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rohamm
08-01-2011, 09:54 PM
With a 4x 1/2" dowel pin buried half way into a collet pulled up just hand-tight (no wrench on the draw bar) how much deflection should I see if I just try to move it back and forth by hand?

If I back off the adjuster all the way, I'll see four-or-so thou. With it as tight as I can make it, about half of that goes away.

Carld
08-01-2011, 10:31 PM
Why are you measuring side movement with the collet hand tight????:confused:

If your getting about .002" side movement with the collet tight you have bad spindle bearings.

tyrone shewlaces
08-01-2011, 10:54 PM
I'm with Carld... Hand tight??
A collet will tend to even out imperfections, i.e. taper of collet to nose and size of bore to size of material, but only if you get it tight. Yea it would be a more perfect world if things were perfect ;) but snug it as normal and then see what you've got. Your bearing might be fine and the error be in the loose collet. I won't tell a guy to buy new expensive bearings if he hasn't tightened the collet on his inspection yet.

Actually, the better way would be to indicate directly off the spindle bore anyway to measure deflection of bearings. Isolate that first and get your adjustment collar set right. Then go after collet inspections.

My guess is the size of the bar isn't perfectly the same as the bore of the collet, so just a slight hand-snug is only tightening things up on a single point on the bar rather down the collet's entire gripping faces. Tapers that don't match can cause this too.

But whatever.
Isolate things and don't make it worse by adding a bunch of links which will just complicate it all.

Black_Moons
08-01-2011, 10:57 PM
With a 4x 1/2" dowel pin buried half way into a collet pulled up just hand-tight (no wrench on the draw bar) how much deflection should I see if I just try to move it back and forth by hand?


Depends how hard you pull. You do realise you can bend a 4" x 1/2" bar 4 mils easy by hand?

Repeat after me: Metal is a wet noodle.

The sooner you realise that, the sooner you'll be happy with machining.

Also, 1+ on what everyone else said about tightening the collet properly.

No idea what 'adjusters' you are talking about, but if they are anything to do with spindle bearings, you set those by running tempature usally, Not by runout.