Inside/outside framed locomotives

[Jon Nazareth]

I intend having a go at scratch building a 2-2-2 electric powered locomotive, I already have the wheels.  What puzzles me at the moment is how to make it up with these double frames.  With the O Gauge engines that I've built in the past, the body simply sits on the frames but it doesn't seem as simple in this case.  Does anyone know of a set of instructions for a similar engine that I could use as a guide?  I've tried several times to attach a picture of the engine but I can't seem to manage it.

Regards
Jon

[jamiepage]

Jon,
Perhaps the outside frames could be entirely cosmetic, and inside frames  do all the work - ie carry the wheels and motor. Wheel bearings therefore inside wheels, axles cut flush with outside face of wheels, (or at least short of the outside frames).
Cosmetic outside frames part of the body to drop on.
It would probably  be feasible for a  structure to include boiler shell, cab side sheets, outside frames, footplating and splashers to fit over the working chassis as a single piece; alternatively, it could be built up in sections to make painting - and lining! - easier.
Buffer beams could be fitted to either the inside frames or the cosmetic outside frames/ body assembly.
Just a thought. Superb prototype, though
Yours
Jamie

[MikeWilliams]

What a lovely little engine Jon.  What is it?  and will you do all that lining yourself?

Mike

[IanT]

Hi Jon,

The only similar published design that immediately comes to mind is 'Rose' by LBSC which has slim outside frames attached to the buffer beams. A version of this engine is also described in Peter Jones book "Building Small Steam Locomotives" and was called 'Wirral'. It's a 2-4-0 design but only the front pair of wheels are actually supported by the outside frames themselves.

However, looking at your engine (Dieppe) I would tend to view the loco as simply being an outside framed design and make them sufficiently robust (e.g. thick) to avoid any flexing. The reason being that all the wheel bearings ride in the outside frame in this locomotive and I'd make them working units rather than dummies. So my suggestion would be to do the opposite to Jamie and make the inside frames the 'cosmetic' ones.

I'm not sure there is anything that needs to be very different in the rest of the build (apart from the wheels being inside the frames that is) as the platework should be pretty similar in most respects to an inside framed engine. Now 'Fire Queen' might be more of a challenge - as she has no frames at all, everything being attached to the boiler!  :-)

Regards,

IanT 

[AllWight]

I do believe that's a LBSC locomotive.  Very nice choice I look forward to seeing it in either the goods green or the stroudley improved engine green.

Mark

[454]

It is a loco made by Robert Stephenson & Co in 1864 original number was 200 later re-numbered to 490 & was indeed on the LBSCR.

This is the link to a very nice full side view including tender.
http://commons.wikimedia.org/wiki/File:2-2-2_London_Brighton_South_Coast_Railway_490_Dieppe.jpg

Hope this helps.

Dave
454

[454]

A drawing & a constructional article in a smaller gauge.

http://www.rmweb.co.uk/community/index.php?/topic/64313-an-express-passenger-loco-from-the-60's/

Dave
454

[Jon Nazareth]

Thanks everyone for your suggestions and I've taken them all on board.

Mike, your question has been partially answered re the name and company.  With regards to painting and lining;  my thinking is to maybe invent my own scheme avoiding the complex lining of the LBSCR.  The only other alternative is to get someone else to paint her and that would be costly.

Jamie, I had been thinking along the lines of your idea as it was the only one where I could see the body, complete with outside frames, being a separate piece to the inside frames.  My only thought was stability if the inside frames carried the wheels.

Ian, how do you envisage the two sections coming apart?

Regards
Jon

[Jon Nazareth]

I keep looking at that dome and thinking how to make a good job of it.  The whole thing looks tapered to me with the flange longer at the sides and quite short fore and aft.  I've read how 'other people' manage domes but it still doesn't make the thinking any easier.  I'm not worried about the turning, just the filing which blends it all in.  All of the above applies to the chimney too.  With regards to the safety valve cover well, I'm hoping that there may be a commercial one out there somewhere.  There isn't a photo or drawing of the backhead so, this will have to be 'invented'.

Regards
Jon

[jamiepage]

Jon,
Stability would be no worse than any other inside framed loco.; regard  the cosmetic outside frames simply as rather ornate footplate valances. It would be nice to include a representation of what looks like bearings for an underslung weighshaft on the inner frames.
Perhaps the buffer beams could be seen as part of the functional inside frame structure, then a boiler/ firebox section and two footplate/cab plate/ splasher sections could bolt on/ off to help the lining process?
I have no simple method to offer for shaping the dome or chimney unfortunately.
Flycut the boiler seating face on the end of a length of bar, blind bore for dome (right through for chimney), then mount on mandrel (soft solder?), turn to main body size/ shape, turn base radius to suit at the fore and aft points on skirt.
Which of course leaves the awkward side skirt area you were asking about! Unfortunately, all I can offer is to dremel.. dremel.. dremel, with a reasonably large diameter round grinding tool.
Leaving the workpiece on its mandrel for this step makes it easier to hold in a vice, and in practice it does not take too long to hack away at brass. Strips of emery cloth to clean up and polish.
This works for me but there are however, cleverer ways of doing it.
Yours
Jamie     

[IanT]

Hi Jon,

I guess my thinking yesterday was based on the general belief that in G3 it's possible to get much nearer the original prototype 'build' than in the smaller gauges.

This morning I've just consulted my 'Bible' for scratch loco builders - "Building Model Locomotives" by FJ Roche & GG Templar (highly recommended if you can find a copy). This is material first published in MRC during the 1947-1951 period but it is all still very relevant.

In the chapter on 'The Erecting Shop' Roche describes a GWR 'City' class 4-4-0. "The main axle boxes were on the outside frames and not on the inside as is popularly supposed and the inside boxes were shallow ones supporting only a portion of the weight of the engine" There's a rather nice drawing of the two frames and a top view of how it went together. Not the same engine of course but I think the general design thinking might have been very similar. I'll send you a scan if useful?

So, to answer your question - looking at this engine, I think I'd use the footplate itself as a base to mount both sets of frames, forming a single unit once assembled. With this arrangement (as the frames are quite shallow) it should be possible to get good rigidity. A possible construction approach would be to make each inside/outside frame as a 'unit' first, effectively forming a rigid 'U' channel and attach these to the footplate via the internal stretcher's. (Easier to draw than describe probably?) I would also certainly make the main 'splasher/sandbox' units part of the footplate unit as they need to fit the base/outside frame exactly.

The actual working springs would be inside the frames but the other detail (dummy springs etc) looks like it could be easily mounted onto this framework. The two 'tanks' at the rear footplate could be separate bolt on units too. The boiler, backhead & smokebox would then of course also be a single unit and removable from the footplate cum chassis unit.  So the loco would come apart in four main units for painting.

Having said all this - I thought that Dave's link to RMWeb was very interesting and it would certainly be very simple & possible to copy this approach too.  I guess figuring this kind of detail out is all part of the fun of scratch building in G3!

Good luck with your project and please keep us updated.

Regards,

IanT

[MikeWilliams]

I guess Jamie is advocating the method common in smaller scales and avoids special extended axles, whereas Ian's taking the engineering approach.  Both work well.

As for the boiler mountings, some on here would say draw them up and solid print, but the only way I've ever done it is as you say with files, small powered grinders and lots and lots of patience.  And when you just need to take off that last little bit, the drill slips, cuts a great gauge out of the flange and it goes in the bin.  That's the way I do it anyway!

Mike

[Jon Nazareth]

Thanks, again, chaps.

I've seen the construction series for the O Gauge version and it will certainly be of use.
Ian, I'm not too sure od what you are saying but, I've printed it off and will read it a few times in the hope that it will sink in.

I appreciate the fact that filing is probably the only way to deal with the fittings that have a skirt and no magic wand exists that will make this work any easier.

Regards
Jon

P.S.  I do have a 2 foot length of brass so, I can afford to make a few mistakes 

[IanT]

Sorry Jon, didn't mean to confuse you! 

Mike is correct to say I was thinking of a more 'engineered' approach to this. I guess people tend to stick to what they are most comfortable with. Others will have a different approach and that's just fine too of course.

If it helps, I would machine the two sets of 'frames' together (inside & outer - and both in mild steel) to their general external dimensions and then screw all four together to machine the axle slots and any other common 'holes' that need to align. The distance between the inner/outer frames will probably not be that great, so I'd probably use brass spacers to fix the two sets of frames together, thereby making two pretty rigid sub-assemblies. These internal vertical spacers could perhaps also act as axle guides? You then have a good chance of getting everything square on each sub-assembly before you then attach them both to the footplate and line them up.

When you mention the boiler fittings, I guess you mainly mean the large steam dome and I would probably make it from solid brass, although you could also make it in three parts instead. I'd probably use my 'ball-turning' attachment to shape the top part of the dome and then fly-cut the curved base to fit the boiler top. If these were separate parts, some brass tube would join the top & bottom together - i.e. a fabrication. I don't think the joins would show once polished up (or painted) but it might be simpler to just make it in one piece. depends what you have to hand in your scrap box perhaps.

Hope these ruminations help (rather than further confuse)

Regards,

IanT   

[IanT]

I meant to add that the problem with getting the 'flair' at the base right has been tackled in several ways but the most recent description I've seen was by Marcus Neeser ("I could never do that") in Part 8 'Making Chimneys'

I seem to be having problems logging into the Forum at the moment though (some issue with cookies John?) so have only just managed to get back on here.

Regards,

IanT