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Post by perkins17 on Nov 20, 2021 23:03:48 GMT -5
I just finished weighing my tumbles (Sorted into 0-20 20-45 45-95 100-and up in grams) and wanted to know how much you guys charge. Mine are mostly self collected and not a ton of store bought stones. I was thinking along 75 cents for the 0-20 stones, 1.50 for 20-45, 2.00 for 45-95, and 3.00 for 100 and up. Any ideas? Is this a good price? Thank you for your advice! flic.kr/p/2mL5P7t (pictures of the bags of stones.)
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Post by rmf on Nov 21, 2021 5:18:53 GMT -5
years ago I calculated it cost me about $3 per pound to tumble. I have not updated that number in 20 years or so. This included the cost of power, grit and polish and took into account of tumbling loss. (Tumbling loss. Buy 100 pounds of rock, Crush it by hand loose 5-10% in fines, Crush in hammer mill loose 30-35%, crush in Jaw crusher loose 15%, Grind away in the tumbler 25%.) The year I did this I finished over 2000 pounds of rock. I had a bunch of rock that I had taken to a Rock shop in Birmingham AL to crush. He had a hammer mill(it gave 30-35% fines less than 1/4", I took 3000 pounds of rock up to PA to a guy with a jaw crusher, that gave me the 15% loss. So the long and short of it was that without depreciation or time cleaning I had $3per pound into tumbling the rock. That also did not include the rough rock value. Retail on tumbled stones is in the $12 - $18 per pound for the more common agates and jasper. expensive or difficult to polish tumbled stones are more. And of course Your mileage may vary.
You should assign a value to found rocks since you took time, gas (usually), and other expenses to pick it up. Yes I know that the value of the find is frequently less than what you spend to find it. Except for the Joy of discovery. There is just something special in finding, learning, processing it yourself for the pleasure it brings.
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Post by perkins17 on Nov 21, 2021 12:39:13 GMT -5
years ago I calculated it cost me about $3 per pound to tumble. I have not updated that number in 20 years or so. This included the cost of power, grit and polish and took into account of tumbling loss. (Tumbling loss. Buy 100 pounds of rock, Crush it by hand loose 5-10% in fines, Crush in hammer mill loose 30-35%, crush in Jaw crusher loose 15%, Grind away in the tumbler 25%.) The year I did this I finished over 2000 pounds of rock. I had a bunch of rock that I had taken to a Rock shop in Birmingham AL to crush. He had a hammer mill(it gave 30-35% fines less than 1/4", I took 3000 pounds of rock up to PA to a guy with a jaw crusher, that gave me the 15% loss. So the long and short of it was that without depreciation or time cleaning I had $3per pound into tumbling the rock. That also did not include the rough rock value. Retail on tumbled stones is in the $12 - $18 per pound for the more common agates and jasper. expensive or difficult to polish tumbled stones are more. And of course Your mileage may vary. You should assign a value to found rocks since you took time, gas (usually), and other expenses to pick it up. Yes I know that the value of the find is frequently less than what you spend to find it. Except for the Joy of discovery. There is just something special in finding, learning, processing it yourself for the pleasure it brings. Thank you for the reply. That really makes sense. I will remember this when I start pricing.
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Post by Bob on Nov 23, 2021 11:57:07 GMT -5
years ago I calculated it cost me about $3 per pound to tumble. I have not updated that number in 20 years or so. This included the cost of power, grit and polish and took into account of tumbling loss. (Tumbling loss. Buy 100 pounds of rock, Crush it by hand loose 5-10% in fines, Crush in hammer mill loose 30-35%, crush in Jaw crusher loose 15%, Grind away in the tumbler 25%.) The year I did this I finished over 2000 pounds of rock. I had a bunch of rock that I had taken to a Rock shop in Birmingham AL to crush. He had a hammer mill(it gave 30-35% fines less than 1/4", I took 3000 pounds of rock up to PA to a guy with a jaw crusher, that gave me the 15% loss. So the long and short of it was that without depreciation or time cleaning I had $3per pound into tumbling the rock. That also did not include the rough rock value. Retail on tumbled stones is in the $12 - $18 per pound for the more common agates and jasper. expensive or difficult to polish tumbled stones are more. And of course Your mileage may vary. You should assign a value to found rocks since you took time, gas (usually), and other expenses to pick it up. Yes I know that the value of the find is frequently less than what you spend to find it. Except for the Joy of discovery. There is just something special in finding, learning, processing it yourself for the pleasure it brings. What is hammer miller vs. a jaw crusher? Is one of these responsible for so much crushed rock for tumbling being of a fairly uniform size and often highly fractured?
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Post by rmf on Nov 23, 2021 15:25:40 GMT -5
Bob A Hammer Mill uses pieces of metal that can pivot and are extended by the centrifugal force of the spinning shaft. Then on the outbound side there is usually a grate of some type that the pieces must fit through to exit. If they are too big the get hammered till they fit the grate. Where as a Jaw Crusher works exactly like your mouth. The Stationary plate (top of mouth is attached to the head and can't move) and the jaw is hinged and opens and closes (like when you chew). They have pros and cons to each method. More fines from a hammer mill. where a jaw crusher can let out big flat pieces that can slip through the jaw opening which would be set at about 1" got tumbling material. Possibly or it could be the fractured material is due to the way it was extracted (explosives, weathering...)
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Post by Bob on Nov 23, 2021 16:04:53 GMT -5
I wonder what type of mill I have seen at mines? It looks sort of like a cone in a housing that shakes and rocks that fall onto the cone from above get broken and fall through a throat to a conveyor belt below. It's loud as heck.
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brybry
Cave Dweller
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Member since October 2021
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Post by brybry on Nov 23, 2021 19:13:12 GMT -5
I wonder what type of mill I have seen at mines? It looks sort of like a cone in a housing that shakes and rocks that fall onto the cone from above get broken and fall through a throat to a conveyor belt below. It's loud as heck. The gravel quarries here use those. I can't think of the name. The guys I talked to there said they are super high maintenance.
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Post by Bob on Nov 24, 2021 10:09:16 GMT -5
I have googled a bit and it appears they are called gyratory crushers, which seems appropriate.
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Post by fernwood on Nov 24, 2021 10:14:45 GMT -5
Going rate for tumbled stones that are 2" or less in my area are 2/$1.00. Unless they are super special.
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Post by perkins17 on Nov 24, 2021 10:39:04 GMT -5
Going rate for tumbled stones that are 2" or less in my area are 2/$1.00. Unless they are super special. Thanks! I've got a bag of stones about that big I weighed. 😃
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