navi
starting to spend too much on rocks
Member since November 2008
Posts: 229
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Post by navi on Dec 19, 2008 10:47:07 GMT -5
i've seen several posts that all say sort of the same thing. something i find hard to believe.
some people are running up to 15 rounds of coarse grinds on quartz. is this right? the resulting photos look no better than what i have going now (this is my first batch in 15 years), on 1 to 2 coarse grinds, or what i did in the past, again in one or two grinds. why so many grinds? are you starting with stones that are too large for your tumbler? seems to me that after 15 grinds, one would be left with pea sized stones.
also, i see a lot of cracks in photos. shouldn't the stones be checked every now and again and anything with a crack be removed from the batch, to avoid having it scratch other stones?
just wondering....
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rallyrocks
fully equipped rock polisher
Member since November 2005
Posts: 1,507
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Post by rallyrocks on Dec 19, 2008 11:14:42 GMT -5
Small barrels (1.5 and 3lb Lortones for example) tend not to cut very much material, so it often takes a lot more then 1-2 rounds of course- especially if the rough is really rough- with shrp corners and such.
As for cracks, setting aside "anything with a crack" would mean never tumbling a whole lot of rocks- yes you want to avoid stones that are actuslly breaking up or those with cracks that are big enough to trap and carry grit from one stage to the next, but a lot of quartz, Feldspars and many other stones are full of "cracks" that are more cosmetic than structural- also one more reason to run course stages longer is to take care of any cracks that might be structural- by breaking the rocks and grinding them smooth again before moving on.
Whether or not one chooses to cull each batch at every recharge is kind of a personal preference anyway, yes it is a valid practice, and it probably gives a higher yield along with faster processing time when compared to running months of course, but that doesn't mean its the only way to get good results.
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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 19, 2008 11:25:55 GMT -5
To each his own...but when you get hooked on tumbling and see only the imperfection you can get a bit anal about this hobby!
Quartz can be very tricky...especially if the rough is not pure crystal and has lots of cracks and imperfections. Fifteen rounds of course is definitely on the AR side...but there are some real perfectionists who are very artistic and make some truly great tumbles. The more you tumble and see other perfectly shaped and polished tumbles , the more your desire for perfection may increase.
Quartz will take a lot more than 15 coarse rough tumbles to get to peas size. It is very hard.
Removing cracked stones is more important after the coarse stage. I doubt cracked stones will hurt a coarse tumble too severely.
csrocv
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Post by Hard Rock Cafe on Dec 19, 2008 11:48:16 GMT -5
If you're tumbling pitted stones, like Lakers, you have a few choices:
1. Leave in the pits so you have bigger rocks, but the pits detract from the overall shine.
2. Tumble until they're gone (which takes a _long_ time and leaves you with much smaller rocks)
3. Grind or cut them off, then tumble.
Agates (esp. Lakers), jaspers, quartzes, etc. frequently have "healed" fractures (in fact, most of the larger Lakers I've seen have fractures). They don't tend to disrupt the tumble, unless they aren't actually healed and they cleave late in the process.
Just my experience.
Chuck
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1rockhound
spending too much on rocks
Member since July 2008
Posts: 286
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Post by 1rockhound on Dec 19, 2008 12:04:17 GMT -5
It also totally depends on what the rough material is like. I have had this Morrisonite in rough since August! Thats about 17 weeks and it will probably take quite a few more to get the results that I am looking for but this material is a very hard porcelain jasper.  Also maybe the material that you tumble is not that hard most of the material here in Idaho is a 7+ on the mohs scale. Jason |
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Post by parfive on Dec 19, 2008 15:07:55 GMT -5
Jason – I hope that pic’s before you started, and not after 17 weeks!  ;D Lotta time is wasted running grinds long after the 60/90 has broken down. If the grit’s worn out after five days and you’re running it for a week or ten days or two weeks – well, multiply that by 15 and . . . Life’s short – grit’s cheap. Save yourself another week and skip the 120/220 – complete waste of time in a rotary tumbler (unless you’re finishin’ up a rough grind a little less aggressively). You can also use a WorkForce saw to speed up crappy rough. It's pretty obvious what pits and vugs and cavities are never gonna tumble out. Either grind 'em out with the saw blade, or cut the rock in half right through 'em. Rich |
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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 19, 2008 19:43:22 GMT -5
navi: gee, I resemble those remarks!  I assume you are making reference to the recent quartz tumbles that I posted over in the photos board. First off, I should explain that although I ran somewhere around 15 rounds (5 days each with 60/90 SC) of coarse, I didn't run the same stones through every round. At the end of each round, I pulled out the rocks that passed muster (smooth all the way around with no feelable pits/cracks/crevices/rough edges) and then added more new rough to fill the barrel to 3/4. During the first 3 or 4 rounds, none of the rocks were good enough, but after that, I would pull a few rocks out of each round. I cannot say for certain how many rounds any individual stone went through, but it was probably less than 10. It took me about 15 rounds to get through most of my rough and to create enough that was ready to go on to the medium tumble. As for cracks, none of my final quartz has any cracks that can be felt. There are internal cracks or fractures, but nothing that interferes with the glassy feel/shine on the outside of the rocks. I wouldn't let a rock out of coarse if it had a crack that could capture any grit, and I check every rock after every stage looking for any that newly cracked. None of my starting quartz material was too big for the Lortone 3# tumbler barrels that I used. This material was all fairly small to begin with. If I have bigger material, I put it in my 6# barrels (but that is usually rough that I prepare myself out of larger rocks). If you are getting results that you make you happy after 1-2 rounds of coarse, then super! To each his own. I prefer my rocks to be really rounded, which requires a fair amount of shaping during the coarse stage (when using my current methods and equipment). But that's just how I like 'em. I have no doubt that others have better equipment and skills than I do, and I have no doubt that I'll get better as time goes by! I just found the quartz and citrine to be particularly difficult to shape, and I wanted to take the time to do the best possible job to end up with a final product that I really liked. |
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Post by Condor on Dec 19, 2008 20:34:56 GMT -5
I agree and understand with what you are saying Navi. I have tumbled stones where they only took me one month (one week in each stage) and others where I left them for several weeks in stage one alone. The end results were minimal at best as far as the shine was concerned. What was very different was the shape of the stone. If you really want them well rounded, and with less pitting, then leaving them longer in the first stage is definately a must.
Condor
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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 19, 2008 21:48:28 GMT -5
hopefully, i didn't step on any toes. wasn't my intention. i've done lots and lots of quartz in the past, so i know about cracks. i just wonder about seeing white polish in cracks when the stone is done. to me, i if think it could wind up like that, i wouldn't let it get that far. i scrutinize the stones hard before each stage. if they have anything that really looks like a crack, i pull it out. i won't run any risk of it falling apart in the next stage and screwing the entire batch up. but that's me.
wasn't speaking of any one person/post in particular. i will say after seeing ejs' post and 15 coarse grinds, it got me thinking about this and eventually posting about it.
maybe i'm using more grit in the grind stage......
my tablespoons are heaping, not level and i use 8. and run for a week. if they are ready, they go on. if not, i go for another round. i don't recall ever doing anything for more than 5 grinds. that was a very pitted brazillian river tumbled smoky quartz.
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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 19, 2008 22:00:54 GMT -5
No toes stepped on here, navi. I'm here to learn and I greatly respect the experience that others bring.
You mentioned "white polish in cracks when the stone is done." Did you see that in any of my photos? The final quartz seems very transparent to me, and I don't see any white polish in any of my stones. They all feel very smooth to me, with no ridges or cracks that I can find.
I use 4 heaping TB of 60/90 SC grit in the 3# barrel. I often include small ceramic pellets. I fill the barrels to 3/4 (as measured by a ruler on the inside) and add water to the base of the last layer of rocks (so that several rocks are poking up above the water). Then I spin for 5-6 days before checking and recharging.
I experimented for a while with a few variables and settled upon that routine as the most efficient. That being said, I'd love to be able to get to my desired end stage with fewer coarse rounds!
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Post by parfive on Dec 19, 2008 23:18:31 GMT -5
Barrel speed makes a big difference in rough times. I’ve got all Thumlers – bunch of Model Ts (53/54 rpm) and an AR-2 (30-34 rpm).
Cleaned and re-charged a couple of barrels tonight, then remembered why I always put 60/90 on the Model Ts – it’s faster, by 60-80%.
Rich
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Post by johnjsgems on Dec 20, 2008 10:24:14 GMT -5
It may be a matter of value. Most of the rock I've tumbled I've collected in the fdesert. You can literally pick up buckets of small rock. I cull the bad rocks after a week and maybe run another week. Any thing that looks like crap by then is not worth dealing with. If you pay for rough you probably have more reason for patience. Pulling the ready rocks and adding more rough until you have a second stage batch of smooth rock is the ideal way as cracked/defective rocks are polished defective rocks if you move them along.
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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 20, 2008 11:38:29 GMT -5
ejs. no not your pics. i have seen cracks, filled with polish, in other photos here.
johnsgems, i agree. if after a cycle or two, if it looks like crap, it isn't worth dealing with. i usually combine the good stones out of 2 coarse grinds, then start the rest of the stages with them. if some of the crapites are small, i'll use them as filler.
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;D
I assume you are making reference to the recent quartz tumbles that I posted over in the photos board.
