Building a 'Princess Royal' pacific in 4mm

[Horsetan]

.....need to crack on with the build.....

*hollow laughter*

[philbax]

Some more pictures

1. Overview showing the Continuos Springy Beam
2. Front end showing the drive to the internal valve gear
3. Motor drive set up
4. 

 

[philbax]

BTY I have used a Masokits front bogie with Comet sides, Still the support bearings on the outside to add

[Guest Lyonesse]

 

Some more pictures

1.  

A good looker and a good runner.  Thanks for sharing.  I look forward to seeing the finished item.

[jrg1]

Cab now finished, apart from the backhead which will be made separate (makes painting much easier). The fallplate is one piece, hinged on wire through .8mm brass tube soldered to the back edge of the cab floor. Full size one was in three pieces, but this serves no purpose in a model (marks are etched underneath if you really want to). Cab/tender doors are a real nuisance on a working model, in 7mm I sometimes hinge them so that they can be folded back, in 4mm they are just folded slightly to avoid fouling the tender and brake/scoop handles on our unrealistic curves. Locos for Carlisle are tested down to 3'6" radius although the minimum a Princess will have to work round is 4'. 3'6" radius is ony on the loops representing the Cumbrian coast line.

 

DSCF2097.JPG

 

 

The back handrail is held in a pillar at the lower end, for the upper end a length of 32swg soft brass wire is soldered to the back edge of the cab, turned out and formed into a loop round the handrail wire. Soft brass is the best material for this, stretch it slightly first to straighten it, handrail wire is .5mm, a bit thicker than it should be but in better proportion to the overscale handrail pillars.

 

DSCF2098.JPG

 

DSCF2100.JPG

 

 

Finally the parts for the trailing truck, at the top of the picture is the actual shape. This is on the etch but can only be used in P4 and even then barely moves from side to side. The alternative gives much more clearance between the frames and looks much the same in practice. Side pieces soldered into grooves in the top flange, bottom flange soldered on next, then sides and back stretcher (seen on right, this will be on the revised etch).

 

DSCF2101.JPG

 

I'll leave the loco now to build the tender (Comet) so more next week.

Looking at the excellent scratch firebox earlier in the thread, if you are revising the etch, I suggest including formers for the boiler and firebox, making the construction considerably easier. 

[Michael Edge]

Already on with that, more tomorrow.

[philbax]

One other small item is the double oil reservoir support behind the centre splashier, those on the etch are single ones

Phil

[Mike G]

Philbax

 

Given that the clearances behind the crosshead and front driver are very tight, how did you get everything to pass without binding? I can't see any thinning done on the connecting rod, obviously the forward coupling rod has been recessed for the locking nut...did you have to move out the stretcher for cylinders to help with clearance? or do you have another secret?

I only ask as I have a Duchess lurking in the shadows and I do love a big engine...regardless of region, well almost.

 

Very nice work on the chassis, are we going to be fortunate enough to see it on the exhibition circuit? 

 

regards

 

Mike

[philbax]

Hi Mike

I had to thin the slide bars down from 4 thicknesses of etch to 3 thicknesses. On the next one I will build it with 3 etches from the start. there is no thinning of the connecting rod.

In P4  and with Ultracale wheels there is very little room. I am sure this is not required for 00 but may need to be considered for EM. A lot can depend on the wheels used, Gibson wheels have narrower tyres I think.

 

I have a number of duchesses in P4, mainly based on Hornby bodies with Comet chassis, cylinder, and valve gear. The comet slide bars are thinner than the Michael Edge Princess etch which are closer to scale.

 

But then I am a glutton for punishment!!

 

As a member of the Risborough District Model Railway Club I will bring these along to Railex 2014

 

Phil

 

[Horsetan]

I've already seen 4767 perform at Scaleforum - mesmerising, and all from the Bill Bedford Stephenson valve gear etch.

[Michael Edge]

I have used this etch with full thickness slidebars in EM (in fact I haven't built a 00 one yet) with both Romford and Gibson wheels - no problem so far. I'll look at the lubricator stand.

[philbax]

Horse

You didnt come and find me at Scaleforum!!

[Horsetan]

HorseYou didnt come and find me at Scaleforum!!

No, but I met your models. And whilst they were running around the test track, I was running my SBB C5/6 2-10-0 on the 16.5 line alongside them

.....

[Mike G]

Phil 

Thanks for the reply, the engines look gorgeous. I shall have to remember this dodge when I build mine. I'm a hair shirt addict as well 

 

Mike

[Michael Edge]

 

The tender was finished on Monday, Comet kit goes together very well and quite quickly, the only modification needed is to the front platform. As supplied in the kit this is far too low for a Princess, higher one is easy to fit though.

Back to the loco and on with the boiler.

 

 

Starting by rolling the smokebox (I use rolling bars for this but it can be done without), solder up the seam and fit the front end. This is in two laminations to give it some thickness, remembering that it protrudes slightly from the wrapper.

 

 

The boiler pattern is printed on a paper template, stick this to a sheet of .010" brass with double-sided sellotape, then cut out and roll. The boiler band position is scored through and the centre lines marked with small nicks.

 

 

 

 

Roll a brass joining ring to fit just inside the smokebox, all three components ready for assembly.

 

 

Finished boiler barrel from the firebox end, the scribed lines marking the cleading band position are clearly seen. I have cut out boiler back and firebox front formers (connected with wire pins), these will be on the revised etch. The firebox back former is cut to rest on the main frame tops to assist in setting the smokebox coreectly. Note that even in EM gauge cut outs in the boiler are needed to clear the trailing drivers.

 

[will5210]

Excellent stuff. How do you work out the dimensions & produce the template for the tapered part of the boiler?

 

cheers

Edited November 22, 2013 by will5210

[ozzyo]

Hello Michel,

 

If I may say one thing, it's that you "may" have drawn your boiler wrong.That is that you may have drawn it as a full cone (taper on both the top and bottom). Most of the L.M.S. and G.W.R boilers were not a true taper as such but had a parallel (flat) bottom that followed the top of the rails. A bad sketch to try and show what I am saying,

 

One of the things about drawing this type of cone (boiler) is that the C/L runs off centre (but parallel to the base), that then causes its own problems with the front and rear faces.    

 

But you will know all of the above,

 

OzzyO. 

[Michael Edge]

This is not a GW boiler,  the bottom is not level - have another look at the drawings. Method is part calculation, part trial and error, there is a gap at the bottom where the barrel joins the smokebox but there's a cleading band here so I don't worry about it.

[Horsetan]

As far as I understand it, the Duchesses have a true cone boiler. For the Princesses, I thought the same, but the LMS Loco Profiles book on the class seems to suggest that the cone was tilted on its axis, so the tapered effect is accentuated.

[farren]

I thought it was a oblique cone not a true cone. on the princess but with the fire box side of the boiler axis higher will the front axis stays in line with the fire/smoke axis

Edited November 22, 2013 by farren

[Horsetan]

I thought it was a oblique cone not a true cone. on the princess but with the fire box side of the boiler axis higher will the front axis stays in line with the fire/smoke axis

That's correct.

[Guest Lyonesse]

The centreline of the cone is not horizontal, so it's not a true frustrum, but the base slopes down less than the top (if you see what I mean).  (See LMS Profiles)

 

Mike:  very, very impressive.  I find I have to put a circular former into each end of a rolled boiler to keep the shape.  But you seem to manage without.  What do you use to roll such regular boilers?

[Horsetan]

I have to use a rolling mill.

[Michael Edge]

I use a set of rolling bars (from Ian Cherry, many years ago) but I used to do it with steel bars of various diameters on a slightly resiliant surface. Mouse mats, unknown back then, are quite good for this. For short items I still often use steel bar in a V block.

[ozzyo]

This is not a GW boiler,  the bottom is not level - have another look at the drawings. Method is part calculation, part trial and error, there is a gap at the bottom where the barrel joins the smokebox but there's a cleading band here so I don't worry about it.

 

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.

Edited November 26, 2013 by ozzyo