As mentioned in my introductory post a few weeks ago, I'm currently working on building an ME Boiler to power my recently completed Stuart 10V.
So I thought I'd post an update of the progress I've made since then.

I was in the process of making the components for the firebox and burner, which you can again see here.

And I've now formed and silver soldered the firebox, along with the rest of the components for the burner which are test fitted together with a camping gas regulator and hose.

The burner components and firebox base silver soldered together

I also had a go at drilling my own gas jet.
The design calls for a No8 jet, which appears to be 0.25mm. The smallest drill I had was 0.3, so I went with that for now.

And, it works!
The flame is a bit large when the regulator is fully open, due to the slightly bigger jet size, but is otherwise stable and burns cleanly over the full range.
I can tweak it later once it's running in the firebox with the boiler fitted.

I also made up the various parts for the hand pump, which I had been putting off, as I thought having the rather blocky pump just sitting there on the base ruins the look somewhat.
In the end I decided to go with the pump roughly as designed, but make a few changes such as the side plates you can see here.

The reason for this is that I'm going to fit it inside a 'water tower', which you can see the basic setup of here alongside the other boiler parts.

So the time has come to make a start on the nerve wracking part, actually silver soldering the boiler together.

The internal parts laid out ready for assembly…

All fitted together and fluxed up with the solder.

First side done, and after coming out of the pickle it's looking good so far….

So repeat for the second side, and oops, something has gone wrong!

I'm not sure why, but the solder has just not taken on the centre tube and I didn't spot it at the time.
So time to heat it all up and try again, thankfully it all worked out much better the second time.

After double checking that the solder had properly penetrated on both sides and I was completely happy,
I did a final drilling and tapping of the bushes to make sure they were truly vertical, and then it was time to fit it into the outer shell.

And the bottom end, where you can also see the now fixed centre tube.

The final step was to solder in the bushes into the boiler shell.
A couple of them were a bit wobbly, so I made the protection plugs with cross-drilled holes so I could run a stainless rod through them for alignment.

And it's done!

Next step, the pressure test!!

Thanks for the warnings Dominic and fizzy.
I was eager to see if it would work at all, and the 0.3mm hole 'only' being 50% over the recommended size in terms of area, I just went with what I had.
However that does result in a huge flame unless you turn the regulator right down, so as you say, I think even the recommended no8 will be far too large.

I've now got a set of carbide drills going down to 0.1mm, so it will be interesting to see if I can successfully drill something that small, and if not I can buy a suitable jet.

So as mentioned above, I decided to make the fittings a bit differently from the design.
Making all the valve seats separate components so they could be turned more precisely rather than using the angled D-bits internally.

I also turned the bodies down leaving only hex sections where needed, which results in a much nicer look than the plain blocky hexes of the original.

The various right-angle parts silver soldered together, along with the pipes.

I think I'll have to make a proper miniature pipe bender at some point, as bending that superheater to fit correctly around evertthing was much more tricky than it first appears.

Everything assembled on the boiler, and hydraulically tested to 1.5xWP to check for any leaks.

And finally on to the the actual steam test.
As Dominic warned above, the flame does want to come out of the lighting hole unless you turn the gas right down. But even at that very minimal setting it only takes a few minutes to raise the pressure, so I'll have to make further adjustments to limit everything to a sensible range.

In the mean time I set the safety valve to keep within working pressure while using the maximum 'not setting the boiler on fire' gas level.

There is one slightly annoying issue, in that once the safety valve has opened, it never seems to quite close completely again unless the pressure has dropped by quite a bit, sometimes as low as 40psi. Although just a gentle press on the stem seems to fix it until the next time it opens.

Thanks Jeff, I've managed to find a copy of the original designs now that I know what to search for.
There is one which about the the right size, although for 100psi, but I should be able to use that as a starting point.

I wasn't sure what to do about mounting the boiler on a base, but then I found some stone mosaic tiles in the local DIY store which seemed like they had a suitable size and appearance.

These come already stuck to a mesh backing to get the grouting gaps the correct size, which of course would be too large for a model. So I stripped them off and then made a base to contain them when they were packed together with just a slightly loose fit.

I also decided to add some fake strengthening hoops to the tower by soldering some half round brass beading, which breaks up the plain sides and gives a more 'scale' appearance.

The tiles were stuck to an 18mm ply base, with just a few strips of paper here and there to get even packing and gaps between the tiles. Once the base was assembled and varnished I was able to work the grout into the very fine gaps by running the end of a cocktail stick along them. Which you can see below with the finished base and the boiler and water tower sitting roughly in position.