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Post by deb193redux on Sept 11, 2012 20:14:53 GMT -5
I made this for a friend. it is designed 3.5" wide to clamp in a vise that opens max 3.75" based on a concept posted here a few years back with 7 positions for screws on both top and bottom, it should do for most rock. best with a cut face, but the screws can be extended to grab some non-flat rocks I am also making one that is 6.5" wide to fit in my LS12 vise. design will differ a bit because the LS12 has a vise with a top plate
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utdigger
noticing nice landscape pebbles
Member since January 2012
Posts: 84
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Post by utdigger on Sept 11, 2012 21:11:41 GMT -5
Good job! When you get the LS12 one done, I'd love to see it since I own that saw also. jeff
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keystonecops
freely admits to licking rocks
Member since October 2010
Posts: 957
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Post by keystonecops on Sept 12, 2012 11:00:56 GMT -5
Gotta friend what uses one o these, an he'll cut a groove with his grindn wheel round one end so the screw heads hold better. Later Clyde
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Post by deb193redux on Sept 12, 2012 12:45:04 GMT -5
If the surface of the rock is perpendicular to the face of the clamp, a groove for the flat-head screw can indeed help. If the cut face is at the equator (so to say) of the rock, and the rock surface tilts slightly down from the face of the clamp, I have not found a groove to be necessary.
In my view, the advantages of this gadget are that it can be fabricated with just a drill press and hardware store components. It does not require welding or milling. It does not require tools the make threads in metal.
This one uses fairly hard HDPE plastic, but I also have made one out of oak, although an even harder wood might be best.
By providing several rows of staggered positions of the screws that grip the rock, the need for the top piece to have a large range of movement is minimized.
Finally, because the body of the gadget is no wider than what would fit into the clamp (note the rock might be wider), very little of the gadget is thus in front of the clamp, and very little range of the cross-feed is lost.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,352
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Post by quartz on Sept 14, 2012 21:43:38 GMT -5
Nice grabber there, I like the use of the plastic and thd. inserts. I have access to a variety of plastics, and find it useful for many different aspects of lapidary machinery.
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