wfpii
off to a rocking start
Member since November 2018
Posts: 4
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Post by wfpii on Jun 24, 2022 12:23:27 GMT -5
When drilling a hole if you drill most of the way through, how do you know where to start drilling on the back side so you don't have a break through?
Bill
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stefan
Cave Dweller
Member since January 2005
Posts: 14,113
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Post by stefan on Jun 24, 2022 13:18:56 GMT -5
I just deal with break through. you could take a set of painstaking measurements, but I used a little silicon mat to set the rock on and break through is minimal.
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Post by vegasjames on Jun 24, 2022 17:34:34 GMT -5
Best to drill the stone before cabbing so the breakthrough can be ground off. Or it already cabbed maybe add a thick layer of glue to the backside, then drill the cab and remove the glue.
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Post by Rockoonz on Jun 24, 2022 20:21:17 GMT -5
I use a ball end burr to drill focal beads, and while drilling I keep a finger over the exit point, when I feel a tickle I flip it and finish.
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Post by jasoninsd on Jun 24, 2022 21:34:11 GMT -5
Out of curiosity...what if a person drilled the hole with a smaller bit...so any "break through" chipping would be minimal? Then the "correct" sized drill bit could be used afterward...
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stefan
Cave Dweller
Member since January 2005
Posts: 14,113
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Post by stefan on Jun 26, 2022 8:36:09 GMT -5
Jason- you would still get break through with the larger bit. I even tried duct tape (which helped some).
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Post by hummingbirdstones on Jun 26, 2022 8:42:09 GMT -5
Out of curiosity...what if a person drilled the hole with a smaller bit...so any "break through" chipping would be minimal? Then the "correct" sized drill bit could be used afterward... I think that would work if you already have the hole. Just drill half way from each end to the center and there should be little or no chipping.
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rockbrain
Cave Dweller
Member since January 2022
Posts: 3,036
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Post by rockbrain on Jun 26, 2022 10:27:19 GMT -5
I've drilled several stones and for some reason I've not had any break through. I'm using cheap bits from Harbor Freight. I tried the trick that I read here. Put your finger behind the stone until you feel a tickle then turn it over and drill from the other side. The blood showed up the same time as the "tickle". We've not drilled a tremendous quantity, maybe a dozen, but we just haven't had any issues yet. Cheap Harbor Freight bits, cheap plastic vice in a pan of water, cheap flexible Dremel shaft.
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Post by greig on Jun 26, 2022 17:22:35 GMT -5
I have only "drilled" a few but have been successful. I put the stone in a cup of water to keep the bit and stone cool and drill(really grind) slowly. If I had a drill press, I would use that for more control.
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wfpii
off to a rocking start
Member since November 2018
Posts: 4
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Post by wfpii on Jun 28, 2022 14:00:45 GMT -5
Thank you for all suggestions!
Bill
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