soft solder or high temperature loctite

[optima21]

Im wanting to make a small toy steam engine and the normal method of attaching the cylinder covers to the cylinder is to use soft solder like on the cylinder below

I need to make a cylinder with 6mm bore and 0.8mm wall thickness, and working pressure is 30psi, so it should only get upto 135C working temperature so Im thinking that if the end cover is a light press fit in the cylinder and held in place with loctite 648 in a groove , would be a better alternative as its operating temperature is upto 180C than using soft solder

LOCTITE® 648

LOCTITE 648 is a low viscosity, high strength retaining compound typically used for holding gears and sprockets onto gearbox shafts and rotors on electric motor shafts.

www.henkel-adhesives.com

the issue with solder is that there has got to be a gap to for it to work and that means that the fit of the piston needs to be looser to allow for any possible misalignment. Im thinking that thermal expansion could be an issue, but unlikely due to the size of the metal components being used although the end cover will heat up much slower than the cylinder.

what do you guys think

 

[Chippie]

To make the cylinder, machine from solid bar, drill down with a 5.8mm drill bit…Ream to 6.00mm.
Or you could make a D bit from silver steel to make the bottom flat….
Or just tin the inside of the cylinder and tin the end cap, push together and sweat….or Loctite…
Meccano steam engines were made with a blind cylinder….

I see you took into account steam temp at elevated pressure…but I don’t think for the small volumes, the temp would reach that high, given you will be exhausting into atmosphere…

Btw, I’ve made numerous steam engines…

2 cents provided…..

 

[gaz1]

if you use the soft solder method optima it will allow the part to also expand with the tightness of the fitting

high temp loctight will act differently and you wont get much heat transfer as you want

 

[Agroshield]

the issue with solder is that there has got to be a gap for it to work

The issue with Loctite is that there has also got to be a gap for it to work. Consult the product datasheet to see how much that gap should be.

Solder paste might allow you to minimise the gap.

You could instead fill the same groove you propose for the loctite with solder paste (think Yorkshire plumbing fitting). Belt and braces would be a groove in both cylinder and cap, offset so there are two ringsof solder.

 

[bricol]

If worried about concentricity, made the blind end the soldered on end.

 

[JMS1972]

I've used loctite 638 for cylinder end caps for a small oscillator engine with no issue. The steam in the cylinder will be cooler than in the boiler especially if you use a displacement lubricator.

 

[optima21]

thanks I think I'll go with the loctite rather than soft solder, I'll get back on with this eventually

small steam engine for a model boat.

last year I decided that I wanted to build a small scale steam plant for a model boat, and the boat in question will be approximately 18" long and look something like this :- and is is designed to be just a static model for sitting on a shelf, so I think it would be nice to make one with a...

www.mig-welding.co.uk