Y-axis coupler question

I just got my cnc put together and was jogging it around, haven’t tried running a job yet, and noticed the coupler on one of my y-axis pulling apart. I fixed it and then it did it again a little bit later. The picture below is the 2nd time it happened. The first time there was a larger gap. Any idea why this would happen and is it going to cause issues? Thanks.

@Dhk I have the older couplers so likely cannot help. I’m curious, though, Bryan. You mention that you fixed it once,but the issue returned. What did you do to fix it?
One end of the coupler is tight on the motor shaft and the other end is tight on the lead screw. Neither the motor nor the lead screw can move lengthwise, so the distance between them cannot change. I don’t understand, then, how the coupler can pull apart unless it is moving on the motor shaft. Can that be the problem?

To fix it, I loosened the motor side of the coupler, pushed them back together and retightened the coupler. I too, am unsure how they could pull apart since both sides are fixed. The motor is tight. Could running the y-axis to its limits cause the lead screw to keep turning, essentially pulling the coupler apart? I’m not sure if I did that, but may have by accident. But I would think both y-axis sides would do the same thing but it’s only the right side.

@Dhk I can’t see how running it to the Y limits could cause this, Bryan. However, looking at your picture, but not having a coupler like yours to look at, I believe that the coupler may be defective. The motor and its shaft cannot move. But, the lead screw can move away from the motor. The only thing stopping it from doing so is the coupler. I should have thought of this when I first saw your picture.

When Chris or Andy see this, I’m sure that they will have a solution. If the rubber in the coupler is supposed to be sandwiched between the two pieces of the coupler, attached to both, then I think yours is “broken”.

Thanks for your help. The more I think about it the more it seems it has to be the coupler not being tight enough on the motor end and sliding up, like you said. Unfortunately it’s as tight as I can get it, I almost stripped the end of the bolt trying to get it more tight. I may order another coupler to replace it and see if that helps. Thanks again.

Dhk, I had the same exact issue with one of my couplers. The set screw that tightens on the motor shaft just can’t get tight enough and slips. I fixed mine by using a small piece of adhesive backed sandpaper around the motor shaft and then tightened the coupler. Thats worked for the past 3 months and have not had an issue. I do thing that the coupler needs to be able to tighten more however, but it’s fixed the best it can be at the moment.

That’s sounds like a good fix, I’ll try that. Thanks.