kevin24018
spending too much on rocks
Member since February 2012
Posts: 284
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Post by kevin24018 on Jun 28, 2017 9:37:52 GMT -5
I'm sure this has been asked before, but from all the searching I couldn't really find the answer. Just got a new/used tumbler, never used one before. Collected a bunch of quartz beach pebbles that I want to use, since they are already pretty smooth what grit should I start them out at?
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Post by manofglass on Jun 28, 2017 9:47:24 GMT -5
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Post by Jugglerguy on Jun 28, 2017 10:06:12 GMT -5
I always run my rocks trough at least one week of coarse grit. Coarse grit could be 80, 60/90, or 46/70. I tumble a lot of beach rocks and almost none of them are ready after only a week. I should say that I'm a bit of a perfectionist when it comes to tumbling, so you might be happy with rocks that aren't as perfect.
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kevin24018
spending too much on rocks
Member since February 2012
Posts: 284
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Post by kevin24018 on Jun 28, 2017 10:10:46 GMT -5
I always run my rocks trough at least one week of coarse grit. Coarse grit could be 80, 60/90, or 46/70. I tumble a lot of beach rocks and almost none of them are ready after only a week. I should say that I'm a bit of a perfectionist when it comes to tumbling, so you might be happy with rocks that aren't as perfect. I want them to be as shiny as they can be. From what I read the first grit 60/90, for example is to shape the stone, but my thought is since they are already shaped, can this step be skipped?
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ChicagoDave
has rocks in the head
Member since June 2016
Posts: 720
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Post by ChicagoDave on Jun 28, 2017 10:22:11 GMT -5
Of course it can be skipped. But no more shaping will be done. If you're happy with them as-is, start with a finer grit.
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Post by johnjsgems on Jun 28, 2017 10:25:46 GMT -5
You still usually benefit from running at least a short run with coarse. When I collected on the Central California coast there were beaches literally loaded with rock. You could pick up buckets of rocks without cracks, pits, etc. I still ran a 5 day or so coarse run. It removes deeper scratches that don't appear until later and removes any organic matter. If you have a grinder or tile saw grind out any big flaws before tumbling. Talking rotary tumblers here.
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notjustone
spending too much on rocks
Member since January 2017
Posts: 426
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Post by notjustone on Jun 28, 2017 10:41:52 GMT -5
it wont hurt to run in coarse if there is any pitting or chipping coarse will take this out. remember them beach rounded cobbles got that way from sliding over and slamming into other rocks. no doubt some have chips and bruises that don't stand out as well against a dull background. remember when people say coarse grit shapes the stone it also means it removes divots pits fine cracks ect so realy it should be coarse grit shapes the stone as well as removing defects and providing a good base on which to polish. any imperfection that goes past coarse will remain as every grit past coarse will only remove scratches left by previous grits.
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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 Jun 28, 2017 17:29:55 GMT -5
Yet another vote to run them for one week through coarse, even if the rocks seem perfectly rounded. If you look at their surface under magnification, and compare that to a rock that has completed a run of coarse grit, you will see why they need a week in coarse.
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Wooferhound
Cave Dweller
Lortone QT66 and 3A
Member since December 2016
Posts: 1,432
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Post by Wooferhound on Jun 28, 2017 19:36:03 GMT -5
I collect rocks from a local river often. these are already round, but I always run them through course grind once.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,553
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Post by jamesp on Jun 30, 2017 9:56:52 GMT -5
Lot of rocks are simply stained and can use a bit of skin removed.
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Jun 30, 2017 10:13:55 GMT -5
Coarse stage is NOT only about shaping.
It's also about smoothing. In your case smoothing dings and divots from nature's grind.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,709
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Post by Fossilman on Jun 30, 2017 13:57:14 GMT -5
I run every stag of grit...It does make a difference...
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ingawh
starting to spend too much on rocks
The rock wants to shine, I just help it get there
Member since February 2011
Posts: 194
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Post by ingawh on Jun 30, 2017 18:11:34 GMT -5
Beach stones and river rock are some of my favorite things to tumble. Often you get lovely surprises emerging from the ugly ducklings.
I always do a course grind with them, even if you like the shapes and they seem smooth. (Others on this board will know that I only do two stages, but that's a story for another thread.) Anyway, to get the bright shine you want, I recommend that you do start with the course grind.
I hope you'll post photos as you go along, or at least when you're done. Best wishes
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