The Unofficial Mamod and Other Steam Forum

Steve_S · Posted: Fri May 08, 2009 7:55 pm Post subject:

I've added the eccentric and slide valve to the diagram. As you can see the slide valve is at opposite ends of its travel in the two situations, so the piston can't be being pushed out by steam pressure in both of them. In one or the other it must be exhausting. The consequence is that it will only run in one direction.

Steve_S · Posted: Sun May 17, 2009 8:42 pm Post subject:

Pulley Wheel

The pulley wheel was in need of some attention. It was mean't to be held onto the crankshaft by two large grub screws, but these didn't secure it very well, or very straight.

I drilled out the wheel so that I could glue in a brass Meccano bush with a smaller grub screw. This is a good fit on the crankshaft.

I filled in the gaps using this stuff:

Milliput is a two part putty like substance. Equal quantities of the two parts are mixed together, and when it has hardened it can be filed and sanded. I've used it before to fill holes in various metal pieces, and it works well. Later I'll be spraying the pulley with silver paint as it was originally.

Safety Valve

The safety valve is made of lead, and is mean't to screw into a lead fitting on the top of the boiler.

As you can see from the pictures at the start of the thread, most of the boiler fitting was broken off and needed replacing. It seemed very unlikely that I would be able to find a nut with the same coarse thread that I could use to make a replacement, so I decided to modify the safety valve to fit a new brass boiler fitting. I bought this brass endcap and compression fitting from the plumbing department at the local DIY suppliers:

I filed the flats off the nut part then spun it in a drill and finished it off with wet and dry paper and wire wool. This part will be soldered to the top of the boiler.

I sawed the lead threads off the bottom of the safety valve and soldered on the brass threads that I had sawn off the brass endcap. I had to be careful doing that because the SV would have been reduced to a pool of lead very quickly if I had pointed the blowtorch at it. I heated up the brass threads and applied some solder to its top edge, then, while the solder was still molten I positioned the SV top on it then quenched the whole with water. It seems to have attached OK! The result is that the SV looks original from the top, but underneath it's all new.

I haven't soldered the brass threads to the boiler yet, as I intend to fit some kind of throttle and I haven't yet decided what form that will take. I gather that later versions of this engine had a throttle, but I haven't yet found a picture of one.

alan2525 · Posted: Sun May 17, 2009 9:03 pm Post subject:

A very engine-ious restoration. Nice work finishing that part without access to a lathe too, and great way of restoring the threaded part on the white metal safety valve!
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Sandman · Posted: Sun May 17, 2009 9:13 pm Post subject:

Steve, you're an inspiration mate.

There's nothing you can't fix using the most simple hand tools.

What a tremendous job.

Keep us posted mate.
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Compound · Posted: Sun May 17, 2009 9:17 pm Post subject:

So far, so good Steve hope to see it running soon.
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Les · Posted: Sun May 17, 2009 10:42 pm Post subject:

Very cleverly done, I wouldn't have thought of using plumbing fittings at all.

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tmuir · Posted: Mon May 18, 2009 12:22 am Post subject:

I like the repair to the safety valve, very clever.

Its all the lead parts that have scared me away from Weedens, that was a very clever way to solder the SV together.
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A nice example of an Australian made Scorpion Donkey Engine

Atticman · Posted: Mon May 18, 2009 9:43 am Post subject:

Fantastic work Steve- and how clever is the SV

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WeedenSteam · Posted: Mon May 18, 2009 2:34 pm Post subject:

WeedenSteam · Posted: Mon May 18, 2009 2:37 pm Post subject:

IndianaRog · Posted: Mon May 18, 2009 2:40 pm Post subject:

Steve, some very clever handiwork there...love the SV with inside new, outside original...
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Steve_S · Posted: Mon May 18, 2009 8:12 pm Post subject:

Thanks for the comments everyone.

Frank, thanks for the SV picture... that's enough to give me a good idea of what's needed. I had assumed it must be something like that but I wasn't sure. I'll have to see what I can find!

RocDoc · Posted: Mon May 18, 2009 8:17 pm Post subject:

Great work Steve.

Time for a well earned ...

Cheers

Pete

mogogear · Posted: Tue May 19, 2009 3:28 am Post subject:

Steve_S · Posted: Wed May 20, 2009 8:22 pm Post subject:

That's what it looks like to me. It should be possible to make something similar.