ME Boiler

[MarkRParticipant @markr87242]

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.

[MarkRParticipant @markr87242]

[Brian HParticipant @brianh50089]

Looking very good Mark!

Brian

[Dominic BramleyParticipant @dominicbramley60728]

Looking Good

Careful when you fire it up for the first time – I found that the flame had a habit of coming out of the lighting hole which charred the cladding. In the end I made a brass plug for the hole to stop it happening. This was with a ceramic burner rather than the fabricated one.

Cheers

Dom

[MarkRParticipant @markr87242]

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!!

[nigel jones 5Participant @nigeljones5]

Dominic hit the nail on the head! When you try to light yours there will likely be a lot of flames from the chimney top and none down below. A 0.3mm jet is massive, you will get much better results using a no.3 jet or at a push a no.5 jet. Using your current set up, assuming you can get the burner to light will give off huge amounts of hydrocarbons so whatever you do, dont use it indoors. Gas burners dont work well with multi tube boilers, or at least not as well as they do in single flue boilers with cross tubes. I make boilers and burners for a living (well I did until Brexit!) and am happy to advise fellow enthusiasts so if you get stuck feel free to pm me. Boiler is looking sound and very well made!

[MarkRParticipant @markr87242]

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.

[MarkRParticipant @markr87242]

I made up the various plugs and adaptors, and did a quick test with some air at 5psi to check for any obvious leaks and get all the plugs properly sealed.

After fitting the pressure gauge and pump, I tried bringing it up to pressure but couldn't get it to hold much above 50psi, with it leaking down fairly quickly with anything higher than that.

The problem was the ball valves in the pump, and despite my efforts to fix the seating I could only get it up to about 80psi, so I ordered some some nitrile balls which solved the issue.

So for the rest of the fittings, I think I'm going to modify the design to use separate parts for the ball seats, rather than using the angled D-bit for cutting the seat in the single piece bodies.

[JasonBModerator @jasonb]

You really want a valve in the line so you can isolate the pump once things are upto pressure which eliminates any losses through the pump.

Also not sure how you are doing the higher pressure tests but you want to fill the boiler with water as it is safer if things should go wrong. Low pressure air is OK for an initial bubble test.

[MarkRParticipant @markr87242]

Hi Jason,
The full pressure test was a hydraulic test, which might not be clear from my description/picture.
In the second pricture, the pipe is going off to the pump in the bucket of water.

My next step was to make a separate valve if I couldn't get the pump to seal, but the nitrile balls solved the problem, and I was able to leave the boiler like that for half an hour before I let the pressure out.

[MarkRParticipant @markr87242]

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.

[Dominic BramleyParticipant @dominicbramley60728]

Good job! I agree – your turned down fittings definitely look better than the original. Tempted to redo my safety valve body now!

Cheers

Dom

[Gerhard NovakParticipant @gerhardnovak66893]

" 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. "

See if you can do a "pop" valve. They have a kind of piston above the valve which helps to open safely and when it closes the pressure was that for the larger piston, so the smaller valve will pressed firmly into its seat. I tried one, probably my precision wasn't good enough. I worked most of the times but not always. (Well it opened but jamed when it should close…)

[MarkRParticipant @markr87242]

Yes I may give that a go Gerhard.

Do you know if the 'tri-wing' design in Harris boilermaking book still a good one to base it off, or are there better ones I can copy from any recent ME articles?

[Jeff DaymanParticipant @jeffdayman43397]

The safety valve designs published by Gordon Smith some years ago work very well and re-seat quickly. Search this site – Jason Ballamy published a link to the designs some time ago.

[Model EnginerdParticipant @modelenginerd]

Very nice!

[MarkRParticipant @markr87242]

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.

[MarkRParticipant @markr87242]

As mentioned previously, rather than just having the rather blocky hand pump sitting next to the boiler I decided to build a water tower to make everything look a bit nicer.

So in the photograph below, you can see all the components ready for assembly. The most tricky bit being the legs being milled from 1/2" brass angle, with both a taper and and angle across the top and base to hopefully give a pleasing appearance when all fitted together.

In this photograph you can see the legs have been silver-soldered to their top and bottom pads and bolted to the base. The lid has had has some flanges added to it to provide a 'bayonet' style attachment with the two pins soldered in place to the body. The cap and 'neck' were flanged and rolled from sheet brass.

The lagging strips for the boiler took a lot more effort than expected, mainly because I couldn't find any wood of a suitable thickness. So I had to make a bunch of planks starting from larger stock. Here they are temporarily mounted to the boiler alongside the assembled water tower.

I also finally got round to making a proper base for my 10V after getting myself a set small router bits.
I did this in the mill, lacking a suitable router table, but even with the realtively low spindle speed the surface finish was still very good on the block of oak.

After a few tests getting the settings correct for the wood I had used, I laser etched the base with my initials.

And here's the finished item after finishing the base and mounting the engine.

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Leslie Williams 1Participant @lesliewilliams1]

Ghee you have done such a good job of this Mark, you surprised me.

I haven't soldered up a boiler, but I know that it takes a huge amount of heat, we used to have this guy Jeff who would do it. But that was his trade, so he was good at all things big and small.

Even your little base for the S10 came up well. …. So good for you.

Leslie

[Ady1Participant @ady1]

Looks awesome

"Jobs' a good 'un" as they say

[MarkRParticipant @markr87242]

Thanks for all the kind words and encouragement gents.
So far it all seems to have gone better than I was expecting for my first attempt, so fingers crossed I don't mess it up before crossing the finishing line

And yes Leslie, the amount of heat was the most surprising difference from smaller bits of silver soldering.

I've had a torch set for ages, but never used any larger burners until now, and the step up in heat produced is massive.
Not just from the torch itself, but the amount of heat being emitted back from what is a relatively small boiler.

On the other hand I actually found the actual soldering part itself to be easier than I was expecting.
The larger mass of metal makes the temperature more stable once it gets up there, so you have more control of what happens,
more time to examine the joints and run a scratch stick around or add more solder to get a neat joint.

[MarkRParticipant @markr87242]

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.

[MarkRParticipant @markr87242]

Finished!

I now just need to make a displacement lubricator, so I can actually run the engine on steam rather than air.

[JasonBModerator @jasonb]

That's all looking rather good and hiding the pump was a great idea, Stone floor came out well too.

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