planza
starting to shine!
Member since March 2012
Posts: 30
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Post by planza on Jan 17, 2019 14:02:00 GMT -5
Hi, all: Has anyone had success using a Dremel-type rotary tool during/after rough grind stage to remove spalls and do other minor touch-up before moving your tumble on to Stage 2? Is there a particular type or brand of bit that you find holds up well on Mohs 6-7 material? Looking for suggestions. Thank you! --Phil
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jimaz
spending too much on rocks
Member since July 2018
Posts: 461
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Post by jimaz on Jan 17, 2019 14:32:26 GMT -5
I've used a rotary for some shaping. Used tungsten carbide bits, as well as drum sanders. If you leave too large os scratches you may need to run in course a little longer.
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Post by gmitch067 on Jan 17, 2019 22:54:43 GMT -5
Hi, all: Has anyone had success using a Dremel-type rotary tool during/after rough grind stage to remove spalls and do other minor touch-up before moving your tumble on to Stage 2? Is there a particular type or brand of bit that you find holds up well on Mohs 6-7 material? Looking for suggestions. Thank you! --Phil planzaI do a bit of hand cabbing using a dremel and contributed to a thread on the topic posted awhile back: forum.rocktumblinghobby.com/thread/80300/hand-cabbing-info-requestIn it I posted some pictures of diamond coated grinding wheels, and later (in the same thread) talked about them. They are expensive (around $12 +/- on Amazon - when available) and wear out quickly when attacking Mohs-6/7 stones. The smaller grinding wheels seem to be around 150-220 grit, and the larger ones seem to be around 80 grit (that is a "guess"... not sure). Check the tightness of the top screw on the larger wheels... some of them I have received were loose enough to allow the wheel to free-spin on the shaft... and needed tightening before use. I even use a small drop of thin epoxy to keep the screw tight during use (I couldn't find my Loktite at the time). Also... check for correct alignment of the wheel in the dremel tool before using them on a stone. If alignment is not true, the feel to your hand (and the stone!) will be rough as the speed ramps up and the wobble could cause damage to the rock - readjust the bit and re-tighten and try again... and again... and again... until you feel the roughness smooth out (or change to a new bit and try again). I hope this helps.
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Post by grumpybill on Jan 18, 2019 9:55:48 GMT -5
I've gotten good results and decent longevity from these inexpensive wheels (needed to buy a 1/4" to 1/8" arbor for the 2 larger ones): Cheap Diamond Wheels
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Post by gmitch067 on Jan 18, 2019 12:27:22 GMT -5
I've gotten good results and decent longevity from these inexpensive wheels (needed to buy a 1/4" to 1/8" arbor for the 2 larger ones): Cheap Diamond WheelsGot this web page bookmarked grumpybill. Thank you for this info+++! Great price... and thanks also for the arbor info too.
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Post by grumpybill on Jan 18, 2019 13:07:11 GMT -5
Got this web page bookmarked grumpybill. Thank you for this info+++! Great price... and thanks also for the arbor info too. Price is especially good with the ever-present 20% coupons. I bought the arbor from Foredom. $6 or $8 if memory serves.
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Post by greig on Jan 18, 2019 14:23:22 GMT -5
I have played around with rocks using a Dremel, with mixed results. The first work of caution is try not to breathe the dust and wash up afterwards. I have worked both wet and dry. Wet is better. As for bits: the little grinding stones are pretty effective on softer rock like calcite and get exponentially less effective as the rocks get harder. Same with carbide bits. For quartz (7 on Mohs) and harder, I prefer diamond bits. I usually get mine from Princess Auto in Canada, which I think is similar to Harbor Freight in the US. I don't really notice the difference between these imported bits vs name brand ... and don't care as much when they heat up and fail. All that said, I am somewhat impatient when "correcting" a marginal rock for tumbling, and instead usually use my saw to adjust it (with the edge of the blade) or simply cut out the imperfection. When I post a Youtube video doing this, people always comment that they worry about my fingers on small stones, but so far, no injuries.
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planza
starting to shine!
Member since March 2012
Posts: 30
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Post by planza on Jan 18, 2019 21:57:56 GMT -5
Thanks for the feedback, everyone. I'm going to give this a try. Ordered up a flex shaft on Amazon, along with a set of diamond burs. I also finally decided to pull the trigger on a QEP650 wet tile saw for $90. I'm really eager to open up some Lake Superior agates I've been saving, and to trim up some other rough rock for better tumbling material. That work may have to wait until spring (expecting our first big winter storm here in MA this weekend) but I'll be ready!
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