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  1. #21
    Quote Originally Posted by JAZZCNC View Post
    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.

  2. #22
    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?

  3. #23
    Here's a picture of my machine in case you're curious what it looks like...

    Click image for larger version. 

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  4. Quote Originally Posted by AlanMJackson View Post
    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.

  5. #25
    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.

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