to track what options there might be eventually. If they’re just longer, could the motor be shimmed out ? Machining an aluminum spacer should be an easy DIY for a HDM owner.

I’m also curious how the SO5 ones are better ?

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Mine slipped as well doing 3d adaptive toolpaths in Fusion with moderate speeds. I tightened them down as much as possible, has not happened since, but it stays on my mind they might need to be replaced…
An upgrade would be nice!

It’s a number of little changes, predominantly they have a larger outer diameter which gives allows for a longer screw this equates to more torque before stripping the coupler. It also features a set screw.

Generally once setup a HDM coupler shouldn’t slip - and I’ve only heard a hand full of reports. That said a dab of thread lock on each shaft prior to tightening eliminates the chance and makes them incredibly difficult to remove.

We’re looking to see if we can create a similar coupling for the HDM - however it’s a tight space to fit into.


Add me to the short list of people with slipping couplers. When you say add thread lock to the shafts, are you referring to the stepper and ball screws? Or the Allen head screws I. The couplers? Blue? Or Red?

I don’t have my machine yet, could someone post a photo of the hdm couplers?

One of the Y-axis couplers (X is the same, just harder to photograph)


I believe @Luke was referring to adding LocTite to the ball screw / motor shaft before putting the connector and tightening. I had pretty severe slipping and binding on my original z axis and once it was replace I tightened every connector and it seemed to help. I’d definitely make it a weekly maintenance check to check that they are tight. A keyed connector and shaft, or flats and set screws would be ideal. I presume you could machine a flat on each motor shaft, and drill / tap a set screw 90 degrees from the clamp screw and it would solve it. Or possibly easier would be to cross drill and pin.

I would go with blue.

Is there a possibility for the operator to put a witness mark on it?

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