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A web-site by Rob Speare

   

Building   34004  -  'Yeovil'        

- words by the late Mike Gipson.

                                  
My love affair with BR, but especially the Southern Region Bulleid Pacifics, stems from my father being responsible for the local village railway station, and a daily 'steam hauled' 25 mile round rail trip to school, over the period 1960-65.

My version of 34004 'Yeovil' started way back when Keith Wilson's 'Ariel' was starting to be serialised.

Knowing both M and J (of M.J. Eng.) an early view of the wheel castings convinced me to have a go, although I decided on a West Country rather than a MN.

                                  
This choice meant having to build it from works drawings rather than Keith's MN drawings – a bold decision given my limited experience in model engineering up to that point.  The engine will carry a 72B shed code plate [Salisbury], not because it's correct, but to reflect my birthplace !

                                  

A vast collection of photo's and field measurements has been amassed over the years taken during detours on business trips !  This together with a few drawings from York has enabled me to get to the position of having an engine frame with all its brackets completed, and I am now starting on cylinders and motion work.

The tender chassis is complete and is for a 4500 gallon version - I intend to finish it in its cut down form with no raves, (though in truth it only carried this combination from April 1966 on).



                                  
It's amazing how many bits are different between the two classes (MN and WC) and you have to keep on your toes and check all references twice before making swarf or you can end up just making nice scrap !

I could not do anything but get the inside eccentric right as Mike Johns who rebuilt the full size Braunton kindly sent me a drawing - a tricky little job but very satisfying - details below.

Other projects inevitably come along, and being a member of GL5, a steady flow of wagons has meant progress on Yeovil has not been as speedy as it might be;  however whilst work is slow this is why the hobby can be so absorbing, especially the problem solving and the desire to make as much as possible exactly as it was in full size.  So - to details:

                                 
Stretchers and bracketry

                                 
The fabrication work was something of a challenge but the brainwave of I believe Mike Casey to pre stick things together with a blob from a MIG torch before silver soldering made things a lot easier, you just have to site the blob so that following silver soldering you can file it off again. 

That together with access to one of the company Oxy/Acetylene torches and a professional glass bead blaster enabled all the brackets etc. to be completed, before early retirement came around.





                                 
Horns

                                 
One of the many differences between the WC/BB classes and the MN's is not so obvious from a casual viewing, and concerns the hornblock arrangements.  While the MN's use large castings, the WC/BB hornblocks are formed from plates welded in saving both weight and cost, and the axleboxes sit central to the frames.

To model this, the hornblock apertures were first cut out to a size 1/8" over the required finished size.  Plates were cut to the width of the hornblocks also from 1/8" material long enough to wrap around inside the aperture with some to spare.  In the flat the plates had a groove half the thickness of the plate cut along the centre line the thickness of the frame material.  This allows them when bent up to be 'sprung' into the frame aperture.  There are some holes to drill in the plates before bending; these are for securing the horncheeks (6 per side - special bolts as well !)





                                  

A test piece made from card will give you the correct locations so it can be translated to the steel plates and drilled/tapped before bending.  There are 2 holes on the inside only at the top for the lub oil supply pipes, these were tapped 7BA.

                                  
Finally before bending around the former shown in the photo a method of securing the bent up frame into the aperture had to be devised.  The full size loco has a bump stop/spring helper in the top of the aperture (see drawing extract) and this was used as a means to secure the top of the U shape plate to the frame.

A small imitation of the stop was turned up in the lathe with a short length of 10BA thread.  A corresponding hole was drilled and tapped in the frame (nothing too fancy it only has to hold the plate whilst silver soldering takes place).

On the bending former you will see a small spigot at the top; this corresponds to this 10BA hole - which needs to be drilled through the centre of the flat plate in the groove.  This locates the plate whilst bending and is used to secure with the stop before soldering.  Bend the finished strips and fit to aperture and trim length of each 'leg'.

The bottom retention of the plate is done either side by some small milled plates which form the axlekeep securing arrangements and if you are careful the small triangular strengthening plates that appear to be welded on the full size loco, also where necessary fit the securing plate for the axlebox oil pipe. 

Again using 10BA screws fix these milled plates to hold the legs of the U plate in the correct position and it’s then ready for s/soldering.  Do each frame side once all 3 plates are fitted.  I found no distortion by hitting it hard with oxy/act or oxy/pro and getting away quickly.





                                  
Eccentric

                                  
No excuse on this one as a drawing (shown, clickable) was kindly sent to me by Mike Johns who rebuilt the full size Braunton.  This shows not only how the eccentric sits in a recess on the crankweb face, but also the stepped split line and bolting arrangements.  These are necessary of course because the eccentric has a clearance around the axle.

This fixture scheme was introduced after the failure of Bibby Line at Crewkerne.  Although you cannot see this item, to my mind if you are going to make it, it should be as best you can like the real thing.





                                  
Tender

The tender chassis is complete and painted (mainly to protect it), and I have the brass in hand to do the bodywork.  Perhaps if I get fed up with endless motion work I will have a break and start to put the tank together.

I chose the 4500 gallon rather than 5500 gallon tender, as I think it might be easier to reach over and drive on the track - only time will tell if I was right!

The drawings I used from York are poor quality (their words!) but with lots of detail photos, a reasonable representation of an original 4500 gallon tender chassis has emerged.

The hand brake gear took a while to work out, and the front drag beam carries an extra casting at the back for the drawbar arrangement.

No really difficult areas but the spring pockets are different to MN's; though it is possible with jigs and a milling machine to convert the ones available from MJ Eng to reflect the WC/BB ones.  The axleboxes and covers are specials made from solid; there is a spacer fitted between the middle spring and axlebox only, which allows the box to move laterally without distorting the spring.

                                  
And some views of the underside of the bogie and trailing truck.

                                  
Yeovil - The Next Chapter - words by Rob

What to say...  Sadly Mike passed away, far too young from Cancer, the terrible scourge of our age.  Some months prior to that He offered me the chassis of Yeovil, and having such respect for his workmanship I couldn't turn it down.  It was some time before the locomotive was available, and there was some inevitable neglect and developing rust, so the first job was a though clean, and to paint the driving wheels.

                                  
The Boiler

I decided to get the boiler sorted, as this was going to be the major cost item.  Having previously adapted the Ariel boiler drawing to suit the dimensions for Bude, this wasn't too dissimilar, but being a rebuild, the number of safety valve bushes is reduced to two, and they are on the firebox side of the dome. 

I also add a few extra bushes at the rear for possible water feeds, and threaded blind bushes for the regulator pad.

At that time I did not have sufficent kit or time to build a boiler, so an order was placed with John Gaunt (Devon Boilers), and he made a superb job of building it.  I was able to visit during the build, and saw that John had it set up on a jig to keep everything in nicely line.

                                  
As the photo shows, it was very well finished, with tidy joints; John is very good at his craft.

                                  
Assembling the Smokebox

The box of bits that accompanied the loco includes a piece of rolled tube for the smoke box, the smoke box door ring and chimney, so I thought that would be a good place to start to move forward. 

The bronze smokebox ring casting was mounted in the four jaw, turned to just fit into the smokebox, and secured with countersunk 8 ba screws.

                                  
Machining the chimney was an interesting task, and fortunately the casting had sufficient extra material to allow it to be held and set up in a 4 jaw lathe chuck.  After lining up, the chimney top profile was shaped as far possible, and then the inside opening was taper turned, setting the angle on the cross slide.  As Bulleid chimneys are a large bore, I could use a fairly robust tool to do this.

Then keeping the same taper angle, I turned a mandrel from aluminium, with a bit of trial and error on the relative diameter, to be a snug fit on the inside of the chimney.  As shown in the photo, the outer shape of the peticoat pipe flare was shaped before parting off the lower part of the casting.

                                  
The Tender Body

I designed the tender body in 3D on the computer and had the parts laser cut.  The outline is of the 5500 gallon tender, which is correct for the period, and was nicely drawn for me by Richard Green. 

This sits on the same frame-set as the earlier 4500 gallon body, but they increased the capacity by raising the rear of the tank.  It was my choice to mimic the open nature of the full size welded bulkheads, though it doesn't really have huge benefits in a model.  Short cut-outs are let into the bottom of the inner bulkheads to allow water to drain through.  There is a folded well tank underneath, bolted on to Mike's supplied sole-plate, and sealed with Puaflex 400 sealant. 

Fold lines in the coal tray were cut though by laser, a repeating pattern of 10mm cut followed by 6mm untouched.  This allowed the floor and angles sides to be easily folded without distortion, and worked very well.  Some soft solder was just run along the creases on assembly to seal any small gaps remaining after bending.  It all went together fairly well in a dry run, but the process of soldering in the bulkheads and coal hopper did distort things slightly, so some extra fettling was required.  Sometimes a CAD design can be a little too precise.

The whole of the rear top section is removable for serious maintenance, while access to the hand pump will be from under the vacuum tanks; hopefully it won't be needed too often.

I am using Mike's unmachined Merchant Navy cylinder castings, but (just as he would have) these have been sized appropriately for a West Country, at 1 7/16" bore.

The brasswork for the running boards has been laser cut, three pieces per side, requiring a down fold on the front edge, and a fold up on the rear edge, giving a sturdy platform.

Work continues...