Collet

[bgrix]

Hi
Have a question, was machining some PVC, long program and shut down for the night to start up in morning, left computer on so I could continue in morning as I was restarting program it closed for some reason. Anyway I worked on a run from here and ran into a problem and my bit and spindle plunged into the material took a few seconds to stop the program. Here is my question, my collet must have gotten hot plunging into the pvc and the result the collet developed a rust coating lost that shiny bright finish almost immediately as did the collet nut, also hard to loosen with my wrench. Cleaned everything up. The next day did a cut with a different collet and bit the cut was fine but a few days later went to remove the bit and the rust loss of shiny surface was evident, also on this collet and had to use penetrating oil and tap the collet nut to remove. No moisture in my shop checked the spindle for heat or damage and seems fine.
Any ideas
Thanks Bill

[bobmoore]

I have vcarve pro and when the machine is moving in the Z direction and I pause the program with the space bar the bit will plunge until it is mechanically stopped when I resume the cut. I can't help with the collet problem but I would try soaking everything in acetone and see if that helps.

[bgrix]

Hi

I'm starting to think I damaged the collet nut and maybe that's why the second time I had a issue with the nut locking on and needing penetrating oil to release, perhaps even when tight it is allowing the collet to move and creating heat. I have a extra that I will try. I have read over the years that these should be replaced if there ever is a issue with them. probably good advise.
Bill

[EricSchimel]

Bob, this is a known bug in SB3. Every time you pause you're increasing the chances that this bug will happen and you Z will plunge as far as it will go. Best bet is to not pause ever.

[GeneMpls]

It is not a well known bug, I look at this forum daily for many years and this is the first I have seen this?

[bobmoore]

So far I have only seen the bug when I paused during a Z motion. Happened on my prt and my prs.
Collets should be replaced every 2000-3000 hours of use since they do wear out. Plunging up to the collet nut probably shortens that life considerably.