Struggling to identify a collet

[greenlinux]

Hi All,

I would appreciate any information on the following: a collet on a relatively small milling machine has eccentric ring in the threaded part that holds the collet captive (suggestive of ER) but, the diameter of the set of collets is 24mm (23.94mm) and the length of the collets are 45mm (45.07mm). It looks like ER or OZ but I have not found any standard that matches this aspect ratio. I would like to identify it as I have some sizes of collet missing and would like to source them. If it proves impossible to identify I will replace the chuck with ER and buy a set of collets.

Many thanks,

James

 

[M.B. Naegle]

TG series?

 

[Milland]

Maybe a RDO (for routers) collet? Whatever it is, it looks like a small size range capacity (not much compression), so changing to ER might be sensible anyway.

 

[Milland]

TG series?

Pretty darn sure it's not TG.

 

[technocrat]

oz20 or eoc20, chinese based on some din I think

 

[greenlinux]

oz20 or eoc20, chinese based on some din I think

Hi technocrat, thanks. Your answer encouraged me to look again at OZ so I had a look in the standard, ISO10897 (formerly DIN as you said), and it does seem very similar. The OZ20 diameter at the widest point is expected to be 29.8mm but the overall length is correct (45mm). When I put the collet into the holder and turn it upside down it drops out easily which is not the expected behaviour - collet should be held by the eccentric ring near the bottom of the holder. My guess is that my collets are not made exactly in accordance with the standard and if they had the correct max OD I would need to angle them to get them out of the holder, which is the expected behaviour.

Something I need to decide now is if I should source the missing collets or change to ER. I rather like the length of this collet set, 45mm, to get the same in ER would mean going to ER40. But, the machine is not so powerful as to warrant having a chuck that can hold such large diameter tools. It will come down to the relative cost and ease of sourcing an ER collet set and chuck against sourcing the 6 or so missing OZ20 collets.

James