Building a 'Princess Royal' pacific in 4mm

[Michael Edge]

The cross sections show quite clearly that the boiler is below the footplate top at the firebox end. These are the drawings I use to set the boiler up on the loco. I'm not really bothered if I don't get the exact developed shape, there's a cleading band at each end anyway which will cover any small gap. My main concern is to get the job done on time and looking right when it's finished and painted.

[trustytrev]

Hello,

        What do you use the copper tube for in the sixth image down of post number #266?

trustytrev.

[Michael Edge]

The copper tube is part of the hand rolling equipment, 1" is mostly used for cab roof forming. I usually have various diameters of tube and bar lying about the workshop.

[Guest Lyonesse]

Hello Michael, all,

 

I've just read the replies to this and my reply., so I've had a look in my loco profiles book and using the drawing on pages 10&11 this is what I have come up with.

...

 

When you start looking at the sizes it becomes clear that it's not a true cone nor is it a flat bottomed cone. Looking at the sizes for the bottom taper from the boiler C/L its 2 25/32", then when you look at the C/L to the top the taper its 4 27/32". When you take the offset in to account the taper from the smokebox to the fire box becomes 1 1/2" (0.5mm in 4mm) maybe that's why most people have always thought that the Princesses have had a flat bottom to the boilers.

Of the 1 1/2" taper 1 9/32" is taken up with the boiler plates over lapping then there is on the drawing a part showing that the 3rd boiler ring is tapered (inclined) by 9/16". So looking at all of the above I would say the the boiler base is horizontal apart from a small section in boiler ring 3.

 

But when you look at the clothing drawing on pages 16&17 it appears that the clothing has a continuous taper from the smokebox to the firebox of approx. 1 1/2".

 

OzzyO.

 

My outline drawing of the what the LMS Loco Profile book calls the combustion chamber boiler (is that an official LMS term?) --- or at least the outside diameter of the boiler clothing, which is what we model --- is attached. The base of the smokebox and the front of the boiler is level with the footplate; the back of the boiler is 2 21/32inch lower.

[Guest Lyonesse]

My outline drawing of the what the LMS Loco Profile book calls the combustion chamber boiler (is that an official LMS term?) --- or at least the outside diameter of the boiler clothing, which is what we model --- is attached. The base of the smokebox and the front of the boiler is level with the footplate; the back of the boiler is 2 21/32inch lower.

 

OK, now attached

[Guest Lyonesse]

My problem with the Princess Royal is still one of getting information.  The LMS Loco Profile book has lots of good drawings, but it concentrates on 6200/6201.  I'm a bit hazy about the arrangement of the reversing lever and the various box shapes covering parts of the motion.  And what is all that stuff on the running plate next to the smokebox?

 

I suppose the thing to do is to concentrate on the parts I do have information for, like the handrail and ejector, and chimney, which I suppose I will have to turn.

[Horsetan]

....what is all that stuff on the running plate next to the smokebox?

 

I thought they were oilboxes.

[Guest Lyonesse]

My problem with the Princess Royal is still one of getting information.  The LMS Loco Profile book has lots of good drawings, but it concentrates on 6200/6201.  I'm a bit hazy about the arrangement of the reversing lever and the various box shapes covering parts of the motion.  And what is all that stuff on the running plate next to the smokebox?

 

I suppose the thing to do is to concentrate on the parts I do have information for, like the handrail and ejector, and chimney, which I suppose I will have to turn.

 

Incidentally, thanks to Wikipedia I've just found the LMS film "Study in Steel" on Youtube, which has lots of interesting stuff on the building of 6207.  That fat smith with the walrus moustache seems to get into all the comtemporary pictures.

Edited November 27, 2013 by Lyonesse

[philbax]

All I can say is the the boiler and firebox formed from mike's developments fit perfectly

See bottom of page 10

 

Philbax

[philbax]

Come on guys, instead of pontificationing build one

[Timara]

Come on guys, instead of pontificationing build one

 

Absolutely agree!  I'm about to order wheels on mine.....  If all goes to plan, I might just have a running chassis before the year is out.

[farren]

My problem with the Princess Royal is still one of getting information.  The LMS Loco Profile book has lots of good drawings, but it concentrates on 6200/6201.  I'm a bit hazy about the arrangement of the reversing lever and the various box shapes covering parts of the motion.  And what is all that stuff on the running plate next to the smokebox?

 

I suppose the thing to do is to concentrate on the parts I do have information for, like the handrail and ejector, and chimney, which I suppose I will have to turn.

Next to the smoke box you have relief values which are bolted to the front of the steam pipes look like  round tins with holes running around the top. Sand box fuller pipes and gravity fed lubreiacater which are the things on top of the plate with a round hole in it the can be facing forwards or backwards 

[farren]

I like the pontificating it helps me when come to do mine wonder what would happen if I mentioned the boilers with out the combustion chamber. 

[Horsetan]

I like the pontificating..... 

 

So do I.

[Michael Edge]

I am trying out a few new ideas with this one, starting with the firebox.

 

 

 

 

The firebox back former is already on the etch and has register holes to locate with the cab - a hole in the middle for a screw might be a good idea here. The firebox front former is hand cut for this one and locates with two pins on the back of the boiler. Joining pieces from scrap were added with the whole loco bolted together to check that it remains straight and square on the track. The lower side ones will be cut out later but the upper corner ones can stay in permanently.

 

 

At the smokebox end the sides and back of the saddle are built up, this will now be filled with plastic padding. The wires across are to reinforce this filler and a greased peg has been soldered into the centre of the smokebox. The underside of the smokebox is also greased and a small screw just in front of the saddle holds it all together. I want the boiler to be removable, at least for now.

 

 

All components dismantled again.

 

 

Firebox sides, paper pattern and cut out of .010" n/s - its the yellow light that makes it look like brass. Washout plug holes drilled, rivets pressed out and plate join scribed on. The firebox for the Princess is made in two halves because there is a cleading joint on the top. It's useful to transfer the position of the cleading bands to the outside, these two were never lined so have to be added.

 

 

Top corners rolled by hand with 1/4" steel bar, the paper is left on at this stage so that I can see the bend lines, it also helps to stop the bending bar slipping.

 

 

The holes in the wrapper were drilled 1.3mm, now lead sheet is soldered on the inside. LMS and BR washout plugs did not have a raised lip on the outside of the cleading so these are just plain holes slightly de-burred. For the GW type which does have a raised lip I drill the holes from the inside with a slightly blunt drill to deliberately raise a burr on the outside. This burr is then sanded down to represent the rim.

 

 

The holes are then drilled through from the outside (.7mm), cleaned up and short legths of .5mm square wire inserted. It's much easier to do this with the firebox sides, rather than an assembled box.

 

 

Finished firebox side

 

 

Finished firebox

 

 

All assembled and sat on the test track, this is a 3'6" radius reverse curve, the Princess is quite comfortable on it.

 

 

 

[will5210]

Simply superb!

[Horsetan]

.....The firebox back former is already on the etch and has register holes to locate with the cab - a hole in the middle for a screw might be a good idea here. The firebox front former is hand cut for this one and locates with two pins on the back of the boiler....

 

 

Register pins are a good idea to line up and lock the components in place. I did the same thing with the reboilered Gresley V2 project.

[philbax]

Information

I have just found on my bookshelf 'The Lizzies' a photographic history of the LMSR  Princess Royal class, by G.W.Goslin and J.E.Conner.

Published byConner & Butler in 2001. ISBN 0 947699 32 5

Has lots of photos with good captions, many of which I have not seen before.

This has been on my bookshelf for years but only rediscovered yesterday!.

 

Other sources

Stanier Pacifics at Work, A.J.Powel, pub Ian Allen1986, ISBN 0 7110 1534 1

Interesting, but not many photos of Princess Royals

 

The book of the Princess Royals, Ian Sixsmith, pub British Railways Illustrated Irwell Press 200. ISBN 1 903266 01 7

Some good large format photos in this

 

The of course there is the Jenkinson & Essary books

LMS locomotives VOl 1 and Vol 5

 

Last but not least are the wild Swan books

LMS Profile No 4 The Princess Royal Pacifics, ISBN 1 874103 86 0

Pictorial supplement to the above ISBN 978 1 905084 91 0

Both these have a good selection of photos and drawings.

 

In split of all this information you still need to get a good photo of the loco in the period you want to model.

For 6205 the texts say that the reversing gear was modified at the same time as the valve gear was converted to have the inside valve gear driven from the outside cylinders.

The photo on page 39 of the profile shows the new valve gear arrangement but still with the original reversing gear set up.

This is what I have modelled but for the period I want, circa 1947 the reversing gear was different. In the above books the straight reversing rod is clear but not the extension forward to the reversing cross shaft.

 

Just have to keep looking.

 

Hope this helps

 

Philbax

[Michael Edge]

I have departed from my normal building sequence now to finish the frames since I want to check all the etched components as soon as possible. All that remains to do on the body amounts to detail, although there is an awful lot of it on a Princess.

 

 

From below, two strips of pcb sleeper for the pickups and brake gear added. The leading brakes are modelled in "worn out" condition to get them away from possible contact with the bogie wheels. This is always a problem with LMS locos as there is very little clearance here and our bogies have to move a lot more than the full size ones do, their's don't short out the railway if they touch something either.

 

 

Sandpipes added, again the leading ones are fitted back from the correct position (and solderd to the brakes). Support stays are made from wire - I know these should be flat strip but it's not very noticeable. The brake pull rod isn't modelled properly either but you can't see much on a working loco, both these items are added more for security than appearance.

 

 

At the other end the injectors have to be fitted now, do this with the trailing truck in place to check clearance. This is the modified truck frame which clears the EM frames, accurately shaped one wouldnt fit here. The injectors are from Comet, not absolutely accurate for this but near enough, although I replaced the very skinny feed pipe to the exhaust injector with some copper wire.

 

 

Cylinders completed, turned valve chests, fabricated valve spindle guide with some spare etch components (I may add something for thsi to the etch) and drains made up from wire and strip. The snifting valves (turned brass in this case but you can get cast ones) for the inside cylinders are fitted on a wire across the frames - there's a hole in the etch here. The cover plate on the cylinder is soldered on, I used to superglue these but they have an annoying habit of detaching after painting. The central part of the cylinder ends has been cut away now to leave room for two sugar cube speakers between the frames.

The slidebar brackets have also been fitted but not the slidebars themselves although they have been made up to test fitting. The Princess motion bracket is difficult from a modelling point of view because it can't just go across the frames, the wheels are in the way. The etch includes this fold up and rear face detail, it is soldered to the rear cylinder end - do this with the footplate bolted on. At the rear end I have soldered on a wire to support it. Also added are the weighshaft and link brackets.

 

 

Next the whole lot is sprayed, Halfords or Hycote (same paint but cheaper, if you can get it) grey primer and satin black. Keep turning the wheels round to get the paint through the spokes on to the frames behind, you can't get behind the wheel rims but this doesn't show.

 

 

When the paint is dry this is how to get it off the tyres, I've shown this before but it's worth repeating here. After lubricating the axles each wheel in turn is run against the rubber ring on the top end of my milling machine (last remaing part of my old Unimat), an old needle file removes most of the paint, followed by a scalpel blade to get into the corner and some wet and dry to finish. Don't forget to do the backs of the tyres as well if the pickups are going to go on to them.

 

 

Finished frames back on the test track. Crankpins and other parts to be soldered are scraped clean now.

 

 

The slidebars fit through the rectangular holes in the cylinder ends and are soldered to the front one (that's why the front cylinder cover was left off) and the motion bracket, coupling rods tried in place - not much clearance here but we don't need much as I will explain later. For the moment make sure that the crankpin can't hit the slidebars, there's just enough left on it for a thin slice of 1mm I.D. tube to form a retainer. This is why it was important not to have any sideplay in the leading axle - and building the loco rigid helps as well. A suggested alternative is to only use three of the slidebar layers but I like them to appear the correct width if at all possible. One thing I have never had to do is to move the cylinders outwards - there's always a better way than that.

 

 

Trailing wheels removed and re-fitted with gearbox in place. Instead of the usual Portescap this loco is being used as a test for the new Comet Maxon motor and gearbox, seems OK so far but I was very disappointed to find a final drive gear with no grubscrew. Easy enough to drill and tap the boss for one - I really don't like using any system which doesn't allow me to turn the wheels by hand while building. The coupling rods are now fitted, left trailing crankpin is not cut off, this one will carry the speedometer drive.

 

 

 

 

 

 

 

 

 

[artisan100]

Mike,

 

>I was very disappointed to find a final drive gear with no grubscrew.

My own preference would be for grub screw fixing as well, but unfortunately the gear that is used as final drive gear in this gearbox was only an intermediate, idler gear originally and so ran free on its layshaft. I have now procured some grub screws and intend to research the possibility of fitting these for those customers who share our preference.

 

Geoff

Comet Models

[Horsetan]

....I really don't like using any system which doesn't allow me to turn the wheels by hand while building. ....

 

At last, someone else who feels the same 

[Michael Edge]

Mike,

 

>I was very disappointed to find a final drive gear with no grubscrew.

My own preference would be for grub screw fixing as well, but unfortunately the gear that is used as final drive gear in this gearbox was only an intermediate, idler gear originally and so ran free on its layshaft. I have now procured some grub screws and intend to research the possibility of fitting these for those customers who share our preference.

 

Geoff

Comet Models

Thanks Geoff, that explains it. It wasn't very difficult to do, there's plenty of metal there.

[Michael Edge]

Now for the motion work.

 

 

Crossheads are etched in the form of front and back plates, there is a half etch on each which will run on the slidebars but nothing to hold them apart. For this I use a piece of scrap etch bent into a U shape as seen, to fit between the slidebars - there is a length of straight scrap on the last etch which is just the right width for this, quite by coincidence.

 

 

This is soldered to the crosshead front - apologies for the shaky photo taken in very poor light.

 

 

back plate soldered on using a broach to keep the holes in line

 

 

Assembled crosshead slid in place and piston rod soldered in between the fingers on the front plate. The connecting rods have already been made up but not fitted yet, the little end pin can be seen on the bench in front. The test fit is done like this before the drop link is fitted because after that the crosshead won't slide back past the motion bracket.

 

 

Drop  link soldered on and little end pin fitted.

 

 

The earlier point about clearance is illustrated here, the leading crankpin can be seen behind the con. rod, it's apparent that it never actually passes behind the crosshead so less clearance is needed. Many locos (but not all) were designed like this - it does make life easier for us.

 

 

The valve rod, combining lever and union link have been assembled with pin joints, the crosshead is slid as far back as it will go in order to fit the last pin through the drop link frm behind.

 

 

The valve rod runs back through the slit in the motion bracket and is supported on the lifting link. I usually build walschaerts geared locos in mid gear, they might look better in full gear but not when they are running the other way. Once again a taper broach holds the hioles in line.

 

 

Return cranks are etched in two layers, giving a boss on each side for clearance without bending them outwards.

 

 

 

The rest of the valve gear components assembled, pins are passed through from the back where possible and well greased before soldering on the next rod. The pin for the eccentric rod to the return crank has the head on the outside but reduced as much as possible, the roller bearing cap will be soldered over it later.

 

 

All now assembled, washers behind the big end, con. rods always run parallel to the cylinders and are always straight, Outside lifting link and weighshaft arm fitted, the expansion link should be thicker than this, I'll add some more layers for anyone who wants to build a proper box link - also another link bracket. I cut the top of the link off to fit under the footplate rather than letting it protrude above, it's all hidden in a box anyway so you can't tell the difference.

 

 

The other side, all finished.

 

 

Last job for now, fitting pickups. These are 28swg phosphor bronze wire, not too easy to fit round the springs and hangers on this and most other relatively modern locos. I've seen all sorts of materials used for pickups but I don't really understand why anyone uses anything else. I used to use phosphor bronze strip many years ago when that was all you could get but it only bends in one plane so is much more difficult to adjust. Any other non-ferrous wire doesn't retain its springiness, arcing heats it up and softens it, leading to more arcing etc.

All finished and tested now, the motor and gearbox run superbly, even without any running or much lubrication.

Normally this job would now be finished and off to the painters but as I said earlier I have finished the frames and running gear out of order to correct the etch so I have to go back to all the detail on the body. I'll put something on later when I get round to the steampipes but otherwise not until it's finished - unless anyone has any other queries.

 

 

 

[PGC]

 

 

I really don't like using any system which doesn't allow me to turn the wheels by hand while building.

 

 

Personally, I use gear boxes that have the motor mounting holes in the horizontal plane or I make a plate that allows me to mount the motor in the same way so I can easily remove the motor by undoing the mounting screws if I want to turn the wheels by hand. That means I can use gears that don't have grub screw fixing, if needs be.

 

Phil

[N15class]

I like to use phospher bronze wire. I normally coil it around a 2mm drill (in 7mm), to make it into a spring. They can be quite short then and be fitted into smaller spaces.