Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

I'm still experimenting with direct laser pcb. There are a lot of variables, and sometimes changing what I though was a minor detail seems to change everything I thought I already knew! I was going to wait till I had it perfected, but got carried away when someone started this thread. I now have a stable physical platform to experiment with, so I think I should be able to control the process and develop a repeatable work flow.

For anyone interested I'm going to write up a fairly detailed description, with pictures, and put it on my pbase site. Unfortunately, I am very busy right now, so it may take me a week or so to get to it.

One thing I haven't mentioned is that, while the mod itself is quite easy, probably much easier than the inkject mods, you do have to cut some plastic to allow the board to pass through the machine. The cuts are not critical, but are a bit messy - I use a dremel with a routing bit. It cuts like butter but leaves lots of bits of plastic all over. I protect the printer by wrapping everything in plastic sheet and masking tape while cutting.

You also have to use a microprocessor to control things. In fact, the board I posted on pbase is a variant of the board I use for the Atmel processor. If anyone wants it, I can supply the Eagle file for the board and the code. I developed the code after using a data logger to record the sensor and high voltage timing.

I also think a safety note is in order. You are working with fairly high voltages here, and if you don't know what you are doing, you can get hurt or even killed! In one of my first setups I used a large rack mounted hv supply and forgot to turn it off when I stuck my hands in the printer. 2500 volts threw me backwards and I wasn't sure I was okay for about 30 seconds after! I am now using a supply that can only deliver 450 microamps, but I am still very careful with it.

Mark