Thread: Are all R8 collets the same?

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Recently (in ) I had this issue come up and the answer has changed, so I figured I'd add it on: nowadays, all R8 collets are not threaded the same.
A lot of the orient ones are threaded M12 x 1.75.
Most of the R8 collets sold in Europe and elsewhere are metric-bore, and threaded metric as well.
Some US retailers offer both; LittleMachineShop (for one example) offers mini-mill drawbars in both English and metric threading to allow using either kinds of collets. Much of what they sell ATM is China-made however.

I got into a situation where I have a Grizzly mill that has a 7/16"x20 thread drawbar, and I wanted a longer ER16 tool holder in order to use tiny mill bits better. I have a 1/8" R8 collet but they don't stick out of that very far.

Most of the cheaper Chinese-made ER collet chucks that have straight shanks have metric-sized shanks, if they don't have an MT shank. So I needed an R8 shank that could hold a 16mm tool....

When I went looking for R8 collets that were 16mm, most of them were titled something like "R8 x 16mm x M12",,,, which led me to investigate the thread issue further.

Metric-bore R8 collets sold by US-based companies will generally have the English thread.
If you buy metric-bore R8 collets from any of the China-direct shopping sites, today they're probably going to have the metric thread too. The few that do have the Imperial thread tend to specify so.

You could also just make another drawbar with the metric threading too, but some lazy people (like me) would rather just avoid the hassle and make sure all your tooling has the same threading.

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The 5C collets I don't know about... None I could find specified the threading they use. I don't use 5c's so this isn't an issue for me.
There is a Euro standard variation of 5c collets is called "K32" that normally does have a metric thread.
There has been some confusion over the K32 collets because some do come with the English threading, and they are similar enough overall to be able to fit in 5c collet holders--but the overall length and closing angle are different as well so it is not really "the same".
Mixing up 5c and k32 tooling will damage ,,,, something. They may appear to fit but really don't.



Buyer beware!........

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