XY LED Light Painter

As much fun as this has been to play around with, the print area is just too small! Using SketchUp I've come up with some designs for a new scaled up version using MakerBeam and pulleys (instead of threaded rods like current design). 

This should give a total print area of about 250mm (as opposed to the 50mm I have now). If I put an SMD LED inside a small enclosure with a tiny 1mm hole, I should be able to decrease the width of the lines to further improve resolution as well. I figure at the moment the lines are about 3mm wide and the print area is 50mm wide. So that's a resolution of about 17x17 pixels. With 250 x 250mm bed and a 2mm wide line that will give a 125x125 resolution, or 250x250 at 1mm wide lines.

Pricing all the parts looks like it'll set me back approximately $400... which is a reasonable sum of money. Also, it occurs to me the design above is complete overkill considering the tiny payload it will carry. My thinking here is that I can adapt it to a homebrew printer or PCB mill later. After all, the whole idea of this project was to be a fun way to learn how steppers work. (As far as that goal is concerned, I could be getting a bit sidetracked here). 

The other problem I will have is my camera. It can only do 15 second exposures, so I'm going to need to buy an DSLR in order for a bigger print area to be useful (unless it moves REALLY fast). Those are expensive too so will probably set me back another $400 or so unless I get a second hand one.

I'm going to leave things as they are for now while I have a think about what to do next. I might grab a SMD LED or two like this or this to see how that looks. In the meantime, more designs with current setup:

I replaced the 5mm LED with a set of 3mm LEDs to provide a little bit of extra resolution. I've reduced light pollution a bit too by painting the bottom of the LEDs and some of the topmost surfaces of PCBs, stages.

Which makes some fun patterns

And a triforce once I realised I needed to set the stepper speeds individually for each coordinate (so they arrived at the same time). The photo on the left is the same set of triforce coords, prior to this change. 

At the moment I'm using Excel to manually set up a set of coordinates, it's slow but it does work!

This is heaps of fun to play around with. I'm going to come up with a few more patterns for this setup before doing anything else. 

Some limitations are making themselves visible however and the pattern above is about the limit of what I can do. Not only is the resolution still pretty small, but it is also the extent of how long it can draw for. That pattern above takes exactly 15 seconds (max exposure length on my camera). I realised also that due to RAM limitations I won't be able to program more than 200 coordinates. For straight line drawings that's fine, but will make drawing curves difficult.

No major developments, though I couldn't refuse trying a few new snaps that were more recognizable as shapes or patterns.

Light pollution obviously still a problem, though I discovered covering the top of the LED with toothpaste does help to diffuse the light being cast upwards!

Also, that last shape was a horrific attempt at a triangle. I might be having some acceleration issues. Going to try and work out a proper coordinate system to replace my caveman approach I've been using so far!

So far I'm using the Arduino Uno, two EasyDriver boards, and two of the cheap rails with an LED on top to test the concept.

So far has been good. Getting the two motors to spin simultaneously was very easy using the AccelStepper library and following two guides:

• http://www.schmalzhaus.com/EasyDriver/Examples/EasyDriverExamples.html
  
• http://www.airspayce.com/mikem/arduino/AccelStepper/MultiStepper_8pde-example.html
  

As pictures show the results of the actual photos aren't that good. Two main reasons for this I think:

• Light pollution. In both of the photos it was pitch black when I took the photo. Even after adding a pot the LED is still way to bright and is throwing light in all directions. I'll buy some nail polish and paint the bottom/sides of the LED to see if that helps.
  
• The LED itself might be too big. The rails only have less than 6cm travel which means the LED takes up too much of that space... I need a smaller LED.

Next steps:

• Fix light pollution, get a smaller LED. 
  
• Build proper coord system and way to turn LED on/off. At the moment the rails are just moving backwards and forwards randomly.
  
• Build some spacers so rails have more travel. At the moment the rails run into each other and that massive pcb with the LED decreases travel for that rail too.