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Melting Lead With Only Limited Facilities

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Conundrum

Sun Jan 20 2019, 05:36AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Interesting, thanks for sharing!
Sounds similar to something I was planning to build but in my case using very small SBM-21 tubes originally intended for portable dosimeters.
Note: I did eventually managed to reconstruct the circuit for the modules in those red counters.
Its actually a unijunction transistor in there with some very basic C-W and other parts, also explains why the module needs 9V as transistor will fire with less but output becomes unpredictable.

Incidentally do you have datasheets for the other >700V submin GM tubes please?
My current test circuit is a variant of earlier idea using Supertex (tm) now Microchip HV850 using active rectification via optocoupler to reduce losses at the cost of output current.
Runs on +4V2 which is a substantial improvement but still need to work out the bugs.

Carbon_Rod

Tue Jan 22 2019, 07:53AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

Check out the youtube tutorials on bullet casting.
They usually have great tips for using candle soot as a mold release agent, and burning sawdust to help clean off the slag.

One can also get a melting-furnace with Ti alloy crucibles used for solder, and they range in 1oz to over 30lb capacities (1500w units are under $200 delivered).

Happy 2019 =)

Proud Mary

Wed Jan 23 2019, 11:03PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Conundrum wrote ...

Interesting, thanks for sharing!

Incidentally do you have datasheets for the other >700V submin GM tubes please?

Do you have a type number for that part?

GM tubes only need microamps to power them. You could put a voltage doubler on the Mains, which in actual practice gives a peak voltage of just about 600V. I have done this with good effect, using an inexpensive miniature PCB-type 240:240 transformer with a fuse in the lead, and then picked off the desired voltage with a resistor and Zener, or series Zeners that you can tap down to have outputs for different types of tubes. If you go for fixed outputs, 350V, 450V and 600V will take you onto the plateau of most halogenated tubes. Antique organic quench tubes usually require much higher voltages, 1kV, or even 2kV, in a few cases I can think of.

Proud Mary

Wed Jan 23 2019, 11:05PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Carbon_Rod wrote ...

Check out the youtube tutorials on bullet casting.
They usually have great tips for using candle soot as a mold release agent, and burning sawdust to help clean off the slag.

One can also get a melting-furnace with Ti alloy crucibles used for solder, and they range in 1oz to over 30lb capacities (1500w units are under $200 delivered).

Happy 2019 =)

Happy New Year to you too! I would never have thought of bullet vasting. without your suggestion. I'll have a look on YouTube as you suggest. Thank you.

Conundrum

Mon Jan 28 2019, 03:36AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

My uRADMonitor is up...

Sulaiman

Mon Jan 28 2019, 06:19AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Rather than the cost of an iron ladle and the risk of voids in the casting,
could you not just wrap with lead sheet ?
e.g.

Conundrum

Sat Feb 02 2019, 06:09AM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Has some lead sheet here.
Also yes BiInSn layered with Pb works if you want to build a shield without all the hassle of having to machine lead. Plus its easily reconfigurable if you screw up as long as you layer some sort of high temperature tape between the various layers.

I have a formula here someplace for a low indium (ie cheaper) alloy which still melts at sensible temperatures.

Proud Mary

Sun Feb 03 2019, 09:59AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Sulaiman wrote ...

Rather than the cost of an iron ladle and the risk of voids in the casting,
could you not just wrap with lead sheet ?
e.g.

Hi Sulaiman,

I haven't rushed into replying because I can't quite see what effect using rolled sheet lead (with all its air gaps and inhomogeneities) would have on a Bruno Rossi type EM cascade detector.

Anyone wondering what a Rossi-type cascade detector is, and how it works when formed from a solid block of lead, might want to look here:
physicsopenlab.org/2016/04/12/cosmic-rays- cascade/

Adam Munich

Fri Feb 22 2019, 06:40PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

I remember making a lead box back when I was building that x-ray machine years ago. A propane burner outdoors with a coffee can seemed to suffice. The hardest thing really was making a suitable mold to pour it into -- any sort of plaster mold must be incredibly dry or the lead will boil the water out and make swiss cheese from the part.

Conundrum

Fri Feb 22 2019, 07:37PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Same with any metal casting. Water is a *MAJOR* problem and extreme safety risk.

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