posts tagged with the keyword ‘motors’

2015.04.22

Electronics

I finally got the electronics for my Turntable Drawing Machine working. It wasn’t easy…

I decided to use a DC gearmotor controlled by an Arduino and potentiometer for the speed. I did a quick test of this with a Leonardo and a DRV8835 Dual Motor Driver Shield for Arduino. It worked fine for controlling the speed of the motor, but I didn’t really want to use the shield, so I used a DRV8835 Dual Motor Driver Carrier I had on hand. (Since I’m only using one DC motor, I probably could have used a DRV8838 Single Brushed DC Motor Driver Carrier.)

Pololu has an easy-to-use Arduino library for the DRV8835 Dual Motor Driver Shield which worked fine for the shield, but doesn’t (I mean didn’t) work with the DRV8835 Dual Motor Driver Carrier. I ended up hacking the library a bit to make it work. All was well until I added a servo. Since the Arduino library for the shield is hard-coded to use pins 7, 8, 9 and 10 there’s an issue because the default Arduino servo library disables PWM control on pins 9 and 10. I then changed the library to not use pins 9 and 10, but that still didn’t quite work… Seems that the servo library and the motor control library both need to use times, so there’s some weirdness there…

I ended up digging through the forums and eventually found some useful posts and a link to ServoTimer2.zip. (It’s worth noting that there are a number of ServoTimer2 libraries, but I tried this one and it worked.)

Once I had the ServoTimer2 library in place, getting it to work with the my hacked ‘DRV8835DualDriver’ library was simple. (I’m saying “simple” but it took a few hours of screwing around with things that should have worked but didn’t) If I had used one of the Arduino Megas I had lying around, I probably could have avoided some of the issues the Servo library causes.

Alright, well… electronics seem good! Next step is to build things, and get the turntable portion constructed to test if the DC gearbox will work out. I think it will, as it’s got plenty of torque, and there shouldn’t be much resistance.

2012.09.26

Laser Kaleidoscope

We managed to get Milwaukee Makerspace invited to another gallery night, and this time we’re taking part in Bay View Gallery Night at Alterra, so I figured I needed a new project. And hey, what’s better than a deadline to get a project done? (It’s like college all over again… in a good way!)

Interociter

When I was at Maker Faire Detroit back in July I saw this laser spinner thingy called “The Interociter” and decided I had to have one. And by “have one” I mean “make one”… so I did.

(There’s some debate over whether it should be called a “Laser Kaleidoscope” or “Laser Spirograph” or “Laser Spinner Thingy” and while I do like “Laser Spinner Thingy” I also get sick of people thinking all my projects are Spirograph-inspired, so I went with Laser Kaleidoscope. Deal with it.)

Laser Kaleidoscope

Laser Kaleidoscope

So where were we? Oh yes, the project! It’s really simple: a laser is pointed at a mirror, and that reflects the laser onto another mirror, and that one reflects it onto another mirror, and then it shows up on the wall. You can make the motors spin by turning them on with a pushbutton, and then adjust the speed by turning the knobs. There are 3 motors (an earlier prototype had 4) and by setting them all to different speeds, you can get some crazy patterns going.

So how does it work? The laser hits the first spinning mirror, and creates what appears to be a circle. It’s really a single dot, but it’s spinning around so fast it looks like a circle. Add a second (and third) mirror, and since they all wobble just a little bit, you get much more than a simple circle.

Here’s a shopping list:

I say “shopping list” because those are the parts I (mostly) bought… Of these parts I’ll note that with the laser I leaned towards the “safe” side, but it can be difficult to see in well-lit rooms, so I may upgrade to this one at some point. The round craft mirrors came in a variety pack with different sizes. I may experiment with larger mirrors in the future.

Laser Kaleidoscope

Laser Kaleidoscope

There are a bunch more parts involved, one being the piece of wood everything is attached to, and the other parts were all designed and 3D printed by me. (OK, I had a little help with the knobs.)

The printed parts are:

  • (1) Laser mount
  • (3) Motor mounts
  • (3) Mirror mounts
  • (3) Knobs

(I also considered printing some small U-shaped things to hold the wires in place, but haven’t bothered with that yet.)

And yeah, this is why I have a 3D printer. The ability to digitally design something, rapidly create it, tweak it a bit and print a new one… that’s what I love.

My original plan was to make up a nice laser-cut case for this (I thought that would be appropriate) but with the lasers down for repair, I didn’t get that done in time. That’s actually fine, as I’ll probably end up redesigning things a bit before I’m totally done with it. So far though, I’m happy with the progress.

The video was quick & dirty, and really doesn’t do it justice, which is why you’ll need to come see it in person I guess. I figured I couldn’t write this post without including some sort of proof that it actually works. :)

Lasers! They’re awesome!

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