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.:)

[scottp55]

Haven't really seen that bug since 3.8.36(?)..way beyond that now:)
DID see it when I downloaded a latest version and did NOT notice it was for Desktop Max with toolchanger and other PRS....they took that down within a week, and I reprogrammed back.

When I first started at 3.8.14 it was a problem...and maybe one time out of a hundred(during a rapid Z movement spacebar P(ause) ever seen it again).
DO recommend not Spacebar Pausing because of that 1%, but if I change SB3 to a low Z MS...I almost always catch that once in a hundred problem(then I change back Z MS).
IF possible....Spacebar Pause during a rapid X,Y move...and problem never seems to happen.
2 cents.
scott
Oh...I notice "banding" on my collets at about 600 hours....and check collet nuts every tool change for bad surfaces. A "Catastrophic" event like a bit spinning in collet often causes galling and means a VERY careful inspection of all collet components!
Spindle cone seems to be the most neglected...that's a regular weekly cleaning when I did production.
I'm 3.5 miles from ocean as the crow flies....salt/humidity is a constant problem in the unheated/conditioned air in garage...takes about 4X precautions for surface rust/corrosion.
Collets/nuts inspected pretty close and blown out every tool change because of past problems with exotics....bits cleaned brass brush and Bladecote every bit change...
So I KNOW when I'm tired that a bit I grab is Clean!
Yes I baby my machine, but throw away 1hp HSD spindle for that$$$....It would mean not eating for 2 months:)
scott

[scottp55]

BTW...That was years ago.

[EricSchimel]

Bob, maybe let us know what version of SB3 you're running.

If you're current, it might be worth asking support about that bug, I haven't seen it specifically listed as fixed in the release notes.

[scottp55]

See Notes 3.8.44 on 2017;
https://www.shopbottools.com/support/control-software
OP may want to call Tech on latest for his machine and machine OS and Firmware.
Highly suspect worn collet and no coating of any kind and high humidity(and maybe salt air like me).
I use Bladecote on bits and brass brush....a bit of Bladecote gets on every collet and nut when I inspect at bit changes.
DOES go back to SB3 3.8.** to 2014 for for multiple Pause/Resumes.....But that's when I started on first of 3 Desktops.....so kinda still cautious from my first days:)
I got BIT about 2 years ago...but not since. Currently 3.8.50 on the Desktop I kept.

(Bob...definitely check for last good working version for your machines....that's NO fun at all!)
Look at hole in "Lady....." at her foot...ticked me off!! :) (had to skim and cut again for collet nut marks!) (and happened 2 other times since VCP 8 Shopbot Edition with multiple P(auses) :(
Didn't use S(pacebar) P(ause) for years afterwards.....and still prefer to cut straight through even 9 hour cuts
(BTW...HIGHLY respect Eric even if he's from B*** town and in the deep South 90 miles away:) )

[bgrix]

Hi Scott
Thanks for the info about banding, That leads me to believe that my collet nut was also damaged, I noticed on the second issue I wrote about that my 1/4' collet also showed some as well as my 1/8". Ordered new nut and collets this morning
Bill

[scottp55]

Glad it helped Bill...it's just a good indication of wear and slippage....the bit may be toast also(usually is?)
You'd also be amazed at the "Gunk" on spindle cone until you clean it well!
Some have bought spindle cone cleaners with exact shape and felt....I just use a quality paper towel and acetone or denatured weekly(sometimes Q-tips).
And then a light touch of Bladecote or similar product for surface protection....3.5 mile from Atlantic here...so Something is needed!

Bit should NOT get hot ever if feeds/speeds are correct....I can run 12 hours and bit is always room temp once "Sweet Spot" is found.
If you ever get "Bluing" oxidation, the carbide edge is pretty well gone.....any time bit or collet has galling or a rough spot...usually time to toss it.
I got 400-600 hours on collets when production.....and about 3X that on collet nut...but things like drilling with collet nut can ruin it in 10 seconds :(
They ARE expendable parts after all!
Spindle cone is the most important to me...once that's gone...all bets are off on Everything:(
scott

[bgrix]

Hi Scott
You mention spindle cone, are you referring to the threaded end of the spindle I know the collets are cone or tapered. I am surrounded by the ocean here will look into bladecoat.
Bill

[scottp55]

Yes Bill,
The tapered inside on the spindle where the collet seats.....Very important to keep clean!! $$$