I have this hole on some of mine too – never used it, only the top three but I thinks it's for dies that are not split – ie don't have a gap so they are held in two places?

If you have a screw in the centre in the split this stops the die rotating but when I was taught to use one I was told you could slacken this centre screw and tighten the outer screws to close the die up a bit to cut a deeper thread?

I never bother, just do all three up, never very tight and nothing has slipped so far (the force it trying to rotate the die in the holder and the screw in the split stops this?)

If I am wrong I am sure someone will correct me

Chris

Hi Chris, the split die should be adjusted so that it runs freely down a standard bolt, this will then cut slightly oversize.It will also make cutting the thread slightly easier. It should then be adjusted to take small finishing cuts which will result in perfectly sized threads with an excellent finish. Do not open the die too much if the die stock is too large, or the button die O.D. is undersized as there is a chance that you could break the die. The two screws to the side of the split should be nipped up to prevent the die from opening while in use (giving an uneven thread or breaking the die). By tightening these against the central screw, fine size adjustment can be made.

Hope this is of interest, Roy.

Edited By Roy M on 04/05/2014 00:02:44

Edited By Roy M on 04/05/2014 00:03:49

Re grub screws…
No none ….apart from neatness..
But with you on the thin wall…but then it does save manufacturing cost..

A set screw has thread all the way down from under the head as opposed to a bolt that only has threads close to the end with a plain portion between the underside of the head and this threaded part.

A grub screw has thread all along and is of constant O/D the head style is usually either internal hex. or slotted. The "point" can have various styles to suit the actual application.

Hope this helps.

Eric