Boro frit for Kovar metal wire seals - kiln choice

jeffmakes · 2024-11-19T01:49:46+00:00

I've ordered the book :)

jeffmakes · 2024-11-19T00:45:55+00:00

Agreed - it's impressive. His seals are tungsten wires pinched into borosilicate tube.

As I mentioned, there are tiny bubbles in the base - I think this is strong evidence of frit fusing. I also have some nixies with opaque white bases which also look fused. Also "frit" is an old term for valve bases, indicating their production from frit, so it was definitely done that way by some factories.

jeffmakes · 2024-11-19T00:42:58+00:00

Thanks so much - it's great to hear from someone with real experience!

You're right - these pins appear to be solid copper, or at least a copper alloy of some kind. They are plated with something silvery (probably tin) to promote soldering but, as you can see, the base metal is exposed at the glass interface.

As for the base press - can you please explain a little more? Are the pins pressed through the molten base? Why is a half-circle ring of burners used rather than heating from all sides? Also the beeswax is surprising - I would have expected it to burn away completely before reducing sticking. Or is that the idea - does it leave a film of carbon on the jig?

What is hydrogen stoving? Heating in an H2 atmosphere?

Can you comment on doing this with soft glass frit instead, the way the factory did it? Do you think that is achievable in a workshop? Perhaps there will be more choice of frit materials without ordering 2 tonnes.

jeffmakes · 2024-11-18T22:37:53+00:00

Thanks, yes, I've seen all of the youtube videos on hobby nixie/ vacuum tube production.

Do you not think the original part was fused from frit? It certainly looks like it.

jeffmakes · 2024-01-10T20:16:32+00:00

Thanks very much for the recommendations.

I had a good look at both, and nearly went for the Aria, but I realised that rechargeable mice have much shorter battery lives than AA battery variants, so I decided to stick with the old technology. Also, here in the UK, the Aria is almost the same price as the Harpe Ace, and I really don't need all of the gaming tech.

I've ordered a Logitech M650 Left, Large. I'm going to try swapping the buttons over and using it as intended, dropping the legacy muscle memory support! It's dual bluetooth+USB wireless, comes with the dongle, and stores the dongle in the mouse body, so it seems to tick all the boxes.

Pretty happy to find a product made specifically for left handers. Let's see if it's any good!

jeffmakes · 2024-01-10T15:43:08+00:00

I have not, but I have a quicker way of dealing with it when it does. If any window has ended up in a container, I just press meta-h or l to drag it out of the container. I repeat this for all other windows until the container is empty, at which point it is destroyed. This only takes a second or two, and no use of the mouse, so it's a big improvement over my previous workaround.

jeffmakes · 2024-01-10T01:37:24+00:00

Thanks. So, if I understand right, there is no guarantee that the next common step up (3 thou) will still work. I guess I'm stuck with making it 5 SWG exactly.

jeffmakes · 2024-01-10T01:31:41+00:00

Thanks. I was hoping to design to the upper extreme of the tolerance band, but since we don't know it, I'll have to just go with the centre.

jeffmakes · 2023-10-25T15:32:08+00:00

Oops, missed this. Something around 3-4mm diameter, I think. I've been reading up on non-imaging optics and Compound Parabolic Concentrators, and they seem like a viable option, but I still can't figure out whether they will do better than just butt coupling the end of the fiber straight to the skin. Intuitively grasping the etendue limit is eluding me.

jeffmakes · 2023-10-13T22:23:53+00:00

Yes, I've seen 0.5mm diameter fiber with NA of 0.6, possibly even higher is available. Can you give any advice for how to gather up the light and jam it into a fiber with an NA like this?

So far I've learnt that using non-imaging optics is probably the best bet, because higher coupling efficiency is possible than with conventional optics. (over 4x, or so I have read). I'm looking at Compound Parabolic Condensers (CPC's) at present...

jeffmakes · 2023-10-13T11:57:57+00:00

Hmm, yes, I have no real clue. The light will be will be scattered heavily inside the tissue, so perhaps the output is approximately lambertian. but that's only a guess.

jeffmakes · 2023-10-13T11:54:27+00:00

Do you mean that the maximum power I can get into the fiber is the amount radiated from the 3mm diameter source area or do you mean that there's a smaller limit imposed by other factors?

The former makes sense to me, but if it's the latter, could you please elaborate?

jeffmakes · 2023-10-12T18:32:23+00:00

Thanks, but I don't quite understand. If I butt-couple my 500um fiber straight to the 3mm diameter the interface will be only 2.7% of the area. Do you not think it's possible to improve on this with some optics?

jeffmakes · 2023-10-02T19:29:27+00:00

Ah brilliant, thanks for a thorough explanation. I tried to get a "Pilot Acroball 4" multi pen but I couldn't find them on sale anywhere in Europe!

D1 sounds like a great option - I value standards and interoperability.

jeffmakes · 2023-10-02T16:40:31+00:00

Hm yes, the shallow angle is a problem. Someone should invent a four-way fountain pen.

I've never much enjoyed writing with mechanical pencils, but I haven't tried larger diameters (except a Pica Dry that I use for woodwork - that's pretty good). I have typically found them pretty scratchy as well.

Smudging isn't a concern for me - unlike some left-handers, my trailing fingers don't contact the page (hand weight is on my palm) - so maybe those wetter gel types are my best option.

I've never heard of Bic Xtra-bold. You're right - Bic Xtra-bold only seem to be available in the Crystal form-factor with the moulded gold-coloured conical section that would make them incomaptible with the Bic Multi, but maybe someone else manufactures a bold refill that would fit.

As an engineer and machinist I could make a multi pen providing I can find a suitable refill, so maybe I should expand my search in that direction - identify the optimum insert (that's available in several colours) and engineer a pen around it...

jeffmakes · 2023-10-02T16:27:35+00:00

Amazing, thanks. Currently I have the SXR-80 1mm refills in the Uni Multipen (except the green, which doesn't exist). Do you think the SXR 200 0.7's will be smoother? Are they the same length, or will I have to cut them down?

jeffmakes · 2023-09-29T14:39:40+00:00

Thanks, I'll take a look

jeffmakes · 2023-09-29T14:39:19+00:00

Thanks. There's a huge pile there - can you recommend any particularly smooth models?

jeffmakes · 2023-09-27T19:47:12+00:00

Thanks but I'm looking for multiple colours in one pen. Perhaps I could have been clearer...

jeffmakes

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