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February 17, 2019, 01:48:55 pm
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Rock Clamps for Slabbing

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Author Topic: Rock Clamps for Slabbing  (Read 6713 times)
Mark
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« on: September 23, 2009, 11:21:58 am »

I was thinking of things to take pics of the other morning and I had been slabbing a bit.  So I took some pics of my rock clamp.  Not sure where it came from, as a friend gave it to me.  I think I remember hearing that a guy makes them.  If  you are into metal shop, you can probably make your own, they are rather simple.  I use mine all the time.  If i can get it to grip a chunk of rock with a reasonably flat side facing the slab saw blade, then I go for it.  If i have a chunk that has already been faced, then it is simple to grab the flat face of the rock.  Using this clamp saves me having to use wedges and trying to get a rock just right in the saw's clamp.  There are 4 screws that can be moved around and screwed into various holes depending on size and shape of rock.  The screw heads are what hold the rock.  You just place the rock against the face of the clamp and tighten the thing down until the screw heads grab or dig into the rock and hold it in place.  You then put the rectangular bar into your saw's regular clamp and tighten down.  This clamp allows you to place the rock so that you can get a good surface facing the saw blade.  I am probably not explaining this very well.  Maybe if i get technical, no that won't help.  I really need to do a video, maybe i could borrow the wife's camera, it does high def video, but thats for another day.   If anyone knows where you can get these clamps, please let us know.  I know they come in at least 3 different sizes.  I believe this is the medium sized one.

Mark


* Rock Clamp 1.JPG (121.93 KB, 1024x683 - viewed 182 times.)

* Rock Clamp 2.JPG (34.07 KB, 448x299 - viewed 132 times.)

* Rock Clamp 3.JPG (129.1 KB, 1024x683 - viewed 142 times.)
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hulagrub
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« Reply #1 on: September 23, 2009, 11:36:29 am »

That looks neat. Are the screws adjustable side to side? Or how? I have been trying to come up with a clamp for geodes, or whatever round rock, that I would like to cut down the middle, but do not thinks this would work. Your clamp would sure save a lot of time, glueing various boards to my end cuts.
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Dave, a certified Rockaholic

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« Reply #2 on: September 23, 2009, 12:02:32 pm »

Mark, thanks for sharing!! That is a great clamp and I think I will steal the concept and make one for myself... Would you mind taking a few more pictures without the rock and from different angles? Thanks...


Gary
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« Reply #3 on: September 23, 2009, 12:05:47 pm »

Gary, I would be glad to.

Mark
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« Reply #4 on: September 23, 2009, 06:34:38 pm »

Mark that is a neat vise.  I also use a short piece of 2X2, 2X4, or 4X4 lumber and glue it on to a semi flat surface and then let it dry for two weeks and put it in the saw vice and start cabbing.  After the last cab is cut  I soak it in water til the glue dissolves and there is virtually no waste of rock.  Jerry
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« Reply #5 on: September 23, 2009, 07:36:17 pm »

I have considered gluing rocks to the end of a 2 x 4 with water glass.  Maybe one day.

Mark
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hulagrub
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« Reply #6 on: September 23, 2009, 08:08:53 pm »

Mark, I have been using elmers glue, with the 1 X's or 2 X's. Just make sure everything is very clean, and then clamp them tightly together, making sure the rock face and wood are flush to one another. When you to your last cut soak it over night or two. My problem is way too many rocks to cut.
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« Reply #7 on: September 23, 2009, 08:22:08 pm »

Dave, I can really understand your problem of too many rocks to cut. I can always help with that problem!!! ;D ;D ;D


Gary
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« Reply #8 on: September 23, 2009, 09:41:17 pm »

Here is my home made version of a slab grabber.
It is made from two 1/4" by 2" by 6"cold rolled steel pieces, two 1/2" by 6" fully threaded bolts and four  1/2" jamb nuts.
The jaws are made by milling a V shaped slot in the ends. I use jamb nuts because they have a low profile and provide more clearance for the rock. Using a wrench you can get almost unlimited power to grip the rock.



I notch the rock with a 4 1/2" dry diamond blade (made for cutting concrete from Home depot or a similar hardware store) mounted on a mandrel in a jacobs chuck.

Here is a 3/4" thick 6" across Montana Agate that I want to cut parallel to the flat faces. Cutting it any other way wouldn't yield much useful material for cabs.

Here are the notches on each of the opposite ends of the rock. It took about 30 seconds to notch them.


Here the rock is mounted in the gripper....another 15 seconds.

Here it is mounted in the saw....another 15 seconds.

It took all of a minute to get the rock prepared and locked in place in the saw ready for slabbing.
Here are the three slabs that I got from a very thin piece of rock.

 The advantage of this method of gripping a rock is the speed in getting it prepared and into the saw. Another advantage is that you can grip any rock in any direction or angle for the best pattern yield possible for the particular material. Another advantage is that you don't have to cut a flat face first before it is gripped. Also you don't have to wait 2 days for the glue to dry or for the remaining rock to soak off the piece of wood.
Here is a Bruneau Jasper piece that required special orienting for the best pattern and yield. Here is how I notched it.


In the gripper.

And the slabs from the rock.

I use the gripper for nearly all the rocks that I slab. On thin rough you can get some fantastic slabs by being able to cut parallel to the color bands.
Bob
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« Reply #9 on: September 24, 2009, 12:00:33 am »

excellent pics, bobby.......  very neat idea.  We have what they call  " the gripper " that we bought in tucson last yr.  it works ok, but you can't cut real close as the feet of it get in the way.

mary ann
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Mark
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« Reply #10 on: September 24, 2009, 04:55:02 am »

Bob, great job.  I had seen pics of clamps like that before, but couldn't figure out they worked.  I had never noticed the groove in them and gripping edge.  The slicing of a groove in the rock is another great idea.  When I have a horribly shaped rock that I can't get my clamp on, I either let it sit forever, or I embedded it in a piece of concrete shaped like a 4 x 4.  My Covington slab saw has the same gripping edge on the end of the saw's clamp.  I have neve used the saw's clamp that way because the grip seems so small.  On my rock clamp, I can screw the screws out farther to increase the "bite" or gripping edge.  I guess that i could also get longer screws for using on the badly shaped rocks to get a better grip.  That saw of yours is great, with that I could actually cut some of my badly shaped rocks by first scoring their surface so that the slab saw blade would not slide around on the bad surface. 

Here's some more pics of the rock clamp so you can get a better idea on how it is built.

Mark


* rock clamp rear view.JPG (28.92 KB, 448x299 - viewed 84 times.)

* rock clamp screw layout.JPG (30.53 KB, 448x299 - viewed 69 times.)

* rock clamp base for clamping.JPG (30.9 KB, 448x299 - viewed 64 times.)

* rock clamp adjusting screw base.JPG (31.14 KB, 448x299 - viewed 89 times.)
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hulagrub
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« Reply #11 on: September 24, 2009, 08:40:11 pm »

Boy, I sure like both clamps. Believe I have the materials to make one like Bobby's. Great thing to be able to orient your rock for the best of cuts, instead of getting the best cut in however you might be able to clamp.
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Dave, a certified Rockaholic

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« Reply #12 on: September 27, 2009, 05:34:18 pm »

This was a great thread and seeing I had been wanting to make one for a while and with this topic putting a new fire under my !@# I took some time this weekend and made one while I still have access to a Mill and Lathe. This one is a two sided (Just in case one side should get worn out) and made from 1/2" thick cold rolled  3 3/4" x 6" and currently has  4 3/4" max jaw opening  which could be made as wide as you need it with longer pieces of all thread.
I still need to go get some jamb nuts as the ones on there now are just reg. 1/2" nuts.
Hopefully this one should last a long time.

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Taogem
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« Reply #13 on: September 27, 2009, 06:00:45 pm »

I have seen these double grooved clamps.. Seemed like one was a bit deeper than the other on them.. Maybe for better grasp on some pieces ??

Went to price these after seeing them again in this thread. Can't seem to find one for under 40.00 with a 5" max capacity..

Seems sorta steep.. ?
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« Reply #14 on: September 27, 2009, 09:09:58 pm »

On the movable clamp, if you put the nut on on the top of the jaw on the end nearest the stone and the nut on the underside of the jaw furthest away from the rock you can use the leverage of pivoting  on the front nut and really get a death grip on the rock. It is shown in my pictures of the clamp. This also eliminates having to perfectly adjust the distance on the clamp. It is a much simpler approach for the clamp.
Bob
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