Are these worn enough to require replacement?

This morning I ran a cut in air in another attempt to track down why I’ve had the machine suddenly stop moving (X-direction only) in every job for the last month. I figured if it was the controller it would still happen - but it didn’t. That suggests something mechanical.
I noticed that the machine was much louder than it had been historically. On checking all the screws, etc. I noticed that a couple of the screws holding the steppers in place were becoming a little loose, especially the X stepper, but also slight loosening on one of the Y motors. Tightening them does seem to help considerably with noise and smoothness.
When I was cleaning the rails and threaded rods I saw that the delrin wheels were starting to look worn:

Should these be replaced? They still seem quite round.
On a separate note - I think I want to lubricate the threaded rods. Can you suggest a dry non-graphite lubricant to use?
Thanks in advance all!

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@falviani FWIW, Frank, that wheel does not look bad to me. It could use some cleaning, perhaps, but other than that, it looks fine.

Why do you want to lubricate the lead screws? Keep in mind that the only things that they are in contact with the lead screws that moves along their length are the anti-backlash nuts, and they are plastic. To me, any lube that you put on them will not make much difference in how the anti-backlash nuts move along them, and you run the risk of introducing a dust magnet to the lead screws.


Looks good to me. For the rods, I use Silicone Lubrication Spray on a regular basis.

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@falviani I have been going round and round with similar issues, I use Bostik Glide coat on many of my shop tools and equipment, it dries quick, does not attract dust and made my machine much more quiet. As far as the x axis (my recent nemesis) check your lower wheels, and as @gwilki says, adjust everything again, tight backlash nuts create enough resistance to stop the stepper motors, check your wheel adjustments, on mine I need to pay special attention to the eccentric nuts, when I get one right, the other gets tight, back and forth, again and again. Also, with my recent issues @chrismakesstuff slowed down my x axis, maybe try $110=2000 and see if that allows it to move, following adjustments it is now back to the $110=4000.

This forum has become an invaluable resource in helping me with my growing pains.

Have you found that worn end mills will “grab”, stalling the movement of the router?

@falviani I’m not sure if your question was directed to me or Bill, Frank. I’ve never experienced that. I’ve snapped off 1/8" bits and the Mill never even slowed down. I think you could freeze the Mill you hit something with a 1/4" bit. I strongly doubt that a dull bit would provide enough grab to stall the Mill. If you are getting stalling, I would look to other causes.

If you haven’t read it yet, Andy posted a maintenance guide a little while back.

Have a read.

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Thanks. He did mention a couple of small things that I just checked - they were working as expected. I now have a large label on my tool box that says “Check CNC screws etc every 1st of the month” to remind me.


@Dlab006 think I have it memorized completely, I will be the first to admit it takes a bit to get used to everything. Guess I can thank Covid, lots of time for reading!