Cutting a slot in a screwhead

The biggest problem with Dave's jig is that it will hold the heads horizontal if in a vice so you have to use very small dia milling cutters with a slow feed so unlikely to be any faster than a saw. Most of the screws I make have slots of 0.8mm width or less. Unless you have a horizontal mill with rack feed then it would be faster

I usually do them in the spin indexer which is quicker to change screws than having to use spanners on a collet block

I mounted a cheap 3 jaw chuck to an angle plate and leave it permanently set up on my D-W miller. No DRO, so I turn a piece of scrap 1/4" rod to form a pip whose diameter equals the thickness of the slitting saw. Then align by eye. If using small countersunk Allen screws, I slot them to allow them to be removed if the hex socket becomes rounded.

+1 for Jasons suggestion of the Spindexer as being faster to change workpieces than a collet block.

I'm surprised how little I use my collet blocks, primarily for that very reason. A box / tube spanner long enough to easily loosen the collet nut when held in my usual vices went on to the to-do list about 5 minutes into my first use of a collet block. Its been on the list about 20 years so far!

As has a base conversion thingy so my Spindexer bolts straight to the Bridgeport table rather than needing clamps. Only 19 years tho'. However I did square off the two long sides in alignment with the spindle so I can set it true (enough for all normal purposes) by setting a parallel in one of the table slots and pushing the Spindexer base up against it.

Clive