MNR Cleminsons

[Northsider]

Rather than hog space on 'What Happened on your Workbench?', I thought I'd start a separate thread.

Having produced CAD drawings, the first stage is to run off some test cuts on the laser cutter. These are in card: cheap and expendable:


These showed a few minor errors, which were corrected. Then the 'proper' cuts, using what has become my usual method: 2mm MDF for the inner sides; a skin of 0.8mm ply and (unusually) beading cut from thin card. Once cut, the surface of the ply and the card were sealed:



After a light rub down with 400 grit wet or dry, they were given a mist coat of primer:



Beading was glued to the ends, as these will have solid colour; the sides will be off-white over purple lake, so need painting before the beading i sfitted.
Using a fine brush, thinned PVA was applied to the beading, and the faces closed and clamped.





The MDF carcase was then glued up and clamped, and the primer on the sides lightly sanded:

 

[Paul M]

Looking good. Out of experience I now know trying to paint beading a different colour to the rest of the coach AFTER its been fully assembled, isn't the best of ideas!

 

[Northsider]

Looking good. Out of experience I now know trying to paint beading a different colour to the rest of the coach AFTER its been fully assembled, isn't the best of ideas!

Yes, I'm with you there! It's a fiddly job whichever way you do it, but some ways are easier than others...

 

[Northsider]

The first job today was to glue the outer skin onto the MDF carcase:

...which used up pretty much every clamp in the workshop! Then, after some careful marking out (centre line, spacings) the roof ribs were glued in place on a piece of 0.8mm ply which had been cut to the right size for the roof. The ends were glued on, too:


The assembled body shows how austere these carriages were:



Then a second (slightly wider) piece of 0.8mm ply was glued to the roof, and the floor was fixed in place. Another couple of hours will see paint, grab and door handles, and windows, fitted. The next stage is the unique bit: to make a working 6-wheel chassis, based on the Cleminson principle. Materials have been ordered...

 

[Paul M]

It's a fiddly job whichever way you do it, but some ways are easier than others...

I can assure you that the way I'm doing it is not the right way to go about it

 

[Northsider]

The roof has been covered (old cotton sheet), and the spilt milk paintwork applied, rubbed back and top coated. The lower panels have had their first coat of purple lake, and have been flatted off; I quite like the look -probably how they appeared in the 1920's!



While that's going on I've started mocking up the Cleminson mechanism for the two outer wheelsets and the middle, radial, truck:

 

[Northsider]

Someone on this forum recommended using a sponge to apply PVA to the frets; it seemed a bit high-risk (what if the glue got on the front surface?), so I had a practice using the test cuts I'd made in card. The fret was a bit fragile, but went on OK

so it was time to try the real thing. They had already received a coat of paint (two on the upper parts, as I won't be able to paint these easily once fitted) and the paint had stiffened the card, making it easier to fit:

I had also fitted rivet detail to the solebars, and painted them. The lower half of the carriage body now needs its final coat of paint.

 

[Paul M]

as I won't be able to paint these easily once fitted
[/QUOTE]
I know by bitter experience! Still doing my way is character building

 

[Northsider]

Paint is now finished, so there are seats to make and external detailing to fit;

but I've also started thinking about how to achieve the Cleminson chassis. This has the two axles at each end mounted on a pivot (a two-wheel bogie, rather like the LGB ones), with a bar attached (via pivots) to the centre set of wheels which move side-to-side across the underframe. So a quick mock-up was in order


I then took leave of my senses, and decided to use a bearing block with two vertical pins running in a track that run across the coach floor:


which meant I got to use my lathe but was in every other way unsatisfactory. So I went back to the prototype and made the wooden frames, with proper joints and everything

The IP Engineering axleboxes aren't correct, but that is one rivet I'm happy not to count...

 

[Northsider]

The frames proved to be too narrow, so a new set was made from 8mm square pine; the connecting bars were then marked, measured and cut from some old imperial stock, 1/16 x 1/2" mild steel -1.6.x 13 in new money. The 'bolts' are 10 BA studding with nuts and washers. Photos show the Cleminson principle: the sliding centre truck 'steers' the out two into any curve:


The two pine strips keep the centre truck perpendicular to the carriage centre line:

Meanwhile, work on the body has also progressed, with windows, interior panelling and seats being fitted, along with door handles and decals for the exterior:

 

[Rhinochugger]

Looking good - apparently the Southwold carriages used to creak and groan quite a lot as the centre truck moved, especially as they got older, a bit like me

 

[Monty]

Beautiful!!!!!!

 

[Northsider]

The axleboxes on the Manx ones ran hot -they had a sponge soaked in oil in them. When the MNR complained the factory fix was to swap hay for the sponges. What is amazing is that virtually all the 6-wheeled coaches lasted into the 1970's, despite being virtually unused since the Great War, and being left outdoors.

 

[Rhinochugger]

The axleboxes on the Manx ones ran hot -they had a sponge soaked in oil in them. When the MNR complained the factory fix was to swap hay for the sponges. What is amazing is that virtually all the 6-wheeled coaches lasted into the 1970's, despite being virtually unused since the Great War, and being left outdoors.

We really do not understand the extent of technological change in the last 100 or so years. I have often suggested that it was my parents' generation that witnessed the greatest upsurge in technological change. While our generation may well see the same, or even more, we are better prepared for it

 

[Northsider]

Now there's always scope in this hobby for a pratfall, such as dedicating time and effort to scratch-building a carriage without knowing if it will negotiate the sharpest curves on your line...

About 4ft radius in my case...and no, it didn't. Having read about attempts to build Cleminsons in other scales, I knew weight and/or springing was needed to keep the middle pair of wheels in contact with the rails, but I was pretty certain the problem was mainly due to a lack of lateral movement in the centre truck. So the centre truck was removed and the frame sides reduced by 3mm on each side. The rivet shanks on the inside of the solebars were trimmed right back, too; and then for good measure a piece of 5 x 40 mild steel flat was bolted to the top of the truck. Success!


Which leaves couplings, handrails and footboards to fit...

 

[ge_rik]

Brilliant! A clever reinterpretation of the original design. As a keen Southwold fan (see my avatar), I was really interested in seeing how you would tackle the undercarriage.

Rik

 

[Rhinochugger]

........................ I was really interested in seeing how you would tackle the undercarriage.

Rik

 

[Paul M]

WE all know what he meant

 

[Northsider]

Brilliant! A clever reinterpretation of the original design. As a keen Southwold fan (see my avatar), I was really interested in seeing how you would tackle the undercarriage.

Rik

I tried all sorts of things in planning, but in the end opted for a fairly close copy, but with an emphasis on being robust. I'm quite surprised by how it turned out, to be honest.

 

[ge_rik]

I tried all sorts of things in planning, but in the end opted for a fairly close copy, but with an emphasis on being robust. I'm quite surprised by how it turned out, to be honest.

I suspect that those little linkages between the end units and the middle section are quite important.

Rik