7mm On Heather's Workbench - a baby Small Prairie

Discussion in 'WR Action' started by Heather Kay, 2 August 2017.

  1. Ian Smith

    Ian Smith Western Thunderer

    Heather, far be it for a 2mm bodge artist like me to comment adversely, but I offer this one in the hope that its's not too late to make a slight correction (assuming that you feel my point is valid). It appears to me that the sanding pipes are a little too short and finish a little high. I checked the arrangement drawing published earlier in the thread which seems to show the pipes terminating closer to both the rail head and the wheel tyre. I have to say that I haven't checked photographic evidence, just the aforesaid drawing.
  2. Heather Kay

    Heather Kay Western Thunderer

    You are absolutely correct. I was attempting to get them fitted without a pair of wheels in place, and misjudged things. I plan to revisit them tomorrow with fresh eyes. Happily, at this stage, they’re not actually attached permanently to anything.
  3. simond

    simond Western Thunderer


    I don’t know if you saw it but Ken /Jazz is having some entertainment with one of these on t’other channel.

    You’re not on your own!

    Pencarrow and GrahameH like this.
  4. Heather Kay

    Heather Kay Western Thunderer

    I have to admit I don’t visit t'other place all that often, so I’ve missed that. I am on record earlier today stating to the room at large I might have been better served scratchbuilding the whole darned loco than attempting to build it from the box of bits!

    Still, it’s been, um, fun?
    Pencarrow, jonte, GrahameH and 2 others like this.
  5. Heather Kay

    Heather Kay Western Thunderer

    In the light of a fresh day, a good night's kip, and feeling energised by some more loud music, I had another go at the sanding gear.



    Now, I know it looks like the pipes end a good way from the wheels, and seem a fair height from the rails, but I’ve done my best to match what I see in the photos. I should add, the original builds of the locos had gravity sanding, where the pipes are a little way from the wheel - probably to enable the fireman to poke something up them to clear blockages! Later, steam sanding was fitted, and it looks like the pipes got closer to the tyres around the same time.

    As ever, that’s my interpretation of the photos. This is the effect I was after…


    What’s next on my to do list? Extending the rear frames to fill a gap, front sanding pipes. I reckon I can manage that by coffee time.
  6. Pencarrow

    Pencarrow Western Thunderer

  7. Heather Kay

    Heather Kay Western Thunderer

    Nearly a week since any updates? Well, there’s not been anything of significance to report. There is a slight holdup with the brake gear, sadly, so I’ll have to roll with that until things resolve themselves. I won’t go into details, as there’s no need. There has also been a hiatus in workbench operations due to my insides deciding they didn’t like my food any more. That, thankfully, is mostly past, and I’m beginning to build up my strength again, albeit slowly. Why does it take longer to get back to full health as we get older?

    So, rather than leave you hanging, and since the model is essentially within reach of handing off to the paint shop in a few weeks, I thought I would explain some of the smaller engineering tasks that went on a while back but mysteriously got ignored.


    I wanted/needed the crosshead to be able to be disassembled should the need arise. I had hoped to allow for the tiny steel screw to be fitted on the inside face, and had countersunk the crosshead castings accordingly. However, the requirement to trap the driver's side crosshead in the slidebars with the air pump ram has meant I’ve had to compromise and insert the screws from the outside. I hope, once painted and weathered, they will be disguised sufficiently to look like the fitting I see on the photos. I think filling the slot with putty or plasticine will do the job nicely, while still allowing disassembly.


    Aside from thinning the crosshead for clearance, the other task is to recess the leading crankpin nuts. These are the usual CPL type cast nickel silver ones. With the nut clamped in a pin vice, two tiny holes are drilled to allow me to insert the tips of a pair of needle nose tweezers so I can tighten them up on the pins, and a suitable tap run through the centre hole. @simond has made a little spanner for this job, I believe. Sadly, my ability to drill holes correctly to suit a tool I might make doesn’t fill me with hope. The twin-hole idea is one that @Dikitriki has explained in one of his many, incredibly helpful workshop threads. If I can muster the strength, I’ll attempt to find one and provide a link at some stage.

    The hole in the coupling rod is recessed: I haven’t sourced a fancy D-shape cutter to achieve this, so I carefully run a 45 degree countersink in the hole to provide a little depth. The nut is then carefully filed until it’s slightly proud on the reverse, and then the front can be filed to give even more flushness. It's easier to do than explain.

    (As I don’t really want to build many more locos, I don’t think acquiring a recessing bit will be worth my while now.)

    I drilled 0.5mm holes in the tops of the coupling rods, and inserted NS wire to represent the cork bungs on the oil pots. It’s a detail I usually neglect, but as the cast connecting rods had this detail I felt duty bound.

    The list of things to complete is getting shorter. Around the chassis, aside from the brakes, I have to fill the backs of the wheel balance weights and finally epoxy the crankpins in their holes. Around the bodywork, it’s mainly cab details that can be left until post-painting. One thing I will do after I stop futzing around here is to rework the cab roof fixings. I’ve never been quite happy with my original scheme. Although it worked, it wasn’t easy to do properly, and might risk damage to paintwork later on. I will probably go a more traditional route.

    Right, even typing this has tired me. I think a few minutes' lying down will be necessary.
    jonte, Tony Conlay, LaScala and 8 others like this.
  8. simond

    simond Western Thunderer

    I did indeed. I file (or more latterly, mill) two flats on the flange and have made a small socket wrench to tighten them. There are some pix on my PD thread in the other place, I can Post a link if anyone wants, please let me know. (Once RMWeb is back online).

    I’m aware that DLOS / IsembardUK did a similar thing with a purpose made peg spanner and two holes, I suspect the peg spanner will avoid twisted tweezers and a subsequent series of pingfxxxit events...

    jonte, D6356, Rob Pulham and 3 others like this.
  9. Hal Nail

    Hal Nail Member

    I'd suspected from various photos of 45xx tanks that the floor is raised up so went to Didcot to check 5572. There are two wooden plinths on either side - on one side it stops by the door, the other side goes right across. If you check Google images for "GWR 44xx" there is a side on photo of 4400 at Much Wenlock and you can see the driver is quite high up so I think its the same arrangement. May have been a later modification though?
    Hope that's of use!

    Last edited: 31 January 2019
    jonte, Len Cattley and GrahameH like this.
  10. Heather Kay

    Heather Kay Western Thunderer

    Thanks for that, belatedly! As you say, it could be a later modification, as all the small prairies went through quite the transformation over their long lives. I think I’ll leave the model as it is, but bear it in mind for the large prairie that's waiting in my rather overlong queue.

    I’ve been letting the loco steep on the workbench for a week or so, in case something obvious that I’d missed jumped out at me. As it turned out, two things came to my notice.

    Coupling stowage hooks under the buffers, and injector drain pipes.

    The stowage hooks seem to have been an afterthought, and fitted wherever a workshop decided they’d suit. I chose randomly, so both front and rear ended up on the driver's side of the loco. Tiny holes were carefully drilled through the buffer planks, in line with and below the inner buffer stock fixing bolt and brass wire was soldered in after forming into a hook. On the real thing the hooks are held by the fixing bolt.


    On these early locos, the injectors were mounted up inside the frames under the cab. In all my peering intently at photos, I hadn’t clocked the drain pipes. Of course, as ever, a compromise has been formulated because the real ones ran almost horizontally from the bottom cab step until they disappeared behind the frames. In order to clear the pony swing (unlikely to be a problem in service, but you never know), I’ve had to form microbore tube to these rather complicated shapes. They are fixed to the pony/brake spacer, and left to float at the step end to allow separation of the chassis and body.


    A teensy bit of tweaking is needed to let the outlet end sit neatly as if it’s attached to the step.

    I wonder if there’s anything else that’ll pop out at me?
    Last edited: 12 February 2019
  11. Heather Kay

    Heather Kay Western Thunderer

    Vac and steam pipes. They popped out at me.

    I needed to find a way to let the vac pipes not actually be fitted at this stage, in case the buffer planks should be lined. While I was thunking about that, I checked on how the things looked OTRT.

    Well, a good job I checked. There is apparently no steam heating on the front, and both vac and steam heating under the bunker are swapped from their orthodox locations of vac left of the coupling and steam to the right. That is fun, because all steam heat pipework castings have the valve lever to the right. Still, that was easy to sort out.

    Things are very close to the coupling, but I wasn’t happy to shift things too far out as it loses that essential "blocking the centre lamp iron but not really" effect!


    On the back end, again things are close to the coupling. In this case, I compromised and shifted the steam heating pipework out a smidge to make it a little easier for 1:1 fingers to couple things to the loco. I’ve fixed the steam bits under the plank, but both vac uprights are held with a wire pin in a hole. A drop of glue can hold things in place once it’s all coloured in.

    Anything else? Not sure, but it’s high time for the ultrasonic bath to be deployed.
  12. Heather Kay

    Heather Kay Western Thunderer

    An ultrasonic bath is a great way to uncover parts that haven’t been fixed to a model properly. :oops: :thumbs: :))
    Phil O and michl080 like this.
  13. Dog Star

    Dog Star Western Thunderer

    Heather, you wrote "uncover parts"... is there a feature to "recover parts"?
  14. Heather Kay

    Heather Kay Western Thunderer

    Parts were recovered as soon as I spotted them, or they risk ending up down the plug 'ole. They’re safely stored now until the model has dried.

    The list includes a handrail knob, the chimney :eek:, and the handbrake stand.
    Malcolm Trevena likes this.
  15. Phil O

    Phil O Western Thunderer

    Heather, been there, done it and got the T shirt. Since the first time this happened, I now pour the contents through an old sieve with a fine mesh, it saves watching stuff go down the plug 'ole.
  16. LarryG

    LarryG Western Thunderer

    I reckon we all learn the hard way. In pre-ultrasonic bath days I stripped a customers loco of paint ready for repainting and although the boiler was soldered together (whitemetal), most everything else was glued on and in the bottom of the pan! I had to build the damn thing before panting it. Couldn't prove a thing of course, but I promptly added an extra paragraph to the painting & lining lists....All loco should arrive unpainted. No stripping!
  17. Heather Kay

    Heather Kay Western Thunderer


    Oh, hello. :)
    Pencarrow, GrahameH, P A D and 9 others like this.
  18. Ressaldar

    Ressaldar Western Thunderer

    'Turned out nice again' :thumbs::thumbs::thumbs:

    looking forward to seeing the finished article in the Gallery - real soon!


    paulc and Wagonman like this.
  19. Wagonman

    Wagonman Western Thunderer

    And I dare say Ian would love a copy for the Newsletter...
    Heather Kay likes this.
  20. john lewsey

    john lewsey Western Thunderer

    Looking good Heather