[underthetire]

Yes, there is UV curable gel. One of those medical type pumps work well for dispensing.

[greybeard]

The more i think about this gel idea, the more worried I am about the surface tension effect. If it's sitting on a clean surface of the copper, what sort of problems will occur re the cross section of the gel trace, interfering with the need to pack the copper 'lines' close together.
(sorry about the vocabulary, the brain is in slow mo at the moment)
John

[underthetire]

If seen stuff about 20 microns separation on a structure, so single layer should be no problem. Your not just dropping gel on top, more like spreading with a little fluid pressure.

[epineh]

Hi John, nice to hear from you, uv cure sounds interesting, I know the pcb houses use the same method with uv cure resist, (not squeezed out of a 3d printer though) haven't tried that myself, there may be cheaper stuff than the proper PCB stuff on the market as well. I had a mate that tried the pre-coated PCB boards but didn't have a great deal of success.

Underthetyre 20 microns is a getting down there in size, the older I get the bigger I need to make things so I can see them !

I wonder if it would be easier to just use the traditional photo resist method instead of hacking the poor old 3d printer

Cheers.

Russell.

[greybeard]

Of course it would be easier, Russell, but hey, where's your sense of adventure :cheers:
John
PS nail decorating parlours may be a local source of small quantities of uv gel, but don't tell the swmbo I said so .

[greybeard]

Yet another idea to throw into the pot, though I'm not sure if I've mentioned it before.

Start with your cnc machine. Replace the router with a spring loaded probe consisting of a polythene tube like the inside of a ball point pen, with a sewing needle down the inside, fixed about 0.5mm above the end of the tube.
Place your coppered board in a small tray containing a weak electrolyte, deep enough to keep the needle tip immersed when the probe runs across the copper, and connect a 3v psu between the needle and the copper.

I refer to this as reverse electroplating, and when I used this to etch away some brass to make originals for subsequent silicone rubber moulds, I was amazed at just how fast the brass was dissolved.

I knew that eventually I should think of another use for it, and believe this may be one.
Although the current supplied from the psu is quite low, the current density is very high at the needle tip, and it should be capable of dissolving the metal at a rate suitable for the cnc to take advantage of.
Obviously experimentation is needed, but the set up is so simple it should be worth a shot.

John