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

[jdb82]

If you followed my last build thread (https://cutt.ly/zQeImru), 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: https://cutt.ly/zQeImru 

 

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

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited July 26, 2021 by jdb82

[Timber]

superb - what cad tool did you use for the etch.  I also noticed that you are using 0.3mm NS, any particular reason for this.....i have always used 0.45mm but there was no science behind that decision.

 

The castings are excellent......really nice and clean.

[hayfield]

A stunning piece of designing in multi materials

[DGO]

13 minutes ago, Timber said:

superb - what cad tool did you use for the etch.  I also noticed that you are using 0.3mm NS, any particular reason for this.....i have always used 0.45mm but there was no science behind that decision.

 

The castings are excellent......really nice and clean.

 

If you look more closely you will find that whilst the Brass  is etched as 0.3mm the Nickle Silver says 0.4mm I too am curious, I assume the brass is thinner to make it just a little easier to form the bodywork ?

 

I'm curious about the castings, did you 3d print them in something exotic and then have them investment cast or something else ? 

[jdb82]

 

2 hours ago, Timber said:

superb - what cad tool did you use for the etch.  I also noticed that you are using 0.3mm NS, any particular reason for this.....i have always used 0.45mm but there was no science behind that decision.

 

The castings are excellent......really nice and clean.

 

I used AutoCAD for the etch artwork. There are many free alternatives that would do just as good a job, but AutoCAD I can use free through work, and it also has the benefit of loads of tutorial videos on YouTube being available to help out the newbie enthusiast!

 

With regard to the material thickness, as DGO says, the brass parts are thinner (0.3mm) than the N/S (0.4mm) purely for ease of forming bends and curves on the bodywork. I admit that when you handle the fret as a whole, it feels pretty thin, but once everything is soldered up together, I hope it will be fine. If not, then I would imagine that having it etched as 0.4mm next time would be achievable without major redesign work. I guess I'm still feeling my way around a bit.....

 

2 hours ago, DGO said:

I'm curious about the castings, did you 3d print them in something exotic and then have them investment cast or something else ? 

 

Basically, yes. After doing a lot of development test prints in a standard ABS-like resin, I bought a castable resin (PowerResin Zero), where you print the pieces, and then had them investment cast. Have a look here from about halfway down the 1st page onwards and you can see what I did.

 

[DGO]

Cheers, would you mind letting us know who did the investment casting for you ? Always nice to know of a company that can handle small scale work

[jdb82]

13 minutes ago, DGO said:

Cheers, would you mind letting us know who did the investment casting for you ? Always nice to know of a company that can handle small scale work

 

It was Jewellery Casting Scotland Ltd. Only used them this once, but really nice people to deal with.

[jdb82]

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. 

 

 

 

 

 

 

[Ruston]

Mind if I pull up a chair and watch this one? I do like a Manning Wardle and this build looks very interesting...

[jdb82]

1 hour ago, Ruston said:

Mind if I pull up a chair and watch this one? I do like a Manning Wardle and this build looks very interesting...

 

Feel free, but don't expect it to be quick! I am aiming to get as much done this summer as I can before September comes and I'm back to work....

[jdb82]

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.

 

 

 

[chris p bacon]

14 hours ago, jdb82 said:

Just as well I had a spare fret!

I do my rods as laminates and put lots of spares on the fret for this reason.

 

I'm interested in your casting as that's the next learning curve for me.

[jdb82]

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.

 

Edited August 15, 2021 by jdb82

[Timber]

wow amazing work.  The additional 3D printed inner hornblocks is a nice touch.

 

I will be interested to see how the boiler fits within the chassis.  On my drawing (something that is probably incorrect) the boiler appears to sit below the top of the frames....interested in your perspective on this.

 

really nice work.

Edited August 16, 2021 by Timber

[jdb82]

3 hours ago, Timber said:

wow amazing work.  Thwe additioonal 3D printed inner hornblocks is a nice touch.

 

I will be interested to see how the boiler fits within the chassis.  On my drawing (something that is probably incorrect) the boiler appears to sit below the top of the frames....interested in your perspective on this.

 

really nice work.

 

Must admit that on the drawing I worked from it looked as though it sat just above the chassis, but it was close - difficult to tell accurately. It should look OK I think.

 

[Izzy]

I don't have any of the drawings I used to make mine anymore to check, but the boiler was 2'9" dia.

[Timber]

Looked again.  JDB is correct.   Lovely job.

[jdb82]

16 minutes ago, Timber said:

Looked again.  JDB is correct.   Lovely job.

 

That's a novelty......according to my wife I'm not right very often.

[jdb82]

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!

 

 

Next up was the front buffer beam. Looking at photos, most i-class prototypes seem to have a thick-ish layer of hardwood 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.

 

[jdb82]

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!

[jdb82]

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. 

 

 

 

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.....

[doilum]

Watching with real anticiption.  There is room for the inside motion. There is room for a motor gearbox. There will be room for some type of current collection. Whether there is room for all three at the same time.......,...

[jdb82]

3 hours ago, doilum said:

Watching with real anticiption.  There is room for the inside motion. There is room for a motor gearbox. There will be room for some type of current collection. Whether there is room for all three at the same time.......,...

 

 That's why I'm working on the body at the moment! The gearbox I think is going to have to be from scratch as I haven't managed to find anything that will fit the space, as well as accommodate the 3/16" axels. HighLevel's Hump Shunter fits the space, but not the axels. So if anyone knows a good source of suitably sized gears, please let me know! I've restricted myself with the size available for the gearbox by hiding it in an enclosed ashpan, but with the chassis frames being so skimpy, I really didn't want to see bits of gearbox through the sides.  I'll probably either etch or laser cut the framework for the gearbox for accuracy. 

[Izzy]

It’s unfortunate the axles aren’t 1/8”. I have just recently reworked my old I along with a Hudswell Clarke and a newly made L to fit HL roadrunner+ 60-1’s to the 1630’s used. Previously they had home produced DR 80-1’s but the HL’s are totally silent, useful when installing sound…. Sadly it doesn’t appear there is the meat to bore the final drive gear for 3/16”. 

[jdb82]

7 hours ago, Izzy said:

Sadly it doesn’t appear there is the meat to bore the final drive gear for 3/16”. 

 

Indeed not....that what what I was hoping for, but not so. The gears used in the HL box are 0.4MOD, which are available elsewhere with a 4mm bore, which would still need opening out a bit, but might be possible. This however would be for a 40T spur gear rather than the 20-something provided, and so would need the framework adapting. Not sure I would back myself to do that accurately enough to mesh well, without producing a new set of etches which I don't really want to spend the money on right now.