rockhound
off to a rocking start
Member since October 2003
Posts: 6
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Post by rockhound on Oct 6, 2003 16:21:06 GMT -5
I am just starting rock tumbling I have found several Petoskey rocks while building our new house. I also have many other cool rocks that I want to get polished up. I may make some jewlery. Anyone tumbled Petoskey rocks before
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WilliamC
spending too much on rocks
Member since August 2003
Posts: 416
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Post by WilliamC on Oct 6, 2003 20:34:07 GMT -5
Greetings All, Hello Rockhound, welcome aboard! What, may I ask, are Petoskey rocks? One moment please while I google myself ...ah, fossils! From www.dayooper.com/petoskey.htm"The primary mineral that makes up the fossil Colony Coral of a Petoskey Stone is Calcite. Petoskey Stones make excellent worry stones, paper weights and conversation pieces. Being Calcite, they are quite easily carved and the calcite will often allow the specimen to take a good polish and show the characteristics of the coral formation of the Michigan State Stone." Hummm, my understanding is that calcite is not very hard, in fact it is the defining rock for a 3 on Mohs scale. Therefore any tumbling you would do should be checked very frequently, especially in the coarser stages. Maybe even every 12 hours. In fact, depending on the beginning condition of the rocks (are they already in the shape you want or not?) you might think to start with 220 grit just to make sure you don't grind them down to nothing. So, speaking out of ignorance since I've never tumbled these before I would suggest either thinking about cabbing them (you would have much more control) or starting them with 220 grit for 8 to 12 hours, wash them off, see how they look and go from there. Maybe someone more knowledgeable can give you better advice, but let us know how they turn out . WilliamC
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rockhound
off to a rocking start
Member since October 2003
Posts: 6
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Post by rockhound on Oct 8, 2003 11:20:39 GMT -5
Thanks, William. What does 'cabbing' mean? I tumbled eight of them for 3 days with a course grit (packaged didnt' have a number). I could tell by looking them over that I needed to go to the polishing now. They sure are a beauitful stone. You are right, they are in the shape I want them, that is makes them cool. How do you cut stones, rocks, gems and such? I have a rock that I think would polish up real nice but it is to big. I thought about a hammer but my husband is a woodworker and thinks that stones are like lumber, you cut them with the grain but we have no clue what to use. Sure would hate to ruin a rock!
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mudd1973
starting to shine!
new member of Culver City Rock and Mineral Club
Member since May 2003
Posts: 33
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Post by mudd1973 on Oct 8, 2003 14:13:04 GMT -5
Hi, I'm also new to this whole rock Biz. I recommend joining a rock and mineral club if you can find one in your area. Many have shops that members can use with diamond/oil cooled saws to cut rock and the machines to grind and shape and polish rocks. Just search on-line for "rock and mineral club". Cab is short for cabechon, a term for a shaped and polished piece that is flat on one surface and usually oval-shaped and slightly rounded on the polished face, although there are many other shapes. Often, for tumbling rock, people use a hammer to break up a large piece. Always wear protective eye goggles. I think you also use padding underneath, like old towels or a sand bag, so that you split up the rock along natural fracture zones without causing as many small cracks which would show in the final polished rock. To cut or drill rocks, you need cool the saw/drill with water or oil to protect the tool and the rock from overheating. Hope this helps, probably some of the more experienced members on this board are rolling their eyes. Hopefully they will reply with a correction if I've given bad advice.
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mudd1973
starting to shine!
new member of Culver City Rock and Mineral Club
Member since May 2003
Posts: 33
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Post by mudd1973 on Oct 8, 2003 14:13:55 GMT -5
Hi, I'm also new to this whole rock Biz. I recommend joining a rock and mineral club if you can find one in your area. Many have shops that members can use with diamond/oil cooled saws to cut rock and the machines to grind and shape and polish rocks. Just search on-line for "rock and mineral club". Cab is short for cabechon, a term for a shaped and polished piece that is flat on one surface and usually oval-shaped and slightly rounded on the polished face, although there are many other shapes. Often, for tumbling rock, people use a hammer to break up a large piece. Always wear protective eye goggles. I think you also use padding underneath, like old towels or a sand bag, so that you split up the rock along natural fracture zones without causing as many small cracks which would show in the final polished rock. To cut or drill rocks, you need cool the saw/drill with water or oil to protect the tool and the rock from overheating. Hope this helps, probably some of the more experienced members on this board are rolling their eyes. Hopefully they will reply with a correction if I've given bad advice.
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donwrob
has rocks in the head
Member since June 2003
Posts: 509
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Post by donwrob on Oct 8, 2003 14:44:10 GMT -5
Speaking as another inexperienced member, I think you did a great job on your post mudd. I'll just roll my eyes to be silly though if you don't mind You covered everything, even safety. Cheers, Don ;D
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rockhound
off to a rocking start
Member since October 2003
Posts: 6
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Post by rockhound on Oct 8, 2003 16:32:30 GMT -5
Thanks, mudd1973. I appreciate all the advice. Okay, towel and hammer here I come to experience.
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Post by docone31 on Oct 8, 2003 21:45:00 GMT -5
Your husband being a wooder, he will have all the tools you need, shy one. A wet tile saw can cut the rock into stones. A grinder with a cup of water to cool the stone will work for rough shaping. A 6" rubber drum, Rio Grande Tools Catalogue item. A leather buff for polishing, fits on the rubber drum. Cerium Oxide for polish on the leather buff. Same catalogue. Saw to shape, grind the shape to where it is what you want to see. With a belt sander, sand starting with 220, moving to 320, moving to 660. All belts that fit the belt sander. Ordering the rubber drum, cerium oxide, also order a 1200 6" belt. With this belt, you will have to break it in before using. Lightly sand something you do not care about. It will knock the sharp grains down. The finish will be amazing. The leather buff will be for the cerium oxide. Take a sponge, wet it, shed the extra water, pad the oxide with the sponge, apply to the leather buff damp. Polish the Petrosky Stone. You will smile. To make holding the stones easier, get a wood dowel smaller than the stone. Go to a stationary store and get sealing wax, or order dop wax from Rio. Melt the wax, put the dowel into it on one square end. Have the stone to be polished on a stone ware plate on the lowest warm on the stove. Put the dowel with wax on the end on the flat on the stone. Push the extra wax around the stone on the flat. To remove the stone. Place in the freezer for five minutes. It pops off and voila. Too much heat will shed the stone while grinding and shaping. Dip often. Good luck.
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rockhound
off to a rocking start
Member since October 2003
Posts: 6
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Post by rockhound on Oct 9, 2003 21:37:45 GMT -5
Thank you, docone31!! You folks on this board are all so friendly and helpful!!
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