readingtype’s workbench

Discussion in 'Workbenches, including workshop techniques.' started by readingtype, 21 February 2021 at 17:54.

  1. readingtype

    readingtype Member

    Welcome to my workbench!

    I'm starting off with something that's been waiting in its box a few months: a London Road Models (ex-Riceworks) 4mm scale ex-LNER J69 kit. The loco is intended to run on Orchard Wharf, the EM gauge layout we are building at the Model Railway Club. Current conditions have slowed progress on the layout, but the day must come when we are able get back to work on it. Meanwhile a little loco could go a long way to keeping the flame burning!

    Thing is, as usual I'm probably going too quickly. I haven't finished my first brass kit, a Judith Edge Hunslet 0-6-0 diesel-hydraulic. It runs and has a superstructure, but no details (not even any buffers). I have probably learned many of the lessons the build can offer, but certainly not all. The superstructure of a steam loco seems much more challenging -- and this is a loco which has many more bits and bobs squeezed into it than the diesel.
     
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  2. readingtype

    readingtype Member

    Anyway: away with these scruples! If I get a running chassis then I will be a long way towards being happy. That will probably carry me through to the rest of the work.

    So here's the first challenge. The Hunslet I built completely rigid. I was very worried I'd make the crankpin holes too big and things would be sloppy, but actually I think things were much too tightly fitting. There must be something that isn't quite true, because the rods would bind on each revolution. The wheels on that model are Markits' Romford-style so they are easy to get square and quartered; the crankpins are beautifully machined brass, and yet I needed to go round each journal on the rods and open it a fraction, reassemble and try, then go to the next one -- those rods must have been on and off fifty times, it feels.

    I've found some Sharman wheels for the J69. They look lovely, but I don't have the security of knowing they'll be quartered automatically and (being made of plastic) I'm not sure I will get them square on the axle. The crankpins are far less sophisticated too -- a screw cast into the moulding, no more no less.

    Then there is the matter of compensation of the axles. I want to try this as a counterpart to the solid Hunslet. I've worked my way through Mike Sharman's booklet about Flexichas, and I have read Guy Williams' description of his similar system (in The 4mm Locomotive -- a book title that may have caused some confusion).

    I've roughly made a sleeve bearing for the centre axle, 5mm diameter, which projects through the etched holes in the frame. In Guy Williams' design, as I understand it, I would fix a set of guides for this bearing on the inner faces of the frames, and then I could enlarge the axle hole into an oval to allow some vertical play for the axle. Then I would repeat this for the front axle and add a compensating beam using a rod mid-way between them as its pivot. The holes are included in the etched frames, and that step is the same in a Sharman Flexichas.

    But instead of trying to make and fix these guides and open out the holes. I could take a step back, buy four hornblocks and try my luck with those.

    This is where I have come to a gentle halt. Any ideas, while it steeps?

    [​IMG]
     
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  3. AJC

    AJC Western Thunderer

    Hello!

    Pleased to see another EM modeller here and intrigued to hear about the new MRC layout which sounds an interesting project.

    Like you I've built one of Mike and Judith's Hunslet 0-6-0s (and like you, it was rigid - works perfectly well; which of the various Hunslets did you go for?) and to be honest, it runs sufficiently well to convince me that I'm really only mucking around with compensation because I can, most of the time. I'd love to see a picture or two (and if you're planning on wasp stripes on the buffer beams, you might find it better to add the buffers later).

    On to the J69 - looking at what you're trying to achieve, I don't think you've anything to lose except perhaps a bit of time in trying the Guy Williams approach: if it all goes awry you can just buy some suitable hornguides and bearings and use the rods to line them up in the usual way. That basically does the same thing, mechanically at any rate and the frames won't mind.

    Two things if you're concerned about the Sharmans. One is that the axles my not be cut precisely to length so do check now! Assuming that they are the right length, putting a gentle chamfer on the axle ends will stop the axles cutting their own way through the centres. Depending on how brave you're feeling you can simply push the wheels on or (and I have one and would recommend it) get hold of a GW Models quartering press which does fitting and quartering in one operation.

    The second is that you don't need to use them to set up the chassis - I have a set of Romford type wheels I use to ensure that I have set the chassis up properly before fitting the proper ones. They aren't any particular size, they just ensure that the rods and wheels work properly which helps with fault finding later: if you can rule out these fundamentals it must be something else. I could probably doo with a larger set for larger locos, thinking about it.

    Hope that helps,

    Adam
     
  4. Overseer

    Overseer Western Thunderer

    I would certainly recommend using the Sharman wheels if you have them, they are not difficult to quarter. I would also recommend compensation using MJT hornguides, set up using the coupling rods and jig axles. Keeps things simple and they work very well. The Guy Williams tube bearings are more of a fiddle and I would worry about excessive bearing surface potentially adding friction, they were designed for a specific operating environment before commercial fittings were available.

    This is a chassis I built in 2001, HO scale on 18.3mm gauge with 16mm Sharman wheels. The prototype was an 1880s tender loco converted to diesel in the 1950s with a war surplus tank gearbox and GM 6-71 diesel engine. It would be very similar size to a J69 in EM. It has spent quite a few days crawling along my 6m long layout at exhibitions, the prototype ran at 6 mph so it needs to run slowly. Very basic but has proved reliable and runs silently. I should fit the brakes sometime. I had forgotten that the motor is held in place with a couple of wires.

    Y IMG_1296.jpg
    Y IMG_1295.jpg
    Y IMG_1294.jpg
    Y IMG_1298.jpg
     
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  5. readingtype

    readingtype Member

    @AJC , @Overseer much obliged for your advice and encouragement.

    The loco prototype is Indian? The view into the frames is very useful. I will see about some photos of the Hunslet. Small beer!

    Incidentally one thing I don't like much is not being able to take axles out; is it a bad idea to have the 'fixed' (motorised) axle sitting in a bearing with an open bottom so to speak?
     
  6. AJC

    AJC Western Thunderer

    Well, if you go for twin beam compensation (or CSB type springs) you can have all the wheels drop out if you so desire, and that would give all wheel suspension which is desirable and quite exciting, but also a fair bit more work. I did it with my second etched loco (a Gibson LSWR O2) and that's an 0-4-4 which was quite entertaining to do and it does work well. The thing is though, I haven't had the wheels out since I built it some nearly 20 years ago, not that was why I did it. I have built another couple of locos with full compensation since, but Mike Edge made it easier for me to do it like that as any other way. Here's one, a bit too modern for my interests really, but I happen to like it. Obviously to can't see the works in this picture!

    Thos_Hill_006.gif

    I guess the question is why do you think you'll need the wheels off? Dead motor? Wheels can stay on. Dead pick-ups? Again, wheels can stay on. Replacement gears? Then the wheels are coming off anyway. Yes, it's helpful for painting but I've always preferred to paint the frames as early as possible and get the thing running properly once rather than having to take the loco to bits to paint it and then go through the pain of making it run again afterwards. For 'normal' three-point compensation with a fixed axle to can arrange the driven axle to drop out in a variety of ways, and some sort of keeper plate and slot is perhaps the best option (it's what Bachmann and Hornby use of course).

    Adam

    PS - Overseer's loco is Australian (Victorian, to be precise).
     
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  7. Overseer

    Overseer Western Thunderer

    I didn't want to drift your thread too far off course but the prototype looked like this when I photographed it running in 1981, hauling gypsum from the pit 16 miles to the Mildura line at Nowingi -
    Sunset Y413 1981.jpg

    Before it was dieselised in 1955 it looked more like this (but black) -
    Npt Y1.jpg

    Y413 (Y413 is its original number, it was Y109 from 1922 to 1954) ran for nearly 30 years as a 150hp diesel after its conversion in 1955. As it was built in 1889 it didn't quite reach a centenary in operation. It had a wheel swap in 1970 with Y108 (ex 395 and 412) in the Newport railway museum due to worn tyres and those wheels are currently being put under Y112 (ex 419) with new tyres from South Africa to keep Y112, seen above with fake 419 plates, in operating condition.

    It is a long way from east London.
     
  8. readingtype

    readingtype Member

    @Overseer Diversions always welcome, especially as the MJT hornblocks are on back order at the EM Gauge Society. Is there a supply issue with these by the way, does anyone know?

    Back to the diversion: yes there's lots of geographical distance between London and the outback but there's quite a lot binding the older locomotive designs in both places together :) What's the black loco behind saying STEAM and looking much more Far Eastern?
     
  9. readingtype

    readingtype Member

    Here's the Hunslet. No point in concealing the quality of my workmanship ;-)

    I can't remember why I used submarine cable to wire up the pickups but I think I might have something slightly finer in stock now. I didn't enjoy dealing with the pickups. Not wildly keen on the fancypants phone camera's performance either, but never mind -- you pays your money.

    [​IMG]

    And if you are still reading, here's the model from the side going slightly uphill. Not a new photo and previously published on another popular railway modelling blog FWIW. I may have to do the cab again -- look closely at the join between cab side and roof and the small offset is soon apparent. The cab is slightly trapezoid and this means the bonnets do not quite fit against the fronts. It may be some time before I can face the thought of tackling this though. The arrangement of the cab floor was a bit challenging as there's nothing to act as a register or witness, so far as I could tell anyway. It all seemed to be absolutely right until after the roof went on!

    [​IMG]

    Ben
     
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  10. AJC

    AJC Western Thunderer

    Hello Ben,

    I see what you mean about the roof. Thinking back, mine might have taken a couple of goes as there’s not a lot of margin for error. It looks as though you’ve formed it well though.

    You can get the MJT hornblocks direct from MJT of course and High Level do a good alternative.

    Adam
     
  11. Overseer

    Overseer Western Thunderer

    The only way to really learn how to build a loco in brass (or nickel silver etc) is to actually do it. If something doesn't work first time it can usually be easily dismantled and redone. Looking at the Hunslet it looks like you might need a higher wattage soldering iron to get a bit more heat into the joints, plus a bit more flux and a little less solder. Brass transfers the heat away from the point of contact much more quickly than nickel silver so more heat is needed to heat the joints quickly enough to avoid disturbing other joints. It doesn't actually matter how messy the hidden parts of a model are.

    MJT parts are now owned by Dart Castings, their website says they are out of stock at present of the plain horn blocks but do have the detailed version at a slightly higher price in stock. I haven't used the High Level horn blocks but they would be similar to use.

    The black loco is a VR K class. See here for some more info - K class steam locomotives.
     
  12. readingtype

    readingtype Member

    Thanks both. The temperature of the iron and the amount of flux has gone up quite a lot since I started on those frames :) I don't like to go crazy with the flux though. I have a bottle of very runny stuff which does have a habit of disappearing into the joint (I take that as a good thing) but you could keep adding more and more. So I try to moderate and add more if things aren't moving. Maybe that's a bit cautious.

    Very much like the K, particularly in its later guise in the colour photo on the Victorian Railways page. Smoke deflectors, lamp and chimney totally transform the front end. Great livery too.

    Ben
     
  13. DavidB

    DavidB Active Member

    What wattage is your iron? For 4mm work, I suggest you need a 50W iron as minimum. I agree with Overseer that you seem to be a bit short of heat and hence may need a more powerful iron. What solder are you using and what temperature have you set your iron at for it?

    As for flux, what are you using? Flooding a joint with flux does not help as heat goes in to boiling the excess off and that flux is wasted. Flux cleans the area (but you still need to clean it first) and helps the solder to flow and form a bond with the metal. Simply adding more flux won't make the joint any better if the joint was not cleaned properly in the beginning. I bought a 250ml bottle of Carr's yellow flux about 15 years ago and I still have well over half left. In that time I have made more that 200 kits using only the yellow flux.
     
  14. readingtype

    readingtype Member

    Thank you @DavidB. You've reminded me that I have a spade-shaped bit that I should try; I've been using a fine diameter cone shaped tip and not thinking. The iron is notionally 50W I think, possibly 80W, and temperature controlled. The flux is 9% phosphoric acid -- almost as runny as water. Not sticky or colourful, not at all like Carr's! The solder for things like the frames 188 C. Smaller bits 145 C.

    I noticed the benefit of greater resistance to heat from nickel silver; it would be nice to be building the chunkiest parts from that.
     
  15. readingtype

    readingtype Member

    Well, Dart Castings, who are out of stock! I'll look into High Level, thank you.
     
  16. DavidB

    DavidB Active Member

    Good thought to have a larger bit as there is more metal which will hold more heat. Phosphoric acid flux (which I understand the Carr's yellow I use to be) is fine and the fact it is watery really does not matter. Make sure you wipe the flux on the joint. This will help to make it really clean. Put a bit of your flux on a piece of scrap etch that has been around for a while. You should see it change colour as the flux cleans it. Then put some solder on the area and the area next to it you have not fluxed. See the difference!

    For 188 solder, I suggest your iron should be set somewhere around 400C, perhaps a little more. I use 179 solder which has silver in it at 400C and it flows very nicely.

    Two other points: firstly, don't over-do the solder. It's easier to add a bit more than take off the surplus (and wasteful, too). Less solder with plenty of heat (you can let the iron dwell a little to get the metal good and hot) will still form a good bond. Secondly, it pays to support your wrists on the bench or rest a little finger on something when you are soldering so that you can place the solder and iron precisely.

    Good luck. Practise and keep on practising, then your soldering will get better and better.
     
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