BOILER BITS

I had an email and it was suggested that this font was too hard to read, so I've changed back to Arial. Let me know if you have any feelings about this.

Well I mounted the ring and had a go at turning the face edge. Like so many castings it proved to be glass hard and had to go back.
While I waited for the ring to be sent, I got on with the regulator, using the commercial lever ball valve from the local plumber.

As can be seen in the photo, I had to shorten it as I got the dimensions wrong. There was also not enough space when the arms were horizontal and the long straps fouled the boiler.(The original design only uses one strap and I'm not keen on a sideways strain.) Hence a little bit of thinning and a bit of filing in the steam dome base.The second picture is a view down the steam dome. It seems to fit OK but the alignment had to be fiddled so that the regulator rod and the steam pipe could be fitted. This took most of one morning as the bracket bolt holes were slightly off centre which pulled the bracket out of line. One worry is whether I've managed to seal round the bolts well enough to withstand boiler pressure. I'll have to check this before the lagging goes on. I used an 'O' ring on the inside and PTFE tape compressed with a washer under the nut on the outside.

A new ring arrived and it's supposed to be OK. First attempts at turning were not too promising. I finally succeeded in turning the ring to size. It was not exactly glass hard but I managed to wear out 3 double sided, indexable tips. Instead of a nice dull grey finish, it looks like it's been chrome plated. It doesn't matter too much as it will be painted. Unfortunately, I couldn't get the inside edge turned properly as it was too hard and kept deflecting the boring bar. It doesn't matter as it's on the inside of the smokebox and won't be seen.
As can be seen in the next picture, I've cut the smokebox door. This was a free hand cut and finished by file. The darkish spot in the middle surface is another hard spot. This casting seems to be softer, so turning has been easier. I'm not ready for the door, but thought I'd do it now while the whole workshop is covered in cast iron dust.

The ring has been riveted in place and the boiler located on the chassis. I had hoped that this would be the last time I would have to lift it in and out of the chassis, but as I began to make up the inlet and exhaust pipes, I discovered that I couldn't get the drill in to cut the bottom flange hole.
Starting with the inlet pipe work I used 7/16" copper tube although 1/2" was quoted. Trouble was, it was 16swg which is very difficult to bend without proper rolling equipment. So I used the smaller tubing with 18swg and there is only a few thou difference in the bore. I thought 16swg was a bit over the top. The flange plates were given as brass 1/8" but I used copper 1/8" which has the very useful advantage that after heating, it is soft and a few taps and it takes up the curvature of the barrel without springing back as brass can do.
Doing the plumbing is not my favourite job! Very time consuming and constant altering until things fit. The outside wasn't so bad, but inside the smokebox is another story. Again the drawings specified 1/2" 16swg and the connection into the wet header was a bend of about 100 degrees on a 1" radius and there was no way I could do that without putting a flat on the bend. As it was, the 7/16" proved too difficult so I reverted to plumbing bits and used 10mm elbows. This has a big enough bore but if I'd used 10mm pipe it would have reduced it too much and maybe the copper is a bit too thin. As 7/16" isn't far off the outside dimension of the elbow, I stuck to the 7/16" and made sleeved joints.
Getting the bends in the tube is tricky but to work this out I cut a length of soft solder from the reel (5mm diameter), which can easily be bent to shape and cut to size, giving me a template for the copper tubing. The whole job involved 12 soldered joints and takes a bit of fiddling to get it through the doorway.
I soldered each end and sleeve first, then assembled and carefully marked tube and sleeve with identification points, then removed for soldering. It wasn't perfect, but being copper, bent the remaining bit quite easily.
So I assembled the inlet pipe work and hopefully have made all joints pressure proof. The nipple on the end of the wet header is for the snifter valve. One mistake I did make early on was that I had intended to fit super-heaters, which meant a different place for the inlet port on the steam chest. As I talked and read about this boiler I think super-heaters are probably not that advantageous as the boiler is so long and much of the extra heat would be lost. However, it did mean that the inside pipework was the wrong side of the exhaust pipework. Still, not too much of a problem. The outside steam inlet pipe has another nipple fitted, which is for the lubricating oil. As there is one each side, I shall be making a double hydrostatic lubricator. Looks a bit OTT, but does ensure even lubrication and I do like this type of lubricator. I've seen so many mechanical ones which over lubricate and others which don't produce enough if they notch back. My first loco, a 5" Crampton, had that problem, in fact, pumped no oil at all when notched back because of the way the pump was actuated. The site glass lubricator lets you see and control exactly how much oil to use. This will be about 3 drops per minute per cylinder.Having plumbed the inlet pipework, I have to consider whether it is worthwhile lagging the outside pipework or just painting it. I've seen both.

The construction of the exhaust pipes and blast nozzle is a little easier. This first picture shows this way on the drawing and suggests this method. i.e. cutting and soldering on a vertical line.
I'm not too happy with it as the top bit is cut off, a ferrule sifbronzed on (to fill the gaps?) and then the blast nozzle is a press fit bush. The second picture shows what I've actually done. The centre piece is an off-cut of bronze bar. It's not actually soldered together because I'll need to do some tweaking to make sure it's central and I haven't got the chimney to do this. I've also made my nozzle screw in so that I can try different sizes at any time without a major stripping job.

I made a start on making a chimney, but it was obvious from the start that it was going to be too heavy made in steel. Next I tried aluminium, but by the time I had priced up the tubes, the top lump and the saddle lump, there wasn't much difference in price from that of the casting. On top of which, there would have been considerably more work. So I lashed out and bought the casting.
While I waited for it to come I finished the smokebox door. The hardest part was fitting the hinges. They were 1/8th thick and riveted to a curved surface. Still a bit on the tight side. Might need some tweaking later. I made the mistake of not looking at the drawings properly. The hinges are fitted before the smokebox ring is riveted in, likewise the crossbar supports for the door bar. So I had to find an alternative method.
The casting arrived and once again not what you'd call a good casting. I managed to do all the external turning without too much trouble and only one small pit which I hope to fill with paint! The inside will have to be just what I can manage with files as I don't have enough movement on the lathe to bore the inside. It's a bit rough and lumps where the seams have let material through. Although there is no petticoat pipe, the casting is belled out to a certain extent. The next part seems to be straight sided and the top section has a slight taper with the top belling out again.
The most tedious bit is fitting the saddle to the smokebox. 8" diameter is just a bit large to fly-cut on my equipment. The chimney is bolted to the smokebox with 4 bolts. I'm not happy about it as the chimney is such a convenient handle to push the engine with and sooner or later somebody will try it.
Having scraped, filed and sanded, I eventually got the chimney to sit on the smokebox. I found that a flap wheel on the electric drill went quite a long way down the chimney, so the finish isn't too bad. Drilling the four holes in a symetrical square and at an angle proved to be much harder than I expected. Then came the problem of seating the bolt heads on the curved surface. What was needed was a spot face drill. Unfortunately, I couldn't hold the chimney and get the drill to work as it was too awkward.

Nothing for it but to make a spot-face drill bit. I used a piece of EN8 and filed it into a rose cutter and then heated it red hot and dropped it in water. The centre was already bored out 8mm, the bolt size diameter, and I then silver soldered it to an 8mm rod. This second heating going some way towards tempering it. The edges of the cutter were very hard and stoned to a sharp edge. Since it was only for cutting aluminium, I was satisfied. I solved the problem of how to support the chimney by bolting three holes to the smokebox. I was then able to use the electric drill with the new cutter. Results were better than I expected. Now that the chimney is bolted on, I'm not so worried about it being used as a handle.

I lagged the two outside steam pipes by spraying a piece of blotting paper with spray adhesive and stuck a sheet of kitchen foil to it. I cut it into thin strips and bandaged the tubes. With overlapping there were about 5 layers. Then I string whipped on the top with household string, then a second layer on top of that. When I paint the smokebox, I'll paint the string too. It is easy to put on another layer at a later stage if I find it's not enough.
Having lagged both sides I then completed the exhaust pipe system and bolted everything together. A little tweaking to get the blast nozzle central, and now the front end is mostly done. Just the snifter valve to do.

21 January 2004.

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