mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on Apr 20, 2012 19:47:07 GMT -5
I have several bucketfuls of Montana agates I need to polish in kind of a hurry. After sawing, I run the halves on a bull wheel through 100/220/400/600 silicon carbide belts (dry). Then what I intended to do was run the pieces on a 1200 and 3000 grit diamond belts on expandable drums.
What I discovered was running a piece on 1200 grit after finishing with the 600 paper from the bull wheel made it worse. Same for the 3000. This surprised me. The finish I am getting from a well-worn 600 belt on the bull wheel is really nice, maybe equal to 5000 or finer? But still not the mirror finish I want.
What next? I have a 14,000 diamond belt I haven't tried yet. Whatever step is next, the process must be reasonably speedy. I am not opposed to investing in an 8" flat lap like the Inland if that would be quick, but I have never used one. If I went this route, given the pretty nice finish I already have, what grit diamond wheels would I use?
I have not got the technique down polishing on a leather wheel with cerium. In any case I suspect the process will be too slow and messy with too much cleanup time. I am open to suggestions. Should I use a finer or coarser diamond belt on either side of the 14,000 belt I already have? I don't mind spending the $ for equipment.
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Post by jakesrocks on Apr 20, 2012 19:52:41 GMT -5
An old timer trick was to save the worn out 600 grit belts and discs. They do an excellent job as pre polish belts. Just go straight from them to a leather or felt wheel with cerium.
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mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on Apr 20, 2012 19:58:09 GMT -5
Jake, ok, so my pieces have been "prepolished"- like I said, my finish off a worn 600 is really nice. We are talking maybe a thousand pieces to work here. To my knowledge nobody makes a leather belt for use on the bull wheel. But wouldn't the whole leathe/cerium thing, given a thousand pieces to process, be way too slow and messy?
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Post by jakesrocks on Apr 20, 2012 20:25:28 GMT -5
It will be messy to say the least. But a minute or two on each piece will have them done. Alternate would be loading a big vibro lap with pieces on a polish pad. You'd have to put some sort of a bumper strip around each piece, to keep them from chipping each other. Rings cut from various sizes of old inner tubes works good for that.
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mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on Apr 20, 2012 20:30:26 GMT -5
How quick would the Inland unit be?
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Post by jakesrocks on Apr 20, 2012 20:49:40 GMT -5
That would take forever. You're limited on size, and can only do one at a time. Plus the Inland flat lap is weak. You'd probably burn it out with the first bucket full of halves.
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mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on Apr 20, 2012 21:30:57 GMT -5
Wow- thanks for that info. You probably just saved me a lot of money. Ok, so I don't have a feel for leather and cerium. Do I keep the leather pretty wet, sorta dry, or?
There was a guy selling 3" wide leather belts for expando drums at Quartzsite, but I wasn't thinking ahead and didn't get one. And I can't recall the manufacturer. I do have a polishing unit built by Richardson Ranch. Just need some training.
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Post by jakesrocks on Apr 20, 2012 21:44:54 GMT -5
Run leather just on the damp side. You should be able to feel a little bit of drag on the rock.
Check with John at jsgems. I'm pretty sure he stocks leather belts. He may even have them to fit your big drum.
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Post by Rockoonz on Apr 21, 2012 12:57:16 GMT -5
John sells belt but they are finished side out for diamond paste. his supplier is also a member here, maybe he han make them rough side outffor cerium. The Richardson unit is perfect for you. Start by carefully using a clean steel wire brush to remove the old polish and pick up the "nap" of the rough side of the leather. If it has old polish residue and you don't know what it is a new piece of leather would be best. Once you're happy with the leather make a thick slurry by adding water to a couple tablespoons of optical grade cerium. Turn it on and use a paint brush to lightly coat the leather from the center to about half or 2/3 of the way to the outside edge then use the edge of a cut rock to work the slurry out to the edge of the wheel. Remember to keep the cerium coated as lightly as possible, the rough leather does as much as the cerium, if it's not too thick it also is not too messy. When using start by spraying a fine mist from a spray bottle then hold the stone firmly against the leather in a way that won't gouge the leather or throw the rock across the room. When polishin domes use the flat area of the wheel. When polishing flats use the rounded area around the perimiter of the wheel. Carpet or rubber mats on the floor is a plus to save feet and rocks. Let the wheel dry out till the surface of the stone grabs a little, especially with agate and hard jaspers as the heat gives a better polish. If your rock comes off the wheel with a coat of dried cerium on it you have too much polish on it you have too much slurry on it, let it dry and use the wire brush, same when the leather surface gets flattened to pick up the rough nap again. If your stone has lots of micropits or fractures getting the cerium out could pose a problem, vinegar water may boil it out but I haven't tried.
BEWARE THE AREA AT THE BOTTOM OF THE WHEEL!! As supplied by Richardsons the space between the bottom of the wheel and the wooden base is a little less than the size of a hand, but once started the hand will go through anyway, resulting in definite pain and possible injury.
Lee
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