suitable motor for small motorized platform?

Perhaps you can adapt something like this: (?) Link:

Gearing the motor speed down is sensible anyway.

That makes me wonder just how big and heavy your "small" camera platform is and what load it has to move around.

You might be able to do what you want with fairly standard radio control servo motors combined with an optical feedback. Otherwise look at the platforms for 3D printer beds for inspiration...

Heck of a lot of geared steppers available for a few dollars on ebay would drive that screw one step at a time if you felt like it :-)

You can find 4096 steps-per-revolution steppers on eBay for a few dollars shipped (internal gear reduction). 5mm diameter flatted shafts. I'm using them to build a 'barn door' DSLR mount to photograph the night sky. The 4096 is based on half-steps, BTW. You can also find proper couplers which allows some lack of axial alignment, or just use a bit of rubber hose.

Best regards, Spehro Pefhany

It sounds like you want motors with gearboxes, AKA gearmotors. most small DC brushmotors reverse with reversed polarity many that don't can easily be modified to reverse

Any permanent magnet DC motor should reverse with reverse polarity input. Small DC motors tend strongly to be PM type.

I've seen lots of surplus XY stages, with stepper motors, on ebay.

You can make most steppers step at 60 Hz with just an AC supply, a pushbutton, and a capacitor. Reversing is easy, too. You can also drive a stepper with DC and a rotary switch.

You've gotten lots of decent answers so far, here's mine:

If those "hobby motors" are from Radio Shack, then they are permanent- magnet DC motors and yes, they'll reverse. But they won't have enough torque for what you want.

How are you controlling your motors? You mentioned strings -- were you just pulling on them yourself? Or are you controlling the camera with a close-by computer, or what?

If you're interested in doing this with a computer and some $$, then look for the X-Y table on ebay with stepper motor drive, then get some compatible stepper motor drivers that "talk" USB.

If you're interested in doing this with 1950's technology, then check out surplus outlets (or eBay) for gear motors. Mount a drum to a gear motor, wind that string around the drum, and put a return spring on each axis of your home-brew X-Y table. Then drive the gear motors with on-off-on DPDT switches connected to reverse the rotation (Google for it, check back here if you can't find any schematics). If your machining skills are up to it, use your jack screw and nut idea, but drive the jack screw with your gear motor.

If you're home-brewing a microprocessor driver for this, then the suggested RC servos are an easy solution; you can find them in a pretty wide range of sizes, so getting really big herky ones is well within reach.

Maybe R/C model servos... the heavier version, for cars? ...Jim Thompson

The second-heaviest ones are elevator and rudder servos for giant-scale airplanes. The HEAVIEST ones are sail winches for RC sailboats, but I'm not even sure if any of those are in production these days.

Someone must make them, though I'm not sure of availability for consumers... I recently bought an R/C Jeep for the 5-year-old grandson, pretty strong steering and the sucker would probably go

Thanks to all for the responses so far. You certainly have given me plenty of ideas. To give you an idea of what I have now, take a look at this:

I don't have this. I fashioned something out of wood and used drawer sliders, cut way down, for each slid-able axis. If I want to move in either x-x or y-y, I just pull the appropriate string attached to the ends. This isn't working out too well though as there's too much friction in the system, plus I designed it on the fly without actually planning anything out.

What I did today was actually purchase that device at the link above. If you look at the picture, it uses a geared sprocket with geared rails for each axis for smooth manual motion as the sprocket is turned. I'm wondering if I could mount a small motor alongside of each sprocket, couple over the motor and sprocket with a rubber band to act as a belt and move each axis by powering the motor. When I converted a small telescope I have from manual to electric focus, that's exactly what was done.... small motor alongside the manual focus and a belt placed over the motor and focuser.

I'm not sure though what speed or type of motor I would need. A motor like on the telescope would be ideal, but I don't have the specs for it. Appreciate any ideas here.

Bill

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something like this?

-Lasse

Take a look at Marlin P. Jones & Assoc Inc.,

Hul

Bill Proms wrote:

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I'm guessing you want a fairly low speed output. We get 1 RPM timing motors from Herbach and Rademan

But I don't think they reverse. Can you measure how much torque you need? That will help in picking a motor.

George H.

Servo City sells gear motors that (iirc) do reverse, plus they have a lot of Meccano-style parts you can bolt together for this sort of job. I bought some of their stuff for the spectrometer I'm working on.

Cheers

Phil Hobbs

I'm not sure if it would fit your needs but I've seen some using radio control servos to make motorized camera platforms. Some are operating R/C vehicles and aircraft this way, they have head tracking devices and video goggles, when they turn or tilt their head, the camera turns & tilts. Many R/C units have a pot knob to adjust a servo position, that could operate the lens distance while a joystick could operate pan & tilt, if that's what you were wanting to do.

RogerN

I recommend you start from an inexpensive plastic X-Y stage. Then add a couple of stepper motors with appropriate reduction drives. You may be able to find all of this surplus (a better X-Y stage will be a big plus).

?-)

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