THE BACKHEAD
FIREHOLE DOOR
I finished the front end with the blower tube, which is the usual tube bent round the blast nozzle
and with 4 holes (1mm) angled inwards slightly. I think that might be a bit over-doing it, but we shall see.
There was one other job to do and that was the snifter valve. I'll do that a bit later on when I make all the
clacks etc.
I'm not keen on the design for the firedoor. It has a sloppy hinge and a fixed handle, so that the door can be
lifted and dropped over the catch. I wanted mine to be a tight fit against the firehole ring. The ring is not
as flat as a copper boiler one due to the welding, although this one is pretty good. So mine might not be in
keeping with narrow gauge practice but I like it.
The boiler maker seemed to think that a baffle plate was necessary, so I fitted a simple plate with one central bolt
and a nut spacer. I turned the head of it to a more decorative shape by mitring the bolt head corners. When I came
to make the door, I found I didn't have a piece of steel wide enough, so I tried welding two pieces of 6mm together.
Being a MIG welder there were no inclusions and having trued it up on the lathe, it is impossible to see the join
from the front. The interesting thing was that on the other side two shiny lines can be seen which means that the
welding hardened it.
I threaded the bottom hinge so that the nut on the bottom of the hinge bolt becomes a
locking one rather than load bearing and prone to undoing as the door opens and closes.
Next job was to complete the regulator bush and gland. I think the drawing may have an error here, as clearance for
the bush bolt heads may have been forgotten. Either that, or there is an awful lot of packing to fit! I used PTFE
tape as packing. I had to estimate the length of the regulator rod and I've got it a bit on the short side. I
really could do with another 1/8".
The picture shows the finished regulator handle. Constructing the brass-work to fit the bush and making sure the
handle can go through 90 degrees and stop flush at either end, is a very time consuming job. However, I did manage
to fit the handle. I used a roll pin to secure it in place. The action is a bit stiff while the packing is new.
I had to reduce the height of the 4 bush bolts to get the right amount of gland packing.
Another interesting
thing in the photo, is that all the numbers can be seen. If you didn't know it, every piece of steel used in the
boiler has its own paperwork and number. The paperwork identifies its quality and place of origin. (mostly Spain)
The Lloyds insurance number is visible too, with the individual inspector's own mark.
As I've had other commitments
this last few weeks and possibly in the next few too, I'm not able to get so much done; hence the smaller amount
this time.
6 February 2004.
SIDE TANKS
I was going to make the tanks of steel but decided it would be less likely to give problems if I used brass. Oddly
enough, it was easier to get brass sheet than it was steel. I bought 3 sheets of 4' x 2' for £111 which I felt wasn't too
bad a price. Still sold in imperial sizes although I could have had a sheet 1 metre x 2 metres but I thought that it
would be too awkward to handle. Building tanks is a slow job and needs careful planning
when it comes to the order of riveting. I used 1/8" copper rivets for all those on show. I got my brass angle from my local
DIY store which sold it in 1 metre lengths and cheaper than the Birmingham emporium. I would have preferred 1/2"
but could only get 10mm.
I have changed the design as the original loco had small side tanks with the one on the
left carrying coal and the one on the right empty. They are nothing like my drawing on the first page! I've
lengthened them to include water capacity as I don't think the well tank will be enough. Both will be linked and
feed water to the boiler via an injector. I will have another tank in the driving truck using a second injector.
I'll probably not need it but I need some ballast in the truck. Should the first injector fail because the water
gets too hot, then the driving truck supply will be useful. Then of course I also have the pumps for the well tank.
Some years ago, I made George Thomas's rolls and used them to roll a 2.5" radius on the leading edge of the tank.
Looks nice, but will no doubt make lining the tank more difficult when it comes to the paint-work.
It's taken me a
week to make one tank and I still have to make the top with a filler cap. I have soft soldered much of the seams but
I will cover the inside with fibreglass resin which will make certain of leak proofing. Rolling the tank on the other
side to be an exact match worked out first time; I think I was lucky. I placed it on top of the other tank, upside
down, to be sure of length and curvature.
Compared to the right side this left tank was a pig's ear. If anything could distort then it did and if anything
could go out of square, then it did. With hind sight I realize I got the riveting order wrong. I put the coal door
panel in before the centre panel, and therefore couldn't get in to rivet.
So I tried just soldering. I should have
drilled a few holes and bolted them together. It's OK to solder along the edges, but as soon as heat is applied to the
large panels in the centre, then it immediately bells out with expansion as it has nowhere to go because of being held
by the rivets.
Even holding it in place with cramps and clamps, the result was a bit of a dog's dinner. Still, I have managed to
finish the basic shape and hopefully most of the mess will be hidden! I got held up by visitors for a week and the
second tank took even longer than the first.
It's surprising how heavy the finished tanks are. I'll make the tops
with the filler caps as soon as I've sealed everything with resin and fibreglass.
A 4 x 2 sheet of brass is quite
heavy and holding it down to cut quite small pieces from it requires clamping down. I found that cutting it is quite easy
if a little noisy. I use a hand jig saw and 3-in-one oil as a lubricant. It's quite accurate and I can cut right up to
a line leaving the minimum of cleaning up.
That's it for another couple of weeks. Soon I'll have to think about paint. I like Dacrelate as it sprays nicely and
leaves a nice finish which can be cut back if necessary. They have an excellent etching primer which is especially for
brass. Trouble is, I believe they only sell paint now in 5 litre cans.
3 March 2004
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I'm not keen on the design for the firedoor. It has a sloppy hinge and a fixed handle, so that the door can be
lifted and dropped over the catch. I wanted mine to be a tight fit against the firehole ring. The ring is not
as flat as a copper boiler one due to the welding, although this one is pretty good. So mine might not be in
keeping with narrow gauge practice but I like it.
The boiler maker seemed to think that a baffle plate was necessary, so I fitted a simple plate with one central bolt
and a nut spacer. I turned the head of it to a more decorative shape by mitring the bolt head corners. When I came
to make the door, I found I didn't have a piece of steel wide enough, so I tried welding two pieces of 6mm together.
Being a MIG welder there were no inclusions and having trued it up on the lathe, it is impossible to see the join
from the front. The interesting thing was that on the other side two shiny lines can be seen which means that the
welding hardened it.
The picture shows the finished regulator handle. Constructing the brass-work to fit the bush and making sure the
handle can go through 90 degrees and stop flush at either end, is a very time consuming job. However, I did manage
to fit the handle. I used a roll pin to secure it in place. The action is a bit stiff while the packing is new.
I had to reduce the height of the 4 bush bolts to get the right amount of gland packing.
