XL lead screw vibration, set screws coming loose

Hey everyone! I recently upgraded my Crossfire with the XL rails and lead screw but now I cant get the set screws to stop coming loose and have scrapped several jobs because of it.

What I’ve noticed: excessive runout on the Y axis when the gantry moves to the front of the table, it vibrates and wobbles close to a 1/2" it looks like. When I slow the job speed down to 10% you can see what looks like a substantial bow in the screw.

Also it seems like the lead screw is too short to get a good grip from the set screws on the coupler end and the bearing holder end.

What I’ve tried: oil or greased lead screw seemed to help a bit, loctite on set screws but still come loose. Washers on top bolts of gantry holder to change angle in case of binding.

Anyone else having these issues or did I get a bad lead screw? any help would be appreciated. I’ll try to post some videos so everyone can see.

Wow! now I have concerns about getting the XL Kit! There’s already quite a bit of wobble on the std length Y-axis leadscrew!

If I cant get it remedied I’m putting the std setup back in, its getting really frustrating!

I feel the leadscrews used by Langmuir are already on the skinny side.

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My XL lead screw is doing the same thing. Did you ever get it figured out?

I just ordered the XL Kit last week, this concerns me as well. Is there a fix @langmuir-daniel ???

Yep, turns out the lead screw was about 3/8" too short. It wouldn’t seat completely so the wobble was causing it to work its self out from the set screws. Langmuir sent me a new one and no issues since!

Awesome! Great to hear I didn’t see your post about this until after I had ordered the XL Kit. Mine is going to be delivered between Xmas & New Years (Delayed Covid Mail Pending) LOL.
Thank you for your post

I had a similar issue, the stepper motor drive does have a flat side where the set screw should be set. It appears that the vibration loosen up the set screw just enough for the stepper motor to spin but not the screw shaft, and it a little hard to see. Take a close look at the motor side of the coupler with a good light. I took out the set screw, adjusted the coupler so the set screw would contact the flat of the motor shaft, and than replaced the set screw with “blue” thread lock. Be careful not to drop the set screw, easy to loose, a small piece of paper towel on the allen wrench will help hold it on the wrench to reinstall it. Good luck.

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I just put together my CrossFire with the XL expansion kit and have a very similar issue. Is there a nominal length the Y lead screw should be? I’ve got the set screw sitting on the flat of the D shaft of the Y stepper, but running the break-in program causes it to come loose within a minute and start slipping.

Y Axis issues

Not sure if there is a specific length but if I recall the new screw they sent me that did end up working, there was only about 1/16"-1/8" gap between the lead screw and the motor shaft. That was with the lead screw seated all the way on the bearing holder side. The original I got had a 3/8" gap and was way too large.