Question: I’m looking for a batch method for smoothing small pieces of hardwood. The pieces would be roughly 1.5″ wide X 2.5″ long X 3/4″ thick. They would start as rough, irregular pieces. I would like to have them finished to the equivalent of 400 grit sandpaper or better. I would like to be able to do them in batches of 20 to 50. Would barrel tumbling work for this? Would they have to be tumbled in stages? If so, how many different grits would be required to achieve the final smoothness?
Response: I calculate that 50 parts would be 1/2 gallon of volume so you will need about 8 gallons of total capacity in a barrel tumbler (see MT Series). This is based on filling the barrel about half full with Hardwood Media and parts at a ratio of 3 to 1 by volume. The KP-2 or KP-4 Hardwood Pegs are commonly used for wood tumbling.
Depending on how rough the parts are initially cut, you may need to start with a relatively coarse 40 Mesh or 70 Mesh White Aluminum Oxide Grit. This could be followed with a 150 Mesh and then a 360 Mesh tumble. Generally, about 5 – 10 pounds of White Aluminum Oxide Grit would be added to 4 gallons of ‘load’ and the cycle will be 4 to 8 hours per batch. You will need to use different Hardwood Pegs for each grit and step.