Drill Chuck Runout

[Enough!Participant @enough]

My chuck has suddenly developed a case of the wobblies

[Enough!Participant @enough]

I have this decent (Rohm) 5/16" keyless drill chuck. A few weeks ago I put it on the mill and found that it had developed highly noticeable runout …. the kind of runout that I couldn't have missed previously. I'm careful with this chuck and certainly don't recall any serious accidents. I just checked the runout as follows:

 

The runout on the spindle and on the arbor shank (point A) was negligible. The runout on the chuck at point B (measured with a centre drill installed) was 0.02" TIR.

The chuck is tight (very) on it's Jacob's Taper arbor and in the absence of any severe handling – which I swear it hasn't had – I don't really know what would cause this to suddenly occur.

– notwithstanding the tightness of the fit on the Jacobs Taper I'd like to remove/refit it (and perhaps check the runout of the JT vs the shank) does anyone have a recommendation for getting these apart (without being rough on the chuck of course).

– Any other suggestions as to what might have caused this?

Edit: just noticed that the leader-line from The 'B' label seems to have gone walkabout. Just imaging a horizontal line from 'B' to the chuck body.

Edited By Bandersnatch on 15/04/2017 01:03:14

[Enough!Participant @enough]

Hmm – always the way – having posted that and looked closely at my own picture, it looks to me as if that spline at the top has moved out. I thought at first that was its normal position but having checked some pics at the Rohm site I think it may have shifted. I'll try pressing it in tomorrow.

[SpurryParticipant @spurry]

To break the taper just get yourself some Chuck Removal Wedges, sized for the taper.

One example from Arc

**LINK**

Pete

[roy entwistleParticipant @royentwistle24699]

For the B measurement I would have gripped something in the chuck rather than use the chuck body

Roy

[Enough!Participant @enough]

Spurry – they look handy. I'll look around on this side of the pond …. or perhaps I could make something.

Roy – yes, I probably should have done – and would have done if I'd been looking for a precise value – but I was only after a ball-park.

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