John, from WNT home page, go to tool holders—rotating tools—- micro precision collets. Hope this helps. I used to deal with them until about 4 months ago. If you can get onto their site proper, there is masses of info on everything you need to know about machining, hope this helps. Roy.
Just a thought, for all those interested, the flat on the cutter shank is positioned so that it is not directly opposite a cutting flute. This effectively reduces the cutter run out.
Edited By Roy M on 07/10/2016 18:07:43