Vacuum system - status report

[jb-electronics]

Hi folks,

I am still working on Nixie tubes, but I have to take it a little slow
at the moment because I switched my university and I am currently sort
of living in two cities ;-)

However, today I had some time so I took a look at my vacuum system. My
problem was that even after I closed the valve to my pump at a pressure
of 1.5E-2 mbar, the pressure would rise up to 20mbar in 20 minutes. So
there was a leak.

I then checked every part of my system (swagelok adapter, needle valve)
by replacing them with a blind flange and recording the pressure after
10s, 20s, 30s, 40s, 50s, 60s, 120s, 300s, 600s, 1200s and plotted them.
I realised that there was insufficient greasing on my needle valve, and
the most interesting thing is that it is not airtight if the scale is
adjusted to just zero. You have to (gently) adjust it below the scale
zero point. Then I get a leakage rate of just 1.2 ï¿œbar/s which is very low.

My system has a volume of at most (!) 65ml, so the leakage rate now is Q
= 5.4E-6 mbar l/s which is pretty good I think. See my results here:

http://www.jb-electronics.de/tmp/leakage.png
http://www.jb-electronics.de/tmp/leakage_extensive.png

Note that the Q value in these diagrams needs to be multiplied with 65ml.

The next step will be to find a good connection to the pressure reducer
for my gas bottle. Right now I am using a PVC hose (terrible), and I
have huge leakage rates.

But as always: One thing at a time ;-)

Jens

[Dalibor Farný]

Hello Jens,

pretty sophisticaed way of leak detection ;-)

what do You think by the "insufficient greasing on my needle valve"? The rubber o-ring used to connect the valve to the system was not greased properly? Or something else?

"it is not airtight if the scale is adjusted to just zero" - does it really let the outside air inside the system? I think that the valve stem is not fully pressed to the valve seat when set to zero, when You screw it further below zero, it gets full contact with valve seat this making thight seal. Do You have the needle valve connected in right direction? To the vacuum system should be connected the line what is on the left on that picture:

By the way, how long did You pump the system before closing and making the test? I am also strugling with pressure rise, but it is caused by outgassing of the materials inside the system - it goes from 5x10-3 torr to 5x10-2 in 10 minutes and to 5x10-1 overnight, and all this pressure rise is caused only by outgassing of rubber rings, air trapped in the metal surface and so.. Let the pump run for one hour and then close it and do the test. Or pump the system to 10-2 torr, close it, let it hold the pressure overnight and then measure it. What pressures are You going to achieve for pumping the nixies before filling by gas?

What valve do You use for isolating the system from vacuum pump (is it the ball valve we discussed recently)?

Dalibor

2013/1/26 jb-electronics <webm...@jb-electronics.de>

Hi folks,

I am still working on Nixie tubes, but I have to take it a little slow at the moment because I switched my university and I am currently sort of living in two cities ;-)

However, today I had some time so I took a look at my vacuum system. My problem was that even after I closed the valve to my pump at a pressure of 1.5E-2 mbar, the pressure would rise up to 20mbar in 20 minutes. So there was a leak.

I then checked every part of my system (swagelok adapter, needle valve) by replacing them with a blind flange and recording the pressure after 10s, 20s, 30s, 40s, 50s, 60s, 120s, 300s, 600s, 1200s and plotted them. I realised that there was insufficient greasing on my needle valve, and the most interesting thing is that it is not airtight if the scale is adjusted to just zero. You have to (gently) adjust it below the scale zero point. Then I get a leakage rate of just 1.2 µbar/s which is very low.

My system has a volume of at most (!) 65ml, so the leakage rate now is Q = 5.4E-6 mbar l/s which is pretty good I think. See my results here:

http://www.jb-electronics.de/tmp/leakage.png
http://www.jb-electronics.de/tmp/leakage_extensive.png

Note that the Q value in these diagrams needs to be multiplied with 65ml.

The next step will be to find a good connection to the pressure reducer for my gas bottle. Right now I am using a PVC hose (terrible), and I have huge leakage rates.

But as always: One thing at a time ;-)

Jens

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Dalibor Farny
http://dalibor.farny.cz

[Dalibor Farný]

I am not sure if the picture is visible, so it is attached..

Dalibor

2013/1/26 Dalibor Farný <dal...@farny.cz>

[Michael Gregg]

On 01/25/2013 03:52 PM, jb-electronics wrote:
> Hi folks,
>
> I am still working on Nixie tubes, but I have to take it a little slow
> at the moment because I switched my university and I am currently sort
> of living in two cities ;-)
>
> However, today I had some time so I took a look at my vacuum system.
> My problem was that even after I closed the valve to my pump at a
> pressure of 1.5E-2 mbar, the pressure would rise up to 20mbar in 20
> minutes. So there was a leak.
>
> I then checked every part of my system (swagelok adapter, needle
> valve) by replacing them with a blind flange and recording the
> pressure after 10s, 20s, 30s, 40s, 50s, 60s, 120s, 300s, 600s, 1200s
> and plotted them. I realised that there was insufficient greasing on
> my needle valve, and the most interesting thing is that it is not
> airtight if the scale is adjusted to just zero. You have to (gently)
> adjust it below the scale zero point. Then I get a leakage rate of

> just 1.2 �bar/s which is very low.

>
> My system has a volume of at most (!) 65ml, so the leakage rate now is
> Q = 5.4E-6 mbar l/s which is pretty good I think. See my results here:
>
> http://www.jb-electronics.de/tmp/leakage.png
> http://www.jb-electronics.de/tmp/leakage_extensive.png
>
> Note that the Q value in these diagrams needs to be multiplied with 65ml.
>
> The next step will be to find a good connection to the pressure
> reducer for my gas bottle. Right now I am using a PVC hose (terrible),
> and I have huge leakage rates.
>
> But as always: One thing at a time ;-)
>
> Jens
>

Very cool.

So the leakage rate seems pretty low, but I'd be concerned about the
total vacuum that your system can accomplish.

Although I have never built nixie tubes myself, I did a good amount of
research to go down that road.

My research came up with some claims that you need to get down in the
10E-6 torr before the fill for good results with a nixie tube.

Anyhow, please keep a image journal of your work. It looks like a great
deal of fun.

Michael-

[Dalibor Farný]

Hello Michael,

10E-6 torr is not necessary. For testing purposes is 10-2 torr enough, because then the tube is filled to somewhere  around 30 torr what is much higher pressure.. The initial pressure is not so critical in nixie tubes, but influeces the total lifetime of the tube.. However it would be better to use at least 10-4 torr for real production..

Dalibor

2013/1/26 Michael Gregg <mgregg...@gmail.com>

On 01/25/2013 03:52 PM, jb-electronics wrote:
> Hi folks,
>
> I am still working on Nixie tubes, but I have to take it a little slow
> at the moment because I switched my university and I am currently sort
> of living in two cities ;-)
>
> However, today I had some time so I took a look at my vacuum system.
> My problem was that even after I closed the valve to my pump at a
> pressure of 1.5E-2 mbar, the pressure would rise up to 20mbar in 20
> minutes. So there was a leak.
>
> I then checked every part of my system (swagelok adapter, needle
> valve) by replacing them with a blind flange and recording the
> pressure after 10s, 20s, 30s, 40s, 50s, 60s, 120s, 300s, 600s, 1200s
> and plotted them. I realised that there was insufficient greasing on
> my needle valve, and the most interesting thing is that it is not
> airtight if the scale is adjusted to just zero. You have to (gently)
> adjust it below the scale zero point. Then I get a leakage rate of

> just 1.2 琨ar/s which is very low.

>
> My system has a volume of at most (!) 65ml, so the leakage rate now is
> Q = 5.4E-6 mbar l/s which is pretty good I think. See my results here:
>
> http://www.jb-electronics.de/tmp/leakage.png
> http://www.jb-electronics.de/tmp/leakage_extensive.png
>
> Note that the Q value in these diagrams needs to be multiplied with 65ml.
>
> The next step will be to find a good connection to the pressure
> reducer for my gas bottle. Right now I am using a PVC hose (terrible),
> and I have huge leakage rates.
>
> But as always: One thing at a time ;-)
>
> Jens
>

Very cool.

So the leakage rate seems pretty low, but I'd be concerned about the
total vacuum that your system can accomplish.

Although I have never built nixie tubes myself, I did a good amount of
research to go down that road.

My research came up with some claims that you need to get down in the
10E-6 torr before the fill for good results with a nixie tube.

Anyhow, please keep a image journal of your work. It looks like a great
deal of fun.

Michael-

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[jb-electronics]

Hi Dalibor,

what do You think by the "insufficient greasing on my needle valve"? The rubber o-ring used to connect the valve to the system was not greased properly?

yes, there was some fibre or something hair-like that caused a small leak.

I think that the valve stem is not fully pressed to the valve seat when set to zero, when You screw it further below zero, it gets full contact with valve seat this making thight seal.

Yes, that is exactly what happened. I just assumed that the scale position "0" implied that it was fully in its seat. It is connected properly (the needle towards the vacuum, it is a rectangular configuration).

By the way, how long did You pump the system before closing and making the test?

About 10 minutes. I did a second test today and pumped it for 20 minutes and the result is much much better (half the leakage rate, Q = 2E-6 mbar l/s).

I guess that this is as good as it is going to get with my two-stage pump. On the long run I will purchase an oil diffusion pump, but not now. As Dalibor explained later, this pressure range is fine for testing and making Neon experiments.

What pressures are You going to achieve for pumping the nixies before filling by gas?

7E-3 mbar is the best I have achieved so far.

What valve do You use for isolating the system from vacuum pump (is it the ball valve we discussed recently)?

The ball valve is leaking, I proved that with another curve. No, I am using a bellow valve that Ron got for me. He is great. I don't know what I would do without his help.

Now I need to connect the pressure reducer next.

Jens

Dalibor

2013/1/26 jb-electronics <webm...@jb-electronics.de>

Hi folks,

I am still working on Nixie tubes, but I have to take it a little slow at the moment because I switched my university and I am currently sort of living in two cities ;-)

However, today I had some time so I took a look at my vacuum system. My problem was that even after I closed the valve to my pump at a pressure of 1.5E-2 mbar, the pressure would rise up to 20mbar in 20 minutes. So there was a leak.

I then checked every part of my system (swagelok adapter, needle valve) by replacing them with a blind flange and recording the pressure after 10s, 20s, 30s, 40s, 50s, 60s, 120s, 300s, 600s, 1200s and plotted them. I realised that there was insufficient greasing on my needle valve, and the most interesting thing is that it is not airtight if the scale is adjusted to just zero. You have to (gently) adjust it below the scale zero point. Then I get a leakage rate of just 1.2 µbar/s which is very low.

My system has a volume of at most (!) 65ml, so the leakage rate now is Q = 5.4E-6 mbar l/s which is pretty good I think. See my results here:

http://www.jb-electronics.de/tmp/leakage.png
http://www.jb-electronics.de/tmp/leakage_extensive.png

Note that the Q value in these diagrams needs to be multiplied with 65ml.

The next step will be to find a good connection to the pressure reducer for my gas bottle. Right now I am using a PVC hose (terrible), and I have huge leakage rates.

But as always: One thing at a time ;-)

Jens

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[jb-electronics]

Hi Michael,

yes, I will document everything on my website. In fact, most of it is
already done, but right now I am writing the vacuum system part and I
want to document all the steps that I did until now. And now it is far
from perfect. So I will show all different setups and number them. My
current setup is setup number III.

It won't be long ;-)

Jens

> On 01/25/2013 03:52 PM, jb-electronics wrote:
>> Hi folks,
>>
>> I am still working on Nixie tubes, but I have to take it a little slow
>> at the moment because I switched my university and I am currently sort
>> of living in two cities ;-)
>>
>> However, today I had some time so I took a look at my vacuum system.
>> My problem was that even after I closed the valve to my pump at a
>> pressure of 1.5E-2 mbar, the pressure would rise up to 20mbar in 20
>> minutes. So there was a leak.
>>
>> I then checked every part of my system (swagelok adapter, needle
>> valve) by replacing them with a blind flange and recording the
>> pressure after 10s, 20s, 30s, 40s, 50s, 60s, 120s, 300s, 600s, 1200s
>> and plotted them. I realised that there was insufficient greasing on
>> my needle valve, and the most interesting thing is that it is not
>> airtight if the scale is adjusted to just zero. You have to (gently)
>> adjust it below the scale zero point. Then I get a leakage rate of

>> just 1.2 琨ar/s which is very low.

[michael gregg]

Sounds good. And yes, other people that have made nixie tubes do seem
to be getting good results with the level of vacuum that you are
getting.

Also, I have all sorts of crazy laser cutters here. I may be able to
come up with a good stack of numbers or other characters if you'd like
them for your nixie tubes. I have never cut anything so fine with
these lasers, but according to the manufacturer, I should be able to
do it.

I am not sure where I would get tiny ceramic separators though.

I am excited to see your results.

Michael-

[John Rehwinkel]

> Also, I have all sorts of crazy laser cutters here. I may be able to
> come up with a good stack of numbers or other characters if you'd like
> them for your nixie tubes. I have never cut anything so fine with
> these lasers, but according to the manufacturer, I should be able to
> do it.

Cool. Let me know if you want help with layout. I made a run at it a while back:

http://www.vitriol.com/images/tech/nixies/cathodes.gif

> I am not sure where I would get tiny ceramic separators though.

I actually got a quote from a ceramic firm for tiny ceramic rings for this purpose,
but it was prohibitive. I think glass or mica separators might be the way to go
initially.

> I am excited to see your results.

As am I!

- John

[Dalibor Farný]

Hi Michael,

the numbers for nixi tubes is one of the problem I havent sufficiently solved yet. Are your laser cutters able to produce numbers that have 0.4mm wide lines? The material would be 0.1mm thick stainless steel sheet (316L).

I could send You some sheets to give it a try, just send me your address ;-)

Thank You!

Dalibor

2013/1/27 michael gregg <mgregg...@gmail.com>

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[Dalibor Farný]

One more thing - I would also provide the layout,

Dalibor

2013/1/28 Dalibor Farný <dal...@farny.cz>

[John Rehwinkel]

> the numbers for nixi tubes is one of the problem I havent sufficiently solved yet. Are your laser cutters able to produce numbers that have 0.4mm wide lines? The material would be 0.1mm thick stainless steel sheet (316L).

I had been planning to photoetch mine, but a laser cutter should be able to do a good job. It would also probably be possible with a water jet cutter, but I don't think any of our members have access to one.

- John

[Dalibor Farný]

Yes, I think the original nixie tubes were made by photo etching.. There is so much work on the tubes (or just preparing the stuff for now) that I would be very glad to get rid of one problem - making the number for nixie tubes.. But I am afraid I will have to photo-etch the anode grid anyway, I cant imagine the laser cutter making it ;-)

Dalibor

2013/1/28 John Rehwinkel <jre...@mac.com>

> the numbers for nixi tubes is one of the problem I havent sufficiently solved yet. Are your laser cutters able to produce numbers that have 0.4mm wide lines? The material would be 0.1mm thick stainless steel sheet (316L).

I had been planning to photoetch mine, but a laser cutter should be able to do a good job.  It would also probably be possible with a water jet cutter, but I don't think any of our members have access to one.

- John

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[kay486]

Im not sure, but i think you might be able to make the grid from multiple horizontal wires that would be spot-welded together. Something like the ZM1175 or ZM1210 have. It really depends oh how well you could weld multiple wirest at once.

[John Rehwinkel]

> Yes, I think the original nixie tubes were made by photo etching.. There is so much work on the tubes (or just preparing the stuff for now) that I would be very glad to get rid of one problem - making the number for nixie tubes.. But I am afraid I will have to photo-etch the anode grid anyway, I cant imagine the laser cutter making it

If you're photoetching the anodes anyway, may as well do 'em all at once:

http://www.vitriol.com/images/tech/nixies/cathodes2.png

- John

[threeneurons]

I use to work closely with the laser people. Use to cut stainless (316 & 304) down to around 0.010" (0,25mm). Should be able to do 0,1mm thick, but cuts 0,4mm (0.016") apart, is going to be iffy.

[David Forbes]

John,

Don't forget the upside-down 8 in the middle of the stack, connected to
the anode.

--
David Forbes, Tucson AZ

[Michael Gregg]

I agree with threeneurons that cuts down to that distance apart are going to be iffy.

I know that there are companies that laser cut solder stencils with machines like I have, though, they might be using a different laser head than the one I cut with.

So, Dalibor, I'll contact you offline with my address, but I already have some rather thin stainless sheet that I can try to cut with.

I don't know if it will work, but it's worth a shot.

Otherwise, is there anybody out there familiar with chemical etching stainless?

Michael-

To view this discussion on the web, visit https://groups.google.com/d/msg/neonixie-l/-/dEZnYg_BWLkJ.

[John Rehwinkel]

> Otherwise, is there anybody out there familiar with chemical etching stainless?

Not much to it - it's like etching a printed circuit board. Coat with resist, expose to pattern, develop, etch.
Places like Micro-Mark sell kits to do this:

http://www.micromark.com/micro-mark-pro-etch-photo-etch-system,8346.html

The main difference is both sides of the metal have to be treated. I'd suggest covering both sides with resist,
and only dissolving away the pattern on one side. That way, you don't have to worry about registration, although
there will be some undercutting.

- John

[Quixotic Nixotic]

I can shed a little light on the photo-etching process, having both had items made professionally and also silk-screened them with my own fair hands with about the same level of accuracy. Because the etching process undercuts the metal in a V shape it is normal to use a pinbar registration system and to have the acid resist on both sides of the metal, one image the reverse of the other. To do otherwise is to end up with a back somewhat skinnier than the front after etching.

It is possible to get quite accurate registration on both sides of the metal, using a home-built silkscreen system and wooden silkscreen frames. In the case of the picture below, it was only a single-sided etch but I found it necessary to print the outline shape on the back too to maintain crisp edges equal on both sides. Hopefully you can see the edge ridge with slight but significant undercut. I don't have my silkscreen equipment any more otherwise I'd offer to do some trials for you.

I think in the days of etched printing plates they used something called "bull's blood" which minimised the undercut somehow.

There used to be companies who specialised in doing this work for modelmakers. Useful for suspension bridges, railings and other filigree work. I am not sure if any are around today.

My guess is if you are going to image directly onto the metal using spray on light-sensitive emulsion, you'd still need to expose an image on both sides of the metal.

John S

[Michel van der Meij]

That is really cool stuff!

Maybe one day it is possible/affordable to use a 3D printer to print these cathodes and grids using a conductive plastic of some sort. As it is all low current, it may not need to have very low resistance. And then of course, if you had 2 types of material in your printer (1 conductive, the other isolating) you could just print the whole set of grids and cathodes! That would save a huge amount of effort!

Michel

John S

[michael gregg]

I don't know about 3d printing the cathodes.

As for chemically etching these plates, I am pretty sure you won't have to put the pattern on both sides of the plate.

You could completely cover one side of the plate with a even coat of etch resist.

Then, you'll be able to put your design on the other side.

This is etching through rather thin metal, so, this single side method should work.

At least, it does for my work on copper.

The research that I did for stainless enchants all seem like they are processes that would require a fume hood. Most of the processes containing HCl and HNO3. I do not have a fume hood :(

Although, I did find a howto site where they just used a electrolyte. I wonder if that process could be turbo charges to etch through...

Maybe if I have time this weekend.

Otherwise, if anybody would like to attempt etching, and would like a enchant mask, and you live in the US, I'll be happy to whip one up on my vinyl cutter and ship you one/several. It shouldn't take more than a few min to make the stencil. I'll be around the machine Thursday.

-Michael

[jb-electronics]

Hi Michel,

> [...] using a conductive plastic of some sort.

I don't know for sure, but you might face a hell of outgassing if you
use plastic.

Jens

[Michel van der Meij]

Well, I mean the envelope is still glass but only the inner works are 3D printed. I had a quick search on google after my post and there is actually quite a development going on in electrically conductive 3D printing technology. Some claim "low cost" but not sure if that would be good enough to make cathodes and grids. If you try to make a new type of nixie tube, then maybe the latest technology available is not such a bad idea?

Michel

[John Rehwinkel]

> The research that I did for stainless enchants all seem like they are processes that would require a fume hood. Most of the processes containing HCl and HNO3. I do not have a fume hood :(

I'll go chase down what Micromark sells in their kit, which specifically states it works with stainless. I doubt they sell stuff that needs a fume hood without warning people ahead of time.

> Although, I did find a howto site where they just used a electrolyte. I wonder if that process could be turbo charges to etch through...

That's a thought. It's possible that adding an electrical current to the flow would both accelerate the process and might even minimize undercutting.

I did some research a while back on photoetching services, and found one that will etch from the front, the back, or both at the customer's option. They point out that this gives a profile to the etched object. I figured I'd etch from the back for nixie cathodes, so the front (facing the viewer) surface was the largest. Since we'd be etching pretty thin material, I doubt it would be a big problem.

> Otherwise, if anybody would like to attempt etching, and would like a enchant mask, and you live in the US, I'll be happy to whip one up on my vinyl cutter and ship you one/several. It shouldn't take more than a few min to make the stencil. I'll be around the machine Thursday.

That's an interesting idea. I have a vinyl cutter too. My first thought was that the vinyl adhesive is really tough, and would bend and tear the delicate metal, but then it occurred to me that there's probably a way to dissolve away the vinyl. I expect there are solvents out there that would do so while leaving metal untouched.

- John

[Michael Gregg]

On 01/29/2013 06:20 AM, John Rehwinkel wrote:
>> The research that I did for stainless enchants all seem like they are processes that would require a fume hood. Most of the processes containing HCl and HNO3. I do not have a fume hood :(
> I'll go chase down what Micromark sells in their kit, which specifically states it works with stainless. I doubt they sell stuff that needs a fume hood without warning people ahead of time.

Please do. It would be nice to make these at home or in the back yard.

>
>> Although, I did find a howto site where they just used a electrolyte. I wonder if that process could be turbo charges to etch through...
> That's a thought. It's possible that adding an electrical current to the flow would both accelerate the process and might even minimize undercutting.
>
> I did some research a while back on photoetching services, and found one that will etch from the front, the back, or both at the customer's option. They point out that this gives a profile to the etched object. I figured I'd etch from the back for nixie cathodes, so the front (facing the viewer) surface was the largest. Since we'd be etching pretty thin material, I doubt it would be a big problem.

That sounds like a good approach.

>
>> Otherwise, if anybody would like to attempt etching, and would like a enchant mask, and you live in the US, I'll be happy to whip one up on my vinyl cutter and ship you one/several. It shouldn't take more than a few min to make the stencil. I'll be around the machine Thursday.
> That's an interesting idea. I have a vinyl cutter too. My first thought was that the vinyl adhesive is really tough, and would bend and tear the delicate metal, but then it occurred to me that there's probably a way to dissolve away the vinyl. I expect there are solvents out there that would do so while leaving metal untouched.

That's what I am thinking. I have etched copper using vinyl cut on a
standard vinyl cuter. I have also gotten surprisingly good results.

As for removing the vinyl, I think you are right, a solvent would
probably be the way to go (this metal is quite thin). I believe acetone
works on vinyl quite well.
>
> - John
>

Next problem we would have is how to get/make the little ceramic
separators for the nixie stackups. maybe somebody here has though of
this already.

Michael-

[Charles MacDonald]

On 13-01-29 02:03 AM, Michel van der Meij wrote:
> That is really cool stuff!
>
> Maybe one day it is possible/affordable to use a 3D printer to print
> these cathodes and grids using a conductive plastic of some sort.

I would expect that the plastic would outgas rather easily, and would
not survive the stage where you use an RF heater to drive gas off the parts.

BUT, You might be able to use a 3D printer to make a model for the Lost
wax casting process. (often used to make Jewelry) The plastic part is
made, and covered in Clay, then the Plastic is burned out and metal is
put in the mold. You then smash the mold and get out a precise metal part.

(my guess is that commercial Nixie tube had the parts stamped out in a
punch and die set. A pricy bit of tooling but simple to make vast
quantities of sharp edged parts)

As far as the spacers, those could be molded in Ceramic Clay and fired
in a Kiln. The mold could be made in Silicon or similar, again the
prototype could be made on a 3D printer, or just turned on a lathe.



--
Charles MacDonald Stittsville Ontario
cm...@zeusprune.ca Just Beyond the Fringe
http://Charles.MacDonald.org/tubes
No Microsoft Products were used in sending this e-mail.

[Michel van der Meij]

OK, I see what you mean. My interpretation of outgassing was wrong, I thought it had to do with gas leaving the envelope but you're referring to trapped gas leaving the metal/plastic parts. I don't know if that problem could be solved, maybe there is a different way that plastic parts can be outgassed somehow without heating them up to their melting point. Or perhaps it is possible to tackle the problem at the source and make sure the plastic parts cannot have trapped gas. I'm only guessing here through :-). If there is a way to utilize 3D printing for cathodes and grids, it would significantly simplify the process of making your own nixie tubes. I am pretty sure within the next 5 years or so someone has figured out how this can be done.

Michel

[Sebastian Götte]

On 01/29/2013 03:20 PM, John Rehwinkel wrote:
> I did some research a while back on photoetching services, and found one that will etch from the front, the back, or both at the customer's option. They point out that this gives a profile to the etched object. I figured I'd etch from the back for nixie cathodes, so the front (facing the viewer) surface was the largest. Since we'd be etching pretty thin material, I doubt it would be a big problem.

If you are etching from the back, the *back* side will be the largest. I
do not think, though, that this will make much of a difference because
the actual glow emission does not happen on but just above the electrode
surface. In the nixies I have seen it appeared to me as though the
diameter of the light-emitting part of the neon gas was large compared
to the width of the numbers.

- jaseg

[Sebastian Götte]

On 01/30/2013 03:44 AM, Charles MacDonald wrote:
> As far as the spacers, those could be molded in Ceramic Clay and fired
> in a Kiln. The mold could be made in Silicon or similar, again the
> prototype could be made on a 3D printer, or just turned on a lathe.

There are very small (1...2mm estimated) glass beads that are used for
art and such, they can be bought in art supplies shops.

[Grahame Marsh]

Perhaps - 5mm dia 5mm long and stackable

http://uk.farnell.com/multicomp/cb3/spacer-ceramic-stand-off-pk50/dp/8919275

[Sebastian Götte]

If I understand this site right, those are 1.8mm long:
http://www.artbeads.com/sb18-0131.html

[John Rehwinkel]

>>>> As far as the spacers, those could be molded in Ceramic Clay and fired
>>>> in a Kiln. The mold could be made in Silicon or similar, again the
>>>> prototype could be made on a 3D printer, or just turned on a lathe.
>>> There are very small (1...2mm estimated) glass beads that are used for
>>> art and such, they can be bought in art supplies shops.
>> Perhaps - 5mm dia 5mm long and stackable
>> http://uk.farnell.com/multicomp/cb3/spacer-ceramic-stand-off-pk50/dp/8919275
> If I understand this site right, those are 1.8mm long:
> http://www.artbeads.com/sb18-0131.html

I talked to two outfits, Du-Co ceramics and Superior Technical Ceramics. Du-Co didn't have a stock
part, so they quoted me a custom run. It was brutal (I can't find their email, so I don't have exact figures).

Superior Technical Ceramics has ceramic washers as stock parts. Their 2-56 washer was $1.40 apiece
and their 0-80 washer was $1.35 apiece with a 4-week lead time when buying a couple thousand washers
at a time. They also offer ceramic nuts and bolts, but they're even more expensive, unsurpisingly (a 1/2"
long 2-56 ceramic bolt was $9 apiece when buying 200 at a time).

It's not hard to find small mica rings, maybe they would be more cost effective, even if you had to stack them
to get the thickness you need.

- John

[NeonJohn]

On 01/30/2013 11:46 AM, John Rehwinkel wrote:

> Superior Technical Ceramics has ceramic washers as stock parts. Their 2-56 washer was $1.40 apiece
> and their 0-80 washer was $1.35 apiece with a 4-week lead time when buying a couple thousand washers
> at a time. They also offer ceramic nuts and bolts, but they're even more expensive, unsurpisingly (a 1/2"
> long 2-56 ceramic bolt was $9 apiece when buying 200 at a time).

You might want to take a look at alibaba.com. They put foreign
manufacturer (mostly Chinese and Indian) together with US buyers. They
have a sleazebay-like satisfaction guarantee whereby if the manufacturer
doesn't do what he said, he'll be de-listed for Alibaba. I think they
have a new store that is more retail oriented.

We relay on them heavily for parts for our Roy induction heater. That
buck-fourty washer would probably be less than a nickel from a chinese
supplier.

There is a place where you can post your needs and the mfrs respond.
The MOQs are HIGHLY flexible. :-)

John


--
John DeArmond
Tellico Plains, Occupied TN
http://www.fluxeon.com <-- THE source for induction heaters
http://www.neon-john.com <-- email from here
http://www.johndearmond.com <-- Best damned Blog on the net
PGP key: wwwkeys.pgp.net: BCB68D77

[Dalibor Farný]

Thats it! I was looking for tiny beads several times, but havent found sich a small ones. The height is important, 1.8mm is exactly what is inside z566m!

I got a quote from a german company for ceramic washers, over 2 eur per piece :-)

Thanks,

Dalibor Farný
http://dalibor.farny.cz

sent from Samsung Galaxy Pad

Dne 30.1.2013 15:53 "Sebastian Götte" <jan.s....@campus.tu-berlin.de> napsal(a):

On 01/30/2013 11:18 AM, Grahame Marsh wrote:

> On 30/01/2013 09:58, Sebastian Götte wrote:
>> On 01/30/2013 03:44 AM, Charles MacDonald wrote:
>>> As far as the spacers, those could be molded in Ceramic Clay and fired
>>> in a Kiln.  The mold could be made in Silicon or similar, again the
>>> prototype could be made on a 3D printer, or just turned on a lathe.
>> There are very small (1...2mm estimated) glass beads that are used for
>> art and such, they can be bought in art supplies shops.
> Perhaps - 5mm dia 5mm long and stackable
> http://uk.farnell.com/multicomp/cb3/spacer-ceramic-stand-off-pk50/dp/8919275
If I understand this site right, those are 1.8mm long:
http://www.artbeads.com/sb18-0131.html

[michael gregg]

An update on etching plates, I found this website of this guy etching
stainless sheet specifically for nixie tubes. Rather cool.

http://imajeenyus.com/workshop/20110320_electrolytic_etching/index.shtml

He was etching from both sides. Given the difficulty in chemical
machine stainless, any efforts for nixie tubes may need to be a two
sided etching.

I also took a few minutes and tried cutting that nixie plate design on
my vinyl cutter here to see how likley it is to work.

I determined that the numbers will cut just fine, it's the screen that
will be a problem.

As you can see in the attached image, I made the cut rather
large(there is a usb bluetooh dongle in there for scale), and the
cutter still had some issues making the screen grid.

I believe that the toner transfer method might work better for these
fine features.

Or, a hybrid approach could be used. Use vinyl transfer to make all
the digits whatever size you like, and the make the anodes out of
woven metal screen wrapped around a fixture. Sort of like here:

http://imajeenyus.com/vacuum/20110310_text_discharge_tube/index.shtml

Michael-

[John Rehwinkel]

> Don't forget the upside-down 8 in the middle of the stack, connected to the anode.

I had, of course, forgotten it. Here it is.

http://www.vitriol.com/images/tech/nixies/cathodes3.png

- John

[John Rehwinkel]

>>> The research that I did for stainless enchants all seem like they are processes that would require a fume hood. Most of the processes containing HCl and HNO3. I do not have a fume hood :(
>> I'll go chase down what Micromark sells in their kit, which specifically states it works with stainless. I doubt they sell stuff that needs a fume hood without warning people ahead of time.
> Please do. It would be nice to make these at home or in the back yard.

Okay, finally found time to go dig out the Micromark kit. The etchant is plain old ferric chloride, the same stuff used to etch copper for printed circuit boards.

- John

[michael gregg]

Really?

Well, that's worth trying.

Maybe a better etch could be gotten with the use of a combination of
ferric chloride and electrolysis.

That would probably mean a printer based press-n-peel system and a battery.

I am also interested in this method to make stainless solder stencils at home.

I have a few hours this Saturday to try this out, and, I should have a
whole day available the following weekend to try this with.

I'll have to see if I can get press-n-peel media here before the weekend.

Now, who here is actually working on making some new nixie tubes? I
need a idea of how large of characters to shoot for.

Michael-

[Smiffy]

I've picked up on this discussion late, so don't know if anyone's suggested this to try: 50/50 copper sulphate/table salt. Don't know if this will work on stainless steel, but has been recommended for etching ordinary steel or aluminium.

[michael gregg]

I do not believe anybody has suggested 50/50 copper sulphate/table salt yet.

For my first try, I was going to try a concentrated solution of ferric
chloride and voltage with stainless as the anode and cathode.

I do not know how it will come out.

I'll also go grab some copper sulphate to give that a try.

The common list of enchants I have found are:

(hydrochloric) acid (HCl), nitric acid (HNO3), or sulfuric acid
(H2SO4). Certain non-acids that form acid in water, such as ferric
chloride (FeCl3) or copper sulfate (CuSO4)

I'd really like to try any of the tree acids, but I do not have a fume
hood here.

I suppose I could set up a rig outside.

I am planning on giving these methods a try Feb 16 or Feb 17.
Unfortunately, I will not be able to attempt the process this weekend
as I will not have the etching supplies by then.

Also, does anybody know where to get a quantity of nitric acid? (100
ml would be great) I already have HCL and H2SO4. I suppose that I
could make some nitric acid using my concentrated sulfuric acid, but
I'd rather not take the time to make my own.

Michael-

[michael gregg]

Ahh, found some nitric acid.

The 6 molar solution should do nicely.

http://wardsci.com/product.asp?pn=IG0015411&sid=google&cm_mmc=google-_-cpc-_-ward-_-nitricacid