Re: [neonixie-l] Etching anodes and cathodes

Michel van der Meij Mon, 28 Jan 2013 23:03:56 -0800

That is really cool stuff!

Maybe one day it is possible/affordable to use a 3D printer to print these cathodes and grids using a conductive plastic of some sort. As it is all low current, it may not need to have very low resistance. And then of course, if you had 2 types of material in your printer (1 conductive, the other isolating) you could just print the whole set of grids and cathodes! That would save a huge amount of effort!

Michel

on Jan 29, 2013, Quixotic Nixotic <[email protected]> wrote:

On 29 Jan 2013, at 01:36, John Rehwinkel wrote:

Yes, I think the original nixie tubes were made by photo etching.. There is so much work on the tubes (or just preparing the stuff for now) that I would be very glad to get rid of one problem - making the number for nixie tubes.. But I am afraid I will have to photo-etch the anode grid anyway, I cant imagine the laser cutter making it

If you're photoetching the anodes anyway, may as well do 'em all at once:

http://www.vitriol.com/images/tech/nixies/cathodes2.png

I can shed a little light on the photo-etching process, having both had items made professionally and also silk-screened them with my own fair hands with about the same level of accuracy. Because the etching process undercuts the metal in a V shape it is normal to use a pinbar registration system and to have the acid resist on both sides of the metal, one image the reverse of the other. To do otherwise is to end up with a back somewhat skinnier than the front after etching.

It is possible to get quite accurate registration on both sides of the metal, using a home-built silkscreen system and wooden silkscreen frames. In the case of the picture below, it was only a single-sided etch but I found it necessary to print the outline shape on the back too to maintain crisp edges equal on both sides. Hopefully you can see the edge ridge with slight but significant undercut. I don't have my silkscreen equipment any more otherwise I'd offer to do some trials for you.

I think in the days of etched printing plates they used something called "bull's blood" which minimised the undercut somehow.

There used to be companies who specialised in doing this work for modelmakers. Useful for suspension bridges, railings and other filigree work. I am not sure if any are around today.
My guess is if you are going to image directly onto the metal using spray on light-sensitive emulsion, you'd still need to expose an image on both sides of the metal.

John S

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Re: [neonixie-l] Etching anodes and cathodes

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