Tapping holes while material is still clamped to my mill table?

[ptjw7uk]

Have a look for the cheap socket sets usually in the £1 shops in most I have seen they have a hex to 1/4 square socket that you could then fit to a socket to fit the tap. Not sure a tap that small will be 1/4, I thought they were a bit smaller. Not sure if the setup will be in line enough to tap square though.
Have you tried tapping the thread holding the material in a vice to try and stop it splitting.

Peter

[HankMcSpank]

Have a look for the cheap socket sets usually in the £1 shops in most I have seen they have a hex to 1/4 square socket that you could then fit to a socket to fit the tap. Not sure a tap that small will be 1/4, I thought they were a bit smaller. Not sure if the setup will be in line enough to tap square though.
Have you tried tapping the thread holding the material in a vice to try and stop it splitting.

Peter

Some top tips there Peter ! But you know what - you're right, the square male end of a standard tap can't be 1/4", becuase the other night, I was trying to find a hex socket to kludge it into ...it transpired that something like a 4.5mm socket was too small & yet a 5mm socket was too large. (then Golidlocks dropped by & we talked about threading & screwing at length lol )

I'm assuming that male square end is an imperial dimension/fitting of some sort? Does anyone know what the square male end dimension is on a tap?

re tapping in a vice afterwards, you know what, sometimes you can get so close to a problem that the solution might be blissfully simple - no I haven't tried tapping in a vice afterwards...but I will! (though it'd still be nice to have the electric screwdriver do it, so my query still stands!)

Edit - Hi Robin, no I haven't got or tried a spiral taper - that sounds like danger to me...I think I'll stay all 'quaint & rural England' & stick with my hand threading!

[ptjw7uk]

Hi HankMcSpank
I dont think the cnc cutting of threads is remotly like hand cutting a thread in that the cutter is much smaller than the diameter of the thread being cut plus the cutter does not have a spiral on it just the thread form at the correct pitch. The cutter is then advanced into the hole centre moved to the edge the required depth and then the cutter is traversed around the hole whilst advancing at the required pitch so the cutter can whizz round as fast as is needed.
Hope decription shows how it should work, I think you are getting confused with power tappers.
Peter

[HankMcSpank]

Thanks Peter.

I've just had an Ebay seller who suggested something like this (a small chuck on a hex shaft)...

http://cgi.ebay.co.uk/CK-1-4-Hex-Sha...item5ad37c932c

which while a little 'cluncky', I suppose will get me away!