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A web-site by Rob Speare


Building 'Clan Line' in 5" gauge

As built and described by Tony Harmsworth.

I have been model engineering since the age of thirteen, with an attempt to make L.B.S.C.'s "Sir Morris de Cowley", which I still have, but have never finished.

I was apprenticed at the Royal Aircraft establishment at Farnborough, and worked there for nineteen years before leaving to work on the restoration of a canal, some change you might think ! - but my family have been associated with this particular canal for 200 years.

In the 1970s I built a 'Schools' followed by a 1" 'Minnie' traction engine, then a 3" Burrell; both were eventually sold, the Minnie going to Australia.  Then followed a self designed 3 1/2" 'King Arthur', which was put aside for a 5" gauge 'Boxhill'.

But, I had always liked the rebuilt Bulleids, having travelled behind them frequently in the late 1950s and early 60s, between Waterloo and Exeter Central, and Woking and Exeter; until the Western Region of B.R. ruined that once great main line.

I avidly read Keith Wilson's articles in Model Engineer for "Ariel", but it was beyond me both time wise and financially at the time.

In October 1998 I took the plunge and ordered the "Ariel" drawings from John Steer (then) at M.J. Engineering, and when I went to collect them he showed me a pair of laser cut frames and I bought them.  An impulse decision, as I had intended to just study the drawings and see if I could possibly stay the course to finish it.

A look at sheet 3 is enough to put you off for life, but I made a start on sheet 4 and made up all the frame stays, and in 2 months I had the chassis erected.  It is only 3 1/2" between the frames, as Bulleid had a thing about keeping the frame plates on the centre line of the axle boxes.

Through the winter months all the motion plates were fabricated, I had access to oxyacetylene so silver soldering was not a problem.

At Easter 1999 I went to the Bluebell Railway to photograph "Port Line" and it was then that I found the shape of the expansion link brackets as drawn (and by now made) were incorrect; also the coupling rods are NOT fluted.  I decided to scrap my link brackets and start again with the correct shape, quite a blow and not too easy with the position of the links in Keith Wilson's design of the motion.  However all went well eventually, also needle roller bearings were fitted to all axles on the loco.

The trailing truck was fabricated using an excellent photo in A.J. Fry's book 'Bulleid Power the Merchant Navy Class'.  The book of the Merchant Navy Pacifics is also useful.  The truck was silver soldered using brass and mild steel with scale lightening holes etc. and is close to scale.

The fabrication at the back end that supports the cab was copied from full size and Keith's drawings.  The two-start square thread and nut for the reversing shaft were a challenge, a silver steel tap being made to finish the bronze nut, it's also left handed !

The half hard bronze sheet for the main springs was obtained from a firm in Eastleigh, Hampshire, and was guillotined into strips for me by a firm of sheet metal workers at Weybridge, Surrey.  They also supplied me with the thin sheet steel to fold up the running boards; in full size they are folded, and do not look correct if angle is used for edging.

The chassis was exhibited each year at M.J. Engineering's open day when they were at Ringwood, Hampshire.  The motion caused no real problems, there is just a lot of it.

I did not like the idea of Keith's lubricator in front of the smokebox, so I designed and made my four tiny replicas to fit on the running boards.  They are scotch crank type with one way roller clutches, driven from cranks via an extension shaft from the expansion links, as in full size; one lubricatior for each cylinder and one for the inside motion.  The valves were set by tramelling up the wheels to find the dead centres, and each cylinder was set up individually and run on air, then stripped down and the next set up, and so on.

The inside cylinder valve cross head was designed as in full size and at the request of John Steer at M.J. Engineering the drawing was added to the set as an extra.  The smokebox was home rolled in 1/8" brass and the blast nozzle was copied from full size, i.e. 5 x 3/16" nozzles as per the full Lemaitre systems, I have recently heard it works well.

It was quite gratifying to find that the little lubricators would pump up to 400 p.s.i.  Neoprene balls were used in the non return valves.  The cylinder drains are steam operated; steam from the operating valve going to a collection box and then pipes to each valve.  Operation and release is via a normal brake type valve.

Steam brakes are fitted to the loco, a small hole was drilled into the brake cylinder so there is a slight hiss when applied and this gives a quicker release and drains the cylinder when warming up.

The boiler was the next challenge.  Three suppliers were approached for a possible supply of flanged plates.  Two did not reply and the third said they possibly could, but there was a 6 month lead time !

One advantage of working on a canal is there is usually plenty of hard wood offcuts available (lock gate building), so I set about making the formers.  The copper sheet, tubes and barrel were ordered from M-Machine at Darlington and the plates flanged up.  The only difficult one was the shaped backhead.  The sequence was as follows:

The taper 2nd ring was rolled and butt strip joint welded using 440 grade silver solder, 650-710 melting point.  The dome hole and safety valve bush holes were machined and all holes in the barrel (tube) likewise.  These two were then set up to marked centre lines, three 3/32" rivets put in to hold it.  It was then pickled, fluxed and soldered with 440.  The dome ring and bushes were put in again using 440.

Don't try to do too much on one heat.  I use oxy propane with a 2nd pure propane torch to preheat.  The actual soldering is done with an oxy acetylene torch using oxy propane.  I personally don't like oxy acetylene for brazing, it's too hot, too local, and too expensive !

The firebox and combustion chamber was made up and the tube plate, combustion chamber and firebox front and wrapper soldered using 440.  Care is needed as it is easy to melt the narrow bars from the drilling on the tube plate.  I leave the firebox back unsoldered at this stage, just temporarily bolted in.

The outer firebox shell was next, a few phos bronze screws hold the wrapper to the throat plate.  Again 440 is used with the back head bolted on loose to help maintain shape.  The outer firebox was then fitted to the barrel assy, great care is needed to keep everything in line and straight, phos bronze homemade screws being used.  The small top corner pieces were flanged up and fixed in.  It was all pickled up and washed off, and set up for brazing after checking all was ok.

This was a big heat requiring two torches, and then using the oxy propane to run in the 440.  440 is not as fluid as 842, but it does run well with enough heat and leaves a good fillet.  Don't overheat though or the flux will burn and you will have to start all over again !  The tubes went into the combustion chamber tube plate next with 842 - 610-620 silver solder.

The firebox and tube assembly was positioned inside the boiler and the front section of the foundation ring fitted temporarily.  The crown stays were then made up to fit.  Removing the inner assembly allowed the crown stay to be soldered to the top of the firebox using 440 solder.

The front foundation ring section and the crown stays were soldered in.  I do this in two heats pickling between, as trying to do both in one heat courts disaster !  I screw in temporarily the firebox and main backheads and rear and side foundation ring pieces to drill the stays, using 3/16", rivets, heads inside as stays.  Removing the backheads after first marking through the fire hole ring onto the firebox backhead, allows better access for brazing.  I don't try to braze all the stays on one side in one go.  I usually do all the inside front stays in one go.  It is easier with a combustion chamber as the tubes are out of the way.  Then half the side stays on one side, and so about five heats and dips in the pickle, 842 is used for all stays.

The backheads are replaced and the stays done on the outside, and any blowdown bushes etc are put in, again usually about five heats.  The firebox backhead is then cut to accept the fire hole ring.  This is then brazed in with 440.  The firebox backhead is then screwed into position, and the main backhead fitted to it.  When all is well, drill the stay holes in the backheads.  I then remove the main backhead and deburr the inside of the firebox, put in the stays from the inside, and to retain them I centre pop the copper plate next to the stay which swells up the copper enough to hold the stay; flux up, and heating the plate from inside the firebox and outside I braze in the stays and the firebox in one go.

The solder (842) leaves a nice little fillet on the waterside of each stay and all around the main joint.  When the main backhead is put on, the stays can be aligned with a scriber through the stay holes and slowly lowered into place.  I usually put in all the backhead bushes beforehand with 440 and the long blower stay and rod stays.  With the backhead in, and back stays done, I put in the foundation ring.  This is where the oxy is really useful.  The last bit is the front tube plate and the long stays through it.  The Merchant Navy boiler is very heavy by this time to lift in and out of the pickle tank, be warned !  There were only two minor leaks, one on a front tube and one on a side stay, both flux holes and they required a lot of heat to deal with.

The hydraulic test was delayed to allow the soft copper to harden up a bit, but was carefully raised to 250 psi.  I left the water in the boiler for a week in case there was any undissolved flux inside, and did the test again - it was ok.  The boiler inspector came and tested it, checking inside and the tubes at 250 psi, and then wacked it up to 300psi.  I said 'it only works at 110 psi you know ?'.  He took another swallow of tea and another biscuit, then gleefully announced "ah, I didn't think it could be that good !".  As a small bead of water showed at one of the crown stay holding rivets, he then grinned, released the pressure and said it was o.k., good job.  He is an excellent inspector who does the full size boilers for the Mid Hants Railway and others and is very interesting to talk to.

The cab and cleading were very difficult for me as I am not much of a sheet metal basher !  Several trips to the Mid Hants Railway to look over 35005 "Canadian Pacific" and West Country "Bodmin" were required to photograph various details.  The cab was fabricated in 18 gauge steel as this does not distort so much when silver soldering, and the cleading was brass.  The reverser gearbox was a challenge, being machined out of a block of alloy and the back in brass.  It is a close copy of the originals, complete with the catch to lock the cutoff.

I took a lot of trouble over the regulator and it paid off with a very smooth action and no leakage.  It allowed a very gentle opening of the first valve and on full opening the cross section more than equalled the section of the main steam pipe.  I fitted a steam chest pressure gauge and it proved most interesting to watch at various throttle openings and cutoffs.

The tender is a straight forward except for the rolling of the curved sides, and the flanging of the 'turn in' at the front.  I made a complicated die and former for this, and flanged it hot.  The former clamped the tender side to stop the curvature distorting.  The bunker top and locker cupboards lift off for driving, otherwise the tender cab denies access to the footplate.

The loco was always in demand at shows at Salisbury, Ringwood and Fareham, as it seems many were started, but few were finished with so much detail.  It was originally intended to be 35018 "British India Line" and I actually fitted these plates to it.  At Salisbury an old driver came up to me and said what a nice model, but you know it is incorrect !  He said the feed pipe runs were not right for No.18, which I already knew but didn't think anyone would notice !  No.18 was the first rebuilt, and the two feed pipes turned horizontally along the boiler for 2 feet before going down through the running plate.  All the future rebuilds had pipes going straight down from the clacks to the running plate.  So the plates came off and it became "Clan Line".  The dummy generator and injectors, plus hopper ash pan and operating gear was copied from "Clan Line" anyway.

In 2005 I sold the model as it was very large in our small home, and we were intending to move to Somerset.    I still regret it !