es355lucilleStart out with good tumble able Mohs 7 rocks.
Grind the heck out of them with SiC30 added every 4 days for fast, 7 days for relaxed. 8-10 times. More if rocks are poorly shaped, less if rocks well shaped.
Don't let the slurry get too thick. If it does, pour some off and add some water.
Let the last SiC 30 addition run 2 weeks.
Clean out well and transfer to vibe with proper filler and AO 500 till shiny~4 days. I use 1 cup water and 1 cup sugar/15 pounds rock.
Top off with an AO 14,000 polish with Borax for 24 hours if necessary.
Vibes vary, may want to follow instructions for your particular vibe.
Simple as it gets.
To do a 30 day tumble I have to pre-grind for 3 hours for 15 pounds of 1-4 ounce rocks.
Pre-ground rocks are run with out smalls. Rocks from shooter marble to golf ball size.
They are shaped WELL enough that smalls are not needed to reach nooks and crannies; the smalls waste grit in the rotary and I like bigger tumbles on occasion.
Many will disagree about not using smalls, but high quality hard agate that is well shaped does not need the smalls for protection if you leave the slurry a bit thick.
A couple of rough Rio Grande golf ball size pebbles as found in nature:
After 5-6 minutes on the super grinder, faceted look:
After 8 days, two SiC 30 grit runs, 4 days each, no smalls:
30 days, finished:
Here is a link to this 30 day/15 pound tumble including the grinder that was used to pre-shape.
The grinding is done dry and requires very good ventilation. Grinding time for the 15 pounds was about 3 hours.
www.flickr.com/photos/67205364@N06/sets/72157648700305650A 5 minute 'marble' out of Rio Grande agate. I have 'burnt' my fingers on this thing but never drawn blood.
Diamond wheels not near as aggressive as metal grinding wheels.
Doing 1-6 ounce rocks is quite safe, small rocks are not recommended due to proximity of fingers.
Doing the AO 500 in the vibe requires 50% smalls(I use quartz aquarium pea gravel) for 1-6 ounce rocks.
So it took two 7.5 pound vibe runs to finish the 15 pound rotary load using 50% smalls.
These are 3-10 ounce rocks with 70% smalls. Very hard agate. Sugar and water, 1 cup each for 15 pounds rock.
Need a higher percentage smalls for big rocks.