fmelvis
starting to spend too much on rocks
Member since November 2010
Posts: 235
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Post by fmelvis on Jan 28, 2011 8:28:53 GMT -5
I've been working on my rookie batch for about 7 weeks now, and most of the rocks are shaping up nicely. A closer look at the surface shows very tiny bumps. Not pits by any means, just not super smooth.
Will the 120/200 grit stage smooth out the surface or do I continue with the rough until totally smooth? I was going to use a fair amount of plastic beads during this 2nd stage to combat chips. Do I really need to use small gravel as well?
Frank
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keystonecops
freely admits to licking rocks
Member since October 2010
Posts: 957
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Post by keystonecops on Jan 28, 2011 8:58:41 GMT -5
Im still fairly new at this, but I use 60/90 for the 1st coarse run. In my little 11/2lb Lortone its been takn bout 7 to 8 days to smooth. I think I need to quit bein so impatient an give er nother few days to really smooth it out. Later Clyde
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Post by parfive on Jan 28, 2011 12:13:02 GMT -5
Frank – Continue with 60/90 until they’re shaped to your satisfaction, then . . .
Skip 120/220 entirely – waste of time.
At the end of a week in 60/90, that grit is broken down WAY beyond 120/220, so why go back and scratch ‘em up again? Just go right to 500.
Rich
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Jan 28, 2011 12:31:14 GMT -5
Like Rich says, if you run longer in 60/90 you can skip the fine grind step. Those bumps though are an indication of undercutting. You probably have a mixed hardness stone so the softer stuff grinds away more than the harder sections leaving those bumps. That problem may not be solvable in a tumbler like it is on cabbing wheels. You really need a homogeneous smooth surface for a good mirror polish.....Mel
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Post by rocklicker on Jan 28, 2011 20:05:02 GMT -5
Good advice! Something to remember. Steve
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Post by gr on Jan 28, 2011 20:09:49 GMT -5
Learned something myself ! Thanks Rich and Mel
Gary
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stefan
Cave Dweller
Member since January 2005
Posts: 14,095
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Post by stefan on Feb 2, 2011 20:49:59 GMT -5
See now I total disagree with skipping 120/220 step. I do agree that you need to run 60/90 until all issues are ground out. Sometimes I'll run stuff in course for several months
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Post by Jack, lapidaryrough on Feb 2, 2011 21:45:08 GMT -5
If your running material for several months, Then you should start of with 40/70, Our do a lot of pre-shaping.
40/70 wont break down, Like 60/90 & 80 grit. after a three week run.
In large tumblers with the weight as ( Parfive ) Said the grit breaks down to a fine grit.
Skipping 220-grit on the 3-F or 400 grit is a time saver.
And saves on Barrel ware. Wallet is a bet fatter, From cost savings.
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stefan
Cave Dweller
Member since January 2005
Posts: 14,095
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Post by stefan on Feb 3, 2011 10:00:39 GMT -5
Hehehe Ask a 100 tumblers about the correct stages and get a 100 answers!! Everyone has there own method and formula. THe key is to try new things and keep track of what works and doesn't work for you!
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,341
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Post by quartz on Feb 11, 2011 20:59:45 GMT -5
For really rough, craggy quartz [we call it "hillside" agate] we use 16 grit to rough it down. Two weeks generally works great, then to 80 grit and so on. An ancient rockhound friend, who also had a shop in Milwaukee, OR for several years said "16, really". Then he tried it, and liked it. We run 1 3/4 & 5 gallon rotaries.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Feb 11, 2011 23:02:52 GMT -5
I know this is different from what a lot of you think but I find the super coarse grits like 40/70 for me at least, don't cut and shape as well as the 60/90. When I check the barrels after a week or so in 40/70 a lot of the grit has sunk to the bottom while 60/90 sticks to the stones and seems to work better. A t any rate, for me, the stones seem to round and smooth better and faster with the 60/90....Mel
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Post by Jack, lapidaryrough on Feb 11, 2011 23:34:32 GMT -5
another great tumbler grit is old grinding wheels, broken down to 1"-minus. I go to the machine shop around my area. i get them free our $1.00 a piece. most of the shops use 80 & 120 grit wheels. The 220 grit wheels i use to re-dress the saw blades and the diamond wheels, i never well use a fire brick or red brick. Obsidian blue sheen or 220 grit. Red brick & fire brick cut`s down the kurf on a diamond blade.
Jack
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