Progress on My Pintograph

Did I mention I’ve been working on making my own pintograph? Here’s the first (decent) image it produced!!

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It’s still a work in progress, but it draws reasonably well for now. Want to know more about how I made it?

Here’s the machine:

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Can you tell that it’s made out of an old (upside down) drawer? I had to saw off the lip of the drawer so that it would lie flat on the ground. Given that a drill is my only power tool, that might have been the most time consuming part of the build so far. It also produced a fair amount of sawdust that was out of place and unwelcome in my small studio apartment 😛 Stormy didn’t mind the mess, though.

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Before I dive into the nitty, gritty details, here’s a video of it in action from my Instagram:

My pintograph is based pretty closely on the description here, but there were a few things I couldn’t figure out based on his description. I think he also assumes quite a bit more woodworking background (and tools) than I started with. The following descriptions should be enough to get you a similarly working machine without wasting money and time on things you don’t need, but it is probably quite boring for anyone who isn’t trying to make one of these things.  And it will be quite disorganized, much like my process of creating the thing. 😛

Based on my back-of-the-envelope/bottom-of-the-wordpress-post calculations, you should be able to do this for under $300 but probably closer to $150 assuming you have some tools, one trip to Lowes, one lucky-ish trip to Goodwill, and a couple weeks max for shipping, assuming you’re in the US.

Materials:

  • 2x motors – I bought these originally, but hobby motors will not work. They spin too fast and don’t have enough torque. And the spinning part is really tiny and totally round, whereas on these it’s bigger and has a slice cut out of it so there’s a flat side. I’ve also seen successful machines made with servos and arduinos, but I couldn’t find anyone telling me exactly what to buy, so I went with these. Unfortunately, this place  had a substantial enough shipping cost that I hesitated, but they really don’t seem to be available other places for a better deal. Same with the motor speed controller I mention at the end.
  • Dresser from Goodwill – $8. I could have used this for all of the wooden parts, but the arms are made of something else, and having long straight pieces pre-cut was very nice given my lack of tools; I could have also bought lumber from the hardware store, but that would have been substantially more expensive, and reusing this incredibly ugly dresser that I’m sure would have ended up in the trash feels good.  If you’re in a city like Seattle, some locations are generally better than others for finding furniture. For example, the location closest to me is tiny, weirdly expensive, and rarely has furniture, whereas the Ballard location has a huge furniture section.
  • Wood for the arms – I can’t find something similar online currently, but I think it came from the moulding section of Lowes.
  • Pen – I didn’t have a drill bit that was the right size to hold the pen tightly, so I pulled it apart and only used the ink cartridge part, which fit very snugly in the hole made from a 9/64″ drill bit. I tried attaching the pen in different ways (e.g., through the really big hole at the end), but that didn’t work well at all. Here’s a video of an early pen attachment mess. To be fair, I was mostly testing the motors at this point and had much longer arms, so the drawing was too big for the surface of the dresser, so the arms were facing off the dresser, and the pen was not tall enough to reach from the arm to the paper.

Not a bad start! I don't think I'll be framing this first drawing, though.

A post shared by Camille Cobb (@cam_and_stormy) on

  • Thick plastic – Reused from packaging of something I’d bought recently. I sawed the arm in half where the pen was attached and used this to re-connect the two pieces of the arm. This way the pen always stays in contact with the paper. I attached it with painter’s tape, but any tape would do. The video above sort of shows the pen being lifted off the paper, but I’d jury rigged it to kind of just hang there, so it’s not clear how big of an issue this was before the plastic hinge.
  • Tape – to connect the plastic to the arm and hold the paper still while the drawing happens.
  • Assorted nuts and bolts and washers – I used these to connect the wood to the motors, the long arms to the spinning wood pieces, and at the hinge between the two arms. But now I understand why the blog post  I linked to before talked about using screws instead, because the spinning motion is creating enough friction for the nut to unscrew itself. So a lot of the imperfections in my drawing above are from me re-tightening one of the nuts. I thought the washers would help, and they did, but not enough. So follow that guy’s instructions for connecting the arms to each other, etc. But my solution for connecting the arms directly to the motors seems good so far, and how to do that wasn’t described in his post. So even though I’d suggest changing out most of the nuts/bolts/washers in my current design for screws and washers, you will want something with a flat end for this part, like these. The size isn’t super important, but the diameter should be somewhat close to the diameter of the spinning part of the motor and not so long that they stick out (so about 1/2 the width of your piece of wood). Here’s a diagram of this setup. It works like a crass version of the part described in this video.

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  • Plastic coated wire – I used wire from this kit, but that’s probably not the most cost-efficient solution. Though actually I did use the bread board from that kit as well, but that wasn’t necessarily necessary. But you will want to be able to leave it on without your involvement and quickly turn it off (e.g., I pulled a single wire out of the bread board to turn it off)
  • 2x 6V lantern batteries

Tools:

  • Power drill
  • Standard small-ish drill bits and a 1.25″ spade drill bit. The spade drill bit was used to make holes for the motors and wasn’t quite big enough (which is a good thing, so that they’ll fit snuggly and not rotate in their own holes), so I kind of manually turned it around in the hole until I could pop the motors in.
  • Sand paper
  • Pliers – to bend the wires to connect them to the various circuit components, though in future iterations of the machine, I plan to solder these connections.
  • Hack saw
  • Clamps

As suggested on the blog I mentioned before, I also have a potentiometer and this motor speed controller. If the motors are going at the same speed, which they should be if they’ve got the same voltage across them, they’ll just trace out one continuous line. So either my two motors have slightly different speeds/resistances/etc. or the loosening of screws produced this pattern or something else funny is happening, because in theory the circuit I made (batteries in series, motors in parallel with each other so that both of them have the full 12V across them) should have had the motors spinning at the same rate as each other. At any rate, I’ll want to change it up more as I make additional drawings, and the speed controller and potentiometer will let me do that.

My plans for future improvements to this machine are:

  • More permanent electric connections (soldering), add speed controls, an on/off switch, and a switch that will change the direction of one of the motors. I’ll be returning this one – it changes the direction of current depending on which way you flip the switch, but breaks the circuit unless you’re actively holding the button down.
  • Screws instead of bolts for the connections between wooden pieces. This probably means starting fresh with un-hole-y wood pieces, which means I’ll probably procrastinate for a while since my wood cutting situation is a hack saw. I’ve seen some machines that use small round magnets super glued to the wood for this, so I might give that a try first.
  • Multiple holes so that the position of the pen, radius of rotation, and length of the arms are easily.
  • Scissor arm variation.
  • Maybe something to create a smoother/flatter/bigger drawing surface? But that might involve more sawing than I’m ready to take on. For now, I’ll just use thick paper or multiple sheets of paper to create a flat surface. I’ve seen several drawing machines that use a metal sheet as their drawing surface, so the paper can be held down with magnets. I think that’s a very elegant solution, but I’m not sure I have a way to acquire a properly sized metal sheet. Hmm.
  • Different pens/colors, maybe adding some weight to the arm so that the pen draws slightly thicker/darker lines.
  • Eventually some mechanical way of moving the paper – either rotating it, which will probably involve a Goodwill lazy suzan, or pulling it, which would mean getting a long roll of paper and could possibly be done manually.

So far, here’s an estimate of what I’ve spent making the machine:

  • $56 — 2x $25 motors + $6 shipping
  • $10 — long wooden moulding board
  • $10 — 2x lantern batteries
  • $8 — dresser
  • $10 — nuts/bolts/washers
  • $15 — electronics kit with wires and bread board
  • $10 — 1.25″ drill bit
  • $20 — clamps
  • $30 — Motor speed controller. I’ll use this at some point, but I haven’t yet ($22 + $5-ish shipping)
  • (Total –> $169)

I already had these things:

  • $30 — drill
  • $1 — pen
  • $3 — paper
  • $5 — tape
  • $6 — hack saw
  • $15 — other drill bits
  • $10 — sand paper
  • $5 — pliers
  • I also have access to soldering tools and materials and haven’t done any research on how much those things would normally cost (though they aren’t strictly necessary, and I haven’t used them yet) but I’ll have to get a friend to show me what to do …

I wasted money on these things that I didn’t use:

  • $15 — switch (but I’ll return it and get $10 back after return shipping)
  • $8 — hobby motors
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