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Thunder Egg/Geode/Round Rock Home Made Clamp

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Author Topic: Thunder Egg/Geode/Round Rock Home Made Clamp  (Read 1821 times)
reefera4m
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« on: October 23, 2010, 10:29:50 am »

First let me say this is not my design, in fact I have no idea who originated the design.  A friend asked me to make one identical to one he had borrowed (with permission).

So I made one for him and tested it on my saw - it worked GREAT.  So I made one for myself.  Then another friend saw it ans wanted one so I made still another.  Then I decided to make the clamp available to any one that wants to make their own by posting photos/documentation.  Here it is.

Holding round rock, such as geodes or thunder eggs in a standard rock vice is difficult and the possibility of the rock slipping or twisting and causing damage to the saw blade is real.  The following ‘round rock clamp’ is one solution to this problem.

This ‘round rock’ clamp consist of a slotted base connected to two tension ‘fingers’ with a hinge at one end.  At the opposite end of the base supports, two uprights (3” lengths of 1” angle iron) are welded perpendicular to the base.  These two pieces support one end of the rock while the two tension fingers clamp the rock to the base and against these supports.  Two carriage bolts (or threaded rods) provide the tension between the top ‘fingers’ and the base, clamping the rock tightly in place and wedging the rock against the uprights. On one side of the base, a short piece of rectangular tubing is attached (welded).  This piece is clamped into the saw’s vice allowing the clamp and rock to move with the carriage/vice.

The slot in the base as well as the slot between the top ‘fingers’ allow the saw blade to cut the rock without cutting the steel clamp. This type of clamp will work well in two different styles of saw.   Mounted upright in the saw rock vice, the clamp will pass over the blade during cutting.  For slab saws with a carriage stop (and no side clearance), the clamp may be mounted horizontally in the saw’s vice.  With the carriage stop set at the proper distance, the blade will pass through the rock and stop before it comes into contact with the hinged end of the clamp. 

Vertical Position:



Horizontal Position:






The real advantages of this clamp are 1) the tension is provided to six places on the rock rather that just two as in a rock vice.  The slotted bottom provides contact on two side of the bottom of the rock, the top fingers on two side of the top of the rock and the two uprights on two side of the end of the rock.  This provides a more secure grip and once the rock is completely cut in two, the tension pushes the rock in place against the uprights, preventing it from dislodging.

This clamp can be made for either type of saw but two considerations are important; 1) it needs to be short enough to clear any lid or cover and 2) tall enough so that the hinge end clears the top of the blade as it passes through while cutting the rock.

In a horizontal mount with an adjustable carriage stop the only consideration is that the base and fingers be long enough to accommodate the radius of the blade. 

The size of the rock clamp depends on the size of the blade and/or cover clearance.  The side of the rock is limited to the radius (half the diameter) of the saw blade less the arbor diameter.  Larger saw blades that will accommodate larger diameter rock will require correspondingly longer/taller clamps.

A couple more photos:


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slabbercabber
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« Reply #1 on: October 23, 2010, 05:25:41 pm »

 yes
I love it.  I'm off to build one now.
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deb193
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« Reply #2 on: October 24, 2010, 06:47:47 pm »

as long as the hinge clears the blade. looks great.
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- Daniel

(when everything is exceptional, nothing is)

MrsWTownsend
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« Reply #3 on: October 24, 2010, 07:19:12 pm »

Well now that is a very cool thing~ I'm going to have to show that to hubby.  Nice work!
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Alvin
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« Reply #4 on: October 24, 2010, 08:49:27 pm »

great idea. got some prints. will have to take the photos to someone better with steal than I am. I can think of many uses for this clamp.
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DMGEMS
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« Reply #5 on: December 30, 2021, 02:24:37 pm »

Do you know anyone who will make me one for trade of premium rock or I will pay gladly? Tom
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