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Brad,
I looked at your artwork scans. WOW. Has anyone suggested that you might be a glutton for punishment?
I noticed that the first two scans are much cleaner than the others. If you have access to the pages that they were scanned from, you should re-scan with the lines square to the scanning direction. This will produce much cleaner results.
Before you invest too much time is trying to make clean artwork using the scans as a basis, make sure that the scanning process didn't distort the dimensions in one direction or the other. I have found small differences in the scaling between the x and y axes that make assembly of 40 pin ICs, or long connectors impossible.
These boards will be difficult to etch. The combination of large open spaces and very narrow traces may make it difficult to keep the traces from over etching.
To answer your question about plated through holes, they can be done, but it is a bit involved. There are a number of tutorials on making plated through holes on YouTube. Here are two of them:
Process 1:
https://www.youtube.com/watch?v=KTNuTv_IQp4
Process 2:
https://www.youtube.com/watch?v=s3GY-j4Gh0E
https://www.youtube.com/watch?v=9rME-XGCcCo
I have not tried either of these processes, but they do seem possible. The difficulty I see with your boards is the sheer number of holes. The possibility that one or more of the holes, especially the small via holes, not getting plated through is very great. Finding an open would be very difficult, not to mention time consuming.
One thing to remember: The holes are drilled and plated before the board is etched. This means that the holes need to be protected during the etching process. It seems to me that the best process for doing this would be the photoresist process. The photomask used for resist exposure would need to have the drill holes omitted, so the resist will tent over the holes during etching. Drilling before photomasking has the benefit that it makes the mask easier to align. I would suggest that some extra pads with holes should be included on the masks to assist with alignment. These pads would include the drill holes. This also improves the probability that two sided boards would have proper alignment between sides.
My TV Typewriter project is getting close to the finish line so I’m working on lining up a new project.
What I’d like to do next is a replica of the SOL terminal prototype that appeared in Popular Electronics in July of 1976. I have the artwork for it here:
http://www.sol20.org/articles/img/PE_SOL.pdf
As you can see, the quality of the scan is pretty lousy. There’s no other sources for this that I’ve found. I can clean it up manually with Photoshop or Illustrator (and in fact have started on the former) but that will take hours (months, probably). I’m wondering if there’s a better technique than endlessly using the rectangle tool to remake the traces and remote the ‘noise’.
I expect there will be other challenges, being that this is a double sided board. There ∗isn’t∗ a way for a home PCB maker to do thru-plate without third party help is there? I don’t want to send this off to a board house because of the likely cost but also because that’s not how a hobbyist would have done it back then. Since this artwork was sent to those that wrote in for it, I’m assuming they just created it as a two sided board the usual way and then soldered in the connections between sides via ICs, jumper wire, etc.
I also don’t want to completely redraw the thing. For me, that would lose the spiritual connection to the original artwork. I’m trying to leave as much of it as original as possible.
Anyway, thoughts and suggestions here are most welcome.