Overhaul of a 9F

[don9f]

Today I removed the cladding off the boiler barrel, to reveal some rather oil soaked lagging material. I used to clean the loco after each running session with a 50/50 mix of white spirit and engine oil and it obviously used to find its way into the lagging through various gaps. Removed all the mess and then dismantled all the crinolines that support the cladding. The crinolines were all assembled with 12BA & 10BA countersunk brass screws and they all came out ok. With the cladding off, the 6 stainless countersunk screws securing the smokebox to the front barrel extension were revealed and once the nuts were off, they came out ok as well. This then meant that the smokebox could be removed....as stated earlier, most of the internal fittings had been taken out years ago. It was a bit tight and had to tap it off with a hammer and a bit of hardwood against the adapter ring. This ring is not as per the full size, but is a convenient way of supporting the front of the cladding and simulating the full size appearance in this area.



I wanted to remove the regulator valve, as when trying to move the actuating rod earlier, found it to be extremely stiff. It needed to come out for overhaul and renewal of the various 'o' ring seals. Problem is though that before the valve will come out of the "dome", the main steam pipe to the superheater header has to be removed. This is a length of 1/2 inch thick walled copper tube, passed through the regulator valve housing (inside the barrel and under the dome cover), with an 'o' ring seal and at the front end, fitted with a flange that gets sealed between the header bush on the front tubeplate and the wet header itself. This main steam pipe and its flange was stuck fast in the header bush and there is no real way to get hold of it to be able to pull it out! Soaked it for a while in WD40, but it still wouldn't move, although this treatment did have the desired effect on the stiff actuating rod, which soon gave up without a fight.
Can't get at the main steam pipe at all at the regulator end, so what I came up with was to run a 7/16 x 26 tap down inside the main steam pipe (3/8 bore) and make up a "sliding hammer" from some bits lying about, which screwed in to the 7/16th thread. This did the trick and out came the flange and pipe after a few blows.
I'll have to replace this pipe but that's simple, so the same method could be used again in another 20 years!





As may be well known, in 1954 when the first 9Fs entered service, it became apparent that drivers were sometimes having problems shutting the regulator under certain conditions. I read somewhere that it was thought to be due to the excellent design of the steam "circuit", that could result in excessive pressure difference across the open valve, "locking" the valve on its seat, until "notching up" increased back pressure, therefore tending to help equalise the pressure difference. I think the solution was to redesign the valve and reduce its total cross sectional area by around 50% (apparently to the same as the class 4 tanks), which on test, only resulted in a 3% drop in steam flow, when the valve was fully open.

The real one was a 2 stage horizontal slide valve, right up under the dome cover but not having the drawings or the EIM Magazines any more, I have no recollection what Les had designed for the model. My own design at the time was a simple vertical slide valve, with about the same cross sectional area as the 3/8 inch bore of the main steam pipe, pitched as high as possible under the cover. It hardly ever suffered from water carry-over when running, although if it did (too high a water level) and the regulator was suddenly closed, it could be a bit alarming, as the generous steam volume in the passages, valves etc. meant there was enough water/steam to keep it going with a closed regulator for quite a while.....something to definitely be wary of!

Cheers   Don

[Jim]

You're doing a great job there Don.

I had a similar problem with the lagging on my Burrell SCC TE in that it was a soggy oily water soaked mess when I came to check it. After removing it I decided, given our climate to forgo the lagging and rely an air gap instead. I also made provision for any oil or condensate to be able to drain out beneath the boiler. The new set up works well with no discernible difference in steaming.

Look forward as I'm sure you are too, to seeing your 9F all back together again and in steam, they're lovely engines as are the Britannias but then I would say that wouldn't I?

Jim

[don9f]

Spent all afternoon cleaning the smokebox tubeplate and tube ends of all the baked on soot, scale, general crud and whatever else there was. Filthy job, done outside with lots of hot soapy water, scrapers (screwdrivers), brass wire brush, stainless pan scrubber and finally some scale remover. End result not too bad for the first session!

Now to fit all the blanking plugs, fill it up and pressurise to see what leaks, as I'm not sure now just where the leak actually was.

Before....



After....



Cheers Don

[doubletop]

Don

A great job and you may as well find all the leaks now you've got this far, A big plastic bin and a bag of citric acid and put it in soak for a week and get it really clean inside and out. You'll need it clean for the repairs anyway

Pete

[don9f]

Hi Pete, thanks for that....I had been wondering about pickling / what to use etc. and since your post have done some research and ordered some citric acid crystals.
When building the boiler, I used sulphuric acid which was more easily available then but haven't got any these days.

When doing all the pipework on the full size, a local model engineer used to visit us most weekends to see progress and so on and one day turned up with a full 10 gallon carboy of the concentrated stuff.....very useful but also very dodgy to have around!

Cheers Don

[Nigel Bennett]

Don - Would your 9F be the one demonstrating haulage of some rather nice 5"G rolling stock at an interlude at the Leeds SMEE IMLEC many moons ago?

[don9f]

Hi Nigel, yes I did do such a demonstration run at the Eggborough Power Station. Can't remember the date but I think the "Riddles" 2-8-2 won that day?
Happy days....and did similar another year at the Leyland track. Good to hear from you.

Just spent the afternoon cleaning more gunge off the boiler, so I can be ready to present it for a first visual inspection.

Found some old diaries yesterday and noted that the first time the completed boiler was hydraulically tested to 200psi was 9th June 1986 and then first steamed 21st August the same year. The first ever actual running of the loco was at the track of the Sheffield society,16th May 1987....where have those 30+ years gone???

Cheers Don

[Tony K]

Don, having got it all hanging out, including the regulator, have you considered a stainless gas valve?
Plenty have fitted these on this forum if you search.

[92220]

May 25, 2017 20:06:44 GMT don9f said:

Hi Pete, thanks for that....I had been wondering about pickling / what to use etc. and since your post have done some research and ordered some citric acid crystals.
When building the boiler, I used sulphuric acid which was more easily available then but haven't got any these days.

When doing all the pipework on the full size, a local model engineer used to visit us most weekends to see progress and so on and one day turned up with a full 10 gallon carboy of the concentrated stuff.....very useful but also very dodgy to have around!

Cheers Don

Hi Don.

If you want sulphuric acid, it's easy to buy. Buy some drain cleaner called 'One Shot'. That is very strong sulphuric acid. I have some and it's great stuff but needs great care when using as it is so strong. Always dilute by adding acid to water, NEVER water to acid, though I'm sure you are well aware of this.

Bob.

[don9f]

May 28, 2017 8:17:25 GMT Tony K said:

Don, having got it all hanging out, including the regulator, have you considered a stainless gas valve?
Plenty have fitted these on this forum if you search.

Sorry, I've tried searching but didn't find anything. Hopefully you can elaborate for me, so 
I understand what you are suggesting?

Cheers   Don

[don9f]

May 28, 2017 12:24:59 GMT 92220 said:

May 25, 2017 20:06:44 GMT don9f said:

Hi Pete, thanks for that....I had been wondering about pickling / what to use etc. and since your post have done some research and ordered some citric acid crystals.
When building the boiler, I used sulphuric acid which was more easily available then but haven't got any these days.

When doing all the pipework on the full size, a local model engineer used to visit us most weekends to see progress and so on and one day turned up with a full 10 gallon carboy of the concentrated stuff.....very useful but also very dodgy to have around!

Cheers Don

Hi Don.

If you want sulphuric acid, it's easy to buy. Buy some drain cleaner called 'One Shot'. That is very strong sulphuric acid. I have some and it's great stuff but needs great care when using as it is so strong. Always dilute by adding acid to water, NEVER water to acid, though I'm sure you are well aware of this.

Bob.

Thanks for that info, I'll look that up. We were taught at school to always add Acid to Water, easy to remember as A is before W in the alphabet!

[Jim]

For what it's worth I'd stick with Citric acid for cleaning the boiler.
It cleans the copper just as well and without all the risks of using and disposing of sulfuric acid. Out here you can buy 125gm packets of Citric acid in the supermarkets in the cooking section where they have the flours, starches etc.
I used a standard plastic garbage bin filled with water and added the small 125gm tinlets of Citric acid until I got the mix to a strength that cleaned the copper and the water tasted lemony.

Jim.

[92220]

Not tried that. I'll have to get some next time we are out, and give it a try. You are right, Jim, citric acid is much safer than sulphuric acid, and tastes much nicer.......................................not that I've tried it!!

Bob

[Tony K]

May 28, 2017 18:29:34 GMT don9f said:

May 28, 2017 8:17:25 GMT Tony K said:

Don, having got it all hanging out, including the regulator, have you considered a stainless gas valve?
Plenty have fitted these on this forum if you search.

Sorry, I've tried searching but didn't find anything. Hopefully you can elaborate for me, so  I understand what you are suggesting? Cheers   Don

Try this and this
There is some duplication but illustrates what I mean.

[don9f]

Ok thanks very much, I now see what you mean. At first glance, it would seem a bit difficult to replace the existing slide valve due to the restricted room....easier maybe if designing it into a new boiler!

Cheers Don

[Jim]

May 29, 2017 8:20:02 GMT Tony K said:

May 28, 2017 18:29:34 GMT don9f said:

Sorry, I've tried searching but didn't find anything. Hopefully you can elaborate for me, so  I understand what you are suggesting? Cheers   Don

Try this and this
There is some duplication but illustrates what I mean.

I must be getting a bit slow in my old age. It took me a while to twig that the link to the gas tap Tony had posted that looked so familiar was because it was the one I was using in Boadicea's boiler.

Back on the use of citric acid I should make clear if you decide to do a taste test you do it before you put the boiler in and not after.

I think I'd best give up soothing ales for a day or two.

Jim

[don9f]

Hi, good advice there but I don't fancy tasting the pickle....with or without copper and other stuff mixed in!

Whilst waiting for the citric acid crystals to be delivered I've got all the blanking plugs ready and have taken the opportunity to make a new set of dome cover screws....some of the threads were just a bit looser than I was happy with, so the new ones (still 5BA) have been cut a few thou bigger in diameter, to tighten things up a bit. I have calculated that at 200psi test pressure, each screw has to resist a force of about 32lbs (14.5kg).

Turned the frames upside down and took the pony truck off to give it a good clean, check the bearings etc. All the oilways in the axleboxes for the journals and horn guides are blocked up with gunge. I have given some thought to the possibility of squeezing a bit more side play out of the truck, to help on sharp curves. I only ever had problems at one local ground level track, where a set of points leading from the steaming area to the running line, contained a curve of only 27 feet radius. This always caused the pony truck to derail but interestingly, no problem with the main driving wheels. Other curves on the main track were allegedly as tight as 30 feet radius, but probably with a bit of gauge widening and the loco coped with these ok.

It may be well known that the real 9Fs were allowed round curves of 6 chains radius (396 feet) without restriction and as tight as 4.5 chains (297 feet) "Dead Slow! In 5 inch gauge, 4.5 chains equates to 26.5 feet.
Real 9Fs had a reputation for derailing the centre flangeless drivers but think its fair to say this would usually be on poorly maintained track that was getting weak and wide to gauge anyway. I personally witnessed this twice whilst running 92214 and on one of those occasions in a shed yard, after bruising a few track fixings/chairs etc. it rerailed itself before the loco was stopped....that saved a lot of work!

With the pony truck out of the way, I have dismantled the original cylinder drain cocks operating mechanism. Les W had designed a reliable mechanical system, operated by a steam cylinder but I'm going to try to make actual steam operated cocks like the real thing. I know someone with these fitted to his 9F and am aware they can be a bit temperamental, so we shall see.

Cheers   Don

[don9f]

After many many miles of running mostly on steel tracks, there was surprisingly little tread wear on the pony wheels, however due to most running being RH direction, the LH wheel flange had worn slightly thin, so I decided to reprofile the wheel set. To get the flange back to standard thickness, required about 40 thou off the tread thickness, so not bad!
Visually, the flanges on the drivers look ok, so won't be disturbing them, which is good, but haven't looked at the tender yet.

With everything cleaned up and a bit of filing done to the side control slots in the pony frame, its back together, ready for a repaint.

Cheers Don

[don9f]

One of the "enhancements" I was determined to try, was replacing the Les Warnett cylinder cock drains with some scale like steam operated ones. The castings for these arrived last week and I've spent several days on them so far....unfortunately the supplier sent 3 LH and 1 RH, so only done 3 so far and am waiting for the missing one to be cast. Its been fiddly work but very enjoyable.

The original arrangement had holes drilled vertically into the bottom of the cylinders, tapped 3/16" x 40. Because of the inclination of the cylinders, this suited the operating rods of the mechanical cocks. On the full size engines, the steam operated cocks are mounted parallel to the inclined bottom of the cylinders, so I re-drilled the holes square to the cylinder bottoms and tapped them out to 1/4" x 40.

The raw castings came with a "machining stub", to be able to create the 1/4" x 40 mounting thread. Then a simple fixture on the faceplate enabled them to be held for machining the main 1/4" bore and 9/32" x 40 thread for the valve cap. I didn't have a boring bar small enough to do the 1/4" , 9/16" deep bore, but after reading somebody's suggestion for boring small holes, mounted a 7/32" slot drill in a piece of 3/8" square in the toolpost. With one of its cutting edges exactly on centre height, this method worked really well and I am well pleased with the result. I did have a miniature internal threading tool, bought many years ago but never actually used until this project! It could just fit inside the 1/4" bore for the 9/32" thread.





Also in the set of castings were the steam chest drain valves. These are not "operated" as such, just opening/closing automatically, depending on steam pressure in the chests. On the LW 9F, no provision was made for steam chest drains, however drillings into the cylinder exhaust passageways were piped along with the cylinder cock discharge pipes, to look like the steam chest drains. I therefore only needed to machine these particular castings to pass the aforementioned exhaust drains through, not as functioning valves. I can't remember if these exhaust drains ever actually did anything on the model, but thats how I'm going to leave it.



A quick mock up to see how it looks (photo inverted as frames are upside down). The connections to the front of the steam chest drain valve and the rear of the leading cylinder cock are quite close together, but I'm sure the scale 1/16" pipes will fit ok. The real 9F uses 3/4" pipes here and they are close together as well!



Finally the most fiddly bit of all....the actual valve. Its made from PTFE and I had several attempts before getting the first (and so far only) one satisfactory. It has to have a fairly thin "seal" formed at the back, by centre drilling and grooving the PTFE, by which time it gets a bit flimsy. It also mustn't be a tight fit in the body, or it would probably stick when hot. This might have to be a bit of trial & error when the engine steams again!

[don9f]

More progress with fiddly parts for the cylinder drains....

A manifold with drip valve to feed the actuating steam to the LH & RH drains. Although similar to the real thing, this is not at all to scale, as it will be fitted where the original steam cylinder/piston was mounted and will be hidden from view between the frames. If I remember correctly, on the real 9Fs, this actuating steam was tee'd off the pipe leading to the LH atomisers, which of course were controlled by the same valve as the drains.

A couple of tees to split each side's feed to front & rear drains.

Finally the actuating valve itself. Although I've made it as per drawings and hope it will work, my original arrangement was "actuated" using the sanding valve on the pedestal. I have yet to explore how the new valve could be operated by a lever in the cab....access for fingers etc! That's the next job, then assembling everything and piping it all up. (Still waiting for one RH casting though).

Cheers Don