Nick Dunhill's workbench CR 0-4-4T Wrexham Tanks

simond

Western Thunderer
Hi Simon
I'm interested to hear your thoughts as I've not had the 0-4-4T conundrum yet. I simply have to fix the driven axle and the front axle will be sprung downwards but sit on a bump stop. I really dont want to go down the route of making rocking beams as I'm determined to stick to the GA as close as money will allow. I'm going to put all the lead in the front of the boiler between the drivers. If I experiment with a suitable spring on the bogie pivot I'm hoping it doesn't wheelie. As you said the Springside 14XX was all cast WM and heavy at the rear, this is all brass sheet.

Hi Nick,

if you can convince it to run as an 0-4-0, and just take the bogie (perhaps lightly sprung) along for the ride, it should be ok on decent track. But I do think that things will become rather lively if it’s sprung at both ends, with a fixed axle in the middle.

you’re absolutely right about the 48xx being a bit tail-heavy...

Atb
Simon
 

Nick Dunhill

Western Thunderer
Hi JB.
The front drivers will ride on the stops and be down. I use similar springs to you for the hornbills, but I'd better use the links above to get some springs for the bogie pivot so I can experiment.
 

Isambarduk

Western Thunderer
... I forgot to get the axles machined.
Not to worry, Nick; they are now ;)

AxlesTurnedDown.jpg

Standard Slater's 3/16" diameter axles before (left) and after turning down to 5/32" diameter (right)
I have have written up 'How I did it' on the G0G Forum, and I'll transfer it to my website in due course, but I won't bore you with it here nor hijack Nick's thread.

David
 
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Isambarduk

Western Thunderer
I resolved that one by a single point rocking pivot for the trailing axle and twin beam compensation for the drivers.
Fair enough, Simon.

GWR_48xx.jpg

The Springside 48xx was one of my first kit-builds but I could see that the arrangement as designed was unlikely to be up to much. I elected to have a rocking beam between the axle-hung motor/gearbox and the rear axle (with a weighting bias towards the driven axle); the leading coupled axle was fixed. I wouldn't do it that way today, I would spring all round.

David
 

Nick Dunhill

Western Thunderer
....this week I have added the couplings. The couplers were kindly supplied by CPL. They sent enough castings to make the Cambrian style 3 link couplings with the top loop pinned to the hook. Luckily there were enough parts to make a pair of loose screw link couplings too, as pictures show both locos with loose screw links on the hook. The first job was to reprofile the cast CPL hooks to look more like the CR ones.


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Then the different styles of chain were made.


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The drag box for the rear hook is the structure under the cab that supports the frame and bogie, so a long shank was made by splicing the cast CPL coulper to a rod that was threaded on the end.


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The front drag box is just the front buffer beam slightly armoured up with angle and gussets.


I then moved on to the brake cylinder and plumbing for the train pipe.


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I even made a good start on the train vacuum pipe that runs under one side of the footplate until the lure of libations in the bank holiday sunshine got the better of me.


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Enjoy the sun............
 

Nick Dunhill

Western Thunderer
.....This week I started by finishing off the vacuum pipe on both models. It's always complicated by having to keep an eye on how the body and chassis will separate when finished! (Some modellers are obsessed with taking their models to bits and use thousands of machine screws.)


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Next I thought it'd be a good idea to add all the splashers for the bogie. They took a while to fit, and I also scratchbuilt mounting brackets for them which can bearly be seen.


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And after I'd done that it seemed logical to add the water tank balance pipes.


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The bogie wheels turned up (they'd gone to visit someone with a lathe who kindly decreased the axle diameter, ta DLOS!) and I duly put them in the bogie. I had to cut some wheel shims to limit the end float.


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So, will the wheels short out on the splashers, and will I have to mount the splashers on the bogie? The only way to find out will be to test it later.


I decided that if I was to fit the driving wheels (to test the above) it would be prudent to make the firebox lower and ashpan first, as the motor and gearing will be contained within......and I like fabrication jobs like this!


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This is how I make an accurate box. Firstly cut the pieces out very accurately, using a square to check all right angles, and then tape the pieces to a machined block. I tack them first then soldering up off the block.


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Then I cut out the pieces for the ashpan. As more bits are added the fabrication becomes stronger.


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This is roughly where the idler gear will sit inside the structure. I'll cut a slot in the front so it can protrude and engage with the gear that is a crank web.


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More fabricating next week.........
 
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