Clarkson holders required, as mentioned can be held in ER collets, I have a mixed bunch of cutters including this type, I use my ER 25 collet to hold ea. type & have had no problems so far.

George.

Most of the usual ME machine and tooling suppliers will have holders to suit so you don't just have to search for old Clarkson branded ones. Myself I just hold them in my ER Collet holder.

The reason for the threaded cutters – Clarkson style – is to prevent the cutter being pulled down form the collet when side cutting or when a deeper cut is applied.

On smaller machine's this is less of a problem but it can still happen particularly if you are using a longer length of the cutter flutes. For most model engineering where smaller cuts and smaller cutters are being used ER collets work very well.

However even on small machines it can and will happen if cutting with larger cutters say 5/8; 3/4" and a fairly deep cut is applied its very possible for the forces to pull the cutter down from an ER collet, this cannot happen with a screw shank Clarkson cutter in a Clarkson chuck.

So just be aware of the limitations of ER collets if you need to remove a fair amount of stock, more smaller cuts are the order f the day — don't be greedy and try one large cut !

John

Derek,

You may find this previous thread of interest: **LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=105995

MichaelG.