Ivatt 2-6-2 Mickey Mouse tank engine in 7mm scale

Discussion in 'Workshop Benches' started by York Paul, Nov 13, 2019.

  1. Keith M

    Keith M Staff Member Moderator

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    The joys of poorly thought out kits eh Paul, one step forwards and two steps back? At least when you've sorted it out, it'll be world away from what the original kit would have produced. Thank goodness for CAD and accurate etches! I was almost tempted today at the Peterborough show, one exhibitor I haven't seen before had a large selection of 'Older' kits for most regions. Recalling the 'valve gear wrangling' I'm having with my Keyser "Lord Nelson" though, I resisted, sanity is currently being tested enough presently anyway without more problems!
    Just got to 'shoehorn' the Hornby 'Nelson' chassis I bought recently into it and that will hopefully resolve things.:giggle:
    Keith.
     
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  2. York Paul

    York Paul Staff Member Moderator

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    So very true Keith and we both sing from the same hymn sheet so to speak because we both enjoy the challenge but accept there are limits. I've always tried to encourage and be encouraged in a positive way and not to call products down on our forum but like you my honest advice to folk is leave old kits alone unless you intend taking the outcome to another level. Generally speaking the Acme kit is dimensionaly correct, the frames are the right length as is the tanks and cab with bunker, its just silly things like the con rods and the like which let it down, I suspect the cylinders were drawn over wide so as to avoid conflictions in the motion which no doubt Acme didn't want to be the recipient of complaints. Anyway apart from the thin etch size which borders on the flimsy it ain't a bad kit, much of the white metal casts such as smokebox door, chimney and steam dome are accurate and that's what I'm after.

    What I will say is the DJH version didn't appeal not because of price but because I think that whitemetal cast boilers look very clumpy, I've seen two built Fairburn tanks from the DJH stable and I'd compere them to looking at a slightly blurred photograph that's all.
     
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  3. Andy_Sollis

    Andy_Sollis Staff Member Moderator

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    All fun stuff eh Paul. Limits... hmm reminds me of the boundaries I was asked to push to make some signal boxes, but, I did it and kept the look.

    I'm interested to see how your going to approach the cylinders. 4 cuts so the middle 5mm comes out and reassemble?

    btw, looked at the leek and manifold. Can’t do much. If you see the design of it, you’d laugh!! (I’ll try and find some photos) but as my first 7mm kit (probably wasn’t the best idea for me really!) I never thought of it any other way.

    locos looking good anyway. Great progress despite the set back.
     
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  4. York Paul

    York Paul Staff Member Moderator

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    Andy in this picture you can see the cylinder block and front footplate is a detachable item which has been put together from many parts so to saw down the centre wouldn't work because that would affect the location of the screw fixing points. So imagine the block as three boxes, the outer two are the cylinders and the middle one carries the footplate and is also the connector to the mainframe just described, you will see on the cylinder without its wrapper fitted tat there are two brass rods holding the front and back face of the cylinder as a strengthener. Now I've decided to saw the cylinders off against the frame face using a piecing saw, the wrapper and brass rods will hold the cylinder units in shape, once removed I shall cut away the excess metal, clean the frames and refix. obviously I'll score mark the new fixing line on the block before cutting and probably add in a couple more rods on the inside to hold the shape when cutting.

    In some way I wish I had seen this issue before soldering the first wrapper in place but it will be possible to work round this... I don't want to remove it as its a half etch and quite thin. Yes its a setback but then its all par for the course when you work with kits of this ilk, its like Keith says the object of the exercise is to make something much better than originally designed, its worth the effort because once done it will look the part.


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  5. York Paul

    York Paul Staff Member Moderator

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    So in the words of a well know Platform 1 celebrity here's that old chestnut of an Ivatt cylinder block again :avatar:, in a chestnut shell I decided the best way short of taking a very heavy hammer to the thing was to melt the whole unit apart and start again... so I fired up the Proxon micro flame and watched all the bits fall like chestnuts onto the workshop floor. Back to the warmth of indoors and I remade some new bits which work a lot better, checked the chassis frame width from outside face to face at 25 mm and checked that width against the other 2-6-2 tank from Scorpio the BR Standard Class 3 and that also measured the same width. So new inside spacers were cut, filed and drilled 8mm narrower at 24 mm widths... the original Acme design was that much out of scale :facepalm: ... how I missed flagging up that fault originally goodness only knows, anyway I now have a new cylinder block front and back face at the correct width, a new piece added to the mainframe which holds the block and it lines up nicely. Just need to solder up the block and add the front footplate back on... but for now I've had enough.

    Hopefully the outside motion set will arrive this week from Laurie along with the lost wax gusset strengthener corner plates, the drawbar plate and the reversing shaft bracket castings, I think we could now be making some forward progress at last. I'll order up the remaing castings for the boiler, running plate, tanks and cab along with water sieve box and the later type LMS pattern vertical injectors.

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  6. York Paul

    York Paul Staff Member Moderator

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    A consignment of goodies from Laurie arrived yesterday, the package consisted of a full outside motion set including con rods and various other lost wax castings I need to dress the chassis with when the time comes, I have to say the slidebars and crossheads are the best I've seen. So its a step forward now and once I've metal hardened the nickel silver cast motion pieces and filed them to a clean fit the slide bars will be the first items to go on the block. Yes the cylinder block frame has now gone back together and in a strange way I'm glad I took the effort to get this right as it has turned out much better than it's predecessor. A motion bracket will have to be scratch built too and once that is fitted in position on a pair of extension legs from the cylinder block then I can mark up and drill 16BA screw fitting points to the mainframe sides. I've now ordered up a raft of boiler and tank fittings, this will keep me busy over Christmas if I can get some peace from the visiting masses arriving to undertake their annual group therapy vocal exercising session. :facepalm:


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  7. York Paul

    York Paul Staff Member Moderator

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    Well postie brought another package containing more lost wax cast shinies from Laurie Griffin, mostly bits for the plumbing and body which I'll show later on when we get to that bit of the build. Now the outside motion kit also from Laurie's stable is where I've been focusing efforts, filing, clean castings and work hardening them in preparation for "dry" fitting, after a bit of delicate filing and polishing I now have crossheads which travel freely along the slidebars... all looking good me thinks. The side rods are "dry" fitted to the wheels and after a bit more jiggery pokery and repositioning an axle bush just ever so slightly on the compensation beam everything turns as it should with no tight spots or binding at all... I must have just slightly miscalculated when drilling the compensation beam as the bush only needed moving less than a gnats hair but it was enough to make the rear driving wheel axle run out of square. Anyway here is the dry fit with con rod and piston assembly fitted to check alignment and to see what needs filing back to make clearances for the rotating motion. I also made up the sanding gear last night, I think it is near enough and will pass muster once painted.


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  8. York Paul

    York Paul Staff Member Moderator

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    The main issue in building kits such as this dinosaur is the need to ensure clearance behind the crosshead and the bush fixing of the side rods on the forward driving wheels, remember this kit has undergone some significant surgery in an attempt to upgrade it and as such much of the fabrication on the cylinder block has been reworked so I need to be extra vigilant when it comes to setting tolerances for moving parts. As the picture shows the nut and pin thread on the front wheel crank has to be filed down to pass freely behind the oscillating axis of the crosshead, this means the soldering of the piston gland casting has to be located as far outward on the cylinder frame as possible bearing in mind the cylinder wrapper and banding have yet to be added. This will give me an extra 0.50mm clearance on the crosshead and 2mm on the crankpin which should be enough, if push comes to shove and the piston gland cover rim edge extends beyond the wrapper face then I'll have to file it back but we shall see, the main thing to remember is that the con rod needs in an ideal world to remain parallel to the side rods. My next task today is to add the wrappers and the inner frame bits to the block, note also the etch brass side wings added which will carry the motion brackets, these will also add additional strength to the chassis frames at a point needed.


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  9. York Paul

    York Paul Staff Member Moderator

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    The rear sand pipes went on nice and easy, I scratched a couple of angle support brackets filed to shape as per the drawing and bent some 0.70mm wire to form the profile, the actual steam blower valve I fashioned from some hollow tube adding a blob of solder to emulate the shape. again it will look ok under paint, the bracket was soldered to the lower edge inside of the mainframe and the sand pipe fitted to the sand box casting which I had previously drilled a fixing hole in.

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    Last edited: Dec 23, 2019
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  10. York Paul

    York Paul Staff Member Moderator

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    The front sand pipes were a different kettle of fish altogether because the brake hangers extrude a tad too far outwards thus impeding the correct positioning of the pipe and blower valve, this is an issue with the original kit which could not be overcome without risking an electrical short between the wheel flange and the brake block. Like most things of this vintage it is a matter of reaching a satisfactory compromise. Anyway I tacked the curved pipe behind the frame in the same manner as the rear ones which meant the sand pipe had to run behind the brake hanger and not below and in front of it... again without sounding sloppy it will be ok once painted I think.

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  11. Rob Pulham

    Rob Pulham Happily making models Staff Member Administrator Feature Contributor

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    Paul,

    Sorry I am a bit late to the party and it may be granny and eggs but you can gain extra clearance on the front crank pins by replacing the pin with a Countersunk 10 ba screw and then tap the Slaters bush 10 ba which will allow you to either file flats for tightening or drill holes and use pointed tweezers or a peg driver to tighten. This replaces the standard 'nut' and does when blackened look much like many similar prototype crankpin 'nuts'. Because all you have is the thickness of the top hat of the bush you can gain a lot of useful clearance and worst case if you still need more you can drill the leading boss on the connecting rod and counter sink the top hat into it giving even more clearance.

    I hope that this makes sense.
     
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  12. paul_l

    paul_l Staff Member Administrator

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    Just caught up with this thread - boy this one has given you a few challenges, and for less money than other "easier" kits, see really good value for money, as an adopted Yorkshireman you should be really chuffed :avatar:

    Excellant work there Yorkie

    Paul
     
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  13. York Paul

    York Paul Staff Member Moderator

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    Thanks Rob for the tip, in the end I did exactly that by turning the brass crank bush over, I also filed excess material of the bush so that it was just a tad over the width of the side rod wall. These cast nickel silver rods from Laurie Griffin are not cheap but certainly look the biz, I had to drill the crank bush holes wider to 2.5mm to accept the brass bush. So far so good, the con rods are now drilled 2.5mm at the crank end and 1.6mm at the crosshead which is now fitted with the little castpin sweated in from the back. Currently I'm scratch building a pair of motion brackets which will fit onto the leg ends of the removable frame assembly, once the slide bars have been trimmed to their correct length I can solder them onto the cylinder and solder the motion bracket to the leg end side pieces... sorry no photos as yet as I wanted to post up a completed assembly to explain my thinking. Pictures to follow in a couple of days time.
     
  14. York Paul

    York Paul Staff Member Moderator

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    Hi there Dundee and thanks for the comments... hope you had a good Christmas and all the best for New Year... I guess you are the family taxi service :avatar:

    Challenges Dundee... you ain't seen anything... boy how close I came several times to flattening the damn thing with a big hammer but you know me I can struggle in the face of adversity refusing to let something like this beat me. Once I've got the motion in and motor / gearbox set up in position I know its home and dry at that point. The body will be a walk in the park once I've added in several dozen rivets from the bunker end which are missing on the etches... the big stash of newly arrived lost wax castings will gratefully enhance the original Acme design. This build is just a personal challenge to push boundaries by taking a basic budget kit to a higher level... I think the next one may well be something simple to make like a Manor, Grange or a Hall ... something devoid of outside valve gear motion which I can sell.:avatar::scratchchin::thumbup:
     
  15. paul_l

    paul_l Staff Member Administrator

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    Oh noooo , he's turning to the Dark Green side
     
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  16. Andy_Sollis

    Andy_Sollis Staff Member Moderator

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    :confused: No. I think @York Paul will always be an NSR man at heart.
     
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  17. York Paul

    York Paul Staff Member Moderator

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    Actually Andy you know that and not just think it. NSR all the way for me... it can take an LMS guise or even a BR period guise and the only dark green around would be remnants of old LMS paint found on station waiting room walls.:avatar:
     
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  18. York Paul

    York Paul Staff Member Moderator

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    T'was merely my funny sense of humour Dundee... honest:avatar::giggle:
     
  19. paul_l

    paul_l Staff Member Administrator

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    Look you've even got Jim going Knotty

    [​IMG]

    http://www.jimmcgeown.com/Loco Kit Pages/BEL 1.html

    So don't let vicious rumours start about the Green stuff :avatar:, just 'cos they couldn't understand Walcherts, there's no need to encourage people to model 'em :whatever: (could this be the last flame war of the decade :avatar:).

    Paul
     
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  20. York Paul

    York Paul Staff Member Moderator

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    Jim knows it makes sense that's why... this is just the start of an incremental incursion into NSR brass kits and that dark green stuff was banned east of Silverdale Junction... anyway such glitzy locos wouldn't go through the Brampton Tunnel with those strangely over wide outside cylinders.
     
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