nchillbilly
starting to spend too much on rocks
Member since January 2018
Posts: 212
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Post by nchillbilly on Mar 29, 2018 8:39:14 GMT -5
I am looking for any suggestions on how to create preforms or do pre-shaping for my tumbles. I'm not interested in making jewelry at this point, and not trying to create full-blown cabs, just trying to get a head start on tumbles. I don't want, nor can afford, a complete cabbing set-up. I have an extra bench grinder. Would it be possible to just add a stone grinding wheel to that? Is there a certain spindle speed on the grinder that I'm looking for. Got any ideas?
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pizzano
Cave Dweller
Member since February 2018
Posts: 1,390
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Post by pizzano on Mar 29, 2018 9:32:57 GMT -5
J.T........I use bench grinders, mostly for buffing/polishing stones that gave me trouble during tumble.
The biggest problem I have found is heat. Unless you can rig some kind of cooling system and splash guard to the grinder without putting yourself (and grinder) in harms way, it's been slow going for me (dip and grind). Depending on the wheel size, there are various wheel grits available but most a little pricey. Wheel RPM's play an important part as well. Typical bench grinders usually run at one constant speed.......reducing the effectiveness of the cutting for agates and jasper. I discovered this while learning how to properly use my Dremel......kind-of the same principal.
It can be done, I do it.........but don't expect your wheels to last long or stay "true" without dressing and cleaning........just my experience.
Note:
Don't use common wheels made for grinding metal like Harbor Freights or Home Depot's........been there done that, a real waste of time and money.
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Post by gmitch067 on Mar 29, 2018 11:18:07 GMT -5
I do all of my preforms by hand using a dremel. I purchased a grinding wheel but have never used it after numerous negative recommendations. Tela rockjunquie created a thread on hand cabbing in which I sketched-out my procedures. forum.rocktumblinghobby.com/thread/80300/hand-cabbing-info-requestMy arthritis is not permitting me to do much hand sanding lately, but after cutting the preforms using a tile saw and grinding the rough shape with the dremel, I have been using the UV-18 or Mini-Sonic-4 to refine the shapes and polish. I have ruined a few because the 220-grit stage caused uneven wear and undercutting when working with agates or jaspers with different material compositions... Oh well... win a few.. loose a few... Glenn
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Post by Peruano on Mar 29, 2018 12:30:14 GMT -5
The cheapest and easiest head start on tumbles is to collect your stones from beaches and riverine deposits where most of the stones are pre-rounded, somewhat polished, and in great abundance where you can sort for sizes, shapes, and blemish-free conditions that you would otherwise produce with the tumbler or a grinding step prior to tumbling. Much of what I initially tumbled was from Mexican beaches and hence I was able to start right with a vibratory tumbler and eliminate the rotary process. Short of that you could devise a grinder, but with a couple of precautions. 1. Typical silicone carbide wheels do not survive well if allowed to become water logged. Always spin them for a few minutes (after the water has been turned off) to get rid of excess water. An out of balance wheel can self-destruct and do serious harm to anyone hit by a fragment of a wheel. Never stand in front of one when you first turn it on in case it has been damaged or waterlogged unknown to you. 2. The wheel on the motor shaft design of typical bench grinders is somewhat vulnerable to water if you do devise a drip or water system. It would be safest to use a remote motor to drive a belt and bench arbor that would thus be isolated from water and electricity. Such arbors are cheap and used motors to drive them also available (if you were here, I'd give you one). 3. I did use such a primitive system when I first started out, but be forewarned you will rapidly convince yourself that it would be worthwhile to get a better system. Used lapidary arbors can be cheap but when you start adding multiple wheels you get into real money. Devising a unit with a 6" expand wheel that could use cheap SicCarbide belts may be one option. 4. Using an angle grinder with a masonary blade might be an option but I have no experience in that line. Safety, safety, and safety are the three cardinal rules of home devised systems. Did I say . . . be safe.
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Post by pauls on Mar 29, 2018 14:43:34 GMT -5
You need a constant water flow on your wheels when grinding rocks, the rock dust is not good for your health. If you can somehow waterproof your bench grinder then you may be good to go. Choose your wheels carefully though, many steel grinding wheels aren't any good for rocks, they are too hard and the grains of Silicon Carbide get blunt, lapidary wheels are fairly soft so they wear down quickly. Go Diamond, plated wheels are fairly cheap and will last about the same time as a Silicon Carbide wheel before getting too blunt to work, you can eke out a bit more grinding by reversing the wheel but once they are blunt thats the end of the story. Sintered wheels can be very expensive initially but they keep on grinding for many many times the life of a plated wheel.
Have you considered a super grinder? basically buy cheap tile blades and gang half a dozen together with spacers in between, they are really agressive and chew into rocks. Jamesp is using tuckpoint blades in a super grinder and reports good results.
Speeds, run at the recommended speeds, slower will cause your wheels to get bumpy quickly, Tile blades for super grinders are designed to run in an angle grinder so make it so it runs quite fast.
I run my rocks for a bit in the tumbler before finessing them on the grinder, this removes any softer bits and makes it easier to see what cracks and pits need to be taken out, grinding tumbling rocks can be a PITA but I think is well worth it in the final results.
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braat
spending too much on rocks
Member since December 2016
Posts: 350
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Post by braat on Mar 29, 2018 16:51:32 GMT -5
I used the bench grinder for a while and gave up on it for reasons already stated above. I bought a cheapie 7" tile saw a year ago and use it regularly to preform rough and to touch up rocks that are near ready to move on from weekly stage one cleanouts. And bonus if I ever need to cut tiles I can .
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pizzano
Cave Dweller
Member since February 2018
Posts: 1,390
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Post by pizzano on Mar 29, 2018 17:46:26 GMT -5
I do all of my preforms by hand using a dremel. I purchased a grinding wheel but have never used it after numerous negative recommendations. Tela rockjunquie created a thread on hand cabbing in which I sketched-out my procedures. forum.rocktumblinghobby.com/thread/80300/hand-cabbing-info-requestMy arthritis is not permitting me to do much hand sanding lately, but after cutting the preforms using a tile saw and grinding the rough shape with the dremel, I have been using the UV-18 or Mini-Sonic-4 to refine the shapes and polish. I have ruined a few because the 220-grit stage caused uneven wear and undercutting when working with agates or jaspers with different material compositions... Oh well... win a few.. loose a few... Glenn I mentioned to another member here that I'm currently rough tumbling "saw-cut" material for a few weeks, then removing stones that need work and cutting or dressing-up with my little MK-170 saw and Dremel.........then back into another 1st stage tumble.........it's working better than the bench grinder method. All said and done, spending about as much time, but getting better quality for the next tumble cycles........the bench grinders are now reserved for buffing/polishing and tool sharpening......unless I'm desperate and in a big-ass hurry, still a pain in the butt...!
Just can't justify the cost associated with horz. laps or combo wheel equipment....even though they both would be the most efficient......to many other expensive hobbies are my problem.......lol
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nchillbilly
starting to spend too much on rocks
Member since January 2018
Posts: 212
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Post by nchillbilly on Mar 29, 2018 22:11:26 GMT -5
Thanks for all of the suggestions. I think I'm going to go with the tile saw method. I had already been considering getting one to help with breaking down large rough to fit in my tumbler barrels, so this way I can kill 2 birds with one stone.
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Post by Garage Rocker on Mar 29, 2018 22:13:29 GMT -5
Thanks for all of the suggestions. I think I'm going to go with the tile saw method. I had already been considering getting one to help with breaking down large rough to fit in my tumbler barrels, so this way I can kill 2 birds with one stone. I think that's a wise choice and a good way to bump up your capabilities.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,555
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Post by jamesp on Mar 30, 2018 5:29:24 GMT -5
Thanks for all of the suggestions. I think I'm going to go with the tile saw method. I had already been considering getting one to help with breaking down large rough to fit in my tumbler barrels, so this way I can kill 2 birds with one stone. I think that's a wise choice and a good way to bump up your capabilities. This man uses a tile saw. look at his tumbles...
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