ruined a mill spindle (maybe)

[SE18]

I ruined (fretted) the spindle on my Clausing 8530 Mill. It all started when it became difficult to release my collets from the drawbar. I keep a brass hammer handy to pound the acorn nut atop the drawbar. To remedy (besides ensuring spindle clean and oiled), I didn't tighten the drawbar nut as tight as I should have, thinking I was overtightening it and contributing to the difficulty to release the collet. While milling, the collet became loose and spun around for a few seconds inside the spindle, which was long enough to produce extensive fretting inside the spindle and on the MT2 collet. Now I don't know what to do. Extensive searches on the Internet reveal no information on corrective action. One person said to use some sort of scraper on a different forum. Perhaps I don't need to do anything at all since the mill is still working? Your feedback would be great.

 

[nautilus29]

I would blue up one of your good collets and tighten it in the mill. When you take it out see how much surface contact you have between the spindle and the collet. You may be able to get away with cleaning up any high spots if there is still enough contact to hold it securely.

I would also try putting dowel pins (or stick your end mills out of your collet a little bit) and check the runout of different collets. Up towards the collet and away from the collet if you can. This can help you decide what you want to do.

If these tests dont look too bad, and you aren't noticing extra chatter in your tools I'd say you can leave it go if this is just a hobby mill. If it gets heavy use you may want to consider getting the spindle reground, although I'm sure that is expensive.

 

[SE18]

thanks; the blueing test was done and doesn't look bad; just the tip part inside the spindle so I'll just continue using it for my occasional hobby work

 

[aonemarine]

I would get an mt2 reamer and spin it lightly in the spindle to clean it up, and be checking it before and after use with a .0001" DTI.

 

[Wizard69]

You can always pull the spindle quill and take it to a grinding shop for rework. If the galling isn't to deep they may be able to clean the taper up. Otherwise you can make a new spindle. At some point almost all spindles end up needing resurfacing due to the draw in of the collets.

You can try the various remediations already described but they generally lead to a loss of precision in run out.

Another option to consider is to have the spindle ground in place. This is done on CAT style tapers but i have no idea if it can be done on a manual morse taper machine.

By the way Morse tapers are locking!! That means one properly set well be hard to release. A Morse taper collet should always require some effort to remove.

 

[SE18]

thanks again, all!

AoneMarine, I'll try your method first with a finishing reamer. I'll turn it by hand.

As for the collett that spun, it shows signs of distress (circular lines). So perhaps put it in lathe chuck and using compound at angle use a finishing bit to lightly clean it up? (semper fi)

BTW, I got more help here than on 2 machine forums

 

[SE18]

Update: I spun the collet MT2 in the lathe while holding sandpaper on it which effectively removed the galling. Ordered the MT2 finishing taper which should arrive before Feb. 7, as I used low-cost shipping