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Gadgets, Gizmos, and Dohickeys => Cutting, Grinding, Polishing => Topic started by: Pebblehopper on December 30, 2016, 04:40:59 PM

Title: Breaking down a big rock
Post by: Pebblehopper on December 30, 2016, 04:40:59 PM
Ok, so I've bitten off more than I can chew...or better said more than my 10"saw can handle. Is there a blade for a 4" angle grinder that I can use to cut around the serpentine and break off bite sized pieces? Harbor Freight cheap kind?  Thanks.
Title: Re: Breaking down a big rock
Post by: Ranger_Dave on December 30, 2016, 06:23:35 PM
I'm not sure if it is true, but it seems reasonable, but you shouldn't hit the rock with big hammers to try and break it apart. I was told that could cause fractures in the whole rock and it would fall apart when you try to cut slabs. It might be worth it to find someone with a bigger saw and they can cut it for you. Offer a slab as payment. That often works.
Title: Re: Breaking down a big rock
Post by: bobby1 on December 30, 2016, 07:02:42 PM
I took the blade guard off my angle grinder and installed a 6" diamond blade on it. I run a garden hose on the rock as I am sawing a groove around the rock. I then take 3 or 4 thin chisels and hammer them into the slot. It will wedge the pieces apart. I did this on a large Priday Polka Dot agate boulder. Some safety precautions: Wear a full face shield and definitely have a GFI circuit protection on the power supply to the grinder. Wear heavy gloves and keep your hands away from the blade.
Bob
Title: Re: Breaking down a big rock
Post by: Pebblehopper on December 30, 2016, 07:30:54 PM
Thanks Bobby1, that's what I was looking for. I found a 4" diamond at HF that might just work with a bit of water and caution(!).
Title: Re: Breaking down a big rock
Post by: Ranger_Dave on December 30, 2016, 10:12:03 PM
That just gave me an idea. They sell surface grinding disks for angle grinders - mine is pneumatic so the water would not be a problem. That would be great for grinding off bumps and making a flat area that would hold better in the vice on my saw.

This is what I have in mind: http://www.harborfreight.com/power-tools/grinding-wheels-accessories/4-in-diamond-turbo-cup-wheel-61416.html
Title: Re: Breaking down a big rock
Post by: Phishisgroovin on December 31, 2016, 06:40:15 AM
an angle grinder with a 4 inch tile blade should work to get a groove around a rock, then with wedges and light taps it should pop apart by placing the steel wedges in the crack and tapping the wedges from center to edges of the rock.
Title: Re: Breaking down a big rock
Post by: Pebblehopper on December 31, 2016, 08:06:32 AM
Thanks all for your replies! I talked with a friend who has a 24" saw and this piece won't fit in that so after a little more digging on the internet and your suggestions I think I'll be able to put together a relatively safe process. I'll keep you posted if there's any interest in my progress.
Title: Re: Breaking down a big rock
Post by: Jhon P on December 31, 2016, 03:22:09 PM
Take pictures and let us know how it goes
Title: Re: Breaking down a big rock
Post by: Pebblehopper on December 31, 2016, 03:37:08 PM
HF had a sale today on "heavy duty" angle grinders so instead of adapting my work horse I bought one there plus blades, a GFCI from big box, now to line out a water supply and I'll start shooting once everything is set up.