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Author Topic: Clamp for cutting awkward shaped cobbles  (Read 4620 times)

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Bentruro

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Clamp for cutting awkward shaped cobbles
« on: November 24, 2015, 11:25:44 AM »

Hi Folks
I am based in the U.K on the north coast of Cornwall and have found some beautiful agates as pebbles and cobbles on some of the very remote and inaccessible beaches there. 
I have  A Barranca Diamond BD-10 which I imported from the US at great expense as lapidary kit is very hard to source in the UK. 
My problem is that most of the pieces I want to cut are discus shaped and I want to cut them along the long axis, which is very difficult with the clamp system provided with the BD-10.  Does anyone have a commercially available solution or a design for a home made clamp that could solve this problem?
Looking forward to your support folks!
All the best,
Ben
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cobbledstones

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Re: Clamp for cutting awkward shaped cobbles
« Reply #1 on: November 24, 2015, 12:00:29 PM »

Welcome to the forum.  I use a device called a slab grabber.  There are many configurations, here is one example http://www.sphereproducts.com/slabgrabber-sphereindexing.htm.  For pancake-shaped rough, I grind little notches in which the screw heads sit. This is accomplished with a rotary tool and diamond bur.
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Bentruro

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Re: Clamp for cutting awkward shaped cobbles
« Reply #2 on: November 24, 2015, 12:24:30 PM »

Thanks cobbledstones - I did not expect such a speedy response! 
I am currently abroad - have just had a great haul of Seaglass on a beach in Martinique in the Carribbean.
I have ordered a slab grabber straight away and hope that it will do the job when I get home.
I will report back.
Thanks for the advice mate!
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vitzitziltecpatl

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Re: Clamp for cutting awkward shaped cobbles
« Reply #3 on: November 24, 2015, 05:31:13 PM »

You could also epoxy it to a block of wood, oriented however you wish. Just saw through the wood block when you've got your slabs and grind the last bits of wood and glue off the back where it was attached.

lithicbeads

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Re: Clamp for cutting awkward shaped cobbles
« Reply #4 on: November 24, 2015, 06:26:35 PM »

Epoxy is also , as mentioned , a standard way of doing this. It is unfortunate that more folks don't try to cut their cobbles correctly. Welcome to the forum. It has been many years since I spent much time reading about climbing of your sea ckiffs, the days of Pete Livesey if that rings a bell. Lately the US climbing magazines have been  heavy on articles about climbing the Old Man of Hoy , a world wide classic sea stack. Looking forward to more posts from you.
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hummingbirdstones

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Re: Clamp for cutting awkward shaped cobbles
« Reply #5 on: November 24, 2015, 07:28:18 PM »

Welcome to the forum, Ben, from Northern Arizona!   :hello:

Glad to have you aboard and look forward to more of your posts.
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Robin

phrankhansen

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Re: Clamp for cutting awkward shaped cobbles
« Reply #6 on: May 07, 2016, 07:34:02 PM »

How did the slab grabber work?  I'm looking for a similar solution
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bobby1

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Re: Clamp for cutting awkward shaped cobbles
« Reply #7 on: May 07, 2016, 10:38:26 PM »

Here is my design for a rock gripper. The jaws are made from 1/4" thick by 2" wide and 6" long cold rolled steel. The bolts are 6" long fully threaded 1/2-13 steel. Make the holes for the bold 5/8" so the jaws can slid easily on the bolts. The jaws have a "V" shaped groove milled across the end where the rock is gripped. The movable jaw has the nut on the top nearest the grooved ends where the rock is gripped. The other end of the jaw has the nut on the underneath side.
I use a 4" dry diamond blade to notch two parallel grooves on the rock to be gripped. The rock is fitted into the jaws with the sharp edge of the jaws fitted into the grooves in the rock. Tighten the upper nut first and the lower one last to get a lot of gripping leverage. The gripper can be mounted most any way you wish.
Bob
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phrankhansen

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Re: Clamp for cutting awkward shaped cobbles
« Reply #8 on: May 08, 2016, 10:30:31 AM »

thanks so much for responding.  The pic and the instructions were perfect and very helpful
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Windenzee

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Re: Clamp for cutting awkward shaped cobbles
« Reply #9 on: May 08, 2016, 11:32:32 PM »

Hi Ben,
Just returned from a short break from down by you. Glad to hear that you were able to find agates etc on the beach. Was hoping to find some as well but was traveling with a person who is wheelchair bound.
I am based by Gatwick so not much around here.
Karen
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Orrum

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Re: Clamp for cutting awkward shaped cobbles
« Reply #10 on: May 09, 2016, 04:11:41 AM »

Slab grabbers are a must have!!!
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Redrummd

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Re: Clamp for cutting awkward shaped cobbles
« Reply #11 on: May 25, 2016, 08:20:47 PM »

Try an adhesive such as JB Weld and blocks of wood.  You can even cut an angle on the block of wood with a miter saw to get the angle you want too.

Do a search for my recent posts as I posted the reasons for using my preferred method.

finegemdesigns

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Re: Clamp for cutting awkward shaped cobbles
« Reply #12 on: May 25, 2016, 11:39:42 PM »

For odd shaped rough like geodes you can try a Lortone Gator Jaw

http://www.kingsleynorth.com/skshop/product.php?id=96084&catID=116

Sometimes they also appear on eBay in the $29.95 price range.



Works well on the Lortone 12 inch slab saw.

Also did you check out the other Slab Grabber thread on here?

http://lapidaryforum.net/group/index.php?topic=643.msg14060#msg14060
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Greg Hiller

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Re: Clamp for cutting awkward shaped cobbles
« Reply #13 on: May 27, 2016, 10:36:08 AM »

>Try an adhesive such as JB Weld and blocks of wood<

Lately I've been using an old brick.  I use gel type super glue and super glue accelerant called 'Zip-Kicker'.  If I'm trying to make another slab out of an odd shaped slab end piece I do the following:

Place the brick in the slab saw's vise and run the brick right up to the saw blade to make sure it's perfectly parallel to the blade.  Then crank down on the slab saw's clamps to hold the brick fast.  Then put some gel super glue (you can purchase this stuff SUPER cheap in bulk) on the slab's flat surface.  Then using a Q-tip swab a bit of the accelerant on the flat surface of the brick.  Quickly put the two together.  Allow it to cure for about 5 minutes and then run the saw.  Works like a charm and FAST. 
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Always interested in trading slabs and rough

Slabbercabber

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Re: Clamp for cutting awkward shaped cobbles
« Reply #14 on: May 28, 2016, 03:52:50 AM »

I've had success inserting small stones in plaster cast in a wax or square plastic milk carton.  Place the entire casting in the saw and slice away.  The difficult thing is that you cannot choose where on the stone you are going to cut.
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