Gentlemen- My name is Dylan Kehde Roelofs; I've been a scientific glassblower for 20 years, and I believe I can answer a few of your questions..
First, check out my website at www.incandescentsculpture.com - I haven't updated it for a few years, or put any of my new vacuum tubes on it, but I believe it will establish my credentials. Since the update, I've made tubes, flasks and bulbs for Columbia pictures, the Discovery channel, and the History channel... I've also got some stuff premiering at a show in Dubai- if any of you happen to be over there in October. (http:// www.indexexhibition.com/page.cfm/link=143) I was approached by a nixie collector about 6 years ago, in the old Yahoo nixie group , who wanted me to make some 200mm tall tubes. I looked into the problem and the literature, and decided that for an order of 6 tubes (which is what he specified) , it wouldn't be worth it at all. Tooling up an entire factory to make 10,000's of tubes is a pipe dream, even if the market exists. The break-even point for a mostly automated factory is far, far higher than the nixie market. Watch the videos on Youtube from the Mullard factory of the 30's - There's just no way to tool up like that. This being said- It is quite possible to make beautiful nixies by hand. The cathodes are all nickel- anything else would be eaten by the mercury. The pressure is about 10-15 torr of Penning mixture (Neon with a little argon in it). A bakeout at 400 C , for an hour or two should be enough to off-gas the interior parts. Induction heaters were usually used to skip this step... You could probably skip the mercury by introducing a higher pressure of xenon gas, and make white nixies, instead of orange.. (the Xe is so large in atomic terms that sputtering is minimized- look at halogen bulbs... The halogens also play a part in the water cycle of the filament, buy we don't have to worry about that in Cold Cathode land...) You'd need to get some thin nickel sheet, and have the numerals cut on a water jet. You'd need to get some high alumina ceramic and make those little washers, if you couldn't find them online. You'd need to get a custom feed-through pin made, with the right lengths and combinations of metals and glasses. You'd need a pile of little wires to attach pins to digits. The blackened 'cage' that sits behind the digits would take some expensive stamping and engineering- but might easily be eliminated by a coating applied to the outside rear of the tube. It might be cool for the end user to have a choice in that arena. Just the main pins are required to hold the digits and anode... The hardest part, by far , is the glassblowing. That glass-to-metal seal with 14-16 pins in it would be quite tricky, and requires 3 different glasses for evening out the strains. (I work in Pyrex, not soda-lime glass. The seals on nixies were made of a soft glass compatible with the pins) Even at the factories, where everything was dialed in perfectly (torch mass-flow controllers, annealing ovens, belt timing) , the seals needed to be inspected by hand for cracking... The system of strains set up by that many pins is very complex and touchy. Those Germans (and Chinese) factories making newer power triodes have it easy- I can make 4 and 5 pin seals all day long, and not loose one... Sadly- this factor will always prevent untrained efforts... Tack welding the little anode cage, and interior wiring would be quite tedious, but not very difficult. As with any new venture, the first tube would require more time than the next 100. Sourcing everything would take many calls and emails... For an end-view tube of 80-100mm or so, I can't imagine the parts and glass costing less than $30, frankly. (Just the last high purity nickel sheet I bought for vacuum tube anodes was nearly $10, and it was only 6x6 inches) Obviously, having thousands of each part made would lower this cost- most of the parts would have to made in that volume anyhow; my glass- to-metal sealing company isn't even interested in orders under 5000 parts (at about 25 cents per part..). Therefore, just the pins through the glass would total about $3 per tube. Corners can certainly be cut, but every decimal place of impurity in the materials equates to diminished tube life. The heart of the matter is this: The labour would be the true cost- each tube would probably take hours, all told. Size is barely a factor here, except in part costs- it would take as long to assemble an IN-18 replica as it would to make a much larger end-view tube. I make lightbulbs as my labour of love, and it took me untold hundreds of hours of R+D to get to the point I could create functional, new forms. The market for lighting is much, much larger than for nixies, obviously, and business is still rather slow for me. I can't really imagine being able to make a set of 6 tubes (for a clock) for under $200-300 a tube, and at that price, i'm not sure the even the world-wide market would support the initial outlay of time and money required. I'll certainly share my further efforts with the group, and be glad to answer questions. I'm glad to be able to chime in a professional opinion in a venue where my unusual and obscure skill set is of some use. [I made a tube a while back that said "f-u-c-k" (pardon my French; I had a little 4-pin glass-to-metal seal i'd made, and couldn't think of a better 4-letter word) I'll try to dig it up , and take some pictures tonight, and send it along with a few pix of my vacuum tubes. (does google groups support images? I know the old Yahoo nixie group had image archives...) - I didn't put a cathode in it (not much hexagonally perforated pure nickel grid lying around, so it's really more of a plasma tube...), but it's cool anyhow.] Cheers- Dylan Kehde Roelofs On Jul 7, 3:28 pm, jb-electronics <[email protected]> wrote: > I think we will have to forget about large volume productions. As others > said it before, there simply is no market open for this kind of product. > And honestly: do we want that? Every person on the world having a Nixie > clock? I wouldn't like that ;-) > > But it also seems to me that it is quite possible to manufacture small > quantites of these tubes manually. True, the materials need further > research. It is a long and tedious process. But it is possible. > > Take a look at the National Union Nixie tubes, for example. They are > very crude, and yet they work. And I am also not sure if we need the > mercury in the tubes, I usually do not like tubes that have some or too > much in them. The digits look so cold as compared to mercury-free tubes. > > So my suggestion is: the more people set out to build some Nixie tubes, > the better it is. Everyone will make valuable experiences, and we have > this great mirror to share our experiences. > > Regards > Jens > > Am 08.07.2011 00:07, schrieb Quixotic Nixotic: > > > > > On 7 Jul 2011, at 21:34, James wrote: > > >> I think a large Nixie tube could be produced at a similar price point > >> and demand as some of the popular audio output tubes. > > > I disagree. > > > John S -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
