ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Sept 1, 2008 22:04:56 GMT -5
Since I want a really nice end product, I am running my rough rock through 6-8 rounds of course 60/90 tumbling, recharging every 7 days.
When I open the barrel after 7 days, there is no grit left, just a fine gray slurry. It seems fairly obvious that the rough grit is completely worn down somewhere before day 7.
I have seen some on this board suggest that 5 days between rechargings is better for the coarse stage. This potentially speeds up the coarse stage from, say, 6 7-day tumbles to 6 5-day tumbles, thereby saving nearly 2 weeks in the coarse stage.
But maybe I am being impatient (wait the extra two days, what's the hurry?) and wasteful (a 7-day tumble might use up more coarse grit if it doesn't all get worn down by day 5).
I plan to open up the next batch at day 5 to see what it looks like. What's the general wisdom here? Recharge the coarse every 5 or every 7? What makes for the best end result?
Thank you, as always, for the advice!
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Post by Condor on Sept 1, 2008 22:14:22 GMT -5
I've always gone 7 days and have had good results. Never tried 5 days. I'd imagine that the grit is not fully ground done at this point. Guess the real expert here would be Mel. He always has great results. Are you out there Mel?
Condor
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Post by LCARS on Sept 2, 2008 22:41:17 GMT -5
If you are just "recharging" (adding more grit) at 5-day intervals vs. 7-day intervals then some of the grit from the previous recharge might not broken down. As long as you're still tumbling them more it will all eventually break down anyway. Just make your last recharge cycle is 7-days to break down most of the grit that is left over, no harm done.
IMO, letting the grit break down completely would just slow the shaping process in the long run so making sure there is ample grit to keep shaping action up would be a good idea to cut down on the total shaping time needed. Other stone types may not eat grit as fast and going the full 7 days may not even be enough to break it all down and in this case less grit should be needed to perpetuate shaping.
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Post by parfive on Sept 2, 2008 23:39:33 GMT -5
ejs: "I plan to open up the next batch at day 5 to see what it looks like. What's the general wisdom here?"
. . . smart thinkin'.
I've said this more than once - If you wanna speed things up, best place to do it is the coarse stage. Check the barrel after four or five days to see how fast the 60/90 is broken down. If it's shot in four days, like mine, recharge 60/90 every four days. That'll save ya three days every charge while you're tryin' to shape the rock. If it takes five charges to shape the rock good enough for the next stage - that's 20 days instead of 35 days to get the job done.
Grit's cheap . . . life is short . . . and there's a lotta rocks backed up in my basement.
Rich
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rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Sept 3, 2008 2:11:24 GMT -5
Ejs,
"General wisdom here"? -- haha, this is one of those things where if you ask 10 different people you'll get 10 different answers.
It's one of those topics that is not at all cut and dry. Many different factors come into play, including personal preference. For starters, how long grit lasts depends on many factors, just a few of them are:
- size of barrel... bigger barrels tend to break grit down faster.
- size of rock... the larger the rough, the faster it breaks down grit.
- hardness of the rock... harder rocks break grit down faster.
- plastic pellets, sugar, or anything else added to slow the action in a barrel... slower action means slower break down of grit.
I once did a bunch of experiments using my 6 lb Lortone rotary barrels, and I found that 60/90 grit typically lasted about 4 days until it was too fine to feel with my fingers (and since I can feel 120/220 grit with my fingers, this meant it had broken down finer than the fine-grind stage.) In the short extreme, using large agates, the grit broke down in as little as 2.5 days. With softer and smaller materials, the grit could last 5 days. Plastic pellets or other additions would make the grit last even longer, though I did not test this.
So... come up with your own recipe... that will be the 11th recipe for 11 different tumblers! :-).
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fanatic
starting to spend too much on rocks
Member since October 2007
Posts: 233
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Post by fanatic on Sept 3, 2008 6:24:49 GMT -5
I agree rollingstone - its like gold prospectors - get two gold prospectors together and you'll get three opinions.
I had the same experience with the 60/90 breaking down in 5 or 6 days. I took a different tactic. I started using 46/70 in the coarse stage and depending on the material, I sometimes let it go 14 days or more before opening it up. I've never had 46/70 break down completely in 14 days and it definitely speeds up the coarse grinding process.
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Sept 3, 2008 11:43:12 GMT -5
Cool discussion. More opinions! That's what I crave! ;D
I am using Lortone 3lb. tumblers (33A and 33B). I am tumbling some hard stuff (quartz/citrine/amythest=7Mohs). I plan to run 6-8 recharges of coarse, pulling out any that is well shaped, until I have enough that is well shaped to move on to the next stage.
I'll start checking the coarse tumble after 5 days. If the grit is broken down, I'll recharge.
Maybe I'll even get motivated enough to open the barrel every day and snap a photo to really follow what is going on. Since I could spend more time in the coarse stage than all the other stages combined, it is worth figuring out how to mimimize time without sacrificing the quality.
Thanks again!
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tombodc
noticing nice landscape pebbles
Member since August 2008
Posts: 88
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Post by tombodc on Sept 3, 2008 17:55:10 GMT -5
Huh? "Recharging" means just adding more grit? I have been emptying out the barrel, rinsing the rocks and the barrel and the lid, and the ceramic/plastic beads. Putting it all together again and adding my grit. So all I had to do was add more grit?
Amythest is hard and needs 6-8 charges of course grit?
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Post by Condor on Sept 3, 2008 18:34:23 GMT -5
Huh? "Recharging" means just adding more grit? I have been emptying out the barrel, rinsing the rocks and the barrel and the lid, and the ceramic/plastic beads. Putting it all together again and adding my grit. So all I had to do was add more grit? Amythest is hard and needs 6-8 charges of course grit? I do the same thing if only to get a look-see at how they are coming along. It's fun for me. Condor |
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Roan
has rocks in the head
Member since January 2008
Posts: 600
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Post by Roan on Sept 3, 2008 18:41:15 GMT -5
Tom, Recharging means: whichever works for you  You'll find half the members here dump and redo and the other half just adds more grit. Eileen |
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Sept 3, 2008 18:53:54 GMT -5
Oh, sorry I was unclear, Tom. I imagine that each cycle of recharging will involve: -dump everything out of the barrel -rinse and clean the rocks with a hose -clean the barrel -remove any rocks that are ready for stage #2 -put the rest of the rocks back in -add more rocks to fill to 3/4 -add fresh grit and water -start tumbling again It never occurred to me to just open, add grit, and restart. What fun would that be? I wouldn't even get to handle the rocks, and that's the whole point!  |
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Post by cookie3rocks on Sept 3, 2008 21:56:17 GMT -5
You must be tumbling some serious hard stuff! There's wisdom in all the advise here. Kinda depends on how much time/patience you have. But me, I'm too impatient to wait so long that the coase is useless. And a recharge for me involves dumping and recharging. If your stones are breaking it down in 5 days, I'd really stay on top and recharge of it till you see some serious progress. Then back off and let it roll.
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rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Sept 4, 2008 3:05:34 GMT -5
Tom,
I think for most people "recharging" means a complete dumping/cleaning of the slurry, then recharging with fresh water and grit.
You CAN just add more grit, but you have to add a lot more water also, so before long the weight off the extra water and grit will strain your tumbler motor. No point wrecking your tumber, when all you really had to do was clean things out and start fresh.
I used to try just adding extra grit and water, but going even one extra cycle was all you could reasonably hope for. I don't do it anymore, because I value the life of my tumblers more than the scant time saved by not doing a proper clean-out.
-Don
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Sept 4, 2008 9:32:53 GMT -5
I really want to get my rough 60/90 tumble optimized (since that is where I spend most of my time). I opened up some ocean jasper that had been tumbling coarse for 6 hours shy of 5 days. I have recharged this batch twice; this was the third tumble in rough. Each time, I added a few more rocks to make up for the volume that had been worn away, so the batch actually contains a majority of 3X-coarse but with some 2X and 1X in there as well. When I opened the barrel, it seemed that the grit has dissolved into a gray soup:   But as I dug more, I did find some grit that was not entirely worn down:  My conclusion is that I should try running it for six days total to see if that last remaining grit gets ground down. Or at least five full days (as opposed to six hours short of five full days). I might as well keep tumbling until all the 60/90 is used up so as not to be wasteful and impatient. Here is how the rocks looked. I placed some untumbled wet rough on the bottom side for comparison.:  A few pieces seemed well shaped and ready for round2 (ignore what looks like a pit toward the upper right, that is just an optical/camera illusion):  Here is a typical rock that I put back in for another coarse round. I don't like the bump on the top and don't quite like the overall shape (hopefully it will improve after another one or few rounds):  Here are two rocks that I've pulled out to be split. Because of the deep pits, I don't think they will ever tumble correctly. So I'll bash them and put the pieces in:   Here are the rocks back in the barrel. I've added lots of various small rocks to aid the tumbling. The barrel is a bit under 3/4 full:  I added a few more pieces of rough to get the volume up, added 4 TB 60/90 coarse grit, and water to just below the top level of the rocks:  Back in for another six days! Comments? Opinions? |
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Post by akansan on Sept 4, 2008 22:23:13 GMT -5
In addition to tumbler and such, I think water has something to do with it as well. It took 9 days in my tumblers to fully break down 60/90 in New Mexico. Same tumbler with soft water, and it's only taking 6 days in Kansas. So, I agree that 5 days might be too short for you. The rocks are looking good! |
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Post by LCARS on Sept 5, 2008 0:51:36 GMT -5
I always add grit without washing because it takes a couple days to build up a decent slurry capable of effectively carrying the grit.
If you start "fresh" every time you need to recharge grit then the efficiency of the cutting is reduced until the slurry forms again.
After the first recharge though I will often let the barrel decant on the counter for about 20min and then pour off some portion of the slurry then top it up with more water before adding grit so it doesn't end up getting too thick, also problematic.
With the harder stone like agate, chalcedony & heliotrope I find my grit breaks down noticeably faster in relation to the cutting action acheived when i'm starting without any established slurry and it takes longer to build that slurry up. Once I have some decent slurry though, the grit is carried much more effectively, cuts faster and wears slower so that is part of my reasoning for not doing a complete clean in between recharges of the same grit.
On another note, I find a decent slurry also significantly reduces occurrances of chipping, spalling, fracturing & bruising with multilayered or more brittle material prone to those issues. A well established high viscosity slurry is like a liquid cushion, reducing the force of impacts within the barrel because the denser medium requires more energy to be expended over a longer time to fully displace it as compared to straight tap water.
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Post by Jack ( Yorkshire) on Sept 5, 2008 4:00:43 GMT -5
Hi [glow=red,2,300]Lycars above has a very good point,[/glow] When you wash you take all the sticky mud out of the barrel THAT stickyness hold's the grit to the rock so rock on rock gets a good grind Recharge into a quanity of the slurry will help the grinding process to start of Imediatly !! You can observe how long to run ,5 to 7 or 8 days by seeing if there is any grit left when you finaly wash up I used to run a 8 day cycle then I altered the speed and size of barrel (to 6lb) which grinds faster not I work on a 6 day cycle (at 42 RPM) In the first course stage you NEED the fresh charging to grind agressivly, Note---- watch that your goop is not to thick when constantly adding grit add water acordingly. You will get the right ballance through time. Jack Yorkshire UK |
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Sept 6, 2008 12:11:15 GMT -5
I opened a second barrel after five full days and once again there was still some not-completely-broken-down rough grit at the bottom of the barrel. There wasn't a lot, and it was partially broken down, but it still seems like five days is too quick. I cleaned and reloaded both (adding a few more rocks and ceramic pellets) and am running for six days. I'll see how they look after that.
Jack and LCARS both make suggestions along the same line: leave some of the slurry in the barrel when recharging. Add more grit to the existing slurry. It's hard for me to understand why slurry would improve grinding action over fresh grit, but I am willing to listen to the voice of experience and give that a try.
I have also started to add ceramic pellets with the rough rock to see if the increase in grit-carrying-surface-area helps with the rough stage.
I've got four separate 3 lb. barrels going in the coarse stage right now, so I've plenty of opportunity to experiment. I really want to optimize the coarse stage!
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lsmike
spending too much on rocks
Maxwell's demon lowers tumbling entropy
Member since January 2007
Posts: 468
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Post by lsmike on Sept 7, 2008 9:41:46 GMT -5
If I'm at the point where I think a lot of rocks will be ready for 150/220 I let that load go longer so they are better prepared.
If you just add grit might you not miss taking out rocks that are ready for the next step?Mike.
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Post by LCARS on Sept 7, 2008 13:02:26 GMT -5
...It's hard for me to understand why slurry would improve grinding action over fresh grit, but I am willing to listen to the voice of experience and give that a try... It is a tried, tested and true fact that slurry building DOES improve grinding action. The underlying theory/principle behind it is not hard to comprehend. Silicon Carbide is much denser than water and therefore sinks very quickly. Most of the action in a tumbler occurs at the top of the barrel where stones are moving past each other more energeticaly than the slight shifting and sliding that occurs lower down. Grit needs to be brought up to the top of the stones and stay in between them as they move past each other to be most effective. The problem at the outset of a new batch is that the water is too thin to keep larger heavier particles in suspension and most of the large grit particles are just sliding along the bottom slope of the barrel as the stones are tumbling over each other near the top. As the slurry forms, the tiny particles of rock and broken down grit that are becoming suspended in the water are thickening it. The thickening slows down the larger grit particles sinking and makes them stick better to the stanes, keeping more grit higher up for longer and allowing more contact with the stones as they move past each other. |
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