geoff59
spending too much on rocks
Member since October 2022
Posts: 288
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Post by geoff59 on Oct 22, 2022 20:12:36 GMT -5
Happy Saturday night! So, in my various reading her and there, I have seen it mentioned that a good way to break rocks up in to smaller sized pieces is by using some sort of curved bit of metal as a base. It is supposed to be a better way to break rocks on to rough, with less waste? So, I am wondering if anyone here can elaborate on this, or even better post a photo or 2 of a “curved metal” anvil-type of thingamajig. Thanks in advance.
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dshanpnw
fully equipped rock polisher
Member since December 2020
Posts: 1,071
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Curved
Oct 23, 2022 8:07:49 GMT -5
Post by dshanpnw on Oct 23, 2022 8:07:49 GMT -5
Hello geoff59, I sometimes break larger rocks for tumbling material. I probably read some of the same things you did about a rounded metal object. I do not wish to say everyone can and should use my idea of a little wooden box with weight plates and a steel rod to break rocks, but it does come in handy. I don't own an anvil and I wanted something small. I do not use the steel rod. I've tried but not to much good. I think as long as you have a metal base and a good size, 2.5 pound or larger hammer and a chisel you'll be fine. Be sure to wear protection as pieces do go ballistic.
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Post by vegasjames on Oct 23, 2022 8:58:47 GMT -5
I use a discarded railroad plate, which is cast iron. I put that in a produce box, which has high walls and a bit of a lip to help catch flying fragments. Then put the rocks on the plate and smack them. Larger rocks I break up some first with my jackhammer.
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nursetumbler
Cave Dweller
Member since February 2022
Posts: 981
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Post by nursetumbler on Oct 23, 2022 9:57:52 GMT -5
May I ask, doesn't all this wacking cause stress fractures?
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Post by susand24224 on Oct 23, 2022 11:59:26 GMT -5
Whacking, at least for me, caused fractures. I used a railroad tie and hammer and chisel on large rocks.
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dshanpnw
fully equipped rock polisher
Member since December 2020
Posts: 1,071
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Curved
Oct 23, 2022 12:33:36 GMT -5
Post by dshanpnw on Oct 23, 2022 12:33:36 GMT -5
May I ask, doesn't all this wacking cause stress fractures? It probably most assuredly does and you might not get the chunks you wanted. You get what you get most of the time. Sometimes you get lucky and the pieces are better than expected.
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nursetumbler
Cave Dweller
Member since February 2022
Posts: 981
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Curved
Oct 23, 2022 14:26:08 GMT -5
via mobile
Post by nursetumbler on Oct 23, 2022 14:26:08 GMT -5
May I ask, doesn't all this wacking cause stress fractures? It probably most assuredly does and you might not get the chunks you wanted. You get what you get most of the time. Sometimes you get lucky and the pieces are better than expected. Thank you dshanpnw
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,558
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Post by jamesp on Oct 23, 2022 14:35:39 GMT -5
How about shooting a rock placed in a heavy duty 55 gallon plastic drum with a rifle. The resulting pieces had no hammer fractures or any intermediate fractures for that matter. Results were also oddly curved in shape. One strike divides the entire rock. All kidding aside it actually worked great.
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Post by vegasjames on Oct 23, 2022 17:07:41 GMT -5
May I ask, doesn't all this wacking cause stress fractures? May depend on the stone. I have not noticed this problem with breaking up the candy rhyolite of Stonewall Canyon jasper. Forgot to earlier that I also collect the smaller fragments for fill, and what is left in those after tumbling are great for crafts or to put in vials.
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Post by hummingbirdstones on Oct 23, 2022 22:41:03 GMT -5
How about shooting a rock placed in a heavy duty 55 gallon plastic drum with a rifle. The resulting pieces had no hammer fractures or any intermediate fractures for that matter. Results were also oddly curved in shape. One strike divides the entire rock. All kidding aside it actually worked great. Only you, jamesp!
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,558
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Post by jamesp on Oct 24, 2022 6:46:20 GMT -5
Best way is to saw the rock into 1 inch thick slabs and then divide slab into smaller pieces with a hammer. Especially with round or chunky shapes. If the rock is already slab like or thin the job is much easier. If collecting quarried material try to pick thinner/flatter pieces and stay away from rotund chunks. The point of impact should be chosen carefully. In all cases strike the rock on the flattest smoothest most solid place like a sawn face or a water worn face. That will usually propagate the longest/largest dividing fracture. If you have no saw then use a sledge to split or chisel the rock into thinner halves. There is no pretty way with a heavy sledge. Some rocks fracture easier than others. Agates and cherts are 'glassy' and easier to divide. Granites and grainy rocks can really be a challenge but may not fracture as readily. This 4 pound chert cobble split neatly into 'slabs' easily with high speed strikes using only a 4 ounce hammer with few to no fractures per slab. Again, agates and cherts are easy to divide with a hammer if they exhibit conchoidal fracture behavior. Grainy rocks can be a whole different story. More field divided and windowed chert and agate cobbles using a small hammer and high speed impacts at the optimum angle of impact. Plus it was a water worn cobble with flat/solid striking surfaces for best fracture control. You can practice on junk rocks to get the knack. www.flickr.com/photos/67205364@N06/albums/72157676247535186Ah, a photo showing the tiny fast 4 once hammer with a fiberglass handle. Next strike will be from the bottom to knock the cantilevered edge off. Then reverse the rock and strike the protruding ledge. Repeat down the rock. Granted this is fine agate and splits easy. Always use the flat side of hammer and not the ball side:
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