jamesp
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Post by jamesp on Nov 17, 2012 5:39:31 GMT -5
I am tired of having pits,hollows,fracture areas,spots that are not smooth.Pre-grinding all that goes in to the tumbler seems like a good practice.It takes so long to tumble off so many types of imperfections.Those new coarse grit dry diamond wheels at Home Depot will remove material quick and last a real long time.They fit on hand grinders,better on a bench grinder.I think they are 50 grit.
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carloscinco
fully equipped rock polisher
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Post by carloscinco on Nov 17, 2012 11:53:43 GMT -5
Somebody posted pix of a bench grinder with multiple 7" diamond blades made for concrete stacked together. You can get them online for about 7-8 bucks apiece. I pregrind on my tile saw with a 7" wet concrete blade. works pretty good. Cuts the coarse grind time down and lets you dictate the shape, eliminates pits, soft spots and visible fractures.
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jspencer
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Post by jspencer on Nov 17, 2012 22:42:45 GMT -5
James do you know the shaft size of the diamond wheels and the diameter of the wheels?
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jamesp
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Post by jamesp on Nov 18, 2012 19:56:24 GMT -5
www.toolocity.com/4-adt-vacuum-brazed-diamond-cup-wheel-coarse.aspx?gclid=CJrNgsXn2bMCFQ2znQod52gAnwI have a similar to this 'diamond cup wheel' on a 4.5 inch hand grinder.It reduces agate quickly-very quickly.I use it to grind a flat glueable bottom on specimen agates.I clamp the hand grinder and hold the rock against it.It is threaded 5/8" for shaft of a 4.5 inch hand grinder.Notice that it is 30-40 grit diamond.Home depot has them.Next tumble load i am going to do what Carlos does-preshape.Avail. in 4,5,6,7 inch dia.My 4 incher is very effective in dry mode.
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Post by johnjsgems on Nov 18, 2012 20:51:29 GMT -5
Most angle grinders are 5/8"-11.
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jamesp
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Post by jamesp on Nov 19, 2012 6:17:00 GMT -5
That's it 5/8 - 11-wish it would screw on to a bench grinder-they do sell adapters for some situations similar to this.The hand grinder is 10,000 RPM w/brushes and too loud.
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Post by johnjsgems on Nov 19, 2012 8:57:38 GMT -5
Any "dry" diamond cup can be used safely with water (if your grinder is a "wet grinder"). The diamonds would likely last longer. At 10,000 rpm your grinder is likely not a wet grinder though. The tile blade grinders work well (still noisy). The bench grinder speed would be OK too.
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jamesp
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Post by jamesp on Nov 21, 2012 9:37:30 GMT -5
That dry diamond wheel has a lot of hard hours on it John.It may have worn 5%.I have a center feed water grinder for kitchen counter top use.It is 5000rpm for velcro back rubber diamond pads.But the fast dry grinder with the cup wheel may not wear out in my lifetime so i skipped the water feed.And the shower.The bench would be the way-got a metal lathe to get rid of the 5/8-11?:>By the way,my cup wheel was purchased from Grandquartz and it is Diarex brand(spelling Dairex??).
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Post by Jugglerguy on Nov 21, 2012 17:19:32 GMT -5
Could you please post a picture of your grinder? I don't know what a kitchen counter grinder is. I use an angle grinder to shape very rough Petoskey stones before doing them on my flat lap. It makes a ton of dust, hurts my back from bending over, and it's difficult to hold small rocks. I need to find a way to make a table or something to hold the angle grinder still while moving the rock with my hands. It might be easier to get whatever it is you have, James.
Rob
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jamesp
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Post by jamesp on Nov 21, 2012 19:07:08 GMT -5
That is what i did Rob.I mounted the angle grinder to a piece of steel.You could get those giant tie wraps and easily mount the grinder to a board.I used U-clamps like muffler clamps.And then attach the board to a bench where you can sit and relax.It still makes a lot of dust-a fan does wonders to get it away from you.I do it outside.I'll post a picture of the mounted angle grinder.
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Post by Jugglerguy on Nov 21, 2012 19:26:55 GMT -5
Ok, that's exactly what I was thinking of doing. I just found a picture of something similar on YouTube. I think I'll go with U-clamps too. The angle grinder works a lot faster than my trim saw and the blade seems really durable. I can cut with it or grind on the side. It would just be a lot easier to hold the rock rather than the grinder.
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Post by johnjsgems on Nov 21, 2012 21:18:12 GMT -5
They have to use a really tough bond for dry use. If you can stand the water spray you could eliminate the dust problem.
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Post by Jugglerguy on Nov 21, 2012 22:00:43 GMT -5
I don't like the idea of mixing water with electricity. Is there a way to use water with an angle grinder without the risk of electrocuting myself?
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Post by johnjsgems on Nov 22, 2012 0:09:58 GMT -5
It is called a GFCI (ground fault circuit interrupter). You should only use a unit with a factory water feed. Barranca Diamond, Flex, Makita, and others make them. They run water through a sealed gearbox supplying water to the center hole in the discs or grinding heads. Barranca has been marketing them since 1998. I've used them for a long time and no shocks yet. They are designed as electric wet polishers.
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jamesp
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Post by jamesp on Nov 22, 2012 6:50:49 GMT -5
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jamesp
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Post by jamesp on Nov 22, 2012 7:36:37 GMT -5
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Post by Jugglerguy on Nov 22, 2012 10:24:37 GMT -5
John, I didn't realize that there were angle grinders designed for water use. Mine is not, which is why I thought using it with water was a bad idea. All of my garage and basement outlets are GFCI, so I'm covered there, but I'm not going to use a tool with water unless it was designed for it.
James, I would expect nothing less than overkill from you. I think every picture you've posted on here is overkill! The blade on my grinder is for cutting, not grinding. I bought it when I installed Cultured Stone on the back of my house. I think I might attach mine to a board so the blade sticks out the end of the board. That way I can still cut off chunks of rock as well as grind with the side of the blade. Thanks for the help.
Rob
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jamesp
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Post by jamesp on Nov 22, 2012 11:12:24 GMT -5
Thank you for noticing overkillman,a fine compliment.The trick is to mounting the grinder to free up your hands.There are many cutting devices out there since diamonds got so involved in cutting equip.So you got a blade that works.By the way,that angle grinder has been sitting out in the weather for almost 10 years.And i have used water on it with no ill effects. Use care,watch you eyes,fingers and lungs please
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Deleted
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Post by Deleted on Nov 23, 2012 16:52:02 GMT -5
wouldn't a 4x4 (or some other properly sized wood) black make it so you can steady the stone against the wood while you grind? Seems safer and fewer rocks flung afield after slipping from your fingers.
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