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Post by Hard Rock Cafe on Nov 3, 2008 9:52:34 GMT -5
I just got a 10" Star Diamond saw with autofeed. This is my first saw and I've been dying to cut open a bucket full of Keokuk (Jacobs) geodes. Can I just put them in the vise? Or do I have to follow advise I've read elsewhere about creating a plaster of paris matrix around them?
Do you have any other advice? These will be my first cuts. Blade appears to be original to the saw (still says "Star") and is close to true (about a 1/16" wobble I would guess).
Maybe I should try a different rock first? Replace the blade before cutting?
Thanks in advance! Chuck
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Post by Hard Rock Cafe on Nov 3, 2008 10:50:14 GMT -5
Forgot a couple of details. The geodes are gumball to baseball size and I expect the walls to be about 1/2 inch thick.
Also, the wobble is due to a little warp in the blade, not worn bearings.
Chuck
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lparker
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Post by lparker on Nov 3, 2008 17:28:11 GMT -5
Assuming the saw uses water not oil, I'd hold them by hand to cut them.
Lee
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Post by Hard Rock Cafe on Nov 3, 2008 17:38:13 GMT -5
Hmmm. I was planning on using mineral oil, but maybe I should reconsider. I gathered that mineral oil was better for notched blades and I wouldn't have to worry about rust.
Water would certainly be easier!
Thanks Lee! Chuck
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darrad
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Post by darrad on Nov 3, 2008 20:58:52 GMT -5
I currently use oil in my 10". I carve out a well in a piece of 2" x 4" and use Elmers glue and let it dry for a few days with Thunder Eggs. Never had one come loose. Soak it in water to get the glued half out and a wire brush to clean off any left over glue.
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Post by Hard Rock Cafe on Nov 4, 2008 9:38:50 GMT -5
Thanks to you both! Now I've got a couple of other options to try.
Chuck
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DeanW
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Post by DeanW on Nov 4, 2008 15:19:21 GMT -5
Stonewizard, can you re-use the 2x4? I've tried similarly but when I attempt to glue a second stone into the hole the glue doesn't stick.
Chuck, I keep a variety of wedge shaped pieces of wood around my saw. When I get odd-shaped pieces I try to grasp them in the vice useng the wedges. Once I think it is held pretty well I try to wiggle the rock out of the vice - actually I put quite a bit of effort trying to 'break it loose' and try several different angles because the last thing you want is a rock coming loose during a cut.
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Post by BuiltonRock on Nov 4, 2008 16:54:06 GMT -5
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Post by Hard Rock Cafe on Nov 4, 2008 18:34:08 GMT -5
Dean: I think I must have read one of your posts about this technique a while back and forgotten it. Thanks for reminding me! I've got a lot of wedges and shims.
John: Yes, I collected them with my kids last year. I broke open the bigger ones (larger than a softball) with a soil pipe cutter or hammer and chisel (basketball size), but these have been sitting in a bucket calling my name ever since. I read about your trip and it looked similar to the Jacobs site, except that his shale is yellow-brown. A few of the ones I broke open had agate rinds. Two or three had water! I guess I stopped that crystal growth... I'll have to post some pics after I get them cut. Mostly quartz, some calcite, some iron staining.
I'm having second thoughts about starting now because I don't know how much longer the warmish weather is going to hold out.
Chuck
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darrad
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Post by darrad on Nov 4, 2008 20:08:48 GMT -5
Dean- Yes I have reused some but I make sure they are good and dry by letting them sit in the Sun for a week or more depending on how warm it is.
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Post by johnjsgems on Nov 4, 2008 23:15:52 GMT -5
I usually push geodes small enough for a 10 inch saw by hand. I use oil and if you don't overfill (just cover bottom 1/4" of blade) it isn't real messy. After an oil shower or two you learn not to raise the blade guard too high. A holder I use on my big saw is a retangular three sided pine frame open on one end. The geode goes in the open end and vise squeezes the boards closed. The boards get a little shorter each time.
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lparker
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Post by lparker on Nov 6, 2008 16:02:36 GMT -5
What I'd like to get is a geode clamp. I went to Howe's Caverns in Eastern NY last year. They were selling geodes and you could break them with a lever/gear chisel thing or they would cut them on 18" saws. Each saw had a geode jig that was held by the vise. I can't remember exactly how it was built, but I think it had a couple angle irons (lengthwise to the blade) to set the geode on and another larger split one that sat on the geode-pivoting on a bar over the blade. One of you geniuses out there might be able to picture it:) Pretty nifty anyway.
Lee
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Post by Hard Rock Cafe on Nov 6, 2008 18:45:28 GMT -5
Hmmm. That's something to think about. The V of the angle iron would do a better job of holding the geode than a straight piece of wood, like stonewizard's wells. You would need some way to clamp the angle irons in the vise so that they wouldn't move...
Dr. Joe, are you reading this thread?
I had another idea: I was thinking of grinding a flat spot on the side of the geode so that the saw would be presented with a flat surface, rather than a round one. I would then put this at the bottom after the geode is cut.
BTW, thanks to all who have offered their suggestions. I'm going to try most of them and see what works for me. I imagine I'll end up holding the really small ones, especially since they won't take long to cut.
Chuck
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DeanW
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Post by DeanW on Nov 7, 2008 1:17:57 GMT -5
There has been a seller on ebay with their own home-made "slab grabber" (dang, now I can't seem to find it). Two flat plates with screws, one above the slab and a second below the slab. These plates were mounted perpendicularly to the plates and screws tightened them down to pinch the slab. I've looked at it many times, almost pulled the trigger to buy it but just never feel quite confident enough that it would work for odd-shaped things. Flat-edged pieces for sure, but geodes/thundereggs, etc. I'm not so sure. I have a couple of different sizes of the lortone-style slab grabber and have not found it very useful for odd-things.
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Post by Hard Rock Cafe on Nov 7, 2008 7:56:49 GMT -5
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DeanW
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Post by DeanW on Nov 8, 2008 0:14:02 GMT -5
Quite similar chuck. The one I saw on ebay also had a 2"x2" square tube that was perpendicular, and on the other side, to the bolt-plates. This tube is what would get grasped by the vice. Let's see if I can do so quick/crude text-art to describe. First, definitely consider the item you pictured in that other thread. |-<(d) (c)|+ |+ +(b) + (a) |+ ================|+ |-<
Where (a) is the square tube I mentioned; (b) is the rock clamped in place; (c) is the upper screw plate; (d) is a screw head holding the rock.
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Post by bobby1 on Nov 8, 2008 8:28:58 GMT -5
Here is what I use to grip rocks. It works on geodes, too. I notch the rock with a dry diamond saw. I suppose you could hand hold the gripper and use it on a smaller saw. Bob ADMIN EDIT - repaired broken images, original code below -------------------- [IMG]http://i151.photobucket.com/albums/s160/Rocksbob/Gripper1.jpg[/IMG] [IMG]http://i151.photobucket.com/albums/s160/Rocksbob/gripper16.jpg[/IMG] [IMG]http://i151.photobucket.com/albums/s160/Rocksbob/Gripper34.jpg[/IMG] [IMG]http://i151.photobucket.com/albums/s160/Rocksbob/Gripper36.jpg[/IMG] [IMG]http://i151.photobucket.com/albums/s160/Rocksbob/Gripper29.jpg[/IMG]
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Post by Hard Rock Cafe on Nov 8, 2008 11:11:20 GMT -5
Dean: I think I remember seeing those on ebay now...
Bob: I read your thread on this. It really helps to have a photo of it holding an odd-shaped rock. I think it's another good thing for me to try. I have that same blade on a hand grinder. I could probably put the grinder in a vise to get a straight cut on the flat stock...
Chuck
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DeanW
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Post by DeanW on Nov 9, 2008 23:29:15 GMT -5
Yup, I too have one of those blades in an elec. die grinder. That solution looks pretty decent and I'll have to give it a whirl.
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