Source for Small 12V DC Gear Motor

Look at MAXON they make very good, small, high power density motors and associated planetary gear. Motor can be equipped with angular incremental transducers for positioning and speed control.

Bodine may be a possible source. Bodine Motors & Gearmotor - BodineDirect.com

I used them 10 years ago to drive conveyorized PWB fab transport systems.

In a previous life I used Bodine motors. One day the customer complained. He had several of our products running outdoors 24/7 for about 4 years and none had failed. Our product was a rather unique safety oriented product and he wanted to open one up. He was at a DOD supervised facility and he couldn't open up equipment unless it failed. I sent him a letter recommending that the motor bearings be replaced after every 4-5 years of use. This allowed him to open up the equipment and have some fun playing with it. I wonder if anyone else ever had to deal with customer complaints about the good quality of Bodine motors?

(During testing I did find that the bearings make an interesting set of squealing sound at about -70C.)

We'd have as many as 10 motors driving segments of our conveyors, all sync'd together. We could process credit card size and thickness PCB's through 100 feet of equipment, three or four different wet spray processes, top & bottom without having any movement of the product relative to each other.

These motors ran 24/7 in develop, strip and etch lines. If a motor failed, we were in LOTS of trouble.

Our (my) process isolation technique is patented.

Bodines and Baldors are both OK in my book.

How low of a backlash? That's where the money is going to be.

In the other posting, a stepper motor was suggested, typical 200 steps per revolution. Is that too quantized? More money in the controller can do micro stepping.

Do you have a target procurement price?

I would like to see less than one arc minute of backlash, if possible. That would be below the threshold of detectability. We can mitigate backlash in software, but it is not as effective as I like.

Our budget is not yet determined, but I am thinking that $400 to $600 is probably where the actual cost will be. It would be nice if it was less. :)

This application is not well suited for a stepper. In this instance we are not driving the mechanism to a specific point, but augmenting the operator's hand movement forward or back based on the amount of force applied by the user and how much "assist" is dialed in by the user.

In some cases it may be desirable to create an artificial detent based on position. We already have a good position sensor as well as a force sensor employed. The gear motor would switch from an assisted force to an opposition force for a detent. It's a little more complicated than that. It's more like pushing a cart over a speed bump. You are switching from a constant force per unit distance to a variably increasing back force until you get to the apex, then a negative back force as you come down the other side, then back to a constant back force as you continue.

Further down the development road we may want to drive the arm to a specific position, but that is not a customer requirement right now.

See what Esterline BVR Technologies located in Wisconsin can do for your product requirements. They made a flight control servo package to our spec.

I could be wrong, but I would have thought a stepper motor would be the ideal solution here. 100-300rpm is a perfect speed-range for a stepper motor, and losing the gearbox (at one time the bane of my life!) reduces size, weight, cost and the risk of backlash.

I can't see how a stepper would work here. It's a synchronous beast; you can't slow it down or speed it up (smoothly) by applying torque to the output shaft.

We microstep our motors up to 1600 steps per revolution. Makes for a much smoother travel.

Have a look at Trident Engineering. We've used them several times over the years (for various makes of motor and gearhead) with no complaints.