jamesp
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Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 17, 2018 10:48:17 GMT -5
Trying these 3mm core bits and not getting as many holes per bit on the 2 bits tested. Say 20 instead of 30. They drill faster and wander way less in the hole.(than the solid bits) They also break the core off several times in the hole and you can hear it rattling in the hole being drilled. I just kept drilling till the hole was completed with out ill effects from the loose core. I tried dressing them as you would a diamond saw blade with AO grinding wheels and noticed little improvement. One of the new core bits got plugged by the core getting stuck it the hole which basically ruins all performance. Not good. i have about 150 drilled pieces rolling in the rotary 6" I.D. barrel at 90 RPM with slurry protection for 24 hours now. May pull some today and inspect for breakage. Glass is 1/4 to 3/8 inch thick. ETA: Sawed the bits shorter so as to reduce wobble. They wobble ! The shorter the bit the less wobble. I sometimes have to re-loosen the collet and rotate the bit in the collet to find a "less wobble" position. Wobble creates severe vibration which can break your work.
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Post by fernwood on Oct 17, 2018 10:51:57 GMT -5
Thanks for the update. Wondering how it was working.
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surreality
starting to spend too much on rocks
is picking up too many rocks at the beach again
Member since January 2012
Posts: 217
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Post by surreality on Oct 17, 2018 11:04:43 GMT -5
Those do look really good thus far -- I need to PM you about stuff when we get back from travel, since I am definitely interested in these and some of the other 'where did the green come from?!' pieces without holes as well. (All current funds are in travel emergency pile, otherwise.)
They'd definitely make really stunning pendants!
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 17, 2018 11:11:52 GMT -5
Thanks for the update. Wondering how it was working. Quality varies tremendously from brand to brand. I have not received the bits with coarser 50 grit. I have a feeling they are going to do the best job. Don't be deceived, drilling agates are much trickier. The softness of glass is a good thing.
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jamesp
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Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 17, 2018 11:15:03 GMT -5
Those do look really good thus far -- I need to PM you about stuff when we get back from travel, since I am definitely interested in these and some of the other 'where did the green come from?!' pieces without holes as well. (All current funds are in travel emergency pile, otherwise.) They'd definitely make really stunning pendants! The tumbles are starting to sell surreality. Posting on various Facebook artisan sites is a great way to market. Not just tumbling sites but any artist that might use deco glass. Paypal paypal paypal, that's how they pay.
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braat
spending too much on rocks
Member since December 2016
Posts: 350
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Post by braat on Oct 17, 2018 13:55:51 GMT -5
Thanks for the update. Wondering how it was working. Quality varies tremendously from brand to brand. I have not received the bits with coarser 50 grit. I have a feeling they are going to do the best job. Don't be deceived, drilling agates are much trickier. The softness of glass is a good thing. So true about quality...I used a 3mm diamond ball bit from an older set of varied bits I had laying around and got a few holes done (5-10 I'm guessing from memory) in mohs 6-7 stuff before it wore out. I couldn't find a local source for 3mm bits but found a set of 30 on Amazon for 3 bucks. Figured I couldn't really lose for 3 bucks so I ordered...3 months later they arrived from China (still blows me away how they can make, ship across the planet and deliver to my door for 3 dollars). Anyhow bad news - I got one hole done and it was toast so lousy quality for sure. Good news - I got 29 left and at my current rate I'm good for eternity But obviously useless for your mass production...I'll be following what works for you so thanks for sharing your info...
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 18, 2018 5:02:57 GMT -5
Quality varies tremendously from brand to brand. I have not received the bits with coarser 50 grit. I have a feeling they are going to do the best job. Don't be deceived, drilling agates are much trickier. The softness of glass is a good thing. So true about quality...I used a 3mm diamond ball bit from an older set of varied bits I had laying around and got a few holes done (5-10 I'm guessing from memory) in mohs 6-7 stuff before it wore out. I couldn't find a local source for 3mm bits but found a set of 30 on Amazon for 3 bucks. Figured I couldn't really lose for 3 bucks so I ordered...3 months later they arrived from China (still blows me away how they can make, ship across the planet and deliver to my door for 3 dollars). Anyhow bad news - I got one hole done and it was toast so lousy quality for sure. Good news - I got 29 left and at my current rate I'm good for eternity But obviously useless for your mass production...I'll be following what works for you so thanks for sharing your info... There is excellent quality from the oversea folks. You just have to sample till you find it. The government must be giving financial backing for them to make/ship so cheap, gotta be. 6 holes out of one bit in agate is typical for a quality bit.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 19, 2018 11:22:00 GMT -5
Started out with all sawn rectangles. After 48 hours with 60% barrel fill/clay slurry/90 RPM/SiC 60/~100% grit breakdown No broken holes even at 90 RPM and low barrel fill ! good thing Going to countersink some with an oval burr and see how they do.
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Post by MsAli on Oct 19, 2018 12:48:47 GMT -5
Really looking good!
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 19, 2018 13:50:43 GMT -5
I'm a slacker compared to the adornments Alison adds. El cheapo holes, maybe it will sell based on the look of the glass ? Perhaps some fancy bails...
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 19, 2018 13:55:02 GMT -5
One of the 3mm core drills drilled over 60 pieces. The next one got a core plugged in it and would not finish the second hole. All I know to do is drill the core out with a 1mm diamond drill.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 20, 2018 6:50:03 GMT -5
This is the latest model Dremel drill press. It is a piece of junk. It bends where the Dremel tool is clamped when drilling with increased down pressure and drills slanted holes. Drilling 1/4 to 3/8 inch thick glass and a larger 3mm bit allows a lot of down pressure without cracking the glass. 1.2 to 1.5mm bits tend to break the corner off easily because the smaller bit becomes a chisel with higher down force. This model no good, the black collar that the Dremel tool screws onto is weak and flexes: Guessing that these older Dremel presses may be stronger. Available on EBAY used and cheap:
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 20, 2018 9:47:10 GMT -5
6mm ball bit sure is user friendly for altering hole entrances. Countersinks and other shapes a dime a dozen. Best with 2nd Dremel drill press. The new crappy Dremel press will perform this operation with no problem.
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Post by hummingbirdstones on Oct 20, 2018 10:16:22 GMT -5
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Post by Drummond Island Rocks on Oct 20, 2018 12:04:22 GMT -5
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 21, 2018 5:19:31 GMT -5
Chuck braat hummingbirdstonesI made some drill speed findings and drill press findings I should share. First the press. All of the presses you guys posted are much more rigid looking than the plastic Dremel press. At a bare minimum the press has to clamp the drill motor firmly and not deflect. That is common sense. Those machines look totally rigid. Secondly, the drill speed. You best keep the RPM well below 5000 on agate. It gets too hot too fast because they generate much more heat at the cutting face. The drill sits a long time on the same material because it is so hard and heat builds, cooking the braze that holds the diamonds. Or drill slowly. With glass the drill cuts it so fast there is little time for heat to build. This allows much higher speeds like the 8,000 to 12,000 RPM that a Dremel is designed for. The drill bits are lasting 30 to 60 holes in 1/4 inch thick glass at 10,000 RPM. They would likely last longer if drilling slower but I was looking at drilling quick and the bits are so cheap... I seem to be lucky to get 6- 8 holes per bit in similar thickness agate at 2000 to 3000 RPM. And 10,000 RPM was cooking the diamonds on first hole. I ordered a used old Model 212 Dremel press hoping it was more rigid. It was certainly cheap. Next step is a way to flow fresh water thru the tray so the work piece can be seen. The water clouds up after 4-5 holes and you can't see your work piece. And a quicky level control to keep the water about 1/8 inch deep over the work piece. Especially when they vary in thickness.
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Post by grumpybill on Oct 21, 2018 7:44:20 GMT -5
You best keep the RPM well below 5000 on agate. It gets too hot too fast because they generate much more heat at the cutting face. That is why I've started using a Foredom rather than my non-variable-speed Dremel. It probably takes more time per hole, but the bits last longer. I've read reviews on several sites and it seems it's difficult to get the tool aligned perpendicular to the work, causing it to break small diameter bits. I made a lowball offer on one, so maybe I'll get a chance to find out. EDIT: Apparently I'm not the only person reading this thread. A few minutes after making the offer, I got an email saying the critter had sold at full price.
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jamesp
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Member since October 2012
Posts: 36,353
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Post by jamesp on Oct 21, 2018 10:28:18 GMT -5
You best keep the RPM well below 5000 on agate. It gets too hot too fast because they generate much more heat at the cutting face. That is why I've started using a Foredom rather than my non-variable-speed Dremel. It probably takes more time per hole, but the bits last longer. I've read reviews on several sites and it seems it's difficult to get the tool aligned perpendicular to the work, causing it to break small diameter bits. I made a lowball offer on one, so maybe I'll get a chance to find out. EDIT: Apparently I'm not the only person reading this thread. A few minutes after making the offer, I got an email saying the critter had sold at full price.
Well at .50 to 1.00 dollars per bit 30+ holes for pendants is not a problem. But drilling agates can get expensive at 7 pendants per bit. Gee Bill, I don't see a way to break a small bit. I would think that much down pressure would have easily broken the agate or glass. Be aware, I got totally frustrated drilling agate back when and gave up completely. I found it real difficult. This glass is a joke, no effort at all.
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Post by grumpybill on Oct 21, 2018 12:13:27 GMT -5
Gee Bill, I don't see a way to break a small bit. I would think that much down pressure would have easily broken the agate or glass. I've broken 1mm bits when drilling by hand for eye-ups. I don't know what the reviewers were drilling or what size bit they were using. Thinking it might have been a thin bit into steel with too much pressure on a drill that wasn't coming down perpendicular.
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