Cookie's Workbench - G1, 16mm and 7/8ths

Discussion in 'Workbenches, including workshop techniques.' started by Steve Cook, 10 October 2010.

  1. Steve Cook

    Steve Cook Flying Squad

    Definitely possible CK, I'm just going to swap between the two figures as I like the fact their hands 'grip' the rear cab rail :)

    Back on with the coach for the moment. The ends were glued in place a week or so ago, despite them being over width, its just as easy to trim them down in situ.

    IPEC2 End glued on.jpg

    After a quick sanding down to make the ends the correct width (a bit of 80 grade emery paper makes short work of 1.5mm thick ply) the next job was to modify the outer fret. There is nowt wrong with it as it stands, but as a fair few people are building these coaches its nice to do something slightly different.

    IPEC3 Fret.jpg

    The four vertical parts of the fret for the bottom of the doors were removed, creating panelling similar to that on Carriage 18 on the Ffestiniog railway. As I'm going for a similar colour scheme (albeit dark blue rather than black (well, today anyway :rolleyes:)) I thought I'd use a bit more inspiration from that coach to tide me along.

    IPEC4 Fret trimmed.jpg

    You can see the error between fret and windows cut outs on the outermost windows. Before fixing that, the fret was glued in place using superglue and some brass bar used to weight everything in place whilst the glue dried.

    IPEC5 Weighted down.jpg

    A bit of sanding saw the window openings enlarged to make the mismatch less obvious (not that this photo shows that particularly well!). The droplights were glued in place, tacking them in with superglue (using accelerator to speed the process up), then filling in any resulting gaps with white glue, but from the rear.

    IPEC6 Windows trimmed.jpg

    As expected, the frets for the end were oversized

    IPEC7 Over width ends.jpg

    so they were trimmed down

    IPEC8 Outer trim removed.jpg

    until they fitted nicely between the side frets

    IPEC9 Noted buffer beam and glue.jpg

    Aside from the bizarre and not yet modified buffer beams, the basic carcass is now complete

    IPEC10 Assembly.jpg

    I am just gluing in some extra strips on the ends to thicken up the fret where it meets the sides, it looks a little thin without them.

    IPEC11 Extra strips glued in.jpg

    They will get sanded down tomorrow whilst I apply filler where its needed and ruminate on whether I'm going to do panels for the interior, or just glue basic seats in place and be done with it. I don't want too much work, there is one more to build like this, then two more to engage in some mating exercise to create a bogie coach :)

    Steve
     
  2. Steve Cook

    Steve Cook Flying Squad

    With the strips sanded down to size on the corners, the chosen wheels were chucked underneath the body to try and gauge a suitable ride height and to see what kind of axleboxes would be required. Up against the Decauville first

    IPEC12 Against the Dec.jpg

    Then the Bagnall

    IPEC13 Against the Bag.jpg

    A set of slate wagon axleboxes were in my spares pile, which combined with strips of wood from the kit, enabled a suitable set of inner solebars to be glued together.

    IPEC14 Solebars.jpg

    Mocked up, it looks OK, buts its going to need the buffer beams sorting out real soon - I just need to pick which couplers to use first.

    IPEC15 On its wheels.jpg

    An outer set of solebars are needed and I think I'd like both upper and lower footboards as well. Just need to work out the easiest way of creating all the brackets needed first, so while the brain churns that over, its back to the Bagnall.

    This is number two, the original 'clanky' version being swapped for a quieter one. Its not perfect, but its a lot better so I shall probably do a bit more fettling when the chance to run it again arises...

    AB14 Blown Apart.jpg

    About five minutes later, the boiler and cab sides were off too :D

    The replacement chimney was rubbed down, as were the smoke box and chimney base. The standard exhaust was also cleaned up as it sits level with the top of the lowered chimney and needs disguising for the moment. A quick jig was knocked up using some wood offcuts to hold everything whilst a spare chunk of brass was threaded so the chimney could be screwed in place.

    AB15 Prep for Paint.jpg

    It was all given three coats of Rustoleum BBQ Paint, then baked in the oven at 100degC for 30 minutes.

    AB16 Baked in the oven.jpg

    I had planned on making a replacement safety valve with the aim of keeping its profile very low and letting me modify the modelled pipework, alas the M10 x 1.0 die I bought is only good enough for chasing existing threads and I can't for the life of me get the ruddy thing to actually start and cut a thread. I've tried tapered lead ins etc and just got nowhere, so a better one is on its way. Its a shame as the M12 x 1 die from the same stable works lovely. Ah well.

    I took that as an opportunity to have a play with the saddle tank. I have to say, I'm not convinced the model one is quite right, I think its a little tall and too wide, despite being told its based off a good set of drawings. I keep looking at photos though, so having convinced myself it needs changing, the debate is by how much. Some cardboard and sticky backed plastic later, a waft with Halfords primer and a rough colour approximation slapped on, I have a new tank to try out :)

    AB17 Cardboard tank.jpg

    Its about 4mm narrower per side and has an overall height 3mm lower than the original.

    The model is apparently based on Woto, so being a bit cheeky I've found this photo on the net and tried to take similar angle shots with both tanks.

    AB18 Woto.jpg
    AB19 New Tank.jpg
    AB20 Old Tank.jpg

    I think the cardboard mock up does a better job of replicating the real thing in terms of proportions, particularly comparing the visible parts of the tank front in relation to the smokebox and looking at the tank edges as they sit inboard of the cab sides. You could probably argue the toss for making it ever so slight narrower and shorter again, but I'm inclined to aim at what I've got so far and leave myself with a little room for fabrication error.

    Pleased with the way the chimney turned out too, its not quite sat on its saddle properly at the moment so thats another small job for tomorrow, hopefully fixing that should make the join between the two parts slightly less obvious. Looking forward to hunting for extra parts at the Garden Railway Show at Peterborough this Saturday, my ever growing shopping list includes cast handles for the smokebox door and a set of makers plates.

    Steve
     
  3. Simon

    Simon Flying Squad

    I think you are definitely on to something with the tank, it is a subtle change but makes a lot of difference to the look I think. The chimney is a work of art in itself, I really must get out and use my lathe some more this year...

    Simon
     
    Steve Cook likes this.
  4. Neil

    Neil Western Thunderer

    Cardboard tank does it for me too.
     
    Steve Cook likes this.
  5. Steve Cook

    Steve Cook Flying Squad

    Thanks for the confirmation chaps, off to make a start on the replacement tank now :)
     
  6. unklian

    unklian Western Thunderer

    The cardboard tank looks better to me too. But don't your passengers deserve a bit of suspension on that coach ? Even better if it actually worked .
    Just saying ;)
     
    Steve Cook likes this.
  7. Steve Cook

    Steve Cook Flying Squad

    They're just going to have to be grateful for roof and windows - bloomin' 3rd Class lot, expecting champagne class on a beer money budget ;):D
     
  8. Steve Cook

    Steve Cook Flying Squad

    The front and rear parts of the new saddle tank have come out OK, which is more than can be said for my attempts to fabricate the outer wrapper :mad:

    Two failed attempts so far using 0.7mm nickel silver sheet, annealing hasn't helped and my rollers just seem to impart a curve along the width of the material when I want just a curve over its length.

    AB21 Saddle tank front and rear plates.jpg

    I was about to get a bit grumpy about it all when the new M10 x 1 die turned up, so I put the sheet metal down and got back on the lathe.
    Everything worked out better today, so here are all the bits for the safety valve.

    AB22 Safety Valve components.jpg

    The reason for making a new one is the rather obtrusive safety valve cover on the model.

    AB23 Safety Valve cover.jpg

    Its needed because the standard safety valve is so large

    AB24 Original Safety Valve.jpg

    I've used a lot of the space inside the mounting bush to house as much of the workings on mine as I can, the new valve will protrude significantly less above the bush as a result.

    AB25 Size Comparison.jpg

    With it mounted

    AB26 On location.jpg

    The internals are based on the modified safety valve on my Aster Castle which has proved itself maintaining or venting pressure at 60 psi, the Bagnall runs at 50 psi so in theory it should function OK assuming there is no significant difference in generated steam volume. I'm looking forward to giving it a test and finding out whether my theory is right or not! If all is well I can come up with a smaller safety valve cover more in keeping with the prototype. If it doesn't, its back to the drawing board :oops:
     
    Last edited: 8 April 2018
  9. Overseer

    Overseer Western Thunderer

    Steve, why are you trying to use 0.7mm nickel silver for the tank? The prototype sheet metal would have been somewhere from 1/8 to 1/4 inch (I think it is marked on the GAs but the books are not to hand) so even in large scale 0.25 or 0.3mm sheet would be plenty strong enough, especially as it is cosmetic. Much easier to work with.

    I like the new chimney and safety valve. Now you have started getting the model looking much closer to scale the cab roof is looking a bit plain. Gutters and a few rivets would add lots to the appearance.......
     
  10. mickoo

    mickoo Western Thunderer

    I agree with Overseer, 0.7mm is battleship foundry plate work territory, especially in nickel silver.

    0.25 mm, or 0.3 mm if you must, should be more than sufficient and even then I suspect you'll still get some bowing along it's length unless you use some seriously thick rolling bars. It's the bars flexing in the middle that'll be generating the bow, but I suspect you are already aware of that trait in rolling bars. If you want to add some strength in the middle of the tank then make two more former's so the internal space is split into three.
     
    Last edited: 6 April 2018
  11. Steph Dale

    Steph Dale Western Thunderer

    Steve,

    It might be time to find a source of tinplate for your tank, much easier to deal with for big jobs than nickel silver.

    Although brass or even copper would be preferable to nickel silver in this instance I suspect.

    Steph
     
  12. adrian

    adrian Flying Squad

    Personally I would stick with nickel-silver, less prone to knocks than copper and takes paint better than brass. However I would use a soft grade of nickel silver. Unfortunately many model suppliers only supply half-hard nickel silver which as the name implies would be harder to work into the curve required.
     
  13. Steve Cook

    Steve Cook Flying Squad

    Thank you very much for all the advice chaps. Interesting to see the recommendations for 0.25 to 0.3mm sheet - whilst I acknowledge it would be much easier to work with, my gut tells me that it is far too thin for the garden environment. The reason for going for 0.7mm was that is the material thickness used on the saddle tanks for all my 16mm / 7/8ths stock by Roundhouse, Accucraft, TME etc - I figured they hit balance between forming, rigidity and hard wearing based on their years selling engines etc.

    I have not tried tinplate at all, so if I can find a source for flat sheet I'd be interested to give that a go and see how it both forms and resists knocks etc. I did keep my eyes open for all options whilst at the 16mm Association Show at Peterborough yesterday, unfortunately it seems that builders are in a minority and there were very few stands selling raw material, I guess thats the way the market is heading, but it was a common complaint amongst my friends who were unable to source even basic things like copper tube, sheet material etc.

    Anyway, today I have come to an arrangement with a sheet of 0.5mm thick brass, and after some annealing to help with the smaller radius, it has formed up into a satisfactory shape without a great deal of bad language.

    AB27 New Saddle Tank.jpg

    I need to make some pads to fit inside to allow enough thread for the fixing brackets and tank balance pipe to be bolted into place, the last job would then be making a new tank filler, that will be a pleasant few minutes on the lathe.

    Steve
     
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  14. Steve Cook

    Steve Cook Flying Squad

    Thank you :)

    The roof is on the target list, I'm just debating with myself how far to go. The lack of rivets and gutters are the big things as you say, but I also think the corner radius where the roof curves down is too tight, and the roof also comes down too far. You could also argue that the roof supports are too large, although body colour would probably mask that to some extent and also keep a reasonable degree of strength in the assembly which is a good thing. I have a horrible feeling I'm going to end up making the whole lot though :oops:
     
    chrisb likes this.
  15. David Taylor

    David Taylor Western Thunderer

    K&S supply little sheets of tinplate. When we had a hobby shop here I used to get that. It's much nicer to work with than brass.