|
|
Post by fernwood on Jan 27, 2022 9:00:33 GMT -5
Strange question.
What is the best way to break rock slabs in a controlled manner?
I have some very large slabs that need to be broken into more manageable sizes.
Would rather not just drop them on concrete.
Is it possible to score the slabs with a glass scorer and then tap with a ballpeen hammer?
Or would it be better to use Dremel diamond disk to mostly cut them and then tap off.
They are all fairly hard, say 6.5 – 7.5. Jasper, agate, pet wood, fossils. They are about 8” to 10” long by up to 6” wide. Normal slab thickness.
I need to make them smaller for sending to others.
Thanks
|
|
|
|
Post by hummingbirdstones on Jan 27, 2022 9:22:37 GMT -5
Beth, you could try scoring one with a glass cutter and see how it works. It may be ok with the agate and jaspers, but I'm unsure what would happen with fossils.
The technique for glass is to score the glass and then snap it off with a quick downward motion on the edge of a table. I've never tried it with stone, so I say give it a go on a piece and see. Be careful of small shards that may come off the edge and how sharp the edges will be if it works.
|
|
saxplayer
fully equipped rock polisher
Member since March 2018
Posts: 1,327
|
Post by saxplayer on Jan 27, 2022 9:54:32 GMT -5
Beth, you could try scoring one with a glass cutter and see how it works. It may be ok with the agate and jaspers, but I'm unsure what would happen with fossils. The technique for glass is to score the glass and then snap it off with a quick downward motion on the edge of a table. I've never tried it with stone, so I say give it a go on a piece and see. Be careful of small shards that may come off the edge and how sharp the edges will be if it works. Thick leather gloves  |
|
|
|
Post by Peruano on Jan 27, 2022 10:10:57 GMT -5
Tile saw! A cheapie from Craigslist. I was really going to do the smash routine, I'd put the slab in bench vice and hit the part that sticks up above the jaws. Or place the slab on a table edge with a piece of plywood on top and clamp with c=clamps. Hit the part that sticks over the edge.
|
|
|
|
Post by rockjunquie on Jan 27, 2022 10:15:36 GMT -5
I saw a tool once that used to available. I think it was called an agate cutter. It was essentially a glass scorer. So, you score the hard rock and prop the slab at an angle and tap the line or the part that sticks up. Basically what Peruano said. It was widely used. |
|
realrockhound
Cave Dweller 
Chucking leaverite at tweekers
Member since June 2020
Posts: 4,500
Member is Online
|
Post by realrockhound on Jan 27, 2022 11:10:31 GMT -5
Personally, I’d say find a really cheap trim or tile saw. Or find a local lapidary club who would cut them or find someone in the area with tools willing to cut them. I feel like in the long run you’ll be happier going that route as opposed to trying to break them up in some other manner.
|
|
|
|
Post by Starguy on Jan 27, 2022 12:24:07 GMT -5
A glass cutter will work on most slabs. It will be problematic on some slabs that have weak bands between strong bands, (crazy lace). I have a photo of a slab specific glass cutter but Cloudinary isn’t working for me right now. It’s basically a glass cutter with a much heavier grip. I’ve seen them on eBay before.
|
|
|
|
Post by Starguy on Jan 27, 2022 12:26:44 GMT -5
|
|
|
|
Post by fernwood on Jan 27, 2022 12:35:52 GMT -5
Tile saw! A cheapie from Craigslist. I was really going to do the smash routine, I'd put the slab in bench vice and hit the part that sticks up above the jaws. Or place the slab on a table edge with a piece of plywood on top and clamp with c=clamps. Hit the part that sticks over the edge. My tile saw is in barn storage for winter. |
|
|
|
Post by fernwood on Jan 27, 2022 12:37:06 GMT -5
Thanks for the suggestions. Will let you know what happens.
|
|
rewdownunder
spending too much on rocks
Member since March 2012
Posts: 357
|
Post by rewdownunder on Jan 27, 2022 14:08:22 GMT -5
If the slabs are worth anything breaking them up will waste a lot of material. Some people like larger slabs and they can be shipped in padded envelopes with a backer. We used to break common slabs for kids grab bags but wasted so much material we started cutting them. let us know how the glass cutter works out.
|
|
|
|
Post by greig on Jan 27, 2022 14:42:30 GMT -5
Here is my experience: A saw is better. If hit with the round side of a ball peen hammer, you will get a tiny circular spider web shape broken right under the centre of the hammer head...and then the rock will crack outwards in a number of pieces. A single sharp hit is better than a bunch of lighter ones. If you see the slab crack, you can usually persuade it to break along the crack without more hammering. With this method, there is no control over direction of the cracks. I have found it better to use a wide blade screwdriver, because it tends to have only one break and better control of the direction of the crack. The cracks are never perfectly straight. If it doesn't break on the first hit, move the screwdriver a short distance in the direction you want the slab to crack and hit again. Good luck!
|
|
|
|
Post by jasoninsd on Jan 27, 2022 17:08:06 GMT -5
Really really small rock wedges??   |
|
brybry
Cave Dweller
Enter your message here...
Member since October 2021
Posts: 1,221
|
Post by brybry on Jan 27, 2022 18:29:11 GMT -5
3-4 inch masonry chisel. Can be had for $9 at HF. Even has the comfy hand protector grip.
|
|
|
|
Post by rockjunquie on Jan 27, 2022 19:18:24 GMT -5
If all else fails... drop them. They will break on the weakest points (fractures) and provide you with some fracture free pieces.
|
|
Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,496
Member is Online
|
Post by Sabre52 on Jan 27, 2022 20:20:00 GMT -5
There are slab braking pliers that go with that heavy duty rock cutter. They work well on homogenous material like picture jasper and obsidian, not so much on true jasper and things like hard agate. The plier jaws have a ridge down the middle that goes on the score line to apply pressure in the correct place.
|
|
|
|
Post by rmf on Jan 27, 2022 20:31:04 GMT -5
fernwood I have used the slab scoring tool shown by Starguy with great success in Brazilian Agate. It works well for uniform agates like that. Less effective on other types. I scored then laid the scored slab on the edge of a table and snapped it. I also purchased a tool (2 actually) from home depot to snap tile and used one from each end of the slab, centering on the score line. Some rocks work better than others.
|
|
|
|
Post by greig on Jan 27, 2022 21:43:35 GMT -5
3-4 inch masonry chisel. Can be had for $9 at HF. Even has the comfy hand protector grip. My masonry chisels are kinda dull. Might give the poor rock a "blunt force trauma". ;-) |
|
