What tooling to drill lots of 10mm holes 45mm deep?

[AlanMJackson]

Much quicker to drill just past half way with No or few Peck's then flip material and use same G-code.

That's basically what I'm doing now. Thanks for the reassurance.

I haven't found the drill / counter bore combination I'm looking for yet. I'm looking for 10mm drill with 16 or 18mm counter bore. The largest I can find so far is 6mm drill with counter bore from trend. All the larger ones I've seen have a smooth short pilot just to locate the counter bore in the hole but not to drill it.

[AlanMJackson]

Mike,

Do you think it would be possible to bore out the counter bore collar of something like this:

Trend CB58-14HSS 1/4 drill dia. x 5/8 counterbore

so it would take a 10mm drill? Is that madness?

[AlanMJackson]

Here's a picture of my machine in case you're curious what it looks like...

[irving2008]

Mike,

Do you think it would be possible to bore out the counter bore collar of something like this:

Trend CB58-14HSS 1/4 drill dia. x 5/8 counterbore

so it would take a 10mm drill? Is that madness?

It might be possible but
a) there'd be 2mm less thread for the locking grub screw which may be an issue; and
b) you'd probably need to bore/drill it out in a lathe for any degree of accuracy in run-out.

[GEOFFREY]

I would think that the counter bore is likely to be hardened steel so may be difficult to machine. If the thread depth on the grub screw is insufficient to get a good grip on the drill, you could try using say 3 grub screws. I would think it would be easier to use a fairly low quality drill (soft) and turn the shank down. G.