Pressure and Vacuum guages

A special section just for steam engines and boilers, as without these you may as well fit a sail.
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marinesteam
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Re: Pressure and Vacuum guages

Post by marinesteam » Tue Mar 20, 2018 3:50 pm

DetroiTug wrote:Quote: "The problem is that I need 5 or 6 gauges and I want them all to be a matched set."

That would be about impossible to find in antique gauges. I've seen perhaps three on a board, all old and matching and they go for insane money. One route you could go and wind up with antique gauges, the cases are typically the same as long as it all one maker, the only difference is the pressure range and the face or dial.

It wouldn't be too difficult to find gauges by the same manufacturer with identical cases. For the face: The faces of just about all these old gauges I have seen were sheet brass and engraved, which is easy with Cad Cam and CNC. Any artwork desired with a .005" deep pocketing routine and .005" tip er so v-bit engraver for the characters (I think the originals were done either by hand or an impression die). Some of the faces were left brass finish, some were finely sandblasted and then Nickle plated for a satin silver finish. When I restored my cars' gauges, I researched how the letters were colored and they used colored wax. I needed black wax, thought about it a bit and it dawned on me - black crayola crayons.. :) Worked perfectly.

Just curious, why are 5 or 6 gauges needed?

-Ron
Ron, Would you site your source that the gage letters were filled with wax. Not that I doubt your research as it matches mine and wax would indeed work, but the antique gages that I have had from several different manufacturers don't seem to bear that out that it is indeed wax. I have a suspicion that the letters are filled with a mixture of carbon black (Gilsonite) and shellac. I am thinking this due to the hardness and shininess of the filled letters and due to the process of silvering a gage face and the affect it would have on the fill of the characters. It doesn't make sense that it's wax. I plan on doing a bit more to verify my theory but am off doing other things currently.


Cheers

Ken
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DetroiTug
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Re: Pressure and Vacuum guages

Post by DetroiTug » Tue Mar 20, 2018 4:25 pm

Quote:

Ken, It didn't sound logical to me at first, but that's how they did it and for steam gauges as well. Steam gauges don't really get very warm as it is a dead ended line with no flow. The line to the steam gauge in my wheelhouse actually remains cold when steam is up. Somewhere along the line steam is fully condensed and water returns to the boiler.

Quote: "I have a suspicion that the letters are filled with a mixture of carbon black (Gilsonite) and shellac."

It could be, who knows and there were probably several different methods tried, it's possible the original wax was mixed with something (probably linseed oil, they used that for everything) and it has became crystalline over time.

http://www.priorypolishes.co.uk/shop/fr ... s-wax.html

-Ron
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Re: Pressure and Vacuum guages

Post by marinesteam » Tue Mar 20, 2018 4:50 pm

Ron,

Thanks, the engravers wax was the missing link. A quick search reveals that it is not wax but in indeed pigmented shellac.
Dial "wax": The dial wax is actually not a wax at all. It is a deeply coloured shellac or lacquer product, and it is sold in sticks. For the purposes of this tutorial I'll simply refer to the product as a wax. Depending where you buy it, it may be called by different names (shellac stick, lacquer sticks, dial wax, dial shellac, etc), but it will always appear as a shiny fragile black stick. Clock parts dealers carry these, but be aware that you can also find them cheaper from woodworking suppliers. The place where I bought mine (Lee Valley Tools) sells the shellac sticks in about a dozen different colours, including clear and amber colours, which could be used for case repairs. I have also seen some rare and unusual engraved clock dials that used red or blue as an accent. The sticks generally cost around 5$ each.
Cheers

Ken
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Re: Pressure and Vacuum guages

Post by DetroiTug » Tue Mar 20, 2018 5:33 pm

This is black wax crayola on this gauge, it's been in there about two years.

The source you provided is from some blogger, and I don't think he knows what hes talking about, every website refers to "melting the wax" If it were just shellac it wouldn't melt and they wouldn't call it "wax". They put shellac over the wax to seal it and that is probably referring to having a hard surface.

-Ron
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Re: Pressure and Vacuum guages

Post by Mike Rometer » Tue Mar 20, 2018 6:25 pm

DetroiTug wrote:Quote: "The problem is that I need 5 or 6 gauges and I want them all to be a matched set."

It wouldn't be too difficult to find gauges by the same manufacturer with identical cases. For the face: The faces of just about all these old gauges I have seen were sheet brass and engraved, which is easy with Cad Cam and CNC. Any artwork desired with a .005" deep pocketing routine and .005" tip er so v-bit engraver for the characters (I think the originals were done either by hand or an impression die). Some of the faces were left brass finish, some were finely sandblasted and then Nickle plated for a satin silver finish. When I restored my cars' gauges, I researched how the letters were colored and they used colored wax. I needed black wax, thought about it a bit and it dawned on me - black crayola crayons.. :) Worked perfectly.

Just curious, why are 5 or 6 gauges needed?

-Ron
That is pretty much how ordinary clock dials are produced.
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Re: Pressure and Vacuum guages

Post by marinesteam » Tue Mar 20, 2018 6:53 pm

I don't disagree that crayon wax will work, It does but it definitely isn't the same at the original fill. I've tried many different waxes and techniques including the hardest wax that I could find (encaustic wax) but it's never as shiny as the original fill material.

Several clockmaking supply vendors websites list their product as either engraver's wax or shellac. One site describes theirs as containing a high proportion of shellac. The woodworking suppliers have an apparently similar product called "burn in sticks" or shellac sticks for repairing damaged furniture which all of the instructions call for melting with a soldering iron. The music repair industry has shellac sticks which are melted to adhere pads to instruments. (They have ones that work like a hot glue gun). These may have some wax content but it's unknown from the descriptions.

So for what it's worth, based on my experience restoring some of my gauges, I'm pretty confident that the engraver's wax is equivalent to the original fill used by the gauge manufacturers. The shellac content makes sense with the finish found on original dials whether or not there is any wax content. I'm going to purchase some to see if my instinct matches the actual results but to this point none of the waxes have met my expectations.

Not meaning to highjack Lionel's thread but the lack of good proper bronze case gauges is what led me down the path of attempting some restorations. Since through this process I have learned how to properly silver a dial face I guess it wouldn't be too difficult to build a recreation dial and case and put in the workings from a modern gauge.

Cheers

Ken
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Re: Pressure and Vacuum guages

Post by DetroiTug » Tue Mar 20, 2018 8:09 pm

I have several old gauges, mostly steam automobile types and maybe it was something particular to those types of gauges, but none of the black in the engraving has any sort of gloss to it, rather it looks like dull carbon. I was reading some of the clock sites and they mentioned putting shellac over the face when completed. The gauges I have, there is no shellac coating apparent.

When I re-waxed my dials, I didn't heat it up, I just took the crayon back forth over the engraved pocket until it was full, then I buffed it out with a heavy piece of leather smooth top side down, that prevented removing the wax.

I'm curious to see what you find out about the "engraving wax" and how it compares to black crayon.

This is along the same vein, but much deeper and acrylic urethane auto paint.

-Ron
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