Garden Railway Forum

I've been quietly beavering away at this project for a couple of weeks but it's at last taking shape. As a long term fan of the Southwold Railway, I have always fancied modelling at least one of the Southwold's six wheeled coaches. A combination of 3D printing and more conventional modelling techniques .....
. . .
Clearly there's still more to do, but most of the time until now has been spent on trying to get the Cleminson six wheel undercarriage modified so it will successfully negotiate the tight curves on my railway. A series of trial and improvement experiments required me to move the two pivoted outside single-axle bogies inward by 35mm and widening the centre sliding truck by 15mm each side. Not perfectly prototypical, but at least it works! . . .
Watching the centre wheelset sliding in and out as it negotiates the curves is quite fascinating. I still need to add some compensation to the end pivoting trucks to keep the wheels in contact with the rails over my uneven trackwork - that's quite a long wheelbase - but I've got a couple of ideas as to how I might do it.

All good fun!!

Rik

That looks a tidy build of the carriage and interesting way of making the wheels follow the curved track. I have thought about trying to make a Cleminson system but never got round to building one.
Perhaps when you have sorted out all the problems I might?

Rik

That looks fantastic!

It looks very even and symmetrical, square and straight - particularly considering the number of openings in it. So how did you achieve that - and which bits were 3 D printed?

The Cleminson undercarriage looks good as well. I have made them before in 4mm scale using thin brass sheet to act as springs and the bogies - but that was many years ago.

The printed springs on the wagonette actually spring so I wonder if all the axles could actually be sprung using printed springs and the axle boxes sliding as per full size? I have thought about doing that for 4 wheel coaches.

Trevor

ge_rik wrote: ↑Tue Nov 24, 2020 9:26 pm I still need to add some compensation to the end pivoting trucks to keep the wheels in contact with the rails over my uneven trackwork - that's quite a long wheelbase - but I've got a couple of ideas as to how I might do it.

I did detail my compensated 4-wheel van a couple of years ago

With slight modification it might help with your coach - which looks magnificent by the way.

https://gardenrails.org/forum/viewtopic ... ls#p134177

Thanks Philip.
That van looks magnificent. I've been thinking along similar lines re compensation, though mine will be a simpler arrangement initially. I might refine it if it works out ok.

Rik

Wow! That's really impressive Rik, it really captures the charm of the originals, and will look great on your line - how long before we get to see it with your Southwold tank and van?

I've never thought of it before (maybe I've never looked at the originals closely enough in their original open-balconied format?), but wouldn't a 3 (or 4, or 5) window version make a lovely tramcar-style 4 wheel carriage? Could you be tempted to try is as a "might have been" Rik - the Wisbech and Upwell had 4 wheel and bogie versions of its carriages after all, and that's "honorary narrow gauge"?! Actually, if you're going down that route you'll have to build one that incorporates a bar...

Andrew.

Andrew wrote: ↑Wed Nov 25, 2020 9:25 am Wow! That's really impressive Rik, it really captures the charm of the originals, and will look great on your line - how long before we get to see it with your Southwold tank and van?

I've never thought of it before (maybe I've never looked at the originals closely enough in their original open-balconied format?), but wouldn't a 3 (or 4, or 5) window version make a lovely tramcar-style 4 wheel carriage? Could you be tempted to try is as a "might have been" Rik - the Wisbech and Upwell had 4 wheel and bogie versions of its carriages after all, and that's "honorary narrow gauge"?! Actually, if you're going down that route you'll have to build one that incorporates a bar...

Andrew.

Thanks Andrew
Still a bit more work to do but, as most of the fiddly stuff has been 3D printed I could make a rake of them. Just trying to decide if I should make a closed-in version as they were later modified. I prefer the look of the original balconied style, though.

I had wondered about shortening the coach to make it easier to negotiate my tight curves and somehow keep faithful with the originals. Not thought of a four wheeler. I like the idea. I've always fancied making a Directors' Saloon, so that could be a good reason for a shorter model...

Rik

Oh my, that really is a lovely coach!

I'm looking at the photographs, and I can certainly guess some bits that were 3D printed, but I'm curious how much was "conventional" modelling and which 3D parts were printed together and which separately and then assembled... Did you take any intermediate photos that would provide more clues?

SimonWood wrote: ↑Wed Nov 25, 2020 11:03 am Oh my, that really is a lovely coach!

I'm looking at the photographs, and I can certainly guess some bits that were 3D printed, but I'm curious how much was "conventional" modelling and which 3D parts were printed together and which separately and then assembled... Did you take any intermediate photos that would provide more clues?

Hi Simon
The majority of visible parts are 3D printed but some parts of the chassis are plasticard. I could have printed things like the floor but it seems unnecessary to have a couple of of large rectangular flat surfaces printed. I'll make the roof from plasticard as well and the railings and curlicues on the balconies will be metal. They'll be too susceptible to damage if I try 3D printing them.

This coach is very much a prototype. I knew I'd probably need to do a fair bit of tinkering to get it to take the tight curves on my railway. I now need to go back and adjust the drawings for some parts, particularly the undercarriages, but also I will probably make aligning the various body parts a bit easier. This is one of the things I like about 3D printing. Not only can I learn by making the first one, I can now improve on the drawings to make assembly of subsequent models easier.

I'll then blog the build with step by step photos.

Rik

ge_rik wrote: ↑Wed Nov 25, 2020 1:04 pm The majority of visible parts are 3D printed but some parts of the chassis are plasticard. I could have printed things like the floor but it seems unnecessary to have a couple of of large rectangular flat surfaces printed. I'll make the roof from plasticard as well and the railings and curlicues on the balconies will be metal. They'll be too susceptible to damage if I try 3D printing them.

Thanks Rik, I guessed the floor and parts of the...what do we call them on Cleminsons - not bogies presumably?

The blog post will be a good read, as ever. Look forward to that!

SimonWood wrote: ↑Wed Nov 25, 2020 1:12 pm Thanks Rik, I guessed the floor and parts of the...what do we call them on Cleminsons - not bogies presumably?

The blog post will be a good read, as ever. Look forward to that!

I've seen them referred to as 'trucks', but even that doesn't seem the most appropriate term.

Rik

Hmmm.... this is more of a conundrum than I thought. Six-wheelers throw up problems I've not had to contend with before - especially as the coach has a long wheelbase. I added domed washer compensation to the outer two 'bogies' and it coped well with slight variations in the track - but then I encountered another issue - gradients! I have a couple of 1:40s on my railway and there's one particular summit which is quite pronounced. I eased the bolts on the bogie mounts to allow the outer bogies to drop down to keep the wheels in contact ...... ..... but then ran into another problem at the bottom of the slope. I think I'll try mounting the middle wheels lower than the outer bogies and see if I can ease the bogie bolts a few more millimetres to allow them to rise as well as fall. I might have to put some weak springs on the bogie pivot bolts to keep the wheels in contact and also to stop the coach from rocking like a see-saw on the centre axle!

OR..... I might end-up fixing the two outer bogies (but still allowing some compensation for uneven track as per Philipy's suggestion) and seeing if I can find a way of making the centre axle float up and down, while also allowing it to slide from side to side on curves.

All good fun!!

I can see why six-wheel coaches were replaced with bogie coaches on real railways - they cope far more readily with uneven track.

Rik

Getting interesting this. I think you are correct in trying to get the centre axle to float up and down, which means the wheels could lift through the floor level. But looking at the pictures of your inverted carriage it seems the wheels extend beyond the outside of the bodywork when at maximum radius curvature.
This idea might work on 32mm gauge but possibly not 45mm?

Peter Butler wrote: ↑Wed Nov 25, 2020 6:47 pm Getting interesting this. I think you are correct in trying to get the centre axle to float up and down, which means the wheels could lift through the floor level. But looking at the pictures of your inverted carriage it seems the wheels extend beyond the outside of the bodywork when at maximum radius curvature.
This idea might work on 32mm gauge but possibly not 45mm?

The only thing I can do is raise the outer bogies and hence raise the whole coach - which might make it look a bit odd.....

There is space within the underframe but, as you say, the centre 'bogie' has to extend beyond the edge of the underframe to allow it to swing out on tight curves. I suppose I could rebuild the railway to get rid of tight curves and gradients ......

Rik

ge_rik wrote: ↑Wed Nov 25, 2020 6:30 pm and seeing if I can find a way of making the centre axle float up and down, while also allowing it to slide from side to side on curves.

Back in my P4 days, we used to allow the centre wheels on a 6-wheeler to float in all directions by fixing two fine steel wires ( guitar strings actually) through the brass frame of the centre axle and allowing them to float freely through holes in both end wheel frames ( one fixed, one rocking) . The centre axle was then constrained with stops on all 4 sides to prevent it moving too far. Never tried it on a Cleminson but in theory I can see it being bodgable.

I found this thread on RM web. Not sure if it helps but near the end someone has a system using wire as compensation for the axels. Not sure if some of the concepts could be borrowed?

https://www.rmweb.co.uk/community/index ... s-drawing/

Ps I now really want to make a 3wheeled milk tanker for no particular reason...

Thanks chaps. All this talk of piano wires and guitar strings reminds me of my 00n3 days when I constructed a Southwold Cleminson 6 wheel open wagon and used a similar though very much simplified system to Philip's.

But I think I've cracked it overnight, well theoretically anyway. Furthermore, I think I can use some existing printed parts - ones I rejected because their dimensions were wrong.

Problem 1. Raising the centre axle without sacrificing the sliding mechanism. I can do this simple by replacing the existing axle box/ hanger assembly by one where the bearing holes are higher in the axle boxes. I'll need to cut a slot in the bearing plate under the carriage chassis but, as long as the flanges stay within the boundaries of the solebars, it should work

Problem 2. Allowing the centre axle to float up and down without fouling the sliding mechanism. I can get round this by replacing the four L shaped retaining brackets with taller ones. Again, I got the dimensions wrong initially and printed four taller ones earlier.

Problem 3. Adding compensation to the outer bogies. I think I can get away with a simplified version of Philipy's suggestion. I already have a large 'washer' which I can use for the laterally 'rigid' bogie and then print out a triangular strip to sit on top of the rocking bogie.

I'll give it a try later and let you know the outcome

Rik

Seems you've dialled that printer in quite well Rik! Fantastic work

I like Philips solution. It is am elegant engineering solution to the problem. As I understand the Cleminson principle it requires springs to hold the axle trucks central under straight track conditions. This solution provides that.

I also made 6 wheel coaches in my 4mm scale days and here are the underneaths of a couple of coaches I built 45 years ago: This solution limits the way in which the middle axle overhangs the bodywork - by effectively making each axle take half of the overhang.
This is effectively a bogie and a half solution. You can see where the two brass frames pivot, each about a third from the end of the coach. They are linked together by the half bogie pressing against the carrier for the middle axle.. Two axles are on one bogie and one axle on the other. Track undulations are catered for by the rather flexible brass shim which is deliberately bent to act as springs for each axle. The result runs well.

This is a slightly different realisation of the same principle:
In this case the bogie is allowed to rock to let the axles rise and fall but prevented from twisting sideways so that the coach doesn't rock from side to side.
The half bogie is allowed to rock freely so that the axle can rise and fall and twist sideways.

Both of these coaches run well - and I think this solution overcomes the issues inherent in the Cleminson principle which make it difficult to model accurately!

Of course what you can do when you are working in 16mm scale can be much more adventurous!

I have already drawn up "W" irons, axle boxes, and springs in sketchup. If you want to try to get them to compensate as per full size I can send you STL files for you to print. If you want to experiment I can easily send them, or modify them to your dimensions and send them.

Trevor

Thanks Trevor. I've already drawn (and printed) the W irons and axle boxes, so am just awaiting the printing of the modified centre 'truck' (5 hour print job) before trying it out. I would have re-used the old truck but the glue holding the old W irons was stronger than I thought!

Rik