| Archive for The Unofficial Mamod and Other Steam Forum The Original Unofficial Toy Steam Forum Established 2006 The biggest, most popular global steam forum around! Accept NO imitations! We have a growing community of regular posting members who chat about all aspects of toy and model steam. |
| 27ace27 |
pressure gaugeshow do the model steam pressure gauges work? I need a diagram.
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| metalhead100 |
Bourdon tubes .....
There is a curved crescent shaped tube inside that tries to straighten out under pressure ...the end of the tube is hooked to linkage and gears that make the needle move. http://www.efunda.com/designstand...s/bourdon_tubes/bourdon_intro.cfm 
Jim |
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| 27ace27 |
thanks Jim! that straightens things out. now what are the tubes made of, and how do you adjust their pressure ranges? | ||||
| Roly Williams |
http://en.wikipedia.org/wiki/Bourdon_tube#Bourdon
In toys and models, of course, they are much simplified but the principal is the same |
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| 27ace27 |
what does the mechanism look like in models? I saw a pic somewhere here before, but I cant remember where... |
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| Keith S |
Please don't try to make one. You'll get burned or something. There are plenty of commercially available ones to use. | ||||
| Roly Williams |
Ditto 
They are similar but the link between the tube and the pointer is a simple lever instead of gears, and there are no adjustments. As Kieth says, if you intend making one - bont bother. The tube itself would be very difficult to make and the rest would be far too fiddly. |
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| 27ace27 |
ooh, a challenge! 
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| Keith S |
Well, it's just going to be really fiddly and frustrating, hey, go ahead! I will say, if you can build a working pressure gauge, I won't have any doubts about your ability to make the rest of a steam engine.
Why don't you start on something easier, like a Belpaire gas-producing firebox? |