Clarkson Princess Royal

[baggo]

Next job was the new longitudinal stays made from 1/4" phosphor bronze with bronze nipples at each end. I had to make the outside of the new nipples larger and retap the plates as the old threads were completely stripped. The new stays were then fitted and caulked with soft solder. They won't be coming out again!

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[baggo]

Backhead end

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[baggo]

We were then ready for another pressure test and what a disaster that turned out to be. I think the only stays that didn't leak were my new ones

This didn't really surprise me though as the original soft soldering was very poorly done. It looks as though the metal had not been cleaned properly and the solder just hadn't taken.

After a 'soothing cup of tea' (didn't have any ale!) I began the slow job of resoldering all the stays. The worst part was getting the metal clean enough to solder but managed it with a combination of files and a sanding drum and diamond points in the dremel. I then used a strong acid flux to carry out the soldering.

Initially, I just did the outside of the firebox stays but also had to then do all the nipples on the cross stays at the top of the firebox wrapper. The soldering on these was so bad that I could unscrew them without even melting the original solder! There were also a few pinholes in the foundation ring and on the top of the firebox wrapper.

Eventually, I got all the stays tight on the outside but some were weeping inside the firebox. I decided to go with Loctite to cure these as there was no way I could get the inside of the firebox clean enough to resolder them. I cleaned up as best I could with a wire brush and then drew a vacuum inside the boiler using a big aquarium air pump in reverse. Each stay was given a drop of Loctite 290 (thin wicking grade) and left overnight to soak in and dry.

Fortunately, this did the trick and after curing a couple more very small weeps, the boiler is finally bone dry and tight at 160psi. Phew!

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[baggo]

Not exactly a shining example of the boiler makers art but it's sound and now usable again. I find it hard to believe that this loco ever did run, although the boiler has definitely been fired.

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[redmog]

Dec 26, 2011 12:28:57 GMT John Baguley said:

Not exactly a shining example of the boiler makers art but it's sound and now usable again. I find it hard to believe that this loco ever did run, although the boiler has definitely been fired.

John.
May I ask - what is the thickness of the outer wrapper?
There seems to be quite an unstayed area at the front of the firebox outer wrapper, and it does not appear to have distortred with the pressure.

Chris

[baggo]

Hi Chris,

yes, that was a concern of mine. The wrapper is actually 1/8"(the drawings call for 3/32") but, in theory, it should really need additional stays. I could put another cross stay in at the top but can't put any further down as the tubes are in the way. The problem is that the firebox doesn't extend far enough forward. The wrapper didn't move at all at 160psi so it's obviously strong enough. The only bulge was in the firebox tubeplate which is now sound. I am going to take it to the club on thursday though for our boiler inspector to have a look. I think the working pressure will have to be lowered. The owner just wants to see it run and pull him around so any loss of power won't matter.

John

[drumkilbo]

Interesting stuff John, nice to see the old girl given the kiss of life.

Ian

[redmog]

Thanks John.
Well done !
Keep us posted.
I still keep one eye on your website.
I don't know if you've seen this, half way down the page.

www.bromsgrovesme.co.uk/6001.html

Chris

[baggo]

Hi Chris,

Dear Bro usually finishes up driving Dennis's engine ;D
Looking forward to coming back again. You made us very welcome

John

[Shawki Shlemon]

Looking at the front end of the boiler , it gives the impression that has been fired a lot , however you have resurrected the boiler and eventually the engine and make someone very happy . Well done , that is the spirit of the hobby .

[kwil]

Somehow I do think I would not like to be firing that one with all that soft solder and loctite about (Inspite of it holding pressure cold)

[baggo]

The worst that would happen is that it will start to leak again. The stays that had the Loctite treatment were only very minor weeps that would have probably sealed themselves eventually. There's at least two boilers in the Chesterfield club that have Loctited stays that have been successful and there's a LOT of boilers with soft soldered stays still running around. I've not heard of a boiler with threaded and cauked stays failing (other than the obvious if someone runs them dry) but there's quite a few boilers with silver soldered plain rivets as stays that have failed where the stays have pulled through the wrapper due to poor soldering. I know which I'd sooner put my faith in

John

[itsbluesteel]

Here here ;D





Steve

[Shawki Shlemon]

Before the codes , all copper boilers were riveted and soft soldered , there are some ( probably many ) still running and certified . The worst that may happen as John says they will leak .

[baggo]

Took the boiler to the club today but there was nobody there Will have to wait for Sunday now.

Made a start on the cylinders yesterday. These are pretty good apart from the port faces so the blocks were mounted in the lathe and the port faces given a light skim with a fly cutter to remove all the marks and make sure they were nice and flat again.

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[baggo]

Next the ports were cleaned up a little in the X1 mill which is ideal for little jobs like this. The steam edges of the ports were quite good and needed very little off but the exhaust edges were a bit wobbly. I used the shank of a drill to get both ports the same width. I gave the exhaust port a bit of a skim but the shape doesn't really matter. The port has no part in the valve timing and is just to let the exhaust steam out.

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[baggo]

Last job today was to make the valves fit the new port dimensions. Both the exhaust cavities were actually too narrow and so the valves had exhaust lap which has the effect of delaying the opening of the exhaust port at the end of the stroke which is not desireable. It's more usual to allow exhaust clearance (the exhaust cavity is a little wider than the distance between the port edges). LBSC was a fan of exhaust clearance but I don't think 'modern designers use it very often, if at all. The idea was to give a freer running engine.

One valve was still long enough to use as it was and just needed the exhaust cavity widening to suit the ports. The other however was about 30thou too short and so I silver soldered a thin strip of brass onto one edge of the valve and then machined to size. The exhaust cavity was then machined to size.

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[baggo]

Hopefully, that's all the cylinders require doing to them and they can be refitted to the chassis. No doubt a few other bits and bobs will crop up though!

John