I really like the update on your page! Yove made quite some progress :) On Sunday, June 17, 2012 8:53:26 PM UTC+1, Dalibor wrote: > > Nice information about making stems are in the Roth's book noticed > recently here.. "Vacuum sealing techniques", for those interested in this > book, let me know outside, I will post link.. > > I have already got a small test mold made from graphite, 13-pin.. My > original intention was to arrange some kind of furnace in microwave oven > and melt the glass directly in the mold with dumet wires inside.. But no > luck yet, I am able to heat a piece of the carbide to 1000C, but the power > is to small to heat all the mold with glass. Another thing is, that at this > temperature, the graphite reacts with oxygen producing CO2 and degrades.. I > think 10 cycles is maximum for one mold. The furnace with controlled > atmosphere (nitrogen, argon, CO2 ..) would be the best.. I am going to ask > my friend to test that process in their lab, he has a special tubular > furnace able to go above 2000C ;-) > > I am preparing some short blogpost about my fail ;-) I will publish it > tonight. Except that, I had also some small success, sealed argon tubes.. > that post is already done: > > http://dalibor.farny.cz > > Dalibor > > 2012/6/17 Dalibor Farný <dali...@farny.cz> > >> Hi John, >> >> are You sure that only gravity is enough for the glass to flow to the >> mold? At what temperatures? I tried 800C and no luck.. >> >> Dalibor >> >> >> 2012/6/17 John Rehwinkel <jreh...@mac.com> >> >>> > How exactly would you proceed making - say - 13 pin tube bases? You >>> need a lot of temperature for that and precisely formed tools. So far this >>> is nothing I can see myself doing in the near future. I know a person who >>> makes his own (borosilicate glass) sockets, I might be able to adopt the >>> principle some day. >>> >>> The tool part isn't too tough, just carve it out of graphite with pin >>> recesses. CNC machining would be the way I'd go, but back in the day it >>> was done by reading scales on handwheels, and obviously it could still >>> be done that way. Once you have your graphite mold/pin holder, >>> get some nice 3-part pins and lead glass tubing of an appropriate >>> diameter. Lead glass is the way to go here - it liquifies enough to >>> gravity flow into molds like this. Slice off rings that have sufficient >>> glass to make your bases, drop pins into your mold, put the glass ring >>> around them, and melt the whole shebang. For extra niceness, you can >>> have an upper mold half that forms little mounds of glass over >>> the pins themselves and flattens the rest of the base into a disc. Let >>> it cool, and violà! The first one will be a real bear, as you have to >>> make the molds determine the amount of glass, temperature to use, etc. >>> But once you have the molds made and the procedure down, >>> you can knock out additional bases fairly easily. >>> >>> - John >>> >>> -- >>> 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. >>> >>> >> >> >> -- >> Dalibor Farny >> http://dalibor.farny.cz >> >> >> > > > -- > Dalibor Farny > http://dalibor.farny.cz > > >
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