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DaveH:
Wong,


--- Quote from: wongster on March 21, 2012, 11:03:30 AM ---Hi Dave,

Would your last sentence about the forces mean that it is not suitable for workholding in the lathe? 
Regards,
Wong

--- End quote ---

Not at all, just the oposite, collets are more than suitable for work holding in the lathe. The work (bar) needs to be round and clean, which silver steel is.
 :beer:
DaveH
DaveH:

--- Quote from: wongster on March 21, 2012, 11:03:30 AM ---Hi Dave,

I read somewhere (can recall now) that each collet in the ER series can hold down to about 1mm smaller in diameter. That is, if I'm putting in a rod or an endmill, of diameter 3/8" (which I've a few endmills or slot drill from sherline with such shank size), I should be using 10mm collet but not 9mm.  Do correct me if I'm wrong.  So for the 1/2" diameter silver steel rod from the Hemingway kit, I was using the 13mm collet.

Regards,
Wong

--- End quote ---

Wong,

You are dead right  :thumbup: :thumbup: :thumbup:
 :beer:
DaveH
wongster:

--- Quote from: Fergus OMore on March 21, 2012, 09:39:48 AM ---
Your book of words suggests that you use Garia H and a razor sharp tool. Again Thomas emphasises rigidity and problems of overhangs.

--- End quote ---

Norman, I thought about your comment on problems of overhangs while I was driving home (I was typing the post on my little iPhone while driving... good that I didn't get caught by the traffic police...).  The ER32 chuck do extend out quite a bit.  If I would like to continue using collet chuck while I get the hang of centering stuff on the 4 jaw, should I be getting, say, ER25 or ER16 collet chuck?  I bought the ER32 because I have the full set of its collets from impulsive buying...  :doh:  and also its bigger range... :hammer:

Regards,
Wong
Miner:
Hi Wong,
Your current ER'S should be just fine, It's the distance away from your lathes spindle bearings that is creating a rigidity problem. I'n not familer with what system Proxxon uses to attach the chucks to your lathes spindle nose. Replicate that exactly on a roughed in ER collet chuck out of a piece of good steel. After its attached to the spindle nose, You then bore the ER internal taper and cut the threads for the ER nut. That will get you as close to the lathes spindle bearings as possible and leave your spindle thru hole open while turning longer stock with the collets. The system you have right now does work fine on a mill. But the chuck is supported much closer to the mills spindle bearings.

Pete
wongster:
Hello Pete,

Thanks for your input. I was thinking of making or finding one ER32 chuck like what you mentioned but couldn't figure out what to do it or find one that fits. The Proxxon lathe holds the 3-jaw chuck by 3 M6 screws. The PCD is 83mm and the recess is 70mm in diameter.

I bought a piece of 100mm diameter mild steel but find it hard to mount on my 4 jaw chuck (my 3 jaw chuck max'd out at 80mm+). I put this on hold for the time being to gain more knowledge doing some simpler project while I think of how I should approach this.

Regards,
Wong
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