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Post by stardiamond on Apr 29, 2015 12:32:40 GMT -5
I've cut a lot of slabs freehand, but my first attempts using a vise have been frustrating. Freehand you cut a slice off the outside and if you like the cut, you continue taking splices toward the inside. Since a lot of my rocks are faced and very V shaped I find it difficult to have much of the large end protruding from the vise so I can't make very many cuts. I haven't tried wedges yet, but I don't know how much they would help. I thought about gluing the face to a board and cutting backward and then realized that I could partially accomplish this by putting the face into the vise and cutting back to face. I've got my saw operating fine but I'm still pretty clueless regarding slabbing.
I need to make same precise cuts at an angle that I know how to do freehand, but am struggling on how to position the rock to do it with a vise.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,711
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Post by Fossilman on Apr 29, 2015 12:59:04 GMT -5
What kind of saw you using???
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Post by stardiamond on Apr 29, 2015 13:01:51 GMT -5
Covington 16" combo saw.
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Fossilman
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Member since January 2009
Posts: 20,711
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Post by Fossilman on Apr 29, 2015 13:07:30 GMT -5
I have a very good clamping system for my saw,plus I use widgets,and wood blocks in the vice also....Never have had a problem yet! Also do use the 2x4 and glue method too for the shorter cuts..
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,711
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Post by Fossilman on Apr 29, 2015 13:08:44 GMT -5
I cut thundereggs using the same system,no problems at all.............
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minerken
Cave Dweller
Member since August 2013
Posts: 466
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Post by minerken on Apr 29, 2015 13:27:25 GMT -5
I'll try to explain what it is that I have done here and hope that the pictures will make it clear. First why did I do this? if you have a 10 inch saw and want to cut a larger hard stone like agate you may get disapointed I have found that the 1/3 the diameter rule of thumb doesn't work with good hard agate like Montana or Brazilian especially.You may be familiar with the process of rolling the stone through the saw where you get drenched with oil and make a funky cut if you can get through it at all. This is my solution to the problem, first I start with a 4"x 4" piece of channel iron with a hole drilled dead center then I had a disk made by a machinest 4" in diameter with a bolt 1/2 " bolt welded dead center to it. The next step is to glue your rock to the disk centered as well as possible. Clamping the channel iron in your vise and sliding the disk with glued rock and bolt through the hole and tightening down with a ratchet. At this point you can start your cut, I start with about a 1 inch long cut first, then I loosen the bolt and rotate the rock one way or the other doesn't really matter, and proceed to cut another 1" swath I continue doing this until I'm almost through the rock then let is go from there hope these pictures show what I am doing. www.dropbox.com/sc/x4oruuoildmtogp/AABkiiv9pTH-SaTKWbDcGxxlaI'm not too good at trying to explain something like this but if you have any questions go for it I'll try to answer for you this has several or at least a few benifits.
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Post by jakesrocks on Apr 29, 2015 14:30:10 GMT -5
If the pieces you want to slab already have a face cut, use Gorilla glue to glue a block of wood to that face. Let the glue cure for 24 hours.It's best to use a bar clamp to cllamp the rock firmly to the block while curing. Clamp the block in your vice. Depending on the thickness of your blade, about 6 turns of the cross feed screw will give you 1/4" slabs on a Covington 16" saw. Starting with the blade just touching the block of wood, back the cross feed out 6 turns at a time until you're near the nub end of your rock. Make a cut. Screw the cross feed in 6 turns & make another cut. Keep going 6 turns at a time until you reach the block of wood. Remove the block of wood & let it soak in water for a couple days. The glued slab should come off of the wood.
Cut your blocks of wood so they fit all the way across the jaws. This will give you firm & even clamping. No chance for rock slippage & blade damage.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,711
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Post by Fossilman on Apr 29, 2015 15:01:13 GMT -5
I didn't know,you were working hoodless! How come? I don't think I could do that myself,I would probably quit cutting...I don't even like water splashing on me-LOL..... Hope you get it worked out!!! Thumbs up
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Post by Rockoonz on May 2, 2015 15:09:46 GMT -5
I'm not familiar with the Covington saws aside from not liking the vice carriage or feed clutch design. If the vice goes all the way to the blade on the crossfeed heres my suggestion for wedge shaped rocks. If I want the slab at the large end of the wedge I clamp it out at the large edge with a block or jacking device at the opposite end to keep the vice jaws parallel. Here's a pic of my dirty 14 inch HP I'm in the process of cleaning. For the small piece in the vice I'm using a jack I made by drilling and tapping the vice. On top of the vice are two jacks made with coupling nuts and an assortment of various length bolts, adjustable to pretty much any length needed. Using them you can clamp a rock way out on the edge of the vice without binding up the vice. As always, when you think you have the rock securely clamped grab it and vigorously attempt to remove it. If it moves AT ALL try again or tighten more. When clamping you must have a minimum of 2 points of contact with the vice jaws, a previously cut flat surface only counts as one. I will also buy the cheap thin soft lath wood strips and crush short pieces between the rock and vice jaw to extend the point of contact when needed, then throw them away when done.
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Roger
fully equipped rock polisher
Member since January 2013
Posts: 1,487
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Post by Roger on May 3, 2015 12:33:52 GMT -5
I will also buy the cheap thin soft lath wood strips and crush short pieces between the rock and vice jaw to extend the point of contact when needed, then throw them away when done. That is a nice tip - thank you
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