Diamond Drill Bits and Fire Polishing

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artisand
Posts: 44
Joined: Thu Sep 18, 2003 7:05 pm
Location: Neptune Beach, FL

Diamond Drill Bits and Fire Polishing

Post by artisand »

Hi,

I have two questions. I just drilled my first holes in some cabochons. I made 20 holes before my drill bit gave out. These were mostly three layer cabochons. I drilled under water with them sitting on a sponge. I did not press exceedingly hard and removed the bit periodically to be sure water was in the hole. This particular bit cost $8.00 so I had hoped for it to last longer. I checked the archives and went to Harbor Freight today where I bought 20 various sizes, most of which I can use, for $6.99. How many holes can I expect to get from a drill bit?

I would also like to fire-polish the holes, as they are a bit frosty looking. Is it possible to polish the small holes without melting them? Is there a special schedule to follow or is it just fire up to 1400 and watch, watch, watch.

Thanks for your help.

Sharon
dee
Posts: 302
Joined: Tue Mar 11, 2003 5:20 pm
Location: Atlanta GA
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Re: Diamond Drill Bits and Fire Polishing

Post by dee »

artisand wrote:Hi,

I have two questions. I just drilled my first holes in some cabochons. I made 20 holes before my drill bit gave out. These were mostly three layer cabochons. I drilled under water with them sitting on a sponge. I did not press exceedingly hard and removed the bit periodically to be sure water was in the hole. This particular bit cost $8.00 so I had hoped for it to last longer. I checked the archives and went to Harbor Freight today where I bought 20 various sizes, most of which I can use, for $6.99. How many holes can I expect to get from a drill bit?

I would also like to fire-polish the holes, as they are a bit frosty looking. Is it possible to polish the small holes without melting them? Is there a special schedule to follow or is it just fire up to 1400 and watch, watch, watch.

Thanks for your help.

Sharon
sharon, you might want to check out more expensive drill bits to get more longevity from them, i think the ones i ordered from my stained glass supplier were a tad more expensive and i get more than 20 holes/bit....

for fire polishing something i drill holes in, i don't go above 1200 in my kiln, 1400 is likely to close the holes - 1150 might even do what you want - try one piece at 1150 and see what it looks like - it's easier to fire polish a 2nd time than drill a second time....

D
Dee Janssen
Unicorn's Creations Studio
http://ucjewelry.com
dee@ucjewelry.com
Mark Kemp
Posts: 59
Joined: Mon Mar 10, 2003 11:57 am
Location: Corvallis, Oregon
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Post by Mark Kemp »

How frequently did you lift the bit? You said periodically. You need to lift it a bit every few seconds, maybe 2 to 5, to let water in under the bit. You develop a rhythm of up and down. Some of the cheap Chinese bits I've used lasted 30 to 60 holes. Lately the ones I have don't seem to be drilling very fast, so I got some expensive ones to try.
artisand
Posts: 44
Joined: Thu Sep 18, 2003 7:05 pm
Location: Neptune Beach, FL

Post by artisand »

Dee and Mark,

Thanks for your help. Mark, I was not lifting the bit that often. Will try that. Dee, I thought $8.00 was a pretty expensive drill bit for only 20 holes, but maybe I wasn't lifting often enough. Will try that now that I know I should be able to get more holes from a bit. Ya'll are wonderful!
Tom White
Posts: 174
Joined: Tue Mar 11, 2003 9:14 am
Location: Houston, Texas

Post by Tom White »

I may be too cautious in my drilling technique but I have drilled 100 holes in pendants with one 2mm drill. I use a variable speed Dremel grinder with a three jaw chuck mounted in a Dremel drill press attachment. I place an 8" cake pan on the drill press table and put a piece of 1/8" or 1/4" plywood larger than the piece I am drilling inside the pan. I place the glass on the plywood then add enough water to cover the glass on the plywood by 1/8". I position the glass beneath the diamond drill (usually about 1/8" to 3/16" from the edge of the cab) with the motor turned off. I raise the drill and start the motor and set the speed to about the middle of the range. I then "woodpecker" the drill against the glass in a kiss and release movement. I doubt that I hold the drill against the glass as much as half a second before I raise it off the glass. I judge the pressure to apply by watching the milky cuttings the bit produces when it is in contact with the glass. I use the minimum pressure needed to produce a nice flowing cloud of milky cuttings moving away from the bit as it sinks into the glass. I can hear a change in the sound of the drill against the glass as it nears the bottom side of the glass and reduce pressure on the bit slightly to avoid excessive chipout on the bottom of the glass. I have found that the minimum pressure needed to keep the drill cutting and a medium speed on the Dremel gives me the longest bit life.

Best wishes,
Tom in Texas
daffodildeb
Posts: 125
Joined: Mon Jul 28, 2003 3:48 am
Location: Hot Springs Village, AR

Post by daffodildeb »

Tom, and others, I haven't started drilling holes with my new Dremel press, but how about this technique--dish of water, cushioned by sheet packing material (don't know what this kind is called but it's white), and water from an IV drip or 60cc syringe dripped steadily on the hole? I know that in the operating room one of the surgical tech's jobs is to trickle water in just this fashion when bone is drilled...

And I HAVE done that! :lol:
Deb
Mike Byers
Posts: 56
Joined: Mon Mar 10, 2003 6:57 pm
Location: west central Indiana
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Post by Mike Byers »

The "triple ripple" bits I got from HIS Glassworks seem to last forever, and even through they're more expensive than other bits I've used, it seems they're the most cost-effective in the long run. My drilling technique is similar to Tom's, except that I made my "basin" out of a piece of Corian countertop material that's been routed out to hold the water. I've had good luck drilling glass on a harder surface like Corian, so long as I clean the basin now and then to prevent little bits of glass from getting between the basin surface and the piece I'm drilling. I've also stuck a piece of wooden toothpick in the hole when fire polishing a drilled piece: the toothpick burns out, but seems to prevent the hole from changing size.
artisand
Posts: 44
Joined: Thu Sep 18, 2003 7:05 pm
Location: Neptune Beach, FL

Post by artisand »

Thanks so much for all the info.

Sharon
watershed
Posts: 166
Joined: Wed Mar 12, 2003 1:44 am

Post by watershed »

As much as I hate to say it. $0.40 a hole, seems a bit pricey and you've gotten some good advice for cutting the cost, , but what are you selling the pieces for? $0.40 is 1/2 a 12oz can of Coke. Most places, 1/2 a candy bar.

Yes improve your technique and your equipment, but $0.40 is less than the daily newspaper. Maybe I've been listening to too many hours of NPR fundraising.

Sorry to seem grumpy

Greg
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