chromenut
fully equipped rock polisher
Member since December 2009
Posts: 1,971
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Post by chromenut on Oct 4, 2010 15:52:40 GMT -5
Not sure this is the proper place for this, but couldn't figure a better place to ask this question. I'm making a bunch of earrings from heart shaped cabs and need to drill a hole for the post & bail. I've followed the lead of a few others here and use my dremel with some very nice diamond impregnated bits, but am having problems keeping the heat down, even under water. The question is pretty simple, should I drill fast, or slow? I know slow and constant gets the job done but it also generates heat, while fast gets the job done but generates heat a lot more rapidly. I'm having minor fracture issues and thought I'd come here for some of your sage advice....  |
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lparker
fully equipped rock polisher
Still doing too much for being retired!
Member since March 2008
Posts: 1,202
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Post by lparker on Oct 4, 2010 16:11:38 GMT -5
Slow and easy with the dremel...lift it up, let the water in, put it back down, drill, lift it up...........
Lee
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chassroc
Cave Dweller 
Rocks are abundant when you have rocktumblinghobby pals
Member since January 2005
Posts: 3,586
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Post by chassroc on Oct 5, 2010 11:57:04 GMT -5
Ditto to what Lee said...I believe the up and down often is most important
Charlie
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Post by Hard Rock Cafe on Oct 5, 2010 12:44:32 GMT -5
I agree with Lee.
You should also finish the hole from the other side to minimize chipping.
Chuck
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chromenut
fully equipped rock polisher
Member since December 2009
Posts: 1,971
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Post by chromenut on Oct 5, 2010 18:22:00 GMT -5
Keep trying to reply and this site keeps dropping offline. Anyway, thanks for the advice. The lift and let water in then drill and lift, that's what I need to try. Also I've been going screaming fast, guess I really need to turn the speed way down. On face-drilling, it's not much of a problem and not very difficult to accomplish. Here's a couple finished recently:  Those were relatively easy. Now these, on the other hand, were a complete PITA!  |
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chassroc
Cave Dweller
Rocks are abundant when you have rocktumblinghobby pals
Member since January 2005
Posts: 3,586
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Post by chassroc on Oct 7, 2010 14:56:25 GMT -5
They are very nice.Are the first two pictures turquoise too...The first is very different(and nicely exotic)
Charlie
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Post by Hard Rock Cafe on Oct 7, 2010 15:52:34 GMT -5
They look great!
Yorkshire Jack is the first one to suggest to me to slow down. He maintains that the bits last longer that way. You'll notice that if you go really fast under water you'll get cavitation (bubbles), which means the water isn't doing any cooling at all because it's not in contact with the bit and stone. Pulsing helps, as does slowing down.
If you think about it, we grind rock on big wheels at about 1750 rpms, yet we're drilling with a tiny little bit at often thousands of rpms, which means the surface feet per minute rate is incredibly high. Slowing down will bring the diamonds back into the range where they're most efficient and you won't have to worry about melting the nickle matrix that holds the bit together.
Chuck
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chromenut
fully equipped rock polisher
Member since December 2009
Posts: 1,971
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Post by chromenut on Oct 7, 2010 21:17:23 GMT -5
Good point Chuck. Got a show this weekend or I'd be out right now popping holes in cabs...lol... Last night's mini-adventure:  |
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