Wolf of Badenoch

Discussion in 'Area 51' started by Richard Spoors, 12 September 2019.

  1. Richard Spoors

    Richard Spoors Western Thunderer

    I spent an enjoyable last 18 months with a Finney V2 on my workbench, from which you can see I'm not the quickest of kit builders. I'm a keen supporter of Missenden Railway Modellers, and I sometimes think as much work gets done there as at home. My early railway interest was the ECML with many a happy Friday night as a teenager spent at Newcastle Central station before steam disappeared. To complete my collection of ECML pacifics, I need to look at the Thompson A2's. DJH produce kits of all three classes, so I'm starting with the A2/2. The kit is quite old and follows the DJH practice of designing the kit so that a decent model can be built by the less experienced modeller. Comments on this forum suggest that the weakness in their kits is a lack of detail below the frame. With that in mind I'll be looking to see what additional detail can be added to make improvements.
    I started with the main frames, which are quite chunky when compared to the Finney V2. Rather than punch out the rivets, I drilled 0.5 mm holes for Scale Hardware rivets. These were soldered in place using paste and a flame. I chose Slater's hornblocks as I needed a hornblock frame with narrow sides to fit between the lower frame spacers. They also have a useful cast mark showing the axle centre. They will be carefully soldered in place such that the spring retaining pegs are vertically aligned to the correct horizontal level.
    Cheers

    Richard IMG_0486.jpg
     
  2. 7mmMick

    7mmMick Western Thunderer

    Hi Richard,

    I’m really looking forward to seeing how you tackle this one as I’m building a DJH A2/3 at the moment. I’ve opted to use the Finney hornguides and adapt the frames for the Finney style of compensation. My build thread has concentrated on the tender to date but I’m well on with the loco and should hopefully get a thread update on next week. As you say the bottom end is a little lacking so I’m adding lots of extra castings and detail to bring it up to speed hopefully,

    Mick
     
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  3. Silverystreaks

    Silverystreaks Western Thunderer

    Well that makes two A2/ threads to follow.

    I wondered what had happened to your A2/3 build Mick.

    Ive fancied doing an A2/3 for a good while

    Bob
     
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  4. 7mmMick

    7mmMick Western Thunderer

    The West Country build took over for a while but i’m Now back on the A2. I have to admit that I’m really enjoying getting back to a prototype I love, it will be a shame to sell it on when it’s finished :(

    Mick​
     
  5. LarryG

    LarryG Western Thunderer

    Another one here looking forward to seeing this develop. I only saw the A2-3's.....Thompsons Pacifics fascinated me no end.
     
  6. Richard Spoors

    Richard Spoors Western Thunderer

    Hi Mick, it will be interesting to see how our approaches to improving the kits develops. I'm researching the way in which the slide bars were supported by the motion bracket. On Gresley engines (or at least the V2) the motion bracket was in line longitudinally with the slide bars and a "foot" to the motion bracket extended forward and supported the slide bars with two bolts. When Thompson ditched Gresley's conjugated drive for the cylinder valves and went to the classic Walschaerts drive, the longitudinal centre line of the motion bracket was offset to the centre line of the slide bars. Therefore the joining plate on the foot of the motion was also offset.
    Now, if you're building your DJH kit "out of the box" the cylinders are designed 1 mm wide on each side. DJH have done this so that the builder needs to pay less attention to the clearance of the leading driving wheel crank pin.
    Having mastered the "scale" clearance on the Finney V2, I've taken the plunge to remove that 1 mm and have scale cylinder width across the frames. The consequence of this (apart from managing the reduced clearance) is that I need to fabricate a small bracket to make the slide bars/motion bracket connection look right.
    I've also improved the appearance of the slide bars by inserting a nickel silver strip to make the upper surface look correct. Then I can add some scale hardware nuts.
     
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  7. Richard Spoors

    Richard Spoors Western Thunderer

    Two photos that relate to my post above. The improved slide bar and an image (reproduced only to illustrate Thompson's motion bracket design -copyright RCTS) Improved slidebar assembly.jpg
     

    Attached Files:

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  8. Richard Spoors

    Richard Spoors Western Thunderer

    Apologies that the slide bar is huge and the motion bracket is tiny.

    Cheers

    Richard
     
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  9. 7mmMick

    7mmMick Western Thunderer

    Hi Richard,

    I too have been pondering the slider/motion bracket connection. I've found these photo's useful and luckily it happens to be the loco i'm modelling 'Chamossaire'. I'd like the cylinder and motion bracket to be one complete assembly but i'm yet to decide how to do that? Like you some scale hardware will be utilised ;)

    A2 4-6-2 | 60514 1961-05-14 Doncaster

    I opted to replace the DJH slider with a Finney V2 one as the DJH etched affair just looked too thin and weedy. I do like the way you have beefed yours up though. I've also replaced the rear valve cover, cylinder gland, front cylinder cover and cylinder relief valves with Finney fittings. I just wasn't happy with the fidelity of the DJH WM parts. I did however keep the crosshead as I do like the LW brass casting from the kit. The only thing i've done to change it is to get rid of the brass slide bar and swap for N/S rod. A bit of a faff but I think the effort is worth it. I also stuck with the DJH cylinder taps as they're a nice representation IMO. Here's progress to date, some webs and bolt detail to add but it's almost there.
    DSCF4862.jpg

    Cheers

    Mick
     
  10. Richard Spoors

    Richard Spoors Western Thunderer

    Hi Mick, I like your progress. I’m on a break until next weekend. Did you make your cylinders detachable? When I milled of the 1mm, I prepared the casting by making 2 short brass tubes and tapping them 2mm. I screwed them in position and filled the void with car body filler. Now the inside face is milled I can screw them in position with 2 cap screws.
    DJH have much better detail on the masters for their lost wax than whit metal.
    Cheers
    Richard
     
  11. 7mmMick

    7mmMick Western Thunderer

    Hi Richard,

    Yes my cylinders are removable. I'm yet to create the lateral fixing to the frames but the vertical fixing is as DJH intended. Your idea for some tapped tube will be the way to go I think,

    Cheers
    Mick
     
  12. Richard Spoors

    Richard Spoors Western Thunderer

    I've persevered with the slide bar support bracket that is an integral part of the motion bracket. The rear needs to be trimmed to align with the motion bracket to which it will be soldered. I used an I section brass channel and four simulated bolts from GHW in Germany. Had I not removed 1mm from the back of the cylinders, the motion bracket would have sat centrally on the slide bar. I've also posted a picture of the rear of the cylinder showing the threaded brass tubes to enable the cylinders to be removable and a photo of the real motion bracket.
    Cheers
    Richard slide  bar support bracket.jpg machined inner face of cylinder.jpg A2-3 motion bracket.jpg
     
  13. 7mmMick

    7mmMick Western Thunderer

    Hi Richard,

    The prototypical shot is really helpful. I started looking at the motion bracket work and found that I needed the footplate in place so I could be sure the motion bracket fits snugly underneath. So I’ve moved onto the body. With everything fitted the gap between the bottom of the motion bracket and top of the slide bar seems too large? Have you found this is the case?

    Mick
     
  14. Richard Spoors

    Richard Spoors Western Thunderer

    Hi Mick, I don't have a problem with a vertical gap, just lateral, hence the little 'foot' I made yesterday. I'm still playing with individual components before fixing anything. Having located the motion bracket in the slot in the frame and bolted the cylinder to the frame this is how it looks:
    A2-2 motion.jpg
    Although you may have a point, as the slide bars look horizontal, where they should be at a slight slope downwards. More trial and error me thinks!
    Cheers

    Richard
     
  15. Richard Spoors

    Richard Spoors Western Thunderer

    Following up I have looked at the pipe and rod drawing, a copy of which I have from the NRM. The cylinder angle is 2 degrees and the motion bracket is also canted such that the support to the slide bars is at 90 degrees.
    A2-3 pipe and rod.jpg
    The foot of the motion bracket scales at 29.5 inches from the footplate. In the model, allowing for the 1.9 mm thick footplate and the height of the etching at 13.62 mm, we have a total of 15.52. so, with 29.5 inches scaling to 17.23 mm we have a gap on the model of 1.71.
    In the kit DJH expect the cylinders to be at the prototype angle as they include a canted packing block to fit between the top of the cylinder and the footplate. The compromise seems to be to pack out the foot of the motion bracket before fitting the etched overlay. Of course one could go down the CAD route and redesign the motion bracket etching!
    In order to get the cylinders and motion bracket at the correct height on the model, they need to be 'dry' fitted to the footplate. So time to start cleaning up the pewter!
    Cheers

    Richard
     
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  16. 7mmMick

    7mmMick Western Thunderer

    Hi Richard,

    That rings true and confirms the position I am in. I have already fitted the overlay to the motion bracket so this will have to be removed and modified as you suggest. Good luck with the Pewter!! I’ll update my thread on progress after the weekend but I’ve had fun and games to say the least:thumbs::D

    Cheers

    Mick