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Post by johnw on Dec 22, 2018 0:02:25 GMT -5
After messing around with river agates I am thinking I should stick to Big Crazy's and Bahia's. BUT, since I bought some River Agate Nodules from Uruguay, on e Bay, I need process them. Problem is they developed some really ugly holes and cracks on the surface after 17 days tumbling in the Covington rotary with 60-90 grit. Here is a picture of what they look like to-day: This is what they looked like at the start of the process.
I think in hindsight I should not have purchased them, but there is a first and last time for everything, mea culpa. So my issue becomes, how to get rid of the holes and cracks? Do I sand them or throw them back in the tumbler with a more coarse grit, say 40 or 60 and just tumble them until there are no defects, or do both? Oh, and since I never had these issues with Bahia's I need a sander and need recommendations on brand. I would appreciate any advice and help that you can give me. Thank You. With Respect, johnw
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Post by manofglass on Dec 22, 2018 10:46:17 GMT -5
You will be tumbling them forever to get them holes Out best to pregrind first
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,666
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Post by Fossilman on Dec 22, 2018 11:23:06 GMT -5
Yuppers, you got a bad deal, going to have to pre grind...
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Post by HankRocks on Dec 22, 2018 11:27:34 GMT -5
johnw If the pits that are visible are surface only then, grinding them away or tumbling for a longer period will help. If the pits run throughout the rock then you will never get rid of them, that depends on the material. Fractures will never go away. I am not a big grind all the defects away fan, just not what I care to spend my time on. Would rather spend the time grinding on preforms. Although I do not tumble to obtain the perfect stone, I do run some rocks in coarse for extended periods. It really depends on the rock. If it's going to be a really nice one with some knock out pattern, then they stay in coarse longer. No hard rules just personal choice. When I sell tumbles a lot of folks aren't too discriminating when buying and they are as likely to pick out an imperfect stone as they are a very nice one. Ran an experiment at the last two shows and placed about 10 really nice tumbles, Bot's, Brazilians into the tub with the rest. Although I sold around 400 to 500 stones, half of my test rocks were still there at the end of the day. Suppose I was just lucky that none of the members of the RTH forum hit the tub! One method I do employ is to produce a stockpile of "ready to move past coarse". When there are enough I start a batch on step 2. All of my coarse(except preforms) run in my double 12 pound tumbler. After 10 days and a couple of re-charges they are graded and maybe half, maybe less are moved to the next stage stockpile. With the next stages there is a lot less reduction of material and maintaining correct fill is a matter of adding previously run pea gravel. There are a good many smaller agates that never make the tumbler and end up in the "erosion control/rock garden bucket". Also been lucky to have decent sources of well rounded river rocks that only require 1 cycle through coarse. Good luck.
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Post by johnw on Dec 22, 2018 11:58:52 GMT -5
johnw If the pits that are visible are surface only then, grinding them away or tumbling for a longer period will help. If the pits run throughout the rock then you will never get rid of them, that depends on the material. Fractures will never go away. I am not a big grind all the defects away fan, just not what I care to spend my time on. Would rather spend the time grinding on preforms. Although I do not tumble to obtain the perfect stone, I do run some rocks in coarse for extended periods. It really depends on the rock. If it's going to be a really nice one with some knock out pattern, then they stay in coarse longer. No hard rules just personal choice. When I sell tumbles a lot of folks aren't too discriminating when buying and they are as likely to pick out an imperfect stone as they are a very nice one. Ran an experiment at the last two shows and placed about 10 really nice tumbles, Bot's, Brazilians into the tub with the rest. Although I sold around 400 to 500 stones, half of my test rocks were still there at the end of the day. Suppose I was just lucky that none of the members of the RTH forum hit the tub! One method I do employ is to produce a stockpile of "ready to move past coarse". When there are enough I start a batch on step 2. All of my coarse(except preforms) run in my double 12 pound tumbler. After 10 days and a couple of re-charges they are graded and maybe half, maybe less are moved to the next stage stockpile. With the next stages there is a lot less reduction of material and maintaining correct fill is a matter of adding previously run pea gravel. There are a good many smaller agates that never make the tumbler and end up in the "erosion control/rock garden bucket". Also been lucky to have decent sources of well rounded river rocks that only require 1 cycle through coarse. Good luck. HankRocks, thank you for the sound advice. I have received several good ideas, but I am leaning towards just taking a couple and dumping the rest and take my loss. If I am going to spend time grinding away it will be only on the 5 pound plus Big Crazy's that I have going to round out the shape for a better overall visual. I do however agree with you I have better things to do with my time that just grinding away defects before tumbling. Best to take what is after coarse tumble and use the miscreants as fill fodder. One final comment: is it better to grind or sand because I need buy the equipment. Cheers, johnw
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Post by HankRocks on Dec 22, 2018 12:10:13 GMT -5
johnw If the pits that are visible are surface only then, grinding them away or tumbling for a longer period will help. If the pits run throughout the rock then you will never get rid of them, that depends on the material. Fractures will never go away. I am not a big grind all the defects away fan, just not what I care to spend my time on. Would rather spend the time grinding on preforms. Although I do not tumble to obtain the perfect stone, I do run some rocks in coarse for extended periods. It really depends on the rock. If it's going to be a really nice one with some knock out pattern, then they stay in coarse longer. No hard rules just personal choice. When I sell tumbles a lot of folks aren't too discriminating when buying and they are as likely to pick out an imperfect stone as they are a very nice one. Ran an experiment at the last two shows and placed about 10 really nice tumbles, Bot's, Brazilians into the tub with the rest. Although I sold around 400 to 500 stones, half of my test rocks were still there at the end of the day. Suppose I was just lucky that none of the members of the RTH forum hit the tub! One method I do employ is to produce a stockpile of "ready to move past coarse". When there are enough I start a batch on step 2. All of my coarse(except preforms) run in my double 12 pound tumbler. After 10 days and a couple of re-charges they are graded and maybe half, maybe less are moved to the next stage stockpile. With the next stages there is a lot less reduction of material and maintaining correct fill is a matter of adding previously run pea gravel. There are a good many smaller agates that never make the tumbler and end up in the "erosion control/rock garden bucket". Also been lucky to have decent sources of well rounded river rocks that only require 1 cycle through coarse. Good luck. HankRocks, thank you for the sound advice. I have received several good ideas, but I am leaning towards just taking a couple and dumping the rest and take my loss. If I am going to spend time grinding away it will be only on the 5 pound plus Big Crazy's that I have going to round out the shape for a better overall visual. I do however agree with you I have better things to do with my time that just grinding away defects before tumbling. Best to take what is after coarse tumble and use the miscreants as fill fodder. One final comment: is it better to grind or sand because I need buy the equipment. Cheers, johnw I would say grinding would be better as it's faster and the wheels last longer. Here again,I would rather save my wheels for preform work. If it's a preform that I might make $7 to $15 on, then it's worth it. For a rock I will sell for .25 cents not so much. It needs to be a special tumble for me. You might consider a super-grinder made with a stack of diamond saw blades. Built one myself and it really takes the material off in a hurry, rather rough and crude, but it's the beginning grind so it doesn't matter.
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