Quite small Scotch boiler

[Team ricky]

Hi Chaps,

I thought I would move this mini project to the boiler section…..

Having just finished building two small marine engines I wanted if possible to build a matching more scale than central flue boiler, I’m always on a bit of a budget so I tend to wait until something pops up second hand.

The risk is there that work to date might not be up to standard so a very cautious approach needed.

Also check it’s designed well so it can be completed safely.

This little  boiler is 3.5” x 5.5”

It should run either twin no problems, They have 11x11mm bore and stroke double acting.

Onto what’s been done and needs work…..

So far only braise and silver solder have been previously used …
All finishing from here will be silver solder.

The boiler leaked fairly badly around one spot on the front head
The braise used to attempt a fix I mostly ground away to reduce the mass around the repair. This worked out well and the leaks fixed! In terms of construction strength the original joint was full and looked to flow well apart from the small section that leaked!

The next job is to make a water gauge mount/manifold, There were some holes in the shell which I will use to feed water in and out of the manifold.

A steam dome was made from bronze to give a good top level for the water gauge and spare steam outlets.

Next I filled the boiler with a little water and pressured with compressed air (1-2psi)
To establish any further obvious leaks, I tend to do this now early and often in build to catch any gaps opening up between operations.

I have a leak in about the worse place possible! Back head behind the dryback…
It’s tiny but completely un accessible!

I’m pretty sure a tiny drop of loctite high temp would plug it…. Other options are to cut away the dry back to provide access and service point for the tubes , I think a good way is to use a hole saw in the lathe and mount the boiler to the cross slide and go slow, Afterwards I would make a back plate and probably add ceramic to the dry back..

Next is boiler bushes make and fit

That’s about as far as I’m into the project 😁

[Team ricky]

Pics

[Team ricky]

Water gauge manifold

[Zephyrin]

the second engine is the Marcher, the piston valve version, by J Bertinat, I would bet...a nice model.
for fixing the leak in the boiler I would remove the back chamber and rebrase the boiler, and test for leaks before mounting the dry back...

[Team ricky]

Yes to the marcher

I built two both piston valve and a great first engine project! I’m almost there with you on committing to the cut out of the dry back

I might be able to find out today exactly what’s next !

[Team ricky]

Here’s the boiler all soldered ready for a test


I silver soldered everything in the first place and had two small leaks to fix to the steam dome and one bush ! Very small issues so I used a lower temperature solder (300 degree C ) to fix those …

I put roughly 6ml of 270 loctite into the back head area and worked it around so I’ll find out soon enough if it’s working

[Team ricky]

Pressure test and first steam complete 😁

I got the leak ……..

100 psi test no failure or back head leak

The steam up was just a quick test with the blanking plugs installed and relief set to 50 psi

It howled like crazy on my central flue burner! However I did buy a pencil style burner that I’ll modify and fit to a base board, this burner is very quiet

Next is the Saftey valve that is an express type so not particularly suitable due to the aggressive action when it opens! You would not want to be anywhere near it when it opens….

I’ll buy a normal progressive opening valve

The next design choice now is lagging, I think I prefer ceramic wool and aluminium sheet but wood’s easy so not sure yet !

[PaulR]

Excellent! 100 psi is quite.... brave!  Oh, I guess that was the hydraulic test?

[Team ricky]

Yes the hydraulic test was 100 psi 😁

Onto the fittings today !

[Team ricky]

Here’s the boiler lagged and running
Howling like crazy 😂

The outside skin will probably be aluminium , I’ll see how tricky it is to make it look good …

Fittings next

[steam guy willy]

Hi Looking good and are all the boiler fittings brass or bronze ?? Is the water gauge attachment to stop turbulence or to make the water level easier to read

 

Willy

[Team ricky]

Hi Willy,

The fittings soldered are all bronze with the exception of the brass water gauge mounting….

The safety valve is brass and the globe valve is bronze
Water gauge was mounted this way to get a better read on the top end of the boiler … I found the upper row of fire tubes a little high so went for max safety

[steam guy willy]

Hi Willy,

The fittings soldered are all bronze with the exception of the brass water gauge mounting….

The safety valve is brass and the globe valve is bronze
Water gauge was mounted this way to get a better read on the top end of the boiler … I found the upper row of fire tubes a little high so went for max safety
 
Thanks for the info ....wqay back in the 60's I made a County Carlow boiler just using brass and can now not get a certificate for it by the local club !!!! in those days I was just using the model engineer mag as my sole source of info ?!!!  this was before all the modern regulations about boilers were required !!

looking good great work

Willy

[Team ricky]

Thanks Willy 😁

Yes it’s a bit odd how Mamods ect are brass too probably from a throw back period too!

They fail regularly when old …. I tend to think if a model boiler accident is reported it probably would be a model like that… I’ve tried to find a failure mode for a copper boiler online but haven’t found a single case ! I wonder if anyone else as heard of a full structural failure of copper / silver solder construction ?

[Team ricky]

Temptation got the better of me!

I ran up the boiler and engine together just to see how they pair , All looks pretty good the boiler reached 40 psi in around 3-4 mins on a number 5 jet ! Very good…

As per most model scotch boilers it will need a water pump .

Interesting I thought I’d experiment with the burner and try to fix the howling. I used a ‘hood’ to the top of the burner body with the idea to leave a small gap at the bottom of the main burner tube , This works very well indeed! The gap draws more air in and settled things down , if anyone is interested in doing the same it’s in the video , main second thing needed for the mod is to angle the front of the main burner tube to the boiler to create the gap .





https://youtube.com/shorts/r75bOUUn8e4?si=gL-fAEorF1o1sb1P

[Team ricky]

Here’s a Quick Look at the aluminium cladding

It’s going well just one more panel to fabricate ,

I’m just waiting for the stainless cable ties to arrive to hold the cladding in place, 
The nice thing with this system its pretty easy to install and remove! Or paint whatever you fancy

[Team ricky]

All finished now

Aluminium Pannels over lap in the top to bottom orientation so the joins are less visible

It’s just the stainless ties holding everything in place which works well,

If I ever install in boat etc another slimline base would need making as the wooden cradle is a bit chunky

[Kim]

That is a beautiful little boiler! 

Kim

[crueby]

Came out looking great!  How do the stainless cable ties tighten/fasten in place? Where did you get them?

[Team ricky]

Thanks chaps !

A little polish up of the brass to go 😁

The cable ties can be pulled very very tight if needed so they just clamp everything down, upside removal possible fairly easily if needed …

They come from Amazon eBay ect 4.8mm wide and 304 SS

[crueby]

Just looked them up, never seen the metal 9nes before. Nice!

[Team ricky]

Nice 👌

You can get black anodised I guess , Ones too