Tag: art

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Turntable Electronics

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 timers, 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.

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Turntable Shaft

Platter System

For my turntable drawing machine I’ll need the platter to spin. In a “real” turntable (the kind used for vinyl albums) there are three methods, idler-wheel, direct drive, and belt-drive. The illustration above shows my original idea for direct-drive, which I quickly abandoned in favor of belt-drive, on the bottom.

Rod & Bearing

Typically I use 8mm rod for things because, well, I have it handy, and lots of 608 bearings as well. For this turntable shaft, Frankie gave me some 6003Z bearings, which have an inside diameter of 17mm. I found some 17mm steel rod from McMaster-Carr, but I didn’t need very much, so I asked Chad about making a piece on the lathe. He said it should be easy if we had some stock just a bit larger, and well… Frankie did indeed have something! (Oh, if I used 17mm rod I would have added shaft collars… luckily by machining the part, we won’t need them.)

Frankie gave me a crash course in the metal lathe. (I last use a lathe back in the 1980s, and it was a wood lathe!) I learned how to face off the material, and then he showed me how to narrow it down to size. We got it to a perfect fit for the bearing!

Plastic pulley

I also had some plastic pulleys on hand from when MakerBot sold off all their old Cupcake CNC parts… I knew they’d come in handy someday! We managed to drill out the center on the lathe so it fits tight over the steel shaft. I may need to add a set screw or some locking collars, but it’s a nice tight fit right now.

Parts

Here’s the shaft, bearing, and pulley all properly sized. Once I determine the length of the shaft we’ll put it on the lathe, cut it down, and then get the other side to the right size. I’ll make some pieces that hold the bearings by either laser cutting some material, or 3D printing something, or maybe via the CNC router.

Perfect Fit!

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Turntable Drawing Machine

Sketches

As previously mentioned, I’m working on a new drawing machine, and it’s based on a turntable. I’ve included some of the sketches here, as I continue to explore a few ideas.

Sketches

There’s a number of aesthetic choices to make in the design of this thing, including the material. Right now I’m focusing on wood for the majority of the build, but may also include some acrylic (which may allow for some LED lighting) and metal. I’d consider Alupanel, as that stuff is pretty nice, but it’s also a bit pricey, especially since I’d need a piece that is 19″ x 15″.

Sketches

There’s also the mechanical build to deal with. I’ve got a good idea of how that will work, and I should be prototyping the spinning platter mechanism this week. I have semi-working Arduino code already, but I’m still contemplating direct drive versus a belt system. (I have all the parts, just need to start experimenting.)

Turntable

I stopped by Bliffert Lumber last week to grab some 1/4″ Baltic Birch plywood, and I cut the top panel and turntable. These may just serve as test pieces and not final pieces, but it’s something to start working with. I used a 90 watt laser cutter as it’s quick and easy. I do have a 1/4″ end mill coming in this week, so I can cut 3/4″ wood on the big CNC router if needed. It’ll all depend on material and time. (This needs to be completed in about a month.)

Hopefully I can start working on the arm mechanism by next week, as there’s a few tricky bits involved there. I’m not sure if I will use limit switches, a servo, or make the pen placement a manual process. Hopefully a prototype will come together soon and answer some of those questions.

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I like to sketch!

Sketch

Graduate reviews are done, and I got feedback from faculty on my current work. I was a great opportunity to gain insight into how others view the work I do. Typically these sort of things help reveal ideas that you don’t think about while making the work, or bring up new questions in regards to why you make specific choices.

One of the interesting takeaways from today was when a few of my pieces were called “sketches”. If you think about a sketch, it’s defined as “a rough or unfinished drawing or painting, often made to assist in making a more finished picture.” Many of the pieces I created are experiments, or explorations of ideas. They’re often not highly crafted pieces. I appreciate craft and people who are skilled at creating beautiful objects, but I often think I don’t have it in me to do that sort of thing.

I thought more about sketches, and the fact that in the Processing and Arduino worlds, the programs are called “sketches”. As I understand it, this was done specifically to appeal to artists and creative people who didn’t have a background in computers. Tell an artist they are going to write a computer program, and that’s a frightening proposition, but tell the same artist they are going to create a sketch and that’s an achievable goal.

I sketch with physical things…

That’s today’s revelation. Many of the things I make are real-world sketches. The physical manifestation of an idea. Often there’s an immediacy to the creating of the thing, but not always. I tend to work in two ways. The first is a reactionary mode, where I have an idea and act on it immediately. I start building without too much thought, and see what the process and the piece reveal. The second method involves thinking, designing, and prototyping as an iterative process. The pieces created from the second method are often more polished, but both methods produce valid work, and the reaction to each kind of work may be equal (meaning, people don’t always gravitate to the work that had more initial thought or took more time.)

Oh, I also want to drop the other definition of sketch here, “a short humorous play or performance, consisting typically of one scene in a comedy program.” This also relates to some of my work, but I’m going to leave that exploration to a future post.

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A New Drawing Machine

I’ve been designing a new drawing machine that is inspired by turntables. You know, those old-fashioned devices that old people used to listen to music…

I’ve made some progress on the electronics so far, and the controls will most likely consist of two potentiometers to control two stepper motors, and there may or may not be a servo involved for the pen lifting. (And yes, two steppers and a servo are sort of the common elements of many drawing machines.)

While many of my drawing machines are cobbled together with bits of wood and hot glue, I’m going to attempt to actually design this one. I’ve been looking at a number of turntables for design ideas, and wow, some of those things are just beautiful! Some examples below…

Turntable

Turntable

Turntable

Turntable

Wood Turntable

Belt Drive

I’ve started to collect other images/links over on a Pinterest board. Some are just interesting machines or mechanisms, but a lot of them are turntables or drawing machine related.