I'm planning to build a sorting sieve out of a set of plastic containers with holes drilled in the bottom. The container with the largest holes will be on top and the one with the smallest holes will be on the bottom. This will allow items to filter down until they can't fall through the holes anymore. It should effectively sort items by size when I pour the items in the top and shake the entire stack.
Since I haven't found a reasonably priced set of sorting sieves, I'm planning to build my own. I'm planning to use Snapware containers that lock together and drill the holes with spade bits.
In general how should I choose the hole size? Obviously I want it to be between the sizes of objects I'm sorting. I fear:
- That if the holes are almost as large as the large objects, the larger objects will get stuck in the holes and block them
- If the holes are too close to the size of the smaller objects, it will take too much shaking for them to fall through.
I think my choices are:
- Split the difference and use a hole size as close to halfway inbetween the object sizes
- Use a hole size closer to the size of the larger object, but small enough that they won't get stuck in the hole. How much smaller (percentage wise) would that need to be?
I have several application of this in mind. I want to try sorting screws, bolts, washers, Lego bricks, and US coins. Let me illustrate with the sizes of US coins. Here are the coin sizes and possible drill bit sizes listed inbetween:
- 0.955" Quarter
- 24mm (0.945")
- 15/16" (0.938")
- 23mm (0.906")
- 7/8" (0.875")
- 22mm (0.866")
- 0.835" Nickel
- 22mm (0.866")
- 21mm (0.827")
- 13/16" (0.813")
- 20mm (0.717")
- 0.750" Penny
- 18mm (0.748")
- 17mm (0.709")
- 0.705" Dime
I'm leaning towards 15/16" for sorting nickels from quarters and for 13/16" for sorting pennies from nickels. However between pennies and dimes I have a lot less choice. Is the 18mm too large a hole and the pennies would get stuck? Is the 17mm too small a hole and the dimes wouldn't fall through easily? They also sell 18.5mm drill bits, but they are comparatively expensive items compared to less specialty sizes.