I can believe it

John K Jordan
>>>I was sanding the inside at a slow speed and it started to wobble so I grabbed the bowl, it was then that I noticed it was unscrewing from the shaft.

I remember someone on another forum reporting a similar incident. I can imagine the harmonics of a vibration at the right frequency working to unscrew the chuck in the opposite direction of rotation.

(Not exactly the same thing but just yesterday I had vibration from a polishing operation loosen a tight thumb screw and spin it off the thread and throw it across the room!)

Do you have locking set screws for your chuck? That should prevent a recurrence.

I tighten chucks by hand, giving the chuck a spin with a "calibrated" flick of the wrist for the last 1/8th turn or so. I have been doing this for years and never has one come loose, even when turning in reverse. (I don't use the locking set screws)

I make sure the seating surfaces are clean before installing the chuck. The chuck is "locked" on so tight it takes a hefty tug with the chuck wrench to remove it. (I always use a chuck wrench.) My wrist is calibrated to apply more flick for a larger piece!

As for sanding, I've given up power sanding with a rotating disk and mostly quit any sanding while the piece is rotating. I use NRS and hand scrapers to remove gouge marks and small (1", 2", and 3") pneumatic random orbital sanders to remove the scraper marks. Little dust, better surface.


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