ER Collet Question

Most companies claim .039" collapse range on typical ER collets...
See: http://www.techniksusa.com/wood/erpcm.htm
I find it hard to believe that a 1MM collet (04208-01.0) can close down to just about zero and still hold something. Anyone know if the smaller collet sizes have a different close-down tolerance that they are simply rounding?
Regards, Joe Agro, Jr. (800) 871-5022 01.908.542.0244 Automatic / Pneumatic Drills: http://www.AutoDrill.com Multiple Spindle Drills: http://www.Multi-Drill.com
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Joe AutoDrill wrote:

When I buy the smaller ER 11 collets, they can get down to about .015" without appreciable runout.
I, uh, haven't tried holding a 0" drill, tho ;-)
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They can. Years ago 1mm was the smallest collet you could get. Today you can get .5mm collets. The .5 will give you good TIR more consistantly than a 1mm collet will. Also when using very small shank drills, they are less apt to get caught in the slots on the smaller collet.
Anymore, I try to use 1mm shank drills for any drill under 1/32". Those drills tend to be straighter and are certainly easier to change. Unfortunately most have a fairly limited drill depth.
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Dan

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Normaly, the smaller ones can only close-down 0.5mm. Above 3mm or so (depending on the collet size), they do 1mm.
Nick
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