Surplus/Used servomotor source?

Take a look at Richard Kinch (regular here) web site on building a servo from a DC motor. pretty easy and DC motors are real cheap and plentiful.

Karl

You can use many kinds of motors as servos; PM DC, brushless, AC induction, etc. Easiest and cheapest may be to fit the appropriate feedback device (usually an encoder) to an ordinary DC permanent magnet motor.

Are they building the amps, the feedback loop, or both? If they already have the amps, that will determine what sort of motors to look for.

Ned Simmons

I have a case of small gear motors..12vt DC..about the size of film cans if that would be of any help, but they are about 5 rpm...

hummm probably not. Never mind.

Anyone else needs em...speak up

Gunner

"If I'm going to reach out to the the Democrats then I need a third hand.There's no way I'm letting go of my wallet or my gun while they're around."

"Democrat. In the dictionary it's right after demobilize and right before demode` (out of fashion).

-Buddy Jordan 2001

I do need a couple... I hope that they are strong enough for a small rock tumbler, which I would like to make. 5 rpm is a nice speed,I think.

i

How small? These as I said..are about the size of a 35mm film can or even smaller.

Ill post a pic this weekend. I found em last weekend cleaning out Stuff

Gunner

"If I'm going to reach out to the the Democrats then I need a third hand.There's no way I'm letting go of my wallet or my gun while they're around."

"Democrat. In the dictionary it's right after demobilize and right before demode` (out of fashion).

-Buddy Jordan 2001

I think that it is good enough for turning around a cylinder the size of a mason jar, at 5 rpm...

i

Mason jar? When I think tumbler..I think 5 gallon bucket at the least.

But yea..Ill take some pictures and post em. Want the whole case? I think..think there are 24 in there.

Gunner

"If I'm going to reach out to the the Democrats then I need a third hand.There's no way I'm letting go of my wallet or my gun while they're around."

"Democrat. In the dictionary it's right after demobilize and right before demode` (out of fashion).

-Buddy Jordan 2001

According to Gunner :

Hmm ... do those motors have a gear on the output shaft? If so, perhaps mounting a large gear on each end of the can, and engaging half a dozen motors per end might handle the load.

Not sure what the original poster will want to do, however.

Enjoy, DoN.

I thought that they could turn a small tub with rocks, like for rock polishing, say the size of a mason jar (2 qt).

i

I believe the intention is to build a general purpose commercial grade device and post the plans. One of the summer projects was a robotic fruit picker that needed servos. As happens in life, the cheap servo controllers couldn't do what they needed and the controllers that could were expensive. With the confidence of youth, they have decided that they could do a better job. I don't know what the design approach will be. My best guess is an integrated controller/amplifier using a FPGA with a core processor, since writing DSP code for FPGAs is one of my kid's claims to fame. I will also guess they will want DC motors, as the PWM amp would be pretty straightforward.

An out of date page that does a poor job of showing some of the kinds of things the kids do can be found here:

Apparently the industry connection has been very sucessful because the kids actually deliver. The only complaint that I have heard from the kids is that classes take too much time away from their projects.

Kevin Gallimore

Jim,

The intention is to design a general purpose box and post the design. I think they plan to design the amplifier section around whatever motors they have, in order to be assured of being able to operate a wide range of devices. Having said that, the robots they have been putting together lately have required fairly big high torque devices.

I want to encourage this project so I can use the controller/amp design to make the world's first CNC Hardinge TM.

Kevin Gallimore

It sounds like a great project. Since they're in Needham and appear to do a lot of collaboration with industry, I'd suggest they get in touch with Copley Controls, which is the neighborhood.

Ned Simmons

Where are you located ? - West Coast ? - Servos are used in all sorts of printers and the like. CNC gear used both stepping motors but the best used servos.

Some of can point to a source if you mention where.

Martin Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member

axolotl wrote:

Thanks, Jim. I'm sure the kids will appreciate it. I'm in New Jersey, and the college (Olin College of Engineering) is outside of Boston. I would be delighted to pay the shipping costs. Just send me a note (my email is real) and I will send the address and a check.

Thanks again,

Kevin Gallimore

Martin,

I am in New Jersey, and the college is outside of Boston.

Thanks,

Kevin Gallimore