Supporting > Boilers

Stainless Stays

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doubletop:
I’m making a small wobbler engine and boiler for my granddaughter The boiler will be horizontal  made from 16 gauge 2.5” copper tube about 7” long. It will be methylated spirit fired and is only going up to 25psi. Pretty much Mamod style. I want to put 2 or three stays in in the end plates. The smallest diameter copper rod I can get is 1/4”, I can’t find small diameter bronze either. Monel is out of the question.

So what about stainless stays? The thermal expansion (Thermal Expansion (10-6 in/(in oF))) is 9.8 for copper, bronze ranges from 9.0 to 10.2 and Monel is7.8. Whereas stainless 316 is 8.8.

I would plan to use 3mm or 4mm stainless threaded with bronze bushes and silver soldered, however, I don’t think I’ve seen stainless stays proposed in any boiler design is there any reason for this?

Pete

gadabout:
Your local hobby shop might have a  KS metals display that has copper rod in 1/16, 3/32 or 1/8 ??
Mark

doubletop:

--- Quote from: gadabout on May 25, 2020, 08:21:47 AM ---Your local hobby shop might have a  KS metals display that has copper rod in 1/16, 3/32 or 1/8 ??
Mark

--- End quote ---

Good suggestion but I've gone through all the NZ hobby shops that come up in Google and as far as their online inventory shows they all seem to have rod in brass aluminium and piano wire but not copper.

Pete

gadabout:
Worth a call maybe? Might just not have everything they have on their website, have seen that before.
Mark

GWRdriver:
What about using copper wire?  :thinking: Your local electrician should have scraps of various gauges of single conductor wire.

What about bronze welding (brazing) rod?  :thinking:  Your local welding shop should have some as small as 3mm.

I've used both as stay material in small boilers (and a few large ones.)

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