jamesp
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Post by jamesp on Jan 11, 2014 16:45:24 GMT -5
This 2 inch thick slab is a coral head cut in half. It is 7 inches across, heated and chipped into 1-2 inch chips. I used the flat cut to strike the thin chips off. The late day sun oranged out this photo,sorry. This is the less colorful center that was left over. I went around in a circle 3 times and carefully knocked flakes of. The outer section is where the most color is. A great way to make tumbles if can saw a nodule in half. Really makes reducing to tumbles much easier. The alternative is breaking the nodule in half sending fractures throughout. This method yields almost fracture free tumbles. You can see how it got grainy on the bottom of the photo greatly hindering the nice flat chip production
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Post by rockpickerforever on Jan 11, 2014 17:05:32 GMT -5
Those are pretty, James. What, you didn't make a video? No blood blisters? Where's the fun in that?
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jamesp
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Post by jamesp on Jan 11, 2014 18:52:14 GMT -5
Small hammer is the trick bloody blister girl. Oh that hurts to think about. Got any more?
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Post by rockpickerforever on Jan 12, 2014 0:14:14 GMT -5
No, been too busy to play with rocks, so no new blood blisters.
I like those yellowish corals, they remind me of a piece of pineapple.
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jamesp
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Post by jamesp on Jan 12, 2014 0:49:32 GMT -5
They taste great. Rough on the teeth....
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grayfingers
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Post by grayfingers on Jan 12, 2014 8:37:38 GMT -5
Seems like it must take a bit of practice to chip those as you do. I have noticed the thinner chips ring like glass when tapped. Bet they would made a great wind chime.
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jamesp
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Post by jamesp on Jan 12, 2014 9:17:20 GMT -5
If you have a 4-8 pound chunk sawed in half you get a flat and predictable impact angle.
The heaviness greatly increases the effect of the blow and reduces the power that you have to strike the rock.
That in turn reduces the fractures that propagate into the chips.
A sawed in half chunk is so easy to chip. Especially if heat treated. It acts just like obsidian. Easy
Get the angle of the hammer and the hammer speed tuned for the given material and it takes little time or skill.
Grainy coral is more of a challenge. The boring gray stuff is common and comes in big chunks. The knappers collect it as it heats to obsidian like material. Heats to a blinding white color.
And it is one of the first knapping materials to sell out when you get to a knap-in.
For a log shaped coral i will saw it into 1.5,2.0 and 2.5 slabs and then chip away.
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bsky4463
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Post by bsky4463 on Jan 12, 2014 9:48:36 GMT -5
Reducing the propagating fractures sure is the key....seems like you have that figured out pretty darn good. Good stuff James. Cheers
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jamesp
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Post by jamesp on Jan 12, 2014 10:30:15 GMT -5
Thanks blue. Lucky to have material that has not been smashed by Montanian glaciers and Montanian freezes.
And it is common at some quality levels to practice with.
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Fossilman
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Post by Fossilman on Jan 12, 2014 19:20:55 GMT -5
Hey thats some nice coral James!
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jamesp
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Post by jamesp on Jan 12, 2014 19:51:56 GMT -5
Hey thats some nice coral James! Is your Willamette full of water Micheal?
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Post by pghram on Jan 13, 2014 10:08:33 GMT -5
Looking forward to the finish.
Rich
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jamesp
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Post by jamesp on Jan 13, 2014 10:49:28 GMT -5
Looking forward to the finish. Rich Rich, scroll down to Location Location Location and see where Micheal and Tracy went to the Savannah River. That is right where you need to go. Namely the first photo.
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Fossilman
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Post by Fossilman on Jan 17, 2014 0:36:21 GMT -5
Hey thats some nice coral James! Is your Willamette full of water Micheal? If there is even a foot wide path of gravel showing,I'm going to look in a day or so....Its been a month!
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Fossilman
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Post by Fossilman on Jan 17, 2014 0:39:15 GMT -5
James,does coral take a good polish without the tumble......Was thinking of buffing the one I got from you... Put it on display in my shelf collection...
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jamesp
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Post by jamesp on Jan 17, 2014 0:44:01 GMT -5
James,does coral take a good polish without the tumble......Was thinking of buffing the one I got from you... Put it on display in my shelf collection... I have polished them with wet diamond pads Micheal. Or you can put them on a lap. You need to start at 400 then 800 then 1500. i got a 3000 wheel but it does good at 1500. You might could do it with a hard wet sponge and tumbling grits 400,800 then 1500 if you are real patient. Glad i made it to the display. Cool. Oh,and thumbs up.LOL.
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Deleted
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Post by Deleted on Jan 17, 2014 13:39:19 GMT -5
James,does coral take a good polish without the tumble......Was thinking of buffing the one I got from you... Put it on display in my shelf collection... Mike, I know I am not Jim, but having polished his coral I can tell you is does polish. Like wet glass underwater if you take your time. What machinery do you have? Cabber?
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jamesp
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Post by jamesp on Jan 17, 2014 14:50:13 GMT -5
Yep. Scott is right. It polishes but to get past the saw cut (usually 400 and then the 800 may take a while.
It takes a polish cause it is real hard. Just saying, the earlier grit can be a lot of work.
I think you could lap it by hand if you had another slab to put the grit between.
Didn't you have a way of hand lapping tiles Scott?
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Deleted
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Post by Deleted on Jan 17, 2014 16:17:34 GMT -5
I used a slab of granite as a surface with a sheet of wet dry sand paper on it, then hand rubbed the pieces to flat. A little bit of elbow grease and some sweat equity and you will have a glowing piece of coral.
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jamesp
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Post by jamesp on Jan 17, 2014 16:44:09 GMT -5
I like that. Fossilman is a bull and can handle such a medial chore.
If he can figure out how to work when it is not 20 below and 50 MPH wind.LOL.
Oh, and 50 feet up a ladder.
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