morticiamonroe
starting to spend too much on rocks
Member since October 2008
Posts: 147
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Post by morticiamonroe on Dec 12, 2008 22:00:25 GMT -5
I seem to be having a hard time getting any type of decent consistency to the slurry in my rotary barrel.
I add water to just barely almost cover the stones, add the grit, and let er' go. ( I purchase my grit from the Rock Shed and add the amount of per their instruction, and I know they are very reputable). But when I check on my stones days later, the slurry is very liquid and there is no gritty feel at all...I've tried with less water and more grit, but it just doesn't seem to be thickening. The stones themselves ARE wearing down, but VERY slowly.
So my question is,,,what consistency should a good slurry have?
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navi
starting to spend too much on rocks
Member since November 2008
Posts: 229
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Post by navi on Dec 12, 2008 23:05:57 GMT -5
water should only go to the BOTTOM of the top layer of stones, not cover the stones entirely.
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Post by Hard Rock Cafe on Dec 12, 2008 23:34:18 GMT -5
Agree with Navi onthe water level; below the top layer of stones. The slurry will become a thin mud. There are a lot of opinions here on whether it is better to have a thicker slurry and how to achieve it. But in general, I would say you have too much water.
Chuck
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Post by johnjsgems on Dec 12, 2008 23:39:13 GMT -5
It sounds like you need more grit. If after several days you don't feel grit it is probably ground down. The slurry should be about like pancake batter. Also you should have a mixture of sizes including small stones or ceramic media to carry grit where it needs to be.
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reelman
starting to spend too much on rocks
Member since July 2008
Posts: 114
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Post by reelman on Dec 12, 2008 23:42:13 GMT -5
Water level at bottom of top layer of rock. After several days the slurry will not be very thick. On the 2nd day you should be able to feel the grit. By the 7th day I can't feel it and clean and if needed, recharge my rough grit stage. Once I noticed my tumbler barrel was running slow and I had to adjust the screws to get it back up to speed.
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drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
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Post by drjo on Dec 12, 2008 23:59:12 GMT -5
What kind of rock?
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Dec 14, 2008 13:50:26 GMT -5
I have found that too much water- definitely a problem for you- makes the stones float around a little too much and grind against each other less intensively. Your slurry should be just thick enough to hold the grit in suspension. If it is too thin, the gritt will immediqately sink to the bottom of the barrel when you remove it from the chassis and that may be why you can't feel it. If the slurry is too thick, it will coat the stones and insulate them against the abrading action of the grit and other stones- more a problem in a vibe where you use little water. Many folks on the board check their vibes frequentl;y- I haven't found it a problem for polishing but with coarser grit I have had to add water to make the stones flow and prevent stones and grit from caking, immobile, in the bottom of the vibe's bowl. For polishing, the slurry should be a little thicker than milk and coat the stones very thinly. I gound the l;earning curve steep- play with it and you'll get it right.
Mark H.
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Dec 15, 2008 14:45:31 GMT -5
I agree that it sounds like you have too much water in there. Try cutting back and/or adding more grit. Here are some photos that I took for you to compare to. These are Lortone 3 lb. tumble barrels after 5 days with 60/90 SC rough grit:    After 5 days, you can see that there is some, but not a lot, of sandy grit left at the bottom. I think that really concerns you isn't the consistency of the grit but the perceived lack of shaping/smoothing of the rock. You can check this out yourself: carefully weigh the rock before and after each round of rough. You should be getting around an 8% reduction in the weight of the rocks during a good round of rough. (It can vary between about 5 and 12% depending on the starting material.) Then you can try adjusting variables to see how it effects your results. This might prove very enlightening! It did for me. |
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morticiamonroe
starting to spend too much on rocks
Member since October 2008
Posts: 147
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Post by morticiamonroe on Dec 16, 2008 8:09:34 GMT -5
What a great place this is! I'd certainly struggle so much more without the benefit of your advice, everyone.
Okay, then, definitely too much water. I thought the water level was supposed to just cover the stones.
I am tumbling a selection of 7-8 hardness stones, with small chips of rough quartz thrown in as a filler and to help with the abrasion.
Thank you for the photos, ejs, they are a tremendous help.
You're right about the grit sinking to the bottom, docharber, that's exactly what has been happening.
When y'all say to recharge the grit,,,do you add more grit to the slurry in the barrel, or dump ot out and start again?
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Post by johnjsgems on Dec 16, 2008 9:35:23 GMT -5
You are back to the trial and error part. If you check in 3 or so days and don't see much happening add a teaspoon or so more grit. If you wait 7 or 8 days and need more rough grind the grit should be worn down by then. On a small barrel it is easier to flush it out (don't worry about really cleaning it) and start with a new mix.
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morticiamonroe
starting to spend too much on rocks
Member since October 2008
Posts: 147
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Post by morticiamonroe on Dec 22, 2008 15:57:15 GMT -5
Update,
Took everyones sage advice, and things are looking SO much better. A most gracious thanks to all of you.
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ace
starting to shine!
Member since August 2008
Posts: 39
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Post by ace on Dec 22, 2008 20:09:26 GMT -5
I am glad someone posted this question, as I had been thinking about it myself. Right now I have 2 tumblers going with my first batches ever. The 3 pounder has a quartz/amethyst/citrine mix and the 4-1/2 pounder has an agate mix both using 60/90 grit. I normally get a nice thick slurry after a few days of tumbling. I usually recharge weekly as it fits my schedule to do so, and have been trying leave the slurry in there for 2 to 3 weeks before I completely clean the barrel and replace the water.
What I had begin to wonder was wouldn't it be better during the rough grind to have a little extra water and keep the viscosity of the slurry down to allow the rocks to move more, which may let the rocks smooth faster. What had me thinking this, is I had read something about keeping the viscosity of the slurry thick during the polishing stages so the rocks do hit each other as hard and cause chipping. But now I see that you need the slurry to be thick to help suspend the grit and keep it around the stones so they will smooth or polish. So today when I recharged and cleaned the barrels I used just a little less water than normal. The barrels are a little noisier than normal, but I think that is a good thing. ;D
Randy
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Post by Hard Rock Cafe on Dec 22, 2008 23:08:34 GMT -5
Randy,
Just make sure that you add filler as your load diminishes in size from the grinding. Too much noise is also a bad thing as it means the load isn't full enough and the rocks are banging against each other instead of sliding over each other. Just keep the barrels about 3/4 full.
Chuck
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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 Dec 23, 2008 8:58:00 GMT -5
Recharge...Means to clean the rocks off and add new grit and water. If I am staying with coarse grit, I will not wash very much, just a rinse and look-see at every rock to see if it is ready to move on(in which case, wash thoroughly).
I save some grit and slurry to jumpstart the process(of making a good slurry); some here agree, some don't. Some may have scientific proof of whether this helps or not, I don't.
I think a thick slurry(like a pancake batter before it sits for 10 minutes) helps.
csroc
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Dec 25, 2008 0:21:27 GMT -5
I don't have really big barrels, and haven't had chipping problems with the 3 lb or even my 12 pound barrel. the 12 pounder has flat surfaces in the interior to make the stones tumble instead of slide. Sliding results from too small a load and in really large barrels the rocks drop on each other and can chip if they are flawed. Stones 6 or more in hardness are tough enough to take the agitation. We've had some lively discussions recently about slurry thickness and thickeners. I still say non-fermentable fiber laxatives aren't just for breakfast anymore-
Mark H.
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firstrune
starting to spend too much on rocks
Member since January 2009
Posts: 156
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Post by firstrune on Jan 7, 2009 13:06:22 GMT -5
ejs, I wanted to agree with others that the pics you took are so helpful. Thank you for sharing that!
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