Kent Fukuzura, Making Science Simple
Good colour printers are so cheap these days it’s amazing we don’t all buy a new one every year. However, there is still something to be said for doing that extra bit of effort that will not only give you a decent printer but also allow you to see how these new printing technologies work.
This week we will make a solid wax thermal printer using old crayons and a few other odds and ends found around every home.
The technology is quite simple. The file to be printed is rasterized into millions of little dots which the printer sprays onto the paper after melting the wax colours. Your computer tells your printer which dots are supposed to be what colour, so the process is real easy.
Start by gathering your crayons. Traditional printers use cyan (light blue), magenta (a fuschia-like pink), yellow, and black to receate all the other colours, but the more colours you use the truer to life your image will be. Why not throw in the whole box of 12, 24, or even 36 colours into our printer? Since we’re designing it there’s nothing keeping us constrained to normal market conditions. Let’s take advantage of that! (Of course, the more colours you use the more nozzles you’ll need to distribute the wax, so keep that in mind, too).
Peel the paper off the crayons and place each one in its own cell of a metal ice cube tray. The heating element from an iron placed underneath will work nicely as a method of melting the wax–keep the temperature setting between polyester and cotton.
There are a few options for getting the ink from the tray to the paper. Garden hose nozzles can provide a variable spray output, from jet-steam to a fine rain, but you’ll have to develop a mechanical system for adjusting the spray. It might be easier to use the heads that come with glass cleaners. Add a few hoses, gears, rollers, and tubes here and there and you’re almost done!
Any old computer will do to interpret your file and convert it into the impulses needed to pump the streams of melted crayon wax through the nozzles and onto the paper. I used a first-generation I-Mac because they’re so colourful to begin with. Connect your printer with a USB cable, because they’re faster, and with all those nozzles, you’re going to need the extra speed.
Create a case for your printer using dad’s plastic extrusion machine in the garage, and there you are!
Designing and building your own colour printer is a good way to use up those left-over crayons from your childhood, and to learn about the challenges facing manufacturers of commercial printers.
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