7mm Manning Wardle Old Class i: a self-designed 'kit'

John Baker

Western Thunderer
If you followed my last build thread on RMWeb (Manning Wardle L Class 0-6-0 (Agenoria Kit)), you’ll know I love a good Manning Wardle. For the last year or so, on and off, I have been designing etches and castings for an Old Class I in 7mm scale, a lovely little loco that was used by contractors up and down the land.

This project has been slowly burning for about a year now whilst I have taught myself the finer points of CAD design and 3D printing, which I have thoroughly enjoyed, as well as being something I can pick up and put down as time permits. And yes, I know Slaters do a 7mm scale kit of a K class, which is very similar, if not the same, but that was part of the reason for choosing this prototype – can I do as well (or better?) than something that is commercially available? I like a challenge!

Having sent the artwork off to the etchers, I received them back all shiny and pristine. If only they stayed like that! A week or so later the castings arrived – more about them and the process over on my 3D printing threads, but I’m fairly pleased with how they have turned out.

The plan is to try and squeeze working inside motion into it – just to see if I can more than anything. That might be a step too far. Anything commercially available was too big, so I designed and had cast the necessary parts. It works, and fits, according to the 3D animation in Fusion360 that I did. But in the real world, with my less than experienced bodgings? We’ll have to wait and see.

I’ve also had a go at some wheels – I had some 3/16” axels, and wanted to try printing some wheel centres for them. I used a high tensile resin, but whether it will be durable enough for repeatably pushing the axels in and out remains to be seen. A local retired engineer turned up the tyres. Below you can see my initial attempts.

You may have seen my dabblings with learning the 3D modelling process on my 3D printing workbench thread, where there are a few more details about the castings and wheels and how I went about creating them. Find it here: JB's 3D CAD & Printing bench

Here’s everything as it arrived to me. Now to hack the frets up and see if I can remember where it all goes!

CADCasting.png CADetch.png IMG_3096.JPG IMG_3098.JPG IMG_3932.jpg IMG_3945.jpg IMG_3949.jpg IMG_3954.jpg IMG_3966.jpg IMG_3972.jpg IMG_3987.jpg IMG_3994.jpg
 

John Baker

Western Thunderer
The first snips into the fret... I made up some of the parts to fit between the frames. Eventually the spacers will position the frames accurately, and the following parts will drop in and soldered to provide extra strength and support. First, I made up the fire box and ash pan representation. This is a series of switchback folds that just need soldering together, after the numerous rivets had been punched out. I really must invest in a proper rivet punch rather than the gravity punches I use – there was a lot of bending in the material to sort out afterwards – a proper punch with an anvil would have eliminated some of that bend. Next, was the cylinder chest and head. The cylinder head is made from 2 laminates (both for the front and back of the chest, sweated together, with a 3rd on top for the end of the cylinder itself. The inner layer is 0.4mm smaller, which provides a nice little recess for the cylinder chest wrapper to be formed around and soldered to. The motion bracket was a simple 2 layer lamination, which also doubles as a spacer, adding much needed rigidity to the frames. To be honest, I didn't have a drawing of the this, and so the result is an amalgam of knowledge of a different MW class, and what was needed as regards support for the cross slides, space for the eccentric rods to pass through, and clearance at the sides for spring balance arms. It won't be too far off. So far, so good.























 

John Baker

Western Thunderer
Next job was to make the coupling rods – a simple 3 layer lamination and a knuckle joint to provide articulation if required. This could be soldered solid if you weren’t using any form of springing. I'm going to spring the centre axel - I need to be able to drop the axel out so I can remove the cranks and eccentrics for the inside motion, so I might as well spring it whilst I'm at it. I lined each layer of the coupling rods up by using drill bits in the holes to ensure the holes were perpendicular to the faces. The holes were then opened up using a broach and cutting oil to accept the crank pin bush. I perhaps ought to point out, that whilst opening out the holes, and for the second loco build in a row, I bent the coupling rod whilst doing this……that’s when I broke out the cutting oil, which worked much better. I remember thinking the first time I bent one that I need to use oil next time. And still forgot. Just as well I had a spare fret! All good now though.





 

John Baker

Western Thunderer
In between an unexpected week in the Lake District, and various bits of DIY directed by Mrs B, I have managed to get a free-rolling chassis without incident. There were a few other small details that I’d have liked to have added to the frames before putting them together (like the guard irons, frame supports and spring balance arms), but the jig I use means I need a flat surface to butt the frame up to. So next, I prepared the frame spacers, cut out the space for the horn guides, and opened out the bearing holes before using the jig the align everything. Having set up the jig using the coupling rods to establish the wheel bases, the spacers, motion bracket, ash pan and cylinder chest were soldered between the frames. I then added the front and rear guard irons, spring balance rocker arms, frame supports, blowdown valves and bearings for the fixed axels and horn guides for the centre axel.

Really, I wanted to build the chassis rigid with no springing or compensation, purely to see if it would run well, but my (over?) ambition to fit inside motion necessitated the centre axel to be removable, so I thought I may as well pop a spring in there too. I'm sure someone will tell me this is a bad idea! However on first inspection, all seems to run well and freely.








I also had a play about with the splashers, simply shaped around a drill bit, and soldered onto the vertical sections which fold up from the running plate. The etch needs changing as the the splasher tops are slightly too short, but nothing that can't be hidden on a test build! Only had time to do the rear two so far. When I designed the etches, I didn't know whether to use a laminated approach for the springs that fold up from the running plate, or cast them. In the end, I've decided to go with the cast option, but either way, I needed to fill the hole left by the top layer of the spring. On the etch, I put a spring-shaped 'void filler' so I could fill that hole, solder in place and sand back smooth. You can also just about see this next to the rear splashers.



Finally, just because I wanted to check the fit, I cleaned up a slide bar and cross head. The fit between the two is too loose and I'll need to change the print next time a send some castings off. I'll shim the cross head for now though.

 

adrian

Flying Squad
When I designed the etches, I didn't know whether to use a laminated approach for the springs that fold up from the running plate, or cast them. In the end, I've decided to go with the cast option,
That would have been my choice if I had the option - laminated springs always seem too much faffing around to get a good 3D representation - I know it can be done well but it's just a lot of work!
The fit between the two is too loose and I'll need to change the print next time a send some castings off. I'll shim the cross head for now though.
To be honest I'm not sure I'd bother - it looks close enough to me. The few occasions I've fitted inside motion I have always ended up removing material to make it a loose fit. With all the alignment, slide bars, crosshead, piston rod, cylinders, eccentrics etc. etc. I've found things start tightening up as you stick it all together.
 

John Baker

Western Thunderer
To be honest I'm not sure I'd bother - it looks close enough to me. The few occasions I've fitted inside motion I have always ended up removing material to make it a loose fit. With all the alignment, slide bars, crosshead, piston rod, cylinders, eccentrics etc. etc. I've found things start tightening up as you stick it all together.

That’s good to know, thanks. I’ll hold off until it’s all fitted and see what happens.
 

John Baker

Western Thunderer
Not had too much time to spend on this recently, but whilst I pluck up the courage to start on the inside motion, I made a start on a couple of bits of body work. I finished the splashers off, filled in the gaps left behind by the fold up springs (not using these, and will eventually remove them from the CAD work) although looking at the photos a couple of areas need some further attention...... The eagled-eyed amongst you will also notice I had to move the holes for the fixing nuts at the rear of the running plate out a bit, as I'd got these a little too narrow on the original CAD drawing. Add it to the growing snagging list!

IMG_4278.JPG.ce9684d9b6bad0f1e15528408e076907.JPG


Next up was the front buffer beam. Looking at photos, most i-class prototypes seem to have a thick-ish layer of wood sandwiched between a front and rear layer of steel. I plan on doing the same, but here's the front layer with the coupling chain bracket and the buffer bodies attached. The buffers themselves are a self-contained sprung buffer - the hole in the side of the body is for a retaining wire that will hold the shank of the buffer head in place that will be soldered in and filed smooth at a later date.

IMG_4299.JPG.31b0e7645ff12f6cf1867fb84c97b117.JPG
 

John Baker

Western Thunderer
Over the last couple of weeks, I've been constructing the buffer beams - the front plate of which is described in my previous post - a 2mm hardwood strip has since been sandwiched in between the buffer beam plates and the buffer beam supports and soldered on to the running plate, along with the valances (I'm sure I shouldn't have found this as fiddly as I did!!).









I have removed the parts for the inside motion from the sprues (apart from the balance weights which I have just noticed I've forgotten about and left on the sprue) and given them a good polish up with various grades of grit paper. I still need to drill out a a couple of holes, and polish a couple of parts further, but otherwise they are ready for fitting the the chassis. Don't expect that to be a quick process!! I'm likely to get side-tracked by the 'easier' bodywork......







When you put the chassis next to all the parts, it looks like it might be a bit of a squeeze. I have faith in my trusty CAD work though - it should all fit!

 

John Baker

Western Thunderer
Starting to build upwards now with the bunker. This is formed from one piece folded up, with the two end sections curved and soldered in the middle. The join is an overlapped half-etch, so it needs flooding with solder and then filing back to smooth. Inevitably, there's plenty of solder on show, which once painted you'll never know is there, but still..... In the final iteration of the etches, I might change the curved section to be a separate piece - it might just make things a bit neater. There is a half-etch strip around the top of the bunker where the bunker flare will be seated against. I don't want to put this on just yet, as I suspect it could be a bit susceptible to damage whilst construction is still ongoing.

IMG_4392.JPG.8271a4f72e618c8817f8a2645f8c253e.JPG


IMG_4398.JPG.ac9f030716c4ba5029fe4df9fc913aa7.JPG


Also made a quick start on the firebox by soldering the trim around the backhead. Castings to be added later this week. Or maybe the wrapper first? Decisions.....

IMG_4402.JPG.1994dfd5adff2b36589d28e144d814b2.JPG
 

John Baker

Western Thunderer
Any tips on bending half round brass wire laterally through a 2.5mm radius, 90 degree bend? Is it just a case of annealing it? Whenever I try, it just ends up bending round the flat side.....
 

simond

Western Thunderer
John,

try soldering it to the edge of an annealed bit of brass of an appropriate thickness, bend both, then unsolder. As long as the brass is a bit wider than the thickness, I’d hope that it would bend properly.
 

John Baker

Western Thunderer
John,

try soldering it to the edge of an annealed bit of brass of an appropriate thickness, bend both, then unsolder. As long as the brass is a bit wider than the thickness, I’d hope that it would bend properly.

Cheers Simon. Another suggestion via Facebook was to solder two pieces together to make a fully round section, bend it and then unsolder. You get 2 for the price of 1 (kind of) that way! I'll try both methods out this evening
 

simond

Western Thunderer
Ah, I suspect doing it “the other way” won’t guarantee that the flat side of your half round will stay flat, as the soldered assembly of two half round wires can twist.
 

John Baker

Western Thunderer
Ah, I suspect doing it “the other way” won’t guarantee that the flat side of your half round will stay flat, as the soldered assembly of two half round wires can twist.

You are quite right - it did just that, although not so badly that it couldn’t be rectified. I’ve only done one side, so I’ll give your method a go in a couple of evenings time when I do the other side of the cab.
 
Top