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

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Originally Posted by JAZZCNC

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

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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.

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?

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

Attachment 11270

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Originally Posted by 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?

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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.

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.