4mm The Sentinel (and derivatives) in EM

Discussion in 'Area 51' started by AJC, 2 November 2012.

  1. AJC

    AJC Western Thunderer

    Well, a Thomas Hill at any rate. The real things were developed from the 0-6-0 version of the Rolls Royce Sentinel DH (itself developed from the chassis of a steam design produced for Dorman Long*), but with a better, taller cab and improved access to the 350hp Rolls Royce engine for maintenance.

    Among all the messy soldering is something that was meant to be a quick build and it was, mostly, and then the Cricket season took precedence over fitting the handrails. I've now run out of wire to finish these so it's back in the box waiting for a length of 0.4mm brass - yes, the difference between that and 0.45 is noticeable... A Judith Edge kit built, unusually for me, more or less as it comes from the box which is a testament to the fact that this is a straightforward, well-designed kit with reasonable instructions and a nice drawing which made working out the motor/gearbox combination easy. Full compensation is designed in and was easy to build and there's even space in that big bonnet for a flywheel on the end of the Mashima 1420 as well as the ballast I've yet to add. There is lots of space under the skirts and inside the body and even in the cavities of the chassis if that proves necessary.

    Thomas 001.gif

    The handrails are not nearly as fragile as they look - I've cheated slightly in the cause of durability and soldered the toe boards to the footplate: there should be a small gap. An earlier Hunslet from the same source suffers soldered joints on less substantial handrails which go 'ping' at every opportunity.

    Thomas 003.gif

    A tip - while the etch was flat, I used the cab sheets as templates to scribe out two sets of windows. The frames will be left until after painting since they were almost invariably left bright aluminium or, in this case, tinned brass.

    Thomas 005.gif

    A bit of filler will be required in the cab/fuel tank joint I think. Almost certainly builder error...


    * Mike Edge has been threatening the steam 0-6-0 for years purely because he likes the prototype - there was an articulated 0-6-0 + 0-6-0 version as well and some rather stylish, but apparently rather useless, fireless locos on the same chassis.
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  2. Pugsley

    Pugsley Western Thunderer

    Very nice. I can't wait to crack on with my 7mm Sentinel, but I have told myself that I must have the 37 finished first!
  3. AJC

    AJC Western Thunderer

    Is it the 0-6-0 version you have Pugs? I think I have some cab interior shots somewhere and in 7mm, the cab heaters (a pair of domestic radiators) have to go in, especially since the very few shots of the real thing show them in operation without at least one door open. ;)

    I'll admit a bit of a thing about Sentinels - they had a very stylish approach to design and marketing and were quite imaginative technologically and ergonomically even in their steam days. I've got one of Roger Slade's S&D Sentinels in the to do drawer once this is done though this will be 'industrialised' rather than built as a 'mainline' loco.

  4. Dave

    Dave Western Thunderer

    Any more progress on this?

    The most powerful (in terms of tractive effort) industrial steam loco ever to run in the UK, according to the article in the latest Industrial Railway Record.
  5. Rob Pulham

    Rob Pulham Western Thunderer

    Like a few others on here I have a thing for Sentinels and I have a Meteor kit in the pile that will be the LNER version when I build it.
    I have also been doing some research on scratch building a Y10 which is the double ended version that was originally built for the Wisbech and Upwell Tramway albeit not very successfully. One or two fellow members have assisted with this research and I am grateful for the help. In anticipation of building both versions I have had these etched by Steve at Narrow Planet.

    Axle box etches.jpg

    The three parts solder together to give the quite distinctive axlebox covers.
    Ressaldar, AJC and Dog Star like this.
  6. Dikitriki

    Dikitriki Flying Squad

    And there was me thinking it was a tax disc holder.
    Rob Pulham likes this.
  7. AJC

    AJC Western Thunderer

    Hi Dave, Rob. There has been, but I've been away for a few days and am currently on the way home so you'll have to wait for pictures. The main cab/bonnet/fuel tank assembly is complete and in primer so looks much the same but in grey! Otherwise, I've completed the handrails and test run the chassis which, barring a now-cured tight spot resulting from the fact that one of the rods was a sliding fit with no play at all: a couple of turns with a taper broach later and all was well. It's surprising, by the way, how much effect the flywheel has, even coupled to a 108:1 gearbox on scale 3' 6" wheels. With a bit more weight in there, running should be pretty good. Final fixing of retainers is the next job, along with securing the motor and adding pickups.

    If all else works out, it'll be time for the paint shop. This will be modelled as a fairly new machine - it's only just appropriate for the period I model - so it'll only get a little weathering.

    Those 'Sentinel' axlebox covers really look the business Rob. Most impressive.

    Rob Pulham likes this.
  8. Dog Star

    Dog Star Western Thunderer

    Surely no need - a heritage vehicle.
    AJC, Rob Pulham and Simon Dunkley like this.
  9. AJC

    AJC Western Thunderer

    Entirely believable - I believe the thing weighed in at about 90 tons and was the better part of 50 feet long! You'd hope it would have the power to match.

  10. Pugsley

    Pugsley Western Thunderer

    Yes, it is the 0-6-0 version - I'm quite looking forward to building it, eventually. I'd be interested in seeing your interior photos - they'd definitely help with detailing the cab.

    The axleboxes are looking good!
  11. AJC

    AJC Western Thunderer

    Just to show that this hasn't been forgotten. I managed to grab five minutes to fit some pickups last night and, while I still haven't wired these to the motor, I have primed the wheels and rods. Both will be red in case you're wondering.


    I've also waved some primer at the cab interior module. This is per the kit with a modified Airfix - the genuine article, slightly adjusted - railwayman and yes, I have allowed for the piece of 20 thou' this is mounted on and adjusted the height of both to suit.


    It's a real swine to photograph. Goodness alone knows what he's looking at... Probably the Roger Slade Sentinel which I've managed to start for some reason. More of that anon.

  12. AJC

    AJC Western Thunderer

    Leaving the Thomas Hill where it is for the moment, waiting for a change in the weather and an airbrush, I mentioned above that, in a moment of weakness, I bought one of the newish CSP kits for an S&D Sentinel. Not, I should add, because I’m a particular fan of the S&D; it was an interesting railway, no doubt, but being bought up in Somerset, I’ve seen plenty of it in model form. That said, the kit does represent a type that Sentinel built for industry in a variety of forms and there is one still working in Brazil. The kit as it comes looks very good; nice etchings and some lovely brass castings and lots of instructions with isometric exploded drawings (in colour) as well as motor, gearbox and a set of spur gears to drive both axles. Here’s even a bit of copper clad and phosphor bronze wire in there. This is the only kit I’ve ever built where pickups are designed in. There’s a run down of this and a build as the maker intended over there and very nice it looks too.
    Of course, I couldn’t simply build the thing out of the box now could I?
    What I’m after is something that looks a bit like this:


    Sentinel 9569 of 1954 seen here derelict at Cynheidre Colliery in south west Wales in 1969. Not in quite that condition, obviously: I’m leaving the boiler in on mine. The other side looks like this:


    From the same batch, 9572 of 1954 again derelict, this time at Pontardulais. Anyone know exactly how many of these the NCB bought in south Wales?

    Of course, what the kit gives you is this:


    This is where Sentinel’s tendency to evolve their designs comes in useful. What was basically the same design, mechanically at least, was continued until Sentinel became part of Rolls Royce and went out of steam production and this, the ‘200hp’ version was reasonably popular though only three survive worldwide, at Midsomer Norton, ex-Croydon Gasworks, in Brazil and, the sole post-war representative, at Henllan in Carmarthenshire at the Teifi Valley Railway. Now the tin work is a bit different I grant you, but there are some other things.

    Here’s a run down of the differences:

    · ‘Bonnet’ – obviously, this is totally different, but should be relatively easy to execute in plastic.
    · Cab front – note that the windows are a different shape. Either the existing cab can be modified using scrap etch or a fresh piece of brass cut.
    · Cab – though not visible here, the right hand side of the cab would have had a tall, narrow door and a small vent panel but the rest is the same. I haven't worked that out just yet.
    · Steps – the industrial version, sensibly, has steps front and rear. Note the tread plate on the verticals, a distinctive feature of most steam Sentinels.
    · Guard irons – both front and rear have heft pieces of channel bolted on. Only the front pair of the two S&D locos did.
    · Sandboxes and associated cutouts on the valances. Scratch.
    · Buffers. These would have been the standard short, squat industrial variety with large heads. My guess is that the Cynheidre fitters pinched 6569’s for use on something else. I have a set of these in stock.
    · For some reason, the drive chains are on the LH side of the post war loco. Not a problem.

    Mostly, that’s relatively straightforward, bonnet excepted. More on how I'm getting on later.

  13. AJC

    AJC Western Thunderer

    The kit so far:

    This is not perfect. There are some issues with the size (and subsequently the fit) and design of components and with the instructions. Not that the instructions are bad – they’re nicely illustrated with good colour isometric drawings - but there are part numbers which don’t show up in the text but which do in the text and vice versa and on the etches there have clearly been a couple of attempts at the rear guard irons to get the sizes correct - you are not told which to use though both are numbered.


    Mind the gap. No, the soldering won't win any prizes.

    There are some size errors which have slipped through. I have, for example, replaced both buffer beams because those supplied are too small. I'm not sure why this should be, but the design does build without gaps so it is deliberate! They should be the same width and the footplate and the same depth as the frames but were both 1mm shy. The works drawing in the instructions gives the width as 8’ as does a nice Don Townsley drawing in Model Railways from March 1975. The cab floor is too short (from front to back) and slightly too narrow. I've left the gap at the front since the boiler will be in the way but had to solder some ‘L’ section to the outer frames to correct this. If it weren't for the half-etched locations for other components I might simply have started with a fresh bit of metal here though I note that ‘Buffalo’ on RMweb seems not to have had this issue. Oddly, the hole for the brake standard is on the wrong side of the footplate: it’s right on the isometric drawing! All of this is either easily remedied or doesn't actually show but it is a little puzzling.


    There are also some odd choices in materials – the cab sides are 10 thou’ nickel, for example, which is lovely to work with but because it’s so thick, making good the corner joints on the lower half of the cab rear will be difficult to do without sacrificing some rivet detail. Similarly, the levers in the cab are intended to be laminated from two thickness of the stuff – the real ones appear to be about 3/16”-1/4” thick so this is overdoing it a bit.


    All these are relatively minor niggles since, buffer beams apart, all the visible bits are the right size and I know what I’m doing. Well, I think I do.

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  14. AJC

    AJC Western Thunderer

    Leaving the main body to one side for the moment, I've paid some attention to the boiler. Quite a compact and complex unit on the real thing, it's a bit of a fiddle on the model in that you have to form three cylinders of different diameters and then hope they hold together while you solder bits on. It's much easier to replace the main bit with some tube - I happen to have a length of 17mm brass tube in stock - and use the original wrapper to mark it out. This was a mistake as it turns out since the gauge glass castings were overscale and the holes (to scale) too close together. Still, it looks good so far. A few more castings and lots of copper wire to add...


  15. mickoo

    mickoo Western Thunderer

    Nice little loco, I prefer the one with the bonnet that looks like a Victoria battleship hull cross section LOL, IE as per the one in the kit, shame you cannot get one (as far as I know) for 7mm.
  16. AJC

    AJC Western Thunderer

    And had Sentinel built more than about 6 of them (four for mainline companies, one with a, sorry, two with a pair of cabs, the Y10, for the LNER and two for Brazil), then I might have considered it. It'd be Dapol pug syndrome - there was a time, still not wholly in the past unfortunately, when every 4mm 'industrial' you saw was a Dapol pug. Any recognisably 'mainline' type suffers the same issue. The S&D version was only ever seen working at Radstock so is even more geographically limiting than an SR/BR period Beattie well tank. In any case, the 'boxiness' is what appeals to me. Can't help with 7mm, not my interest.

    The next bit of entertainment is working out how to compensate it...

  17. adrian

    adrian Flying Squad

    Just in from RMWeb
    Website is a bit convoluted and I can't seem to get a direct link to the loco.

    Kit price £175 - RTR £225

    mickoo likes this.
  18. AJC

    AJC Western Thunderer

    After a certain amount of head scratching and a few chats with dad, I've decided to go with plan A on the chassis and try what the kit provides. the reasoning is relatively simple: in EM I wouldn't ordinarily think of compensating anything with a wheelbase as short as this so why should I here? Dad has a Judith Edge Ruston 48DS and that is compensated but it is a lot smaller and, consequently, carries a lot less weight for adhesion - to the extent that dad has made brass sandboxes and headlights for it to replace the resin ones supplied; anything to get the weight up. In other words, the idea is to stuff every available space with lead and be careful with the pick ups.

    If this doesn't work then we can try and get funky later.

    So what does this mean in terms of progress? Well, the basis chassis frame is assembled throwing up some more interesting design and construction challenges. There are errors here which should have been eliminated but they are easy enough to overcome.


    This underside view shows the boiler bottom and ashpan soldered in place. As designed, this is intended to be removeable though I am not entirely sure why.

    What neither of these pictures make entirely clear is that I have taken thin slices off the sides of the subassembly to allow it to fit between the frames. This was done very carefully using a piercing saw and then filing a little to acheive a snug fit. The result is that it now functions as a frame stretcher and this is useful because I shall have to detach the rear of the frames. Why? Well, if you look at the earlier pictures up the thread you will notice that there are two very substantial bits of channel fore and aft acting as guard irons and attached to the outer, cosmetic, frames; basically, you can't actually get the full length, functional, frames under the body.

    This is easily resolved, however, by cutting off the rear assembly which holds the steam brake and handbrake bits and soldering that to the body. This is a very easy mod' but a slightly irritating one to have to do since it should have been addressed in the design phase although, in fairness, I'm not certain that the channel was a feature of both ends of the S&D variety. Still, it's gradually going somewhere and that's something. The next step is adding the brakegear and then making it go...

    Dave likes this.
  19. AJC

    AJC Western Thunderer

    And an update showing last night's work. It isn't the most exciting to look at but you should be able to see the corrections I've made to my own work.


    Note the changes to the guard irons - this is how they should have been all along and the change is not an error with the kit; the post-war versions were different. I've also added the cab footsteps and will need to make some for the front too (the S&D machines didn't have these). I have made an amendment here by laminating a layer of 'Durbar' plating per the real thing. This is a very thin etch from, I think, Intercity Models (Shawplan do something similar). The boiler assembly is temporarily in position; cramped.


    Turning the thing upside down you can see a number of changes. The rear of the frames have been cut off and soldered to the body; even with the change to the guard irons the chassis still would go in (but this is because I'm doing something different - my amendment, my problem). The other thing you should be able to see is an error; the steps should have holes etched all the way through to allow the steps to be tabbed in and here they're only half-etched. No matter, they're in the wrong place for the post-war machines anyway and will be replaced with little bits of milled angle. Still, coming on.

    Rob Pulham and Dog Star like this.
  20. dltaylor

    dltaylor Western Thunderer

    Very nice indeed Adam. Which gearbox did you use in the Hunslet? I can see its a Highlevel, is it the Loadhauler?
    Cheers, Dave.