I only pitched the Thumler Model B rock instructions about 6 months ago ... I do remember being impressed with the duty cycle of the tumbler. IIRC, a rock batch schedule was 24*7 for 21 days with a different grit at 7 and 14.
/Bryan
ETA: Found instructions from a grit vendor...
1. Fill barrel 1/2 to 5/8 full of stones. Pour in package marked COARSE (60-90). Add water even with top stones. Run tumbler with this mixture for approximately 7 days, 24 hours a day, or until smooth. WASH STONES AND BARREL WELL. (Kitchen colander is ideal for washing stones, but do not wash into sink drains.)
2. Place stones back into barrel. Pour in package marked FINE (120-220). Add water even with top of stones. Run tumbler with this mixture for approximately 7 days, 24 hours a day, or until rocks are shiny when wet. WASH STONES AND BARREL WELL.
3. Place stones back into barrel. Pour in package marked PRE-POLISH (500F). Add water even with top of stones. Run the tumbler with this mixture approximately 3 days, 24 hours a day, or until rocks show a luster when dry. WASH STONE AND BARREL WELL.
4. Place stones back into barrel. Pour in package marked POLISH. Add water even with top of stones. Run tumbler with this mixture approximately 7 days, 24 hours a day, or until rocks show a luster when dry. WASH STONES AND BARREL WELL.
5. Place stones back into barrel. Add enough powdered detergent to make a stiff suds. Add water even with top of stones. You may also add sawdust or some similar material to cushion the rocks during this clean-up stage. Run tumbler with this mixture overnight. WASH STONES AND BARREL WELL. SPREAD OUT ROCKS ON DRY SURFACE AND INSPECT YOUR FINISHED GEMSTONES.
Geez! That's 25 days ... the average kid will have a new hobby by the time the first batch emerges!