A Cracker locomotive

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sbwhart:
Lovely clean copper work Arnold :clap: :clap: :clap: :clap: :clap: :clap:

And well shown to boot :thumbup: :thumbup: :thumbup: :thumbup: :thumbup: :thumbup:

Stew

arnoldb:
Thanks Stew :beer:

Not a lot done today ::) - just made the bushes and filler cap from phosphor bronze.

The safety and steam take-off bushes are threaded M6x0.5. The filler bush is threaded M10x1.25; M10x1 would have been better, but I have not found taps and dies for this yet.
I also hollowed out the filler cap as far as I could to get rid of excess mass that would need heating up and made it look approximately like a steam dome. In fact, I'm seriously contemplating using the filler cap as an actual steam dome; the regulator bush on the backhead is not far above the maximum water line, and if the loco lurches a bit, water is bound to get into the main steam line. It's a fairly simple job to add a dry pipe that will extend part-way up the steam dome, and it won't hamper filling too much...

I still have to decide what I want the chimney to look like...:

:beer:, Arnold

DaveH:
Arnold,

Don’t worry about the boiler. In the UK all they say is go and see “your boiler inspector”. You ain’t got one Arnold.

Nicely documented and made. As usual well photographed, I see you made good use of your tooling jig. :thumbup:

This is a very nice posting, makes me want to make one. :clap: :clap: :clap: We could have a race!

It’s coming on, looking good. :D :D :D

DaveH

saw:
Fantastic I just love it. :clap: :clap:

arnoldb:
Dave, Benny, :beer: - thanks gents.

Dave, I might not have a boiler inspector, but knowing the "system" here in Namibia, one might be "invented" at any time :lol: - besides, I'd rather have things up to standard, especially since I'm showing it publicly and I do value my own and other people's body parts :thumbup:.
I love that tooling plate; I can kick myself for not making it earlier in my short machining "career" - and there will definitely be more of them made :ddb:
Do you have tracks - or are you going to fit rubber wheels to yours ? :poke: - :D - we can definitely have a race :ddb:

Well, a coolish day here in Windhoek today, and nothing heats up a cold shop like a big torch :) - so I started soldering things together.

First off, some flux around the bushings, and left the flux to dry out a bit while I bent some rings out of some 40% silver solder. I have two types of silver solder - this 40% cadmium free, and some 40% that contains cadmium. The non-cadmium needs a higher temperature to melt and flows less easily into joints. It is also good to note that if solder containing cadmium is used, there are potential health risks associated with it - so I tend to use those very sparingly - only if I need to fix up an already-soldered joint or if I really need the slightly lower melting point:

I also brushed some flux around the holes on the inside of the barrel - I just use a small paintbrush for this:

Then I used a permanent marker to draw "rings" around the holes - this is just some intentional contamination to prevent solder from flowing all over the show. One can use a soft lead pencil or error correction fluid ("Tippex") for this as well. I pushed the bushes into their holes. The rings of solder will actually go on the inside of the barrel:

The assembly was then put down on a fire brick resting on the bushes, and I added the silver solder rings on the inside, with a bit more flux on the rings. Then I closed up the one side and one end with fire bricks standing vertically. The front side was left open, as that's where I would be applying the heat (right at the very bottom), and the left side so that I could look into the barrel and check on the progress:

I heated that lot up playing the flame along the bottom - it needs to get dull red for this solder to flow.
The first couple of times two years ago that I tried silver soldering, I had a lot of problems. The biggest one was thinking the job was a bad 'un when the flux turned black and stopping the heat at that point. Once I discovered that the flux I have turns black, and with a bit more heat goes crystal clear and the work needs to glow dull red, things suddenly came together.
Once I could see from the open end that the solder had flowed, I left it to cool down a bit, then turned it around to check the result:

While it might look like a dog's breakfast, it is actually a good 'un; the yellowish coloured rings are where the flux did it's job of cleaning and protecting the metal from the flame, and the pinkish-orangey shiny stuff is actually flux that floated to the surface. There is a nice fillet of silver solder all round the base of the bushes that was wicked through.

Into a bit of pickle it went; I use Citric Acid which is available in the cake baking supplies section of the grocer just down the road. It's relatively cheap, non-toxic (in fact, I mix the powder with water and just have a quick taste now-and-then till it tastes sour enough) and can safely and environmentally friendly be disposed of down the drain:

While that lot was pickling, I turned up a new bush for the backhead. In the last post I said I'll add a dry-pipe, so I needed a longer bush tapped M6x0.5 with a short section in the back just drilled out to 3.2mm for the thin copper pipe I have:

Ready to solder the bit of copper pipe on it:

The pipe still needs to be bent to fit up into the middle of the steam dome and trimmed to length.

The end caps are a loose fit in the barrel to allow flux and solder to wick in, but that presents a couple of problems when trying to solder things together, as nothing wants to stay put, and one have to resort to jigs or something to keep things in place.
I chose to resort to the "or something" bit :ddb:
I used an automatic centre punch at a slight angle to pop some evenly spaced dimples around the circumference of each end cap - the slight angle causes the soft malleable copper to raise a nice burr on one side of each punch mark:

Now it doesn't just fall down the barrel any more - it has to be lightly tapped into place, and it will leave an even gap right around for the flux and solder to wick in:

More rings of solder; one to fit the barrel and one to fit the flue, and a slight flare added to the flue by tapping it on the end with an old lathe centre I have lying around:

A bit of fluxing later - flux brushed around the inside the barrel where the end cap will go, around the end of the flue (with it's ring of solder already in place) and around the outside and inside the flue hole of the end cap:

Then I tapped the end cap gently into place in the barrel, added the flue, and ring of solder. I used the other end cap partly pushed in on the bottom (leaving it sticking out so I could get a grip to remove it again) to keep the flue in it's correct position, and supported the bottom end cap in a bit of excess copper tube sawn off the barrel initially. Some fire bricks were stood on end to help retain and localise heat:

I carefully brushed some more flux over the ring of solder, and heated the lot slowly at first; the flux I brushed on the ring in the barrel was quite wet, and I wanted it to dry out without bubbling all over the show. Once it dried out and stopped bubbling, I turned open the tap on the torch and played the flame just below the bottom of the end cap, moving it around the outside of the barrel. The fire bricks really help here by deflecting the flame around the back of the barrel and heating it there as well. Once the solder around the barrel flowed, I kept the heat on a bit longer and the solder around the flue followed suit.

Once again, the top of the job looks a bit unimpressive - I would have liked a nice even fillet of solder around the barrel rim, but there's a couple of bits that look like there's not enough solder in there. The fillet around the flue is quite satisfactory:

The back side is a different story though :ddb: - There's a nice even fillet of solder around both the flue and the barrel rim, indicating that the solder flowed between the bits as I had intended, and the joints are good 'uns :D.:

Apologies for the crappy photo; it's a bit difficult to get the light to catch the inside of the barrel and get the camera at an appropriate angle and focus "down there" :doh:
I'll use a bit of the other silver solder I have to fill in the top rim fillet - if it is really needed.

I put that lot back in the pickle to overnight and called it a day; hopefully I'll get some more done tomorrow.

:beer:, Arnold

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