Anyone ever made Galvos from scratch?

[DJ DoubleBass]

I don't have any galvanometers, or a full projector yet for that matter, but I've been playing around with parts and got to thinking.

I came up with the idea of gluing mirrors to 2 speakers in an X Y format, like galvos, and playing them bass heavy for an effect. Then I saw someone online do it already:

http://www.youtube.com/watch?v=BUODENfz_d4

(obviously I'm not the first to come up with that)

I also came across a video where someone used keyboards as signal generators, ran signal through an amp, and used actual galvos instead of speakers:

http://www.youtube.com/user/DJDouble...68/qCUiCs-aYNk

After considering/deciding to use keyboards through an amp for generating signal, (I'm a musician) then I thought, "I wonder what a regular electric motor with forward and reverse would do when hooked up like that?"

Then I saw in the comments section of the video above that he's made Galvos from "simple motors and used a bit of hot glue to keep it from creeping."

(so I wasn't the first to come up with using motors either)

I also found where someone was trying to use "stepper motors" as galvos, or more likely just for beam effects, and someone chimed in about that:

If you want to play with steppers, I recommend you find the smallest stepper you can. There are some that have the diameter of a US Dime. While looking at data sheets, you want to look at the "steps per second" rating. I have seen some small steppers that go up to 6000 steps per second. And lastly, you want the largest "per step" angle that you can get.

After you have found a suitable, small, stepper, the next thing you should do is build your own amp. The easiest way to do it is to put a constant voltage into one of the coils, and a varying (AC) voltage into the other coil. The constant voltage will serve as what's called a "holding coil" or also known as an electronic spring. The other coil will give you motion.
This will give you the best performance that could be had for stepper motors.

I'm going to try and make some galvos with 2 techniques:

The first is using a 1.5-3.6V motor like this:

http://www.allelectronics.com/index.php?page=item&id=DCM-299&extra=a%3A2%3A{i%3A0%3Bs%3A40%3A%2203823345592 a403b2f4a37a59384e7ab28f02be1%22%3Bi%3A1%3Bs%3A0%3 A%22%22%3B}

and try a spot of glue to keep them from creeping and see what I get.

The second is giving a shot at a 3.1V stepper motor like this one:

http://www.allelectronics.com/index.php?page=item&id=SMT-355&extra=a%3A2%3A{i%3A0%3Bs%3A40%3A%2203823345592 a403b2f4a37a59384e7ab28f02be1%22%3Bi%3A1%3Bs%3A0%3 A%22%22%3B}

"giving a constant voltage on one of the coils" using that as a "holding coil" then hook the 2 neighboring coils up to a signal generater AKA my keyboard/amp config and see what I get with that as well.

That particular stepper motor gives 7.5 Degree per step...so I figure with the method that I'll be trying I'll get a scan angle of 15 Degrees. Couldn't find steps per second though...


Any opinions on any of the above?

Has anyone been able to create galvos out of parts somehow?

It'd be interesting if one of these worked

[weartronics]

The first is using a 1.5-3.6V motor like this: http://www.allelectronics.com/index....tem&id=DCM-299

This motor is designed for continuous rotation. It means the commutator has very few poles and any servo performance will be very bad. My advice is not to waste your time.

The second is giving a shot at a 3.1V stepper motor like this one: http://www.allelectronics.com/index....tem&id=SMT-355

You can produce some interesting patterns, but they are too slow to produce any recognisable graphics. Some example pictures and schematics: http://thebayseller.com/laser/galvo/.

Has anyone been able to create galvos out of parts somehow?

The best "home-made" galvos I have seen are made by Elm: http://elm-chan.org/works/vlp/report_e.html.

One other article you might find interesting, if you haven't already seen it: www.ctrnd.com/NormLaserShow/GalvoInfo_86-prutchi.pdf

Whatever experiment you do, take some photos and share them with us. Everybody is interested to see them, and you will get some useful comments.

Best regards,
weartronics

[weartronics]

One other idea, if you are going to drive the stepper motor with audio signals, you can use the stepper motor for the Y-axis, and a spinning polygon mirror (removed from any laser printer) for the X-axis, to produce an oscilloscope effect:













Beautiful and interesting visualisations for music, without any computer, software, DAC or expensive galvos.

[ltaudi1]

This may not be the safest thing to try but pull apart an old hard drive and remove the platters, and center motor with out destroying the galvo type apparatus with the stylus's.
remove any boards connecting to the stylus galvo. Find the pins coming from the flexy strip on the underside of the unit. Usually it plugs into the bottom main board. Place a light spring on the tip of the stylus and connect it to the side of the case to center the stylus. Next carefully epoxy a mirror across the hole that the galvo pivots on. While not letting any drip in and locking the unit up. Now connect it to your +- source can be anything from a small amp to a keyboard.

Also this can be accomplished with a tachometer as well. The tinkering process makes buying the first set of production galvos all that much more magical.

[DJ DoubleBass]

VERY cool! I knew that SOMEBODY has likely tried to make galvos from scratch.

The projector using a stepper motor and another spinning mirror was also nice.

I was unable to bring up the link that you provided:

www.ctrnd.com/NormLaserShow/GalvoInfo_86-prutchi.pdf

It brought up a sort of error screen, but all of the other links were great.

There are a lot of effects that I've found besides Galvos that are pretty cool, and fairly easy to make especially with general electronics knowledge. The current projector that I'm working on will feature several separate effects housed in one projector. I'll keep everyone posted on that project in another thread.

On this thread however, as soon as I get my parts in the mail, I'll post pics of any successes that I have with making something work with motors driven by audio signals. (keyboards likely)

Any other "home made" galvo stories are totally welcome.

Thanks for the response

[mixedgas]

[QUOTE=DJ DoubleBass;118722]VERY cool! I knew that SOMEBODY has likely tried to make galvos from scratch.

The projector using a stepper motor and another spinning mirror was also nice.

I was unable to bring up the link that you provided:

www.ctrnd.com/NormLaserShow/GalvoInfo_86-prutchi.pdf

Prutchi is not a normal stepper, his had a centering coil and was out of a bar code scanner.

He didn't know the difference.

Steve

[FourDee]

But you could use one coil of a normal stepper for centering and the other for driving ...

[weartronics]

I was unable to bring up the link that you provided:
www.ctrnd.com/NormLaserShow/GalvoInfo_86-prutchi.pdf

Sorry, the link is broken. But if you copy and paste the address into the top bar of the web browser, it works. Anyway, I will try again here:
http://www.ctrnd.com/NormLaserShow/G...86-prutchi.pdf

Prutchi is not a normal stepper, his had a centering coil and was out of a bar code scanner. He didn't know the difference.

But you could use one coil of a normal stepper for centering and the other for driving ...

Both of these points are true. I think you will get the best results using the stepper motor out of a barcode scanner. You can identify this type because it already has a mirror mounted on it, instead of a gear.

If the application is not critical, even the centering coil is not required. In my oscilloscope experiment, the first coil is connected directly to some audio amplifier, and the second coil is not used. I used a piece of foam behind the mirror to make sure the motor always snaps to the right pole when it is turned on, and to provide the centering force (you can see it in the first photo). Of course, maybe using the second coil for centering will give better results, but it's not absolutely necessary.

[Zoof]

speaker scanners and hard disk drive magnet galvos is exactly how I got started!
Here are some pics of my prototypes on my webalbum: http://picasaweb.google.com/DrZoof/HowItStarted#
It is great fun but beware: you'll get hooked and soon be spending money on the real thing!

[shrad]

if you find it interesting, and understand french (or if you don't fear a little use of google translator), you might visit this: http://www.laserfreak.net/forum/view...=galvos+maison

a friend who made his own galvanometers himself

they do easily 24Kpps, they are lightweight, tiny, and very well designed...

remember this guy has access to a 5 axis CNC milling machine, so you might not manage to do the same, but still a valuable source of information