A WATERTUBE BOILER FOR MY TRIPLE EXPANSION ENGINE

[steamer]

Hey John,

What is the desired working pressure for your boiler?   100 psi?

Dave

[simplyloco]

Hey John,

What is the desired working pressure for your boiler?   100 psi?

Dave

Hi Dave. I'll spec it at 120 psi superheated, but cut it back if I don't need it.
John

[steamer]

Hey John,

What is the desired working pressure for your boiler?   100 psi?

Dave

Hi Dave. I'll spec it at 120 psi superheated, but cut it back if I don't need it.
John

Good     The reason I ask is expansion ratio.   A triple will obviously expand quite a bit, though I can't recall the cylinder sizes of your engine off the top of my head.   A bit of superheat is a good thing  ( 100 F) and will give nice dry steam.   Much more than that and you'll have cylinder lubrication problems as the walls will get quite dry and a bit of condensation does wonders as a cylinder lubricant.    120 is probably enough to get decent results from a small engine if the expansion isn't too big,   I seem to remember that engine not expanding too much.....but ICBW.

I will assume you're "doing the math" regarding boiler construction, and not delve into that.   

Dave

[Michael S.]

Hello Dave,
That was exactly my experience with a Stuart compound. At an exhibition everyone said I had to run the engine at high pressure so that everything worked well. So I ran the boiler at 5 bar pressure and at first everything was fine. After two hours the engine's pistons were blocked. The condensate oiler failed because my boiler has a superheater. The engine ran very well with steam but it was better to only run it with an oil pump.

Michael

<a href="https://www.youtube.com/watch?v=XIHWTt5oXpY" target="_blank">http://www.youtube.com/watch?v=XIHWTt5oXpY</a>

[Laurentic]

Thanks for the answer John, I'm watching this thread with interest!

Chris

[steamer]

Hello Dave,
That was exactly my experience with a Stuart compound. At an exhibition everyone said I had to run the engine at high pressure so that everything worked well. So I ran the boiler at 5 bar pressure and at first everything was fine. After two hours the engine's pistons were blocked. The condensate oiler failed because my boiler has a superheater. The engine ran very well with steam but it was better to only run it with an oil pump.

Michael

<a href="https://www.youtube.com/watch?v=XIHWTt5oXpY" target="_blank">http://www.youtube.com/watch?v=XIHWTt5oXpY</a>

Yes....and with a mechanical pump, you need to make sure to get the oil out of the condensate before you pump it back into the boiler...so it gets ugly!   

Nice looking engine!

Dave

[simplyloco]

No drilling today. I was turning the ends of the connecting tubes. After three hours and 100 ops I'd had enough...
Some pics and a video.

What was required.


Three hours later, I have 50 of the beasties. I need 72 so I'll cut off some more blanks this weekend.


How I did it, not to say how you should do it! I quickly dumped the DRO length setting and used a 4mm drill against the depth stop. Much quicker!
https://www.facebook.com/1045066958/videos/pcb.3640580186230087/1852430158538622

[crueby]

Quite a lot of parts!!

For some reason I can't see your videos, says the video is no longer available. Maybe since I am not a Facebook member? Lots of people are not. Pictures are good though.

[simplyloco]

Hi Chris. I believe you have to be logged into your FB account to see the video.

Preparing to drill 120 accurately placed holes!

I've made a fixture to assist in the assembly of the three parts after they have been silver soldered. The fixture will (hopefully) keep the loose ends of the tubes in the right place while soldering into the headers. I'll assemble them into the main tube using a small hook to wangle the ends into the waiting holes. Quite frankly, I can't think of any other way to do it! 🙂
When I'm happy, I'll put the end caps on and solder it up...!😱🤩😇

[cnr6400]

 

[Kim]

That's a LOT of copper tubes!  Nice soldering jig too. 
Looking forward to seeing how it all comes together.

Kim

[simplyloco]

First 29 accurately placed holes!
Just a couple of hours in the workshop today: after all it is Sunday!
Some pics.

Drilled 5.9mm to a depth stop. This size will create 0.1mm clearance, just enough for the silver solder to penetrate properly. The tubes have to be a little slack in the holes!!!!


Cleaned up ready for assembly.


The fixture had to be drilled 0,3mm clearance as the tubing was supplied on a coil and I couldn't get it straight enough to go through easily at the original size..


Bird's eye view. It'll do!

[crueby]

A great multi-barrel spit-wad shooter! 


Seriously, great progress on the parts, following along here!

[steamer]

Looking good Loco!    Watching along.....that's going to be a challenging silver solder job.

Dave

[simplyloco]

Lined up in the hearth, flux applied with a pipette. I'm reminded of my visit to the Valley of The Kings!



I used the 20mm Sievert torch, just dabbing a 2mm Easyflo stick against the rear tubes.


Thirty minutes in the battery acid to clean off the flux.


Just about as close to perfect as I could get!


The other side is OK too. Next!