Hello,
I am looking for help on how to calculate the torque requirements of a motor for my project, so I can select one that is appropriate.
The project has four 6" diameter 1/2" thick Baltic Birch plywood gears, each with 36 teeth. They are lined up in a row and interlocked, so turning one turns all four gears.
Each gear will carry a small amount of weight, and each of the four gears will have to overcome a small amount of resistance created by a small flexible tine as it rotates (one for each gear).
So, is the procedure I have outlined below correct? I am just looking for an estimate so I can choose a motor.
- Weigh the gears and the amount of weight carried by each gear. Let’s say each gear is 1/2 pound, and each will carry a 1/2 pound, for a total of 4 pounds.
- Attach one of the tines to the edge of a table like a little diving board, and tie a string with a weight to it. Add weight until the tine flexes enough to clear the impediment. Repeat for all four tines, and add the weights together. Let’s say each tine requires 1 pound to bend, for an additional 4 pounds. So I need a motor capable of moving 8 pounds. I will arbitrarily add 2 pounds to make sure I have a motor that is powerful enough.
- If t = r x F, and I had a single 6" wheel that had to move 10 pounds, I think I would need a motor that had a minimum torque of 3 x 160 = 480 oz-in. Is this correct so far?
- Now, here is where I’m a little confused. How do the 4 gears affect this? Since the gears are identical, the gear ratio is 1:1, so there is no increase or decrease in torque. So would I just need a motor capable of producing at least 480 oz-in.? Or do I need to take into consideration the radii of the other 3 gears? It seems like it would be mechanically advantageous to put the motor on one of the two inner gears, but I’m not sure if this is correct. Will the torque be equal across all four gears even if I put the motor on one of the end gears?
Thank you very much for your assistance!
Greg