THE BOILER

At last my boiler man has started. Not much to say, just some photos which explains things so far. He aims to build a batch of boilers every 6 to 8 weeks and then have them tested. Note the large firehole door. This is the only way I can get the grate in. It will be in two pieces. This wheel arrangement doesn't lend itself to being able to drop the fire easily.

While I was there, he had an old boiler cut open. It was the third Romulus to be built and the washout plugs were inside the frames, so the boiler had never been washed out! I believe he'd been asked to repair it. The sides between the firebox inner and outer were solid. I wonder how it ever got up steam. Needless to say there was nothing to save and even the barrel was down to half its thickness in places.



7 April 2008



Making the windows is about the last job I can think of before I get the boiler. Nothing to them really; they're just a sandwich construction. These windows are a bit smaller than my last engine and I kept the circular cutouts, so I used these to make the rings and didn't need to cut into a new sheet. The full size ones open, so I've done the same but they also had bars across which I've left off for the time being. I can't come up with a neat way of fixing them to the frame as yet.

A funny thing happened during the work. My pickle, which is acetic acid, had gone quite a dark green. It still worked, but also left a copper coating on everything. This didn't matter as it was easily removed with a wire brush etc. So, in stead of renewing it I thought I'd put the copper top to the chimney in and see if it plated so as to hide the silver solder lines which I find obtrusive. I couldn't get the top off the chimney easily, so I left it on and stood the thing upside down in the pickle. This was just deep enough to cover the copper. Then of course I forgot all about it. When I did remember, it was ten days later!

When I took it out, it was a bright pink. Fine, but the steel was a different story. The inside had been etched away as to be expected but the problem was on the outside where the copper and the steel were together. There must have been some sort of electrolytic action as the steel wasn't neatly etched but had made great pits in long runs. I managed to get the top off. I cleaned it up and filled the pits with the mig welder and then turned it on the lathe. I lost about a mm in height otherwise it was OK. Now the good news! I took some of the finest steel wool and worked on the copper top. It came up beautifully and in spite of hard rubbing, the plating was more than enough to hide the silver solder. I suppose the next test will come when it's fired up and gets to full heat. I wonder if the steel was a necessary factor in the plating process?

While all this was going on, I've been experimenting with colours, paints and lining. I've managed to get a tin of etching primer which I know works well. I bought a pack of 5 cans of grey primer on ebay for nearly half price including postage. Pity I can't do the same with the colour. I've decided to try using car spray paint cans. Probably a bit expensive as a way but saves all the hassle of spraygun, mixing, cleaning, and filtering etc. The finish is excellent. I use one coat of etching primer, 2 coats of grey primer, then rub down with the finest steel wool. Wet or dry is too messy for me. This removes any bits which can occur in the etching primer, and leaves a matt surface for the top coat. This is followed by 3 coats of top coat, the first being a very thin one, and the last one matted with the steel wool. I finish with 2 coats of clear acrylic. On top of that goes the white lining. Some might say the finish has to high a shine for a loco as they weren't like that in full size. I tried putting the white lines under the lacquer but they lifted off and floated and when dry looked as though I'd been drunk when I'd done them.

My boiler arrived today. A bit on the heavy side, but I was able to lift it out of the boot with some help. Perhaps now I can get on with work. There are a few things to sort out. Fitting a sliding firebox door might not be possible as it needs to open very wide so that the doorway is clear to allow fitting of the grate through the doorway. I also want to try fitting the boiler into the frame. There's no chance of doing so while it's on the lifting stand so I'm going back to my old stand which is close to the floor. Not so convenient to use but much safer and I can use the block and tackle for any lifting. I did have to extend it by a couple of inches though.

One other problem to sort out and that is how to support the grate. Dropping the fire will not be easy; I'll have to make up a tool to reach through the firehole. Other jobs are drilling and tapping for water gauges, bush and base for regulator and the wet header, fitting safety valves and whistle to the steam dome etc.

12 May 2008

I managed to lower the boiler into the frame and found it was a perfect fit. One small problem was that the ashpan was too high and fouled the foundation ring. Quite a job to lower it. The problem being that in doing so, the bars supporting the ashpan floor were now in the wrong place. There being no room to drill another hole lower down, I had to come up with another way of keeping the floor shut. In the end I had a much better system by having a spring loaded bar utilizing the same hole. Now there is no chance that the flap will become loose during running. A second problem was the fit in the smokebox. Either there was some slight distortion in the boiler tube or, more likely, a distortion of the ring when I welded it. Anyway, a bit of filing here and there and the smokebox fits tightly. I then lowered the boiler and smokebox together into the frame so as to get the final position marked.

I decided to stick to full size and made a sliding door. On advice from the boiler maker I made the doors 6mm thick. Even this thickness he said was doubtful. He's only ever used round doors which are fitted with a baffle plate as I have on the Romulant. I've never found that doors get that hot as the fire is being drawn away from them. Anyway, the action is smooth but no doubt will suffer from sliding door problems i.e. ash etc. getting in the slide and stopping the doors from closing properly. The doors open to the maximum and the complete hole is visible so that I'll be able to get the grate through in two parts without too much trouble depending upon its depth rather than its width.

Having finished the door, I realized I should have drilled the hole in the smokebox end for the wet header while I could stand the boiler on its end. Now I can't because of the door! All the bushes have been left blind for me to drill. This was because he didn't have the taps I requested. He seems to use just bsp threads; not my favourites. Another problem is that the washout plugs are at the front end of the firebox which I can't get at, so I've blanked them off and cut new ones at the other end where I can get to them easily.

I was a bit concerned about the swarf when drilling all the bushes and most of it ending up inside the boiler. When I mentioned this to the boiler maker he said drill round a magnet and that would catch it all. I happened to have a very powerful circular magnet from and old microwave. This proved to be the answer but the drill bit becomes a magnet as can be seen from the picture. Fortunately, many moons ago, I made a de-magnetizer from an old transformer which works well. I often use it as milling cutters somehow seem to get magnetized. I made a 3mm thick steel ring and welded the join and this is a drive fit on the boiler and seals around the smokebox.

I managed to prop the boiler on end without damaging the doors. But first I had to make the wet header since the holes in the boiler had to be tapped and in line. Likewise, I had to make the bush for the regulator at the other end for the same reason. It being much easier to drill and tap in a vertical position. I've now lowered the boiler into its proper position between the frames and it was a perfect fit. The boiler isn't perfectly symmetrical being 6mm wider on one side of the firebox. This means the spectacle plate will have to be made to fit accordingly. I'm considering the insulation problem. I used 12mm thick carpet underlay (natural fibre) on the Romulant but I think that will be too thick this time. A friend has used two layers of thin felt with baking foil between. I've just bought a remnant of cheap acrylic carpet which is about 6mm thick and I've been trying heat tests. I've a laser thermometer and so able to check temperatures accurately. It's OK backing side to the boiler at 200C but the acrylic melts if in touch with the metal. I'll keep thinking about it!

I'm a bit late with this update, but I've been on holiday.

23 June 2008

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