David Andrews Castle Build

Discussion in 'Workbenches, including workshop techniques.' started by Focalplane, 4 April 2019.

  1. Focalplane

    Focalplane Western Thunderer

    I started building the chassis for this locomotive some time ago when helping my wife to renovate her holiday self-catering cottage in Borth Y Gest, North Wales. It was a timely project to relax with in between carpentry, flooring, painting and acting as general contractor for the specialist work. When the cottage was completed and ready to let, the Castle was put away for a rainy day. Last week I dug it out and started to do some more work while waiting on supplies for the Finney7 Princess Coronation kit.

    Some history on the wheres and whys of this project. Like most railway fans I have always admired the Castle Class for its looks, performance and outward simplicity for a 4 cylinder locomotive. My prototype is 5070, Sir Daniel Gooch. Why? Because it was a Midlands based locomotive often to be seen at Stafford Road shed, Wolverhampton and immortalized in the painting Summer Saturday at Snow Hill by Philip Hawkins. I have a print of this painting hanging in the railway room and also a jig saw puzzle of the same waiting to be opened. The Large Pannier in the painting is also my chosen prototype for the Heljan model, number 4175. The Cornishman was also the only named train that used the North Warwickshire Line from Tyseley to Stratford-upon-Avon - I grew up in Earlswood, at the highest elevation on the line.

    Like all David Andrews kits I have seen, the standard and quality of the Castle kit is near the top of the charts and once you have built one or two (my LMS Compound was the first) you pretty well know what to expect before opening the box. I added Slaters' wheels, an MSC motor/gearbox and Slaters' hornblocks and pickups. Originally I went with David's recommendation to use smaller drivers (from the King Class) but have since decided to go with the proper 6'9" diameter wheels as it is said to be possible to fit them in (I am almost there so I would agree with the recommendation, however, the ongoing thread will explain what I have had to do).

    The next few posts will show what was done in early 2017. Everything was then put on hold as I decided to model Penmaenpool and Castles were not going to be a priority!
    Last edited: 5 April 2019
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  2. Focalplane

    Focalplane Western Thunderer

    Back in March 2017 I set up a portable workbench and opened the box. Unusually I ignored the tender and started on the loco chassis. The first thing was to fit the Slaters' hornblocks:



    I sometimes use the Poppy's builder box and had bought one for the LMS Compound kit. This meant laminating the coupling rods (which now need to be finished off and polished) and setting up the chassis for soldering.


    The builder box doesn't really like sprung hornblocks but alligator clips helped to hold everything square so that the hornblocks could be soldered onto the frames.



    I then soldered the two frames together and cleaned up the very robust nickel silver chassis:


    By the way, I also had drilled and tested the holes for the Slaters' pickups before starting on the assembly.

    Next, will, the wheels fit?
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  3. Focalplane

    Focalplane Western Thunderer

    Well, they do, but only just, and even then. . . .


    There is a space between the rims of the front and centre drivers. Just.


    I had been warned that it would be necessary to grind off some of the rims of the tyres. This I have recently done. More on that later!

    The first sign of a problem came when I started to fit the brake rigging:


    It would appear that the upper brake hanger for the front driver had virtually no room and would have to be "cranked" a few millimeters.
  4. Dog Star

    Dog Star Western Thunderer

    Or use the GWR 6'8" wheels from the S7 Group Stores... with a tyre of scale width and flange of scale depth then such could be a better fit than the standard Slater's FS wheelset. Of course you need to change the axle and those are available from Slaters.

    regards, Graham
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  5. LarryG

    LarryG Western Thunderer

    Looking good.....But then anything GW would in my eyes. Personally, I would have turned a bit off the centre flanges. They make no difference to running anyway even if the flanges were completely removed. They often were when I built locos for a living (key to violins playing).
  6. Focalplane

    Focalplane Western Thunderer

    Fast forward two years!

    In the past few days I have been working on the Castle chassis, fettling and fitting the cylinder parts, motion, etc. The most critical aspect of the "large wheel" build has now been seen to be the motion brackets which fit between the front and centre drivers.



    The photos hopefully explain the problem better than words. Just fitting the axles and wheels is a major effort and it is easier to remove one brake shoe, on the other side, until all is working correctly.

    This is what I have had to do so far.

    First I put all six drivers on the lathe and removed about 0.5mm of rim from the tyres. I then had to remove more from the centre driver, this being the best option (thinking flangeless wheels are always in the centre of 6 coupled models!).

    Second, the motion brackets consist of two laminated parts soldered together. The problem area between the wheel flanges consists of half etches only with the full thickness lamination restricted to the area you can see in the lower photo. So I have ground out some of the half etch material where the two drivers touch. I only ground out the area in line with the axles when the hornblock springs are compressed. What I now need to do is grind out more of the half etches so that there is more of a gap when the hornblock springs are extended. How do I know this? Testing for shorts I had none when the springs were compressed (as would be the case when the full weight of the loco is bearing down) but shorts occurred when I pushed the chassis with no additional weight.

    I may have to remove all of the half etch material to be certain of no shorts. This could introduce a weakness into the motion brackets and slide bars, except there is the option to solder the brake hanger wire to the motion bracket and also there is a brass slide bar tie to be fitted on the outside.

    The lower photo was taken with no compression on the hornblock springs and one look at the brake shoes suggests there is also a high risk of shorting with up and down movement. I have ground down the shoes surfaces to fit the profile of the flanges and some subsequent tests suggest I may be OK.

    So, the problem of fitting the larger driving wheels is nearly resolved.

    Edited to add: Thank you, Graham, for your suggestion but I hope I won't have to go down this route!
  7. Focalplane

    Focalplane Western Thunderer

    Well, Larry, I think you know that great minds think alike!

  8. Focalplane

    Focalplane Western Thunderer

    This afternoon I blued the wheels in preparation for assembling a first pass at a free running chassis. I hope I don’t have too many stops and starts with this so I am doing a lot of preparation beforehand. The laminated connecting and coupling rods have been improved and filed down, scraped and polished and the holes reamed out for the bushes. I have removed more of the potential shorting areas on the motion brackets as well.

    The plan is to start with the wheels and motor gearbox, add the coupling rods and then install the slide bars and connecting rods which means completing the outside cylinders, etc. If all goes well I will have chassis that works and can then dissemble, prime, paint and add the Slaters’ pickups before reassembling the motion. What I will move on to next will be weather dependent! It snowed yesterday in the mountains and hills around Perpignan and if the cold spell continues I may work on the layout (Penmaenpool) downstairs.
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  9. Focalplane

    Focalplane Western Thunderer

    98A13287-7DF2-45F7-821B-1E995FB465BB.jpeg A rather featureless photo of the rear axle and wheels spinning around. I have only included this photo for completeness. Now this works it is time to add the coupling rods.
  10. Focalplane

    Focalplane Western Thunderer

    Well, I have hit a slight snag, there is a tight spot with the coupling rods which needs to be eased. I have also discovered that I have been mounting the motor/gearbox the wrong way round (yes, that is possible!) when it comes to clearance for the plunger pickups. Rather than sticking up into the upper firebox, the motor needs to be horizontal in the lower firebox. The remedy is simple but requires everything to be undone and I was getting hungry. So it will happen tomorrow.

    Meantime I took a photo of the motion bracket to explain what has been done to get clearance for the "big" wheels:


    That's the front driver on the upper left, the centre driver is not installed so that you can see what has been ground out of the inside of the motion bracket. The nickel silver is paper thin opposite the problem area of contact with the flanges. I ground more out since my last posting and no shorts have been seen on tests.

    It is clear that there are going to be conflicts between moving parts on the connecting rods, even without outside valve gear there is very little room. The sand box is part of the problem but the main conflicts are going to be the between the motion parts themselves, i.e. shortening the fixings on the crankpins. But before I tackle this problem I have to solve the tight spot(s). I am hoping this will simply involve slightly elongating the hole in one or more of the coupling rods. I just need to work out which hole(s) and this will be done by elimination.

    Incidentally, and I might be teaching some grandmothers to suck eggs here, it is very easy to trap the driving axle washers between axle and wheel. Each wheel must be checked that it is truly screwed all the way. A visual check is easy to do but if in doubt a back-to-back measurement is a good idea.
    Last edited: 5 April 2019
  11. Focalplane

    Focalplane Western Thunderer

    This morning I managed to ease the motion (that doesn't sound good, does it?), mainly by drilling out all the coupling rod holes to 2.5mm. However, although this has introduced the required minimal slop I now have occasional shorts while pushing the chassis around Penmaenpool that trip the DCC circuit (a useful test as long as you don't overdo it). The reason would appear to be the additional movement causes shorts against the brake blocks which were soldered in with very tight tolerances.

    The solutions include, moving the brake blocks away from the wheels, grinding more metal from the shoe surfaces, and possibly coating the ground off surfaces with CA glue to act as an insulator. I am reluctant to move the brake blocks as they took a while to set up, so more grinding is going to be done first.

    I am also considering some extra axle washers as the chassis easily negotiates 1.8 meter radii, and even doing away with the sprung hornblocks on the rear, motor driven, axle. The hornblocks will be soldered in the compressed state with the option to un-solder them if it makes no difference to running.

    All this is taking time but I feel sure will be worth it in the long run. Alongside the chassis I have made a start on the footplate.
    Last edited: 6 April 2019
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  12. Focalplane

    Focalplane Western Thunderer

    Now late afternoon and some of the "to do" items in the previous post have been tackled, with success! I have removed two sets of brake blocks for the time being while other work is being done. I first went ahead and soldered pieces of nickel silver scrap to the keepers of the rear axle hornblocks. This way I can always remove them in the future. I doubt if I will, however.

    Next I ground away more metal from the motion bracket as I thought to test them in the dark and sparks occasionally flew. I hadn't thought of this before but the stay alive capacitor on another loco actually prevented very brief shorts from tripping the controller. I have now got a much better separation between wheels and bracket. Eventually I will solder the bracket to the frame but first the slide bars have to be installed.

    Finally I added two washers to the front axle. I chose this one because this where where the motion is tightest (crossheads, etc.) This should help but still allow the 3 coupled to take a 1.8m curve.

    Next I will ready the brake blocks to be replaced but will not re-install them until the connecting rod and slide bars are in and working well. But I also need to connect up the motor, now installed the right way round, and do some preliminary running in on the rolling road.

    Some photos, though there is really nothing new to add to earlier photos!


  13. Deano747

    Deano747 Western Thunderer

    Excellent work Paul. I'm following with interest as it's another one of the many D Andrews kits I have on the shelf and I have the full size wheels to go with it, (Also a set of King drivers but I don't want to cheat!!)

    Regards, Rob
  14. oldravendale

    oldravendale Western Thunderer

    Just wondering, Paul.....

    You're having problems with shorting in part because of the brake blocks. Have you considered the use of plastic ones?

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  15. Focalplane

    Focalplane Western Thunderer


    Glad you are watching, we've both been on a forum tour! I traded my King drivers for the Princess Coronation wheel sets at Telford last year so there is no going back. If others can do this, so can we!

    Best wishes, Paul
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  16. Focalplane

    Focalplane Western Thunderer


    It has crossed my mind but I see all these young(er) maestros working with metal near metal and getting away with it, so I will try too! It is slowly dawning in me that too much slack is not a good thing! (as the fireman said to the shed superintendent).

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  17. simond

    simond Western Thunderer

    I had a problem with the brakes on my (mostly) scrathbuilt 28xx. I used some cast brake levers & shoes, and suffered the sparks...

    So I stuck the cast parts to the wax from a tea light, moulded rtv silicone over them, and then cast resin replacements in the silicone mould. Worked very well. Can’t find the supplier that the casting kit came from but there’s loads of kits out there.

    Was quite fun. I did wheels for my Corgi Thorneycroft van too.

    Conversely, my second-hand Duchess came with some lovely cast brass blocks - and the clearances are horribly tight - so I mounted them on 1mm pultruded glass fibre rod (look for fishing gear suppliers on eBay) rather than the brass brake pivots & beams supplied with the loco. These are entirely non conductive, and dead cheap (a couple of quid a dozen 6” lengths), and providing you sand them, they glue well with epoxy or cyano. That solved that issue :)

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  18. Focalplane

    Focalplane Western Thunderer

    Thanks, Simon

    I see this as a possible solution but there is something about metal kits. I am willing to try though.

    I am hoping what I did today (tightening things up) will allow the kit’s brakes to be used. We shall see!

  19. simond

    simond Western Thunderer

    Rizla and araldite forms a very serviceable (and durable) insulating layer should you stick with metal...
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  20. Focalplane

    Focalplane Western Thunderer

    6 photos from Didcot's Drysllwyn Castle, on shed in December 2015, most of them on the cylinders. I wasn't think of this model at the time, I just like Castles!







    Actually, come to think of it, I have stashed away a 4mm scale S E Finecast kit of the Castle Class, which is probably why I took the photos during a short visit (very expensive parking!)
    Last edited: 7 April 2019