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BR Caprotti Crosti Standard 5

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Mention is made in a couple of books of the plan to combine Caprotti valve gear and the preheater Crosti boiler in variants of the Standard Class 5. In the event, these were never built partly because the 9F Crostis were hardly an unqualified success. In fact, not a success at all...... It was therefore felt that the potential efficiencies from the boiler and valve gear combination would never arise in practice.


So here we go.....


I've come across 2 drawings of this: one in the Edward Talbot book on Standard Steam (vol 1) and one in the RCTS Standard Steam vol 2. Some of the raw materials for the project are pictured with the drawing from the RCTS book.




A few years ago I attempted to build a Crownline Caprotti Standard 5, and hit a few obstacles that I wasn't skilled enough to overcome. So I have a chassis, with Romford wheels. It rolls freely with the rods on, which is a start.

Because of my epic lack of success thus far fitting pickups and making simple chassis work, I've got options with this. Either I will use a Hornby BR standard tender drive chassis and power it that way, or I will eventually motorise the loco chassis, or I'll leave it as a static loco.


The front of the cab is different to the normal standard 5, and the running plate is lower.




So it made sense to cannibalise an old Hornby Britannia body - simply adjusting the profile of the front of the cab.


Remove the firebox, boiler and smokebox, then shorten the running plate.




The Crownline kit had a resin firebox, boiler and smokebox supplied, I was fairly sure I could use the firebox section, and fixed it accordingly.




I then played around a bit with possibilities for representing the rest. I think, but I'm not sure, of the following, if this thing had ever been built:


The main boiler looks parallel on the drawing but it isn't - it's just pitched higher so the chimney and dome are much shallower

The taper of the boiler is actually more on the bottom (does that make sense?)

I think this is clear when I tried a piece of 22mm plastic pipe as a potential parallel boiler:




So it's a case of changing the angles between firebox and boiler, and between boiler and smokebox. This was achieved by cutting and rejoining.






So a start made....



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You are a brave man, Iain!

This looks very interesting and I'll look forward to seeing the results.

I love a good "might have been". There is one good thing about doing this sort of project, too ... that is, no one can say you got it wrong if you have to bodge something as you go!! (Not that you will have to do that, of course!) :D

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  • 1 year later...

I've made a bit of progress with this. It's been a bit of a test bed for learning some new techniques, and partly as a result, it has a fully functioning chassis.


The Crownline front bogie etch was very narrow, light and lacking in detail. It also had a swing link that was the wrong shape and size. So I recycled a Hornby spare Royal Scot mounting and added scrap brass, plastic and some extra mass.




Body and chassis together. Crownline Caprotti gear was chunky so I made my own.




Test fit of an old Golden Arrow crosti side chimney that I had spare. The main chimney is a Craftsman 9F spare, which is fractionally too big.




Replaced part of the faulty casting with copper wire, and added the tender, which is a Bachmann BR1F spare top on the Crownline chassis, with Comet steps, sieve boxes from I don't know where, Gibson buffer and a few bits of wire.




Some steam pipes, lubricator bracket added, and tender chassis painted.




Scratchbuilt reverser (copied from the drawings as far as I could), front steps and more steam pipes. A remnant from the DoG Caprotti gear recycled. At some point I added the handrails too.












I'll chip away at this a bit from time to time.



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Clack valves and pipes added - 5A fuse wire wound around the front rhs one.

Scratchbuilt smoke deflector from a piece of 5 thou brass sheet. I've tried to add bolt heads for the mountings, plus scribe the hinged flap for access to sandboxes. It's attached to a plastic base and placed in position - will be painted separately before final fixing.

Steam lance cock from a handrail knob and some 5A fuse wire.

Handrail by main chimney

RHS Injector pipework.


All of this has been good practice for a few skills, and if I get things slightly wrong, at least there isn't a prototype to compare it to.









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  • 2 weeks later...

Thanks Baz/Phil/Corbs.

I'll grant you it's definitely not the most elegant loco. It's been quite fun and interesting to build, and I've used it as a way to use a load of otherwise redundant components and to learn a few more skills. It runs too. Which, given where my chassis-building skills were a few months ago, is a bonus.


Below is a phone pic of the more detailed drawing of the proposed loco, from the Talbot book on the BR Standards. Hopefully it looks as if I've got somewhere close to getting that design captured correctly.




I'll paint it when I get decent enough conditions. I'm assuming it will be lined black as a mixed traffic loco, though eventually, it will be weathered enough hardly to show the lining. 73274.



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  • 2 weeks later...

Apart from the front coupling, weathering, crew, lamps.......so it's not really finished. Maybe nearly finished?


Runs ok too. I fitted tender pickups again, which helps smoothness I think.
























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  • 2 weeks later...
  • 1 year later...

I tak


Apart from the front coupling, weathering, crew, lamps.......so it's not really finished. Maybe nearly finished?

Runs ok too. I fitted tender pickups again, which helps smoothness I think.












I take it this engine is built for heavy mixed-traffic work?

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