jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Jan 31, 2016 15:54:52 GMT -5
A saw to make 1.5-2 inch slabs. rockpickerforever's prized gift of glassy palm wood weighing 6 pounds. Love this stuff. Said thick slabs Required tools. 4 once hammer with mild radius ground on face. Knee pad for anvil, reduces fractures. Important part is striking sawn surface from top, ledge below. Pick strike point for desired thickness of tumble. Then chip looks free of fractures 5 pounds of tumbles from 6 pound rock at various thicknesses. A few. This stuff a bit squirelly but not bad. Looked them over. Maybe 70% looking like nice tumble shapes with little fractures. Should yield nice tumbles.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,711
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Post by Fossilman on Jan 31, 2016 21:45:57 GMT -5
Looks like you have that figured out James.....Nice colors,should bring out some great tumbles..........
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Post by Peruano on Feb 1, 2016 6:10:17 GMT -5
Thanks James, I had been contemplating just such a process for flakes of Pedernal Chert to tumble. I've produced some (as you call them) random pendants from flakes found beside the road, but knew that some hammer action would work on larger pieces collected on a second trip. I'm on to it. Tom
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Feb 1, 2016 7:29:00 GMT -5
Thanks James, I had been contemplating just such a process for flakes of Pedernal Chert to tumble. I've produced some (as you call them) random pendants from flakes found beside the road, but knew that some hammer action would work on larger pieces collected on a second trip. I'm on to it. Tom Tom, that is basically knapping on a large scale in terms of technique. Knappers are very cautious about propagating fractures and control of material removal. They use softer hammers of copper brass or annealed steel with hammer face rounded. Often sawing pre-shaped flat faced blanks to begin percussion. The small hammer can be swung with higher speed with great location and angular control. speed vs. mass... To soften the face of the hammer you can grind a rounded face on it bearing down hard to get it very hot on a bench grinder and quench it in water to anneal it. Works sometimes, depends on steel in hammer. --Rounded face means everything-- Anyway, for a practice run I suggest 1.25-1.5 inch slabs of a chert and give it a go. Bigger slabs chip easier as they have more mass. As you chip them smaller you have to sing the hammer faster assisting in error. For real glassy agates/cherts 2 and even 3 inch slabs will chip all the way down making long shapes. Shapes darn near impossible to make on wheels and a heck of a lot faster. I had never chipped palm. Was nervous doing the one in this thread as I did not want to make trash out of it. i practiced on some waste coral for a few minutes to get my 'Zen'. You can take a plain 12 ounce claw hammer and cut the claws off and as much material as you can to get it in the 4-6 ounce zone. I prefer the 4 ounce ball peen, it's mass is distributed for perfect blows. Wood handle. please post results
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Post by Peruano on Feb 1, 2016 8:36:54 GMT -5
Great follow up info. I may be on a new path of rock chipping. Seems like Dad had a brass hammer which I'll have to dig for. I collect hammers like some folks collect ashtrays so I'll have to consider various options. This chert is the one that Anazazi (Pueblo) used a great deal for tool making and it does have great knapping potential and history. Ironically I had a few flakes tumbling this weekend (used to help fill an agate load). Thanks again. Tom
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,562
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Post by jamesp on Feb 1, 2016 9:20:20 GMT -5
Great follow up info. I may be on a new path of rock chipping. Seems like Dad had a brass hammer which I'll have to dig for. I collect hammers like some folks collect ashtrays so I'll have to consider various options. This chert is the one that Anazazi (Pueblo) used a great deal for tool making and it does have great knapping potential and history. Ironically I had a few flakes tumbling this weekend (used to help fill an agate load). Thanks again. Tom Pendant size chips are my prime target Tom. I mix them in on about every tumble. Hoard them for future metal smith projects. Give away the non pendant tumbles. I have a comfortable chair and a 2 X 12 with a thin layer of rubber on it. Throw the two in the boat and go to a coral rich river bar. Walk around and collect 10-20 pound corals and sledge big slabs off them. Set them in a pile, chair next, sit down and chip 5 gallon bucket or two. Only keeping the finest of shapes. Addictive activity. Reducing the spalls is effortless if you sledge them right.
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