Where can you find very think Phosphor Bronze sheet?

[Kim]

I'm planning to follow Kozo's plans for making a pressure gauge.  The most critical component of the gauge is the Bourdon Tube, which Kozo fabricates from 0.004" Phosphor Bronze sheet.

This seems more like shim stock than sheet, but I haven't been able to find it listed in either way.  Non of my usual on-line suppliers seem to have it.  I've found 0.008" Phosphor Bronze, but that's double the specified thickness.  I'm sure 0.1mm would work just fine too (that's probably what Kozo used anyway) but I can't find that either - except for on Alibaba where I have to purchase a minimum of 1 ton. And that's a bit much for me.

Any suggestions or pointers?

I can find 0.003" or 0.005" brass, either of which would probably work, but I'm assuming that he specifies Phosphor Bronze since the gauge could come in contact with the steam, and there's some issue with Brass and steam, isn't there?

Thanks for any ideas,
Kim

[crueby]

McMaster-Carr has it, search on their site for bronze shim stock, they have it in .005" thickness, which is pretty darn close to what Kozo mentions. They list it as 510 bronze, which a quick lookup says is phosphor bronze.
 

[zeeprogrammer]

I'm planning to follow Kozo's plans for making a pressure gauge.

Detailed log please. I'll be interested in how that goes.

[crueby]

I'm planning to follow Kozo's plans for making a pressure gauge.

Detailed log please. I'll be interested in how that goes.

Absolutely. I remember seeing the gauge in his book, but didn't dare make one. Love to see your build of it.

[10KPete]

Me too!!  I have Kozo's book on the Penn. Switcher but it doesn't have the gauge build in it. I'd love to get my hands on that part of his book...

 

Pete

[Kim]

McMaster-Carr has it, search on their site for bronze shim stock, they have it in .005" thickness, which is pretty darn close to what Kozo mentions. They list it as 510 bronze, which a quick lookup says is phosphor bronze.
 

Hot digity!  You're right Chris!  I thought I'd looked there.  Probably searched for Phosphor Bronze Sheet or something.  Their search doesn't always work that well for me (or I just don't know how to use it).  Google's search works much better - even on their site!

Yeah, I think 0.005" would be plenty good!  You can adjust the 'sensitivity' of the gauge in other ways too, so I'm betting changing the material a little bit would be fine.

Thanks for pointing that out for me, Chris! 
Kim

[Kim]

You bet!  I'll be doing a build log for it.

Pete, its in his Heisler book.  It's in the back in one of the appendices.  The plans are for a 1" dial face pressure gauge for 0-150 lbs.  And he has a tester to verify that it works and calibrate it from zero all the way up.  It is quite cool!  I'm very excited to give that a try too! 

But FIRST, I have to finish up the Steam Tractor.  It's going well, but it'll be a few more months for me. But I've still been planning and scheming on my Pensy project!

Kim

[Zephyrin]

No, the brass shim won't do it, no springiness(?) in it, you have to find true phosphor bronze shim which have the required properties.
you can find a sheet of 0.1mm phosphor bronze here too.
https://www.octantenligne.com/04537d9dc40f7690c/index.html

I've done a small pressure gauge in the past, (12mm dia) and the Bourdon's tube has required a awful lot of work with trial and error to get at the end a functional gauge...
I've read much later Kozo's description, and it is absolutely obvious that this fellows really solved all the problems that made this manufacturing so difficult for me, incredible, a pity I have not read that before ...May I add just that the 0.004" seems on the thick side.

[jadge]

A quick look shows that M-Machine Metals in Darlington list 0.004" PB102 shim; albeit not much use to those in the US.

I'll be interested to see how you get on. I have a plan to build the pressure gauges for my 4" scale traction engines. I'm well aware of the work by Kozo, and there have been several articles over the years in Model Engineer. But they're all basically the same procedure. Being a paid up member of the awkward squad I want to do something different. To start with my engine runs at 170psi  so I need the gauge to go to ~300psi. Second I want a centre needle sweeping around 270°. That means I'll definitely need some gearing.

As Zephrin says the Bourdon tube is key. I've not found any useful theory, so it's a matter of trial and error. I've tried thin copper tube (machined down from thicker tube) brass tube and assorted copper tubes. I found that if the tubes are not annealed they kink when you try and bend them. Of the dozen or more tubes I've tested on my deadweight pressure tester they've either not moved at all, or mostly have opened up and refused to go back to the original shape. My finished pressure gauge will be on the order of 1-3/4" diameter and I only need an end movement of 60-80 thou, so I would think that most metals would have enough "spring". The next plan is to try some thicker copper tube and possibly some thin stainless steel tubing.

Andrew

[Kim]

Thanks for some additional pointers Zephyrin and Andrew.

Zephyrin, that's cool 5hat you've made a 12mm pressure gauge.  That is quite small!  Hmm...  if 0.004" it on the thick side, 0.005" might be out of the question?

Andrew, yeah, Kozo keeps the gage simple by not using any gearing, only the lever to give some increased movement to the needle.  It will be interesting to see what you come up with.  Please be sure and post your work when you do it.

Kim

[Zephyrin]

 if 0.004" it on the thick side, 0.005" might be out of the question ?
I'm afraid yes Kim...IMO the Bourdon tube can be made but once rolled it could be really too stiff, and won't move measurably at the pressure you expect ie 15-60 psi, without gearing or watchmaking!