Low RPM motor solution... finally!

[absolom7691]

Hey, lumia painters! Thanks to some inspiration from Brian (Laserist) in another lumia thread, I tried out some gear reduced stepper motors that were microstepped using an A4988 driver, set to 16th steps. I was amazed at how smooth the lumia pattern moved when I was running the stepper at about 0.04 RPM. Very smooth. The square wave signal generator I built to pulse the stepper driver will go from 100hz to 3khz. This translates to a variable shaft speed of 0.04 RPM to 1.1 RPM. This is right in the sweet spot for me as this will be powering a double disk lumia that throws a smoke-like pattern at low speed and flowing water pattern at high speed. I have seen other threads talk about steppers for lumia but the consensus was that the motor's "steps" would be visible. With the steppers I found, joined with the A4988 drivers, I could not detect any staccato motion whatsoever, even at a ridiculously slow speed. These are a total win.

The Stepper: https://www.frankhumotor.com/nema-8-...604S-PG64.html And for some reason, the picture on the site is wrong for the stepper and gearbox.

The driver: https://www.amazon.com/HiLetgo-Steps...s%2C163&sr=8-3

These motors have a pretty small footprint, too.

[laserist]

Nice............

[Bradfo69]

Cool! You know... back in the day, I would have ordered 5 motors and 5 drivers already which would then arrive and languish in a box in the storage unit for years because eventually "that day" would come when I laughably believed I was going to build a lumia rig. I show SO much more restraint these days.

[laserist]

only 5? You showed more restraint way back when than I did.

[buffo]

I think he mentioned buying 5 of each only because the Amazon listing is for a set of 5 drivers...

And that also means that he CLICKED the link (just as I did) and seriously considered purchasing them. (Just as I did...)

Adam

[absolom7691]

Bradford and restraint go together like Democrats and Republicans! The other problem he has is that both the angel and devil on his shoulders tell him "Buy it!"

Yeah, the drivers are in sets of 5 but seriously, that's a little over $2 apiece after taxes. Not bad considering the performance. For other applications, I think they can handle up to 4 amps. I think it would be more expensive to buy them individually.

[clickamouse]

Gotta try this.

Thanks…Mike

[buffo]

Well, after thinking about this for a while, I decided to give it a try as well!

Ordered the stepper motors from China, and also ordered both the drivers and an adjustable squarewave generator from Amazon. Probably going to have to wait a while to get the steppers delivered, but we'll see I guess.

Looking forward to seeing what sort of effects I can get with the classic shower glass that Greg (Displaser) discovered years ago. Previously I'd been using a .5 RPM Hankscraft 12V DC motor and running it down around 9 volts or so, but this should give me lots more control over the speed.

Sigh - Yet another project that I need to finish before SELEM!

Adam

[absolom7691]

Well, after thinking about this for a while, I decided to give it a try as well!

Ordered the stepper motors from China, and also ordered both the drivers and an adjustable squarewave generator from Amazon. Probably going to have to wait a while to get the steppers delivered, but we'll see I guess.

Looking forward to seeing what sort of effects I can get with the classic shower glass that Greg (Displaser) discovered years ago. Previously I'd been using a .5 RPM Hankscraft 12V DC motor and running it down around 9 volts or so, but this should give me lots more control over the speed.

Sigh - Yet another project that I need to finish before SELEM!

Adam

I know those feels. I have been working on this Lumia projector for about 13 years now. And by "working on it" I mean, I have really only been working on it for the last 3. The previous 10 years involved gathering parts, designing, redesigning, and alerting the design. Part of that was due to technology changes in new diodes and the obsolescence of some DPSS lasers and new drivers and such. I can't tell you how many active projects I have that have been active for years! At least I am never bored!

[clickamouse]

Yup, just ordered 2 myself, based on what I saw at SELEM.

We’ll see how I do.
…Mike