Best way to convert motor power to wheel power?

I have a dolly cart and motor, and I want to motor to move the dolly cart as slowly as possible (It's already four RPM, but just take that into account in the method you recommend). I need one of the inner/vertical wheels to be spun by the motor. Both the cart and the motor are pictured below. I am using this for time-lapses, so it should be as consistent as possible.

What is the best way to connect the two parts so the motor spins one of the wheels?

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rickharris6 years ago
As slow as possible could be VERY slow is there a range you need to be in.

Will the speed need to be changeable?

Is the track fixed.

Do you need to go forward slow and back quick?

With the information we have I suggest that driving the wheels is going to be a hard task, you would need to fabricate and fix an axle then arrange some sort of drive mechanism - gears or pulley/belt systems to drive the axle.

If the track isn't too long - say 1 mete,r then why not have a threaded rod down the middle with a nut fixed to the cart. Turning the rod with the motor will drive the nut forward and back VERY slowly in deed.

Alternatively pull the cart along the track by fixing the motor at the end and attaching a cord to the motor shaft this will wind up and pull the cart along. You may need to provide a bungee strap in the other direction to keep tension on the cord.

sblaptopman (author)  rickharris6 years ago
I'm leaving the pulley as a last resort, I want to try this first. Speed will be changeable, but by PWM and not anything else. The track is fixed, yes. I do not need it to go forward fast and back quickly. I was thinking of maybe having a belt that is very thin, and to accomplish this I would cut a groove in one of the wheels. The track is 6 feel long, a threaded rod is not a reliable option IMO. Since the track is six feet long, how would I have something that provides the same amount of tension throughout?
The cord and bungee would do that (provide constant tension. or if you really want a constant tension then weight pulling back.

Don't write off the threaded rod too quickly it's not for nothing that the CNC industry use it for high precision movement.

I believe driving the wheels is going to be a) difficult b) liable to slippage unless you go for a toothed belt.

You still don't say how slow this has to go.
sblaptopman (author)  rickharris6 years ago
6 feet in about 30 minutes at full power. The wheels are approximately 2.5 in in diameter. Where could I purchase a 2 meter long threaded rod and how would I get the motor to drive it?
Use the motor you have you just need to fabricate a connection a bit of brass tube with a couple of set screws would do.

A steel stock holder should be able to get 2 mtr of threaded rod - i would use M10 so it doesn't droop in the middle although you may still need to figure out some kind of support over 2 mter

personally i wouold try the cord pull firt - its cheap and easy to do,
orksecurity6 years ago
"Best" in what sense? How much slippage/irregularity can you tolerate? What are the limits of travel (since this appears to be intended to run within a channel of some sort)?

"As slowly as possible": Use gears, or belts, so the motor rotates many times per rotation of the wheel. The reduction can be pretty drastic, but slop will also accumulate.
sblaptopman (author)  orksecurity6 years ago
I'm not sure how to quantify irregularity, but I can't tolerate a noticeable amount (I.E. if i watch a sped up video of it moving I shouldn't see any variation.) The limits of travel are a 8" x 6' aluminum track. How would I get a belt to drive the wheels? I don't mean where would I find one I mean how would I attach it to the wheels. They are standard roller blade wheels.
No idea how to attach to those wheels. _Somehow_, you would need to get a gear or pulley affixed to the side of the wheel for you to transfer the force to. Or you need to go with a friction drive against the wheel's surface.

Or you need to bypass the wheels. If there's a guide channel, engage with the channel. See the worm gear drives used for the various computer-controlled routing/laser projects, for example.