That's good to know. How many coins can you put in one of the tumblers?
Well they can be used with a single coin. The maximum depends on the coins put inside (denomination) and how much gravel/grit with water is used, but somewhere around 100-150 coins per barrel at a time. In the dual barrel model that means 200-300 coins total of course.
It actually can do more coins but the problem is the barrels for the
HF dual tumbler are rated at 3 pounds each. That includes the rocks/grit, water, and coins placed inside. Internally the barrels measure a bit smaller than 4 1/2" round and 4 1/4" tall (inside) and do their best cleaning with air in the barrel too. See the photo I did with a silver quarter for size reference of a barrel. If you do much more than 3 pounds per barrel however it will burn up the belts much faster, and put excess wear on your rollers and motor causing them to fail much quicker - it won't help clean the coins any faster but will take more time as they have less mechanical tumbling to get clean.
You can get fancy with weighing out the barrels, as
seen here but is not necessary.
If you fill the barrels about halfway full then you should not have any problems with weight or excess wear. The extra room for air also helps ensure a good mechanical mix as they tumble.
A bit more help if needed
Any aquarium gravel ("river stone" or colored) works fine and does not seem to cause any problems. I could only find the mixed color variety years ago locally and it did not color/discolor the coins at all. Or if you want to get really cheap
see here for other ideas on where to find material.
Again I only use just everyday dish washing soap such as Dawn or the dollar store varieties. Some people like to also use vinegar, baking soda, ketchup on pennies (I guess due to the vinegar that is ketchup), CLR (Calcium, Lime, Rust chemical), Comet/Ajax cleaning abrasive, etc. I simply find using them does nothing but make it more expensive to clean clad and could easily damage the rubber barrels.
I find letting the coins tumble typically 1-2 hours is enough to cash them in at a Coinstar. At 4 hours it puts them into shinny circulation condition that can be used in regular change. Longer than that doesn't seem to make any difference besides adding wear and smoothing out the details on the coins.
Once tumbled, empty the barrel into a strainer and clean off the gunk with a quick rinse in water. Afterwards
the best trick to separate the clad from the gravel is to use a mesh basket over a bowl or bucket,
see here for an example and pour the strainer into the basket. That will save you the hassle of pulling each coin out of the gravel by hand, and the bowl is emptied back into the clean barrel for next time.
Empty the basket on a towel and they are ready. See my photo of a batch of clad I ran for about 4 hours, and how shinny the pennies are even. Any bent, mangled, rotted/mutilated (zinc pennies 1982+), and such will need to be removed from the rest and cashed in with change at a store. Or in the case of the zinc pennies thrown in a junk pile or
see here for ideas.
Occasionally a coin will still look bad (beyond the zinc pennies), typically nickles for me, and they can be tossed in the barrel for another go next time.
To see the basic process in action
watch it here but warning loud music at the start