Don B.
having dreams about rocks
Member since August 2012
Posts: 52
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Post by Don B. on Oct 14, 2014 15:33:24 GMT -5
So you have a fresh cut face, right off your saw... how long does it take you to get a nice polished face on it? Most of the cutting I do on my saw is just to cut a display face on rocks I find. I just get a smooth face on them, and put some wax on them at the moment, but I was curious how long it generally takes people to get a nice polished face on a rock using different methods (vibralap vs grinding on flat lap).
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Post by mohs on Oct 14, 2014 16:00:30 GMT -5
takes a long time to polish my face but to your more serious question I'm hoping to find out... Ed
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Post by jakesrocks on Oct 14, 2014 16:03:46 GMT -5
Time would depend on how smooth of a cut you're starting out with, and also how hard your specimen piece is. With my saw, cutting agate or pet wood,I can go straight into 220 grit on my vibrolap. I'm generally ready for final polish after 1-1/2 days. One of the large old rotating laps is much quicker, but more labor intensive.
You must remember to grind off the break out nub, and also grind a very slight chamfer around the outer edge before going to the lap.
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spiritstone
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Member since August 2014
Posts: 2,061
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Post by spiritstone on Oct 14, 2014 16:50:57 GMT -5
Like Jake said. Depends on how smooth your cut is and the size of the rock face. I would have to say 1 hour or so on the flat lap for one rock, average size under 8 inches. Longer with vibes and tumblers.
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Don B.
having dreams about rocks
Member since August 2012
Posts: 52
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Post by Don B. on Oct 14, 2014 16:57:19 GMT -5
Other than the break out nub, the cut is nice and smooth, to the point that I sometimes don't want to grind off the break off nub because it will end up scratching up the cut surface. The primary rocks that I want a better face on are the "Coldwater" Agates I have been finding in my area. I haven't polished any yet because I am working on making some polishing pads/wheels to use on them. Here is one of the ones I am hoping to shine up though. www.psychoticnature.com/photo/14396-agates-img_1303
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spiritstone
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Member since August 2014
Posts: 2,061
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Post by spiritstone on Oct 14, 2014 17:16:23 GMT -5
Other than the break out nub, the cut is nice and smooth, to the point that I sometimes don't want to grind off the break off nub because it will end up scratching up the cut surface. The primary rocks that I want a better face on are the "Coldwater" Agates I have been finding in my area. I haven't polished any yet because I am working on making some polishing pads/wheels to use on them. Here is one of the ones I am hoping to shine up though. www.psychoticnature.com/photo/14396-agates-img_1303Nice slabs. Your getting into sizes I'm just not equipped for. JamesP threads show some good power hand tools that would work.
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Don B.
having dreams about rocks
Member since August 2012
Posts: 52
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Post by Don B. on Oct 14, 2014 17:36:03 GMT -5
They are halves, not slabs I actually only have a 6 inch flat lap that I made out of an old drill press. The nice thing is though, that the grinding discs are attached via a magnetic pad, rather than screwed down, so I can use the full surface, rather than just half of it. Just have to go back and forth so that one part doesn't stay over the center where there is no grit. I've been trying to make some 6" steel discs that I can affix some polishing pads to, that will work with the system, but shaping the 1/16" steel that I found on my in-laws farm is proving difficult since I don't have proper tools. I need to use some thinner metal, or find a shop locally to cut me some discs that I can then put polishing pads on.
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Post by jakesrocks on Oct 14, 2014 17:40:39 GMT -5
With out removing the break out nub, it's going to take for ever to get a nice flat face on your agates. If you grind slowly and watch what you're doing, you should be able to remove them with very little damage. You're going to be removing a little material in the first couple of stages of lapping. You should loose any grinding marks at the same time.
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spiritstone
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Member since August 2014
Posts: 2,061
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Post by spiritstone on Oct 14, 2014 17:45:00 GMT -5
Thats right, halves. What I tend to do is just use my old diamond disks when they are worn out. Glue on a stiff sponge backing, then add new smoothing disks to them or whatever the case I may need it for. You can purchase silicone carbide sanding paper for working on cars, then cut them to fit size? But I can only find them up to 2000 grit.
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Don B.
having dreams about rocks
Member since August 2012
Posts: 52
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Post by Don B. on Oct 14, 2014 17:52:30 GMT -5
With out removing the break out nub, it's going to take for ever to get a nice flat face on your agates. If you grind slowly and watch what you're doing, you should be able to remove them with very little damage. You're going to be removing a little material in the first couple of stages of lapping. You should loose any grinding marks at the same time. I know I have to remove it to get a good polish. Sometimes though, I am just happy with how the face looks from the cut that I leave it that way for a while until I have the time to do the full grinding.
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Post by roy on Oct 16, 2014 8:17:24 GMT -5
if it is a good cut and i start at 220 about 2 to 3 hours tops
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Post by captbob on Oct 16, 2014 8:27:24 GMT -5
2 to 3 hours on a vibrating lap?
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Post by johnjsgems on Oct 16, 2014 11:07:01 GMT -5
On a wet polisher (hand held angle grinder type tool) about 20 minutes. For small flats I use a no hole 100 grit spin on lap on my Genie. Followed up with 6" magnetic Novas in 280, 600, 1200, and 3000. Polish with diamond compound (usually 14K) on canvas. On the no hole discs you can't get uniform water spray or disc speed so you really can't use the full 6" face. I put about half the rock on the bottom of disc and just keep turning it. I've never timed it but if cut is smooth it is pretty fast. I had a Lortone (older model) vibe lap. It took a long time to get a good finish (like many hours). Thew old spinning laps were much faster and the high tech method many are going to is using magnetic diamond discs. The old laps have fallen from grace so can be purchased pretty cheap. The diamond discs in 20" or larger are very expensive though.
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jamesp
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Member since October 2012
Posts: 36,155
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Post by jamesp on Oct 16, 2014 11:22:52 GMT -5
Same wet polisher as John mentioned above except mounted on small bench grinders. A 4 inch slab in about 10 minutes, but you can get wet w/this rig. It is 3 five inch grinders with wetted four inch diamond pads. Going clockwise they are 100,200,400,800,1500 and 3000 diamond grit. with poorly adjusted saw I may start with 200 pad, 400 if saw adjusted well. Then 800,1500 and final polish of 3000. They are $39 Walmart bench grinders. after 4 years one of them had a bearing failure. The pads were $6 at McGill Warehouse. They are epoxied onto home brewed backing plates. The backing plates were the most work. 4 inch washers welded to the nuts that came with the grinders. And then ground while spinning by holding an angle grinder up to them and truing them before gluing the pads. the pads hardly wear with agate. Concrete will sure wear them down due to sand particles releasing. A 2 inch slab can be done very fast. Specimens polished on it My shoulders got tired with this 25 pounder
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Deleted
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Post by Deleted on Oct 16, 2014 12:28:27 GMT -5
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Don B.
having dreams about rocks
Member since August 2012
Posts: 52
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Post by Don B. on Oct 16, 2014 14:24:00 GMT -5
I've got some spare motors, and even an old bench grinder. I'm going to have to build something to try out some of those polishing pads.
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jamesp
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Member since October 2012
Posts: 36,155
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Post by jamesp on Oct 16, 2014 16:34:44 GMT -5
I've got some spare motors, and even an old bench grinder. I'm going to have to build something to try out some of those polishing pads. I chose to glue the pads Don. I ground the velcro off the back so that they were very flat. the flatter they spin the better the finish. they are desiged for 3600 RPM. Any faster can melt the rubber. they will work at slower speeds. I would make them out of the 5 inch or bigger(if available) pads next time. That rig has 2 ground fault extension cords plugged in series. A bit tricky to keep the very center wet, so the water drips right along the face of the pad. I have yet to wear those pads out. They have lots of hours, oddly, softer material wears them faster. they are not so good at getting bad saw marks, but not much is. They are also not good at getting the 100 pad grit scratches out. They come in 10,000 and maybe 50,000. And nasty 50 grit. Get wet pads, they come for dry use too. The wet better. I think they make 12 inch pads for some type of lappers, but cost a bunch.
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jamesp
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Member since October 2012
Posts: 36,155
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Post by jamesp on Oct 17, 2014 11:39:11 GMT -5
That was cold blooded LMAO
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Post by Rockoonz on Oct 17, 2014 19:17:35 GMT -5
takes a long time to polish my face but to your more serious question I'm hoping to find out... Ed I have that problem too Ed, too much hair, scars and wrinkles Won't take a polish...
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Post by roy on Oct 17, 2014 23:21:53 GMT -5
2 to 3 hours on a vibrating lap? custom built 36" lap
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