Hi Gene, We've been doing quite a bit of research on glass to metal feedthroughs at Sixsmith. There are a few different methods and different types of glass used, and the best reference I've found so far is here: http://www.pmillett.com/tubebooks/Books/kohl_materials.pdf
Take a look at the feedthrough method using copper and cane glass. We haven't tried it yet in the shop, but it seems like we could reproduce it. Seems like it is good for pins, but we are still working with wire. To make new nixie tubes we ended up deciding on going with soda-lime glass and dumet wire, annealing them in house and then looking at them with the polariscope to see where the stress is. I don't know that his will be our final solution, but it is easy enough to get started with. If you just want to temporarily reinforce a seal, there are high vacuum glass to metal epoxies such as Celvaseal which may not have much longevity, but can help you troubleshoot the problem. I know what you mean about the color wrapped around the pins. Some literature I've run across reference asbestos tape to help insulate parts of the structure, but I've convinced myself that's not it. May be part of the jig that held the pins in place while the glass was formed? I don't know. It's a good question. If you are in the Boston area, feel free to bring your Nixies over to play. We have both Neon and Argon on hand. I hope something in there helps you. Meredith www.6smith.com On Tue, Jun 7, 2011 at 7:06 PM, Gene Segal <wavefr...@earthlink.net> wrote: > Yes, I have a few of those as well, which show no cracks or physical > damage, yet have lost gas, probably through the pins. Does anybody have any > ideas on how to fix that kind of problem? How to seal the metal-to-glass > interface? By the way, isn't that a special material between the pins and > the glass, whose coefficient of thermal expansion is somewhere in between > the coefficients of the glass and the metal? I can see an orange kind of > substance painted on the pins, at the glass interface. > > Jens, thank you for the clarification, but I think the definition of vacuum > is "negative pressure", so a loss of vacuum is a loss of negative pressure, > and a loss of a negative is a gain of a positive, so therefore it is an > increase in pressure. And of course, PV does equal nRT, especially in a > nixie tube, because neon and argon are pretty close to being ideal gases. > > Gene > > > > I have one that no longer works, have no idea why, I may have lost vacuum > when I was pulling or re-inserting it into my clock after doing some work on > one of my clocks. > > On 2011 Jun 07, at 15:02 , Gene Segal wrote: > > Nixie Gang, > > Is there anybody interested in bringing their IN-18's back from the dead? > Specifically, those of you who have suffered broken "pupiks" (glass bibs or > pips between the pins). I am not an expert, but was thinking that those > could be refilled and sealed. If we get a decent number of these casualties > together, then perhaps it would be interesting to some expert neon glass guy > to refill them. So the question is - how many of these could we get > together in one location, in order to approach an expert. I can get us > started with about 20. > > Perhaps we could devise a voucher system, so that everyone sends their dead > guys to one person, then an estimate is obtained for the lot, and everybody > pitches in their share. These would be only for private use, since > longevity would probably suffer...but it might be worth it for some to pay > $20 per tube, for example, to have a backup. Thoughts? > > Gene > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To post to this group, send an email to neonixie-l@googlegroups.com. > To unsubscribe from this group, send email to > neonixie-l+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/neonixie-l?hl=en-GB. > > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To post to this group, send an email to neonixie-l@googlegroups.com. > To unsubscribe from this group, send email to > neonixie-l+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/neonixie-l?hl=en-GB. > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To post to this group, send an email to neonixie-l@googlegroups.com. > To unsubscribe from this group, send email to > neonixie-l+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/neonixie-l?hl=en-GB. > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
