Collet sizes ER???

[steam4ian]

G'day all.

I have recently purchased a set of collets and a 3MT chuck. I want to add to the collets included in the set but I don't know what size the collets are compared to the chuck.
I can measure the major and minor diameters and the length of the tapered section but then I need to relate that to an ER number.

How are ERxx sizes measured? Please advise.

Regards
Ian

[dickdastardly40]

Ian,

I'm not at home so can't refer to my ER25 set however I think that the popular sizes for sets are ER16, ER25 and ER32 and possibly ER40. I'd guess ER32 for a 3MT chuck. If you have a set of say 18 then the chances are that you have all the bases covered regarding sizes for that set. Each collet covers a 1mm range so 6-7mm includes 1/4".

See the link for other info:

www.colletsdirect.co.uk/html/about_er_collets.html
www.colletsdirect.co.uk/html/er_32_collets.html

Hope this sorts you out.

Al

[AndrewP]

Does this help Ian?

www.pcmtooling.co.uk/ER%20Collets%20+%20seals.htm

It would appear that the diameter at the top of the taper is 1mm more than the ER series number

Which must make my set which are 24mm at that point complete b*****ds

[steam4ian]

G'day Al, AndrewP.
Thank you for the info, most helpful. I think my set is something like ER32 but it has some 2mm gaps. It was comparatively low cost, made in the "far east".
When I get out to the shop today I shall measure it up and see if my set has more reliable parentage that AndrewP's

Thanks again.
Regards,
Ian

[mmaidnz]

I always thought that the number was relative to the maximum diameter collet the chuck could accept.
However,Ihave an ER32 chuck,and the max diameter is 20mm.A trifle illogical,no?
of course,you can buy an endmill 25mm,with a 20mm shank.So,realistically,your ER32 set can use up to 25mm cutters.
Ian,what is the largest collet you got in the set?That would indicate the ER size.The 2mm gaps are presumably there to make you buy more collets at $47 a pop:(.I assume you got 6 with the chuck,that seems to be the standard issue around these parts.

[Deleted]

This should clarify things:



Cheers.