wargle
off to a rocking start
Member since September 2010
Posts: 2
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Post by wargle on Sept 28, 2010 21:19:37 GMT -5
Hi, I'm new to the site and to tumbling. I am trying to tumble some rough my granddaughter found in Franklin, N.C. last summer. I have a dual barrel, 3 lb. ea., rotating tumbler. I started the load with 60-90 grit silicon carbide for a week, then a week with 220 grit, followed by a week of pre-polish and a week with polishing grit. They did not shine up, so I ran another week with polishing grit with no change. The stones look good when wet, but are dull when dry. What am I doing wrong.
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Post by Toad on Sept 28, 2010 22:59:13 GMT -5
You're not leaving them in rough long enough and/or may not have stones that will polish well. Can you post pics of your stones? 60/90 grit should usually run at least a month, re-charging with fresh grit every week.
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Post by 150FromFundy on Sept 29, 2010 10:04:22 GMT -5
A month may not even be long enough. The stones should be the finished size and shape that you want with no pits, scratches, or blemishes before you move them on from the 60/90 grit. The 60/90 grit stage is where all the time and work in grinding is. Everyy stage after the 60/90 should be considered polishing. You are removing microscratches only. You are not removing pits, scratches, or blemishes.
Darryl.
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chassroc
Cave Dweller
Rocks are abundant when you have rocktumblinghobby pals
Member since January 2005
Posts: 3,586
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Post by chassroc on Sept 29, 2010 10:50:25 GMT -5
Another thing to consider is that the rough from Franklin is often an assortment of precious stone rough, like sapphires, garnets, rubies, mixed with quartz which will only glaze over with the other rocks.
Do you know what is included in the mix from Franklin?
Charlie
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Post by tanyafrench on Sept 29, 2010 13:23:14 GMT -5
When I started tumbling I was told several time to be patient with the Course tumble (60/90). That was the hardest part for me. I wanted to move on. I have also found that some stones are ready to move on in maybe 3 weeks and other in 4 or 5 weeks. I have 4 tumblers so they can move from step to step and continue on so some are in polish while others are still in course. I had to wait when there was just one tumbler. Believe me it is worth the wait but it will be hard for your granddaughter. Welcome aboard the RTH. Tanya
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wargle
off to a rocking start
Member since September 2010
Posts: 2
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Post by wargle on Sept 29, 2010 20:22:34 GMT -5
Wow. I read on some other web sites that you only need to tumble with each grit for about a week each. When I started out with the 60-90, it really wore the stones down and rounded up the edges. I thought it was doing what it was supposed to. In the mix I have quartz, amethist, garnet, emerald in matrix, topaz, and several that I don't know. So I should start over and run 60-90 for 2-3 more weeks? The way the first run of one week wore the stones down, I might not have anything left.
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Post by Toad on Sept 29, 2010 21:12:56 GMT -5
As Darryl said, course grind should go until all blemishes are gone. After that, all remaining stages should only take a week, or two tops. But that first stage can be 2 weeks to 2 months...
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jasperblue
starting to spend too much on rocks
Diggin' This
Member since August 2010
Posts: 140
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Post by jasperblue on Sept 29, 2010 22:40:13 GMT -5
Wargle, welcome to the best tumbling site there is! You will need to log in quite a few hours to get it right. By starting with those types of stones, you have jumped in with both feet! It will be trial & error for a little while. But don't be discouraged. It could be, as Toad says, those particular stones may just not want to polish all the way. It sounds like you got the coarse right, if they are already small. Coarse is mainly for shaping. You might want to start again in medium, 220 for a week or 2, recharging as the grits wear away. In med. is where you want to make sure your stones are blemish-free. Don't go on from here until you are satisfied. Then go to fine, 400, for at least 2 weeks, pre-polish for at least 2 weeks, also recharging if needed, and then on to polish. If you have really nice rocks/stones, polish first in aluminum oxide, a week or so, then another week or 2 in either cerium oxide or tin oxide. then burnish in ivory soap bar flakes for a day. Also, from 'fine' on, add plastic beads to keep your good stones from cracking each other. Simple enough? Really, it's not as complicated as it sounds. Now good luck! -Chris
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Post by Toad on Sept 30, 2010 7:26:31 GMT -5
Chris might have luck getting rid of blemishes in 220, but this grit is not nearly as aggressive as the 60/90. You'll be stuck with blemishes (fractures, pits, etc.) a lot longer if you wait to the second grind to get rid of them. Todd
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Post by Hard Rock Cafe on Sept 30, 2010 9:53:07 GMT -5
I think Charlie is also on the right track: you'll want to separate the load into batches of equal hardness. Otherwise, the hard stones will polish and the rest will just get ground away.
Garnet hardness is 6-7.5 Topaz is 8 Quartz and Amethyst are up to 7 Emerald is 7.5-8
If you can't identify the stones then use hardness (scratch) tests to figure out which ones can run together.
Chuck
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