TreadBot

[mister_e]

Yeah it's one of those machine some may want to have hanging on their bench

Maybe your tube haven't the right specs, were to far of your PCB, or your exposure time was not appropriate. You have to use special wave lenght tube (UV). regular Black-light tube (or lamp)have nothing to do with that. I usually pre-heat my tube before for 1-2 minutes.... once again for safety sake.

Once you have did few experiments, you know how much time your exposure time will be... it's almost the same everytime.

At least you will scrap 1 big PCB. if you're using 2-3 tube, this MUST take less than 2.5 minutes.

1. Start the exposure lamps and hide major part of your whole PCB with an opaque material
2. wait at least 1.5 minutes
3. move the opaque material to reduce the 'hidden from UV' PCB area every 5-10 seconds
4. develop the whole PCB and look where your PCB look the best.

At the bottom of this link, it's almost what i said... but in english
http://www.turbokeu.com/myprojects/pcb.htm
Enjoy and have fun with the pcb etching and... drilling job

EDIT: i heard some use now ultraviolet LEDs...