Y axis problems

[norton]

I have had my SharkPro Plus for a few of months and have had only one other mechanical issue that Next Wave quickly helped me to solve. Now I am struggling with the Y axis, specifically the coupling of the spiral lead screw to the stepper motor. Even with the allen screw turned down as hard as possible and secured with glue it still manages to loosen resulting in ever increasing slop, then stoppage.

I can’t tighten the allen screw any more than I have already. The flat surface of the spiral lead screw doesn’t appear to have an indentation for the allen screw to seat into. This permits the lead screw to begin sliding at the very first loosening of the allen screw, eventually up to 0.20” in the Y direction, before it loses its grip altogether.

I am interested in the solution posted by hbutch8 on August 19, 2011.
“I shimmed out the bearing on the end of Y axis lead screw where it terminates into the plastic base in the rear of machine. It is a couple washers behind the bearing, which pushes the lead screw into the motor eliminating the motor shaft end play. no binding always returns to zero, no problems. have run many many hours this way, and actually seems to have a better cut quality, cleaner more defined.”

Doing this would eliminate the slop in the end play and perhaps reduce the forces that are loosening the allen screw. This seems like a good idea to me, although the bearing is set so tightly into the plastic base that I’m not sure how to unseat it and get the shims in place. I would appreciate any thoughts on what hbutch8 did. Also, any thoughts on how to keep that allen screw DOWN and doing its job…

PS I would have been lost without the information in this forum. Thank you to all those who share their knowledge and experience.

[Kryptik]

I haven't had this issue, so am not sure of the type of grub screw used. However, I have always made sure my fitters drill a dimple into any flats that they are securing in bushes then install using Loctite. The consequences of having a 750Kg Ferinium bowl tear out of a centrifuge at 3000 RPM doesn't bear thinking about, so this is one of the things we do.

[hbutch8]

This seems to be a depth problem on some machines y axis bearings where the drilled too deep in the plastic to mount the bearing.You should be able to fashion a hook bent on the end of a rod to get behind the bearing and gently pry it out. I have never had anymore trouble with y axis scince doing this, oh yeah and eventually had to do it on the x axis also. Another tip, when you tighten the set screw, do it first without connecting the motor shaft or the lead screw shaft and run the set screw all the way through the coupling. Once it slips it boogers the end of the threads and makes you think you have it tight, but it is not putting pressure on the shaft, if it was it should make a dimple itself, or at least a mark very visable. Set with one drop ,crazy glue or the like and you will still be able to take it apart if needed. I have run many many hours this way no more problems. If you need to email me with any questions feel free hbutch8@aol.com Good Luck Happy cutting