Sourcing DrawBot Parts

I’ve previously discussed sourcing the main electronic components for a drawing robot.¹ Since there’s more to a robot than just the electronics that make it work, I thought I would list my other resources in one place.

• Electronics.  The electronics are the brain and heart of this project.  There’s really only two parts that could not be found or scavenged – these parts being the Arduino and the Adafruit Motor Shield.
  • Adafruit.  I’m going with Adafruit all the way.  Great website, great blog, great service, and their tutorials are super comprehensive.
    • 9 VDC 1000mA regulated switching power adapter – UL listed, $6.95
    • Stepper motor – 200 steps/rev, 12V 350mA, $14.00 each
    • Micro servo, $5.95
    • Arduino Uno R3 (Atmega328 – assembled), $29.95
    • Adafruit Motor Shield, $19.50
  • These were the exact items I bought.  To date I still have never hooked up the servo motor to anything, but I hope to soon.  I could probably have substituted these smaller cheaper motors and used a left over power supply from some random project, but I knew these parts worked for others and would probably work for me.
  • If you were really just had to build a similar robot for as cheaply as possible, you could probably pull a pair of steppers and possibly a servo from some old printers, copiers, and the like.

• Project Box. I’m using a long thin pine box left over after a huge catering party platter order. Frankly, you could mount the parts on nearly anything – a 2×4 or a nice custom box – it’s entirely up to you.  Heck, you could even screw these parts directly into a wall if you were feeling particularly adventurous.

• Structural Parts.  Besides these main components, it’s really really useful to have a 3D printer to manufacture all the parts necessary to make it all work.  Motor mounts, spools, etc.  If you had a laser cutter or a ton of quick-set plastic, you could probably fabricate perfectly serviceable parts.  The parts I’ve designed are ideally suited for my own project, could be modified for your own project, or you could just design some parts from scratch.
• Hardware.  There are also all the little bits of hardware to hold everything together.  I still have a ton of M3x16 bolts and M3 nuts left over from building a Cupcake CNC and Thing-O-Matic.  Besides these M3x16 bolts and M3 nuts, I did use two screwhead M3x16 bolts to hold the Polargraph case in place and eight M3x8 bolts to attach the two motors to the mounts.
  • McMaster has a truly amazing website.  Even if you want to build a drawing robot and have zero parts on hand, you could pick up all the hardware you need from them super-cheaply.  Update:  The only thing I don’t care for about their website is that they don’t have a way of getting an estimate on shipping.  Among McMaster’s virtues is their amazingly responsive customer support.  I just asked them for a shipping estimate on these parts and they got right back to me.  You could pick up a set of 100 nuts, 100 M3x16 bolts, and 100 M3x8 bolts for about $6.  This is an absolute bargain for way more nuts and bolts than you’ll ever need for this project.
    • M3 Nuts, plain are $1.04, zinc plated are $1.39, and black oxide are $5.39² for 100 count
    • M3x16 socket head bolts are $6.05 for 100 count
    • Yesterday I spent six dollars on eight lousy M3x8 bolts.  Had I simply waited for McMaster, I could have had 100 M3x8 bolts for only $4.84
  • Chances are if you really had to you could use whatever bits of hardware you can find lying around your place.  I’ve seen examples of similar drawing robots using zip ties to hold the motors in place.
• Electronic Bits.  I still need to track down some rainbow colored ribbon cable and connectors.  While I do actually have all the pieces of scrap around my home to finish the robot right now, I don’t want to do this half-way.  I want to use a rainbow ribbon cable because (a) I need to extend the motor leads to reach the circuit board, (b) it would be very helpful to have each lead color coded separately, and (c) they’re really pretty.  As for the wire connectors, all the other parts to my setup are very modular and it would be very nice to have the electronic connections just as modular.  After searching around, I found that Sparkfun has all the little pieces I need to finish this project.
  • Sparkfun.  I’ve never really bought anything from Sparkfun before – but people I trust have spoken highly of them.  I say never “really” because I bought into the Makey Makey kickstarter and they used Sparkfun to fulfill their orders.
    • 15′ of rainbow ribbon cable, 10 colors over 10 wires for $4.95.  That’s a fantastic deal in my book.
    • 4″ of 4-pin jumper wire for $0.95.  My plan is to simply cut this female/female ended connector in half, solder each half to one set of motor leads, and then use normal headers to connect to these.
    • I’m tempted to splurge and get two of these cheaper steppers at $6.95 a piece.
  • I’m completely confident that you could pull plenty of wire out of old electronics.  They always have a ton of wire and connectors inside.

I recently had a very unsatisfactory experience trying to source some parts locally, so I”ll be placing an order for some ribbon cable and jumper wires from Sparkfun.

1. Photo courtesy of Jes [↩]
2. This is the type I have left over from building my MakerBots [↩]