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

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

  1. York Paul

    York Paul Staff Member Moderator

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    I know there is a tendency to either curse or joke about the Jim Harris kits and their "difficult" building stance but I overcame the BR Standard 4 and managed to construct the motion bracket on the Brit which was originally from the same stable and soldering tiny bits together to make an etched fabrication wasn't much of an issue to me, just a matter of thinking it through firstly and then creating the correct support frame to hold all the bits together. I guess it also relies on developing a soldering technique which works first time as well, a quick in / out with the right iron at the correct heat level delivers a satisfactory result I have learnt. I only ever use 145 solder on all my fabrications and find it works for me. But this Acme Ivatt kit Pete represents a totally different breed that demands a different approach... one in which I'm feeling my way in the dark but gives results with perseverance. The issues I've found with this kit is that A)etches are too thin thus frames are prone to flexing, B) etches are hand drawn and need fettling to fit and C) whilst the model is dimensionally correct it falls short in detail of shape, e.g that cylinder block and now this morning I've discovered the cab roof profile is wrong. To summarize though it will build into a nice kit and hopefully importing better grade castings it will capture the essence and character of the real thing more so but, would I build another from this stable... definitely not because of the time involved. By today's expected standards this kit doesn't cut the mustard however I knew that when I bought it... I'm just a glutton for setting challenges for myself.:avatar:
     
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  2. York Paul

    York Paul Staff Member Moderator

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    Forward progress at last and now its starting to look more like an engine, I had to dismantle the side tanks from the footplate because of a lack of foundation support for the thin etches which literally had started to started to distort. The mistake I made was to screw the body onto the chassis as I thought this would make for a solid foundation.... wrong because the holding down screw over the cylinder block pulled the footplate sown between the chassis frames causing the footplate to bow, the result was the forward part of the side tanks started to lean inwards and twist, sadly this lost the square angular shape and design of the Ivatt locos. Only one thing for it and that involved drastic action, using my Proxxon micro-flame I gently undid the inner side tank faces and reintroduced sharp angles again, a few pieces of offcut etch made an angled foundation base for the footplate to be set back onto without twisting when screwed down. The front end smokebox footstep and buffer beam can now be soldered back on, a prototypical vacuum stem and pipe will replace the current one which was only put there to see how things looked.

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  3. York Paul

    York Paul Staff Member Moderator

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    A trade off or rather a fault on the part of the designer of these old kits is the level of inaccuracies one encounters when you diverge away from the original construction plans... or in this case a badly drawn fag packet sketch which is of little use. Note how the inner side tank faces fail to line up along the top edge rivet line and the 2mm gap along the bottom of the forward part of the footplate. I can add some scrap etch in along the bottom of the tanks to aid strength but the exposed rivet line can only beflooded with solder once I finally seam the piece up, I can't raise the inner tank side and top because if I did it would foul the front can spectacle window openings... which incidentally are drawn marginally wrong, well according to my LMS general arrangement drawings they are. So filled with code 3 lead strip to add tractive weight the job not only feels right now but is starting to take shape. It's nice to start putting thing on as opposed to either remaking anew or just plain doing things twice over.

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  4. York Paul

    York Paul Staff Member Moderator

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    So the smokebox foot step and buffer beam is on now and lines up at the correct height properly (always a dodgy time wondering if the measurements are correct), the body has regained its square angular shape, the siderods and con rods rotate freely and the driving wheel compensation beams does its job, great so what is there to go wrong now. Well hopefully nothing much and even the wheel flanges on the front and rear trucks clear the mainframes nicely, but its decision time and this is the plan. Now I have the tanks in position I can make up the injector plumbing and fit the injector brackets on the chassis, I need now to also fit the motor and gearbox and start to add in the wiper pick ups, but before any of that I'm going to finish the body build which involves making the smokebox saddle and the boiler... I already have made a start on the firebox. Building up the saddle will add strength to the front portion of the footplate and then I'll know how the boiler will sit, so quite a bit more as yet and once I have a basic body structure I can remove it from the chassis and go back to finishing the delicate motion and valve parts.


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  5. York Paul

    York Paul Staff Member Moderator

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    Tomorrow's job is to make up the smokebox saddle which will potentially involve some scratch building and continue making up the bunker and cab back. Once happy with everything being straight I'll seam up all the tacked in pieces and joints then the detailing can be fitted, there are a lot of nice new shiny brass casting ready to go on. I'll still have to buy in a few bits such as boiler banding cleats and the backhead / reversing gear or bacon slicer, otherwise I've pretty much go everything I need.


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  6. York Paul

    York Paul Staff Member Moderator

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    This morning the sun was shining and luck was shining on the old Ivatt loco kit too because I gotten the smokebox saddle rolled and made the front cover plate the other day, a few adjustments to make fit nicely in the widened front frames but I happy now with the results. All is now looking good, tanks are level and straight, chassis and rods run freely and now the next major component the boiler can be made. When this is made and test fitted I'll solder up the smokebox saddle and fully seam up the tanks and cab front, once that is done I'll turn attention to the cab and bunker which will complete the body build I can then return to the chassis to add in the remaining motion and plumbing along with a motor and wiring. So here is the saddle dry fitted and posing alongside 75030 on Elton Crossing layout, notice the tiny little three feed box box on the left side below the step bracket to the top running plate ... scratch made ... no wonder I'm seeing things double. Heck I've now suddenlygot twice as many kits as I thought I had. :avatar::avatar:


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  7. York Paul

    York Paul Staff Member Moderator

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    The design of this firebox is very old fashioned, there is nothing fancy about it at all and it expects that you file the necessary profile curves yourself, literally this fabricates as a front and a back section and a wrap over middle bit which you solder up along the edges... :facepalm:, there is no inner support frame for strength.:facepalm: So I shall add in some thick copper wire to file the curve into and some thinner wire at the back for strength, as luck has it in the depths of my store cupboard I have the very thing needed :giggle:. Years ago when I was a mature student at Wolverhampton studying sculpture I purchased a few lengths of copper cable from a metal merchant down on Canal Street round the back of the old GW goods yard, thankfully I still have some left and this will do the trick nicely. Once soldered in I'll file the curve shape I want and the firebox will remain intact.


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  8. York Paul

    York Paul Staff Member Moderator

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    Using my Rexon bench grinding wheel with mop I gently ground back the corner bevels on the firebox front forming the general outline of curve needed, this put holes on the piece which were fillered with solder to keep the strength and shape. Once sufficient grinding had been done I flooded the edges with more solder to give me the basis to start the smoothing out process, from hereon in its a slow job of filing, fillering and then polishing the soldered surface, when this goes to paint I shall stopper the piece when priming. so here we are as we speak, hopefully a fully formed firebox by tonight.


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  9. jakesdad13

    jakesdad13 Staff Member Moderator

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    A great solution to a pretty big problem :tophat:. I have seen similar before but using layers of plasticard, indeed I have used it to form the tumblehomes on my scratch built coaches.
    I have been collecting the parts to scratch build a Johnson 1F tank and I will more than likely use your solution to build the fire box on that. :thumbs:

    Cheer's, Pete.
     
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  10. York Paul

    York Paul Staff Member Moderator

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    Thanks Pete but I cannot really lay full claim to this technique for I'd be fibbing if I did... credit must go to Peter Cross who did the same loco about five years ago now. For this job plasticard is out because I will have to solder the boiler to the firebox and so must have a tinned surface, suppose I could Araldite it together but it seems such a faff and it still leaves me all the other stuff like banding and pipework to solder on. The 1F tankie sound like an interesting one Pete... looking forward to following that one. :thumbup:
     
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  11. York Paul

    York Paul Staff Member Moderator

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    With patience and a lot of elbow grease the required shape starts to emerge, another few dabs with a loaded iron to filler the dints and then more gentle filing and a final polish on the mopping wheel and we should be there. The boiler barrel is a great guide letting you see where to go next.


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  12. Gary

    Gary Will the real Gary please stand up... Staff Member Administrator

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    Coming along a treat. :thumbs::thumbs::thumbs:

    Now knowing that these older Acme kits were not so true, as to putting them together, is this the reason why Wile E. Coyote couldn't catch the Road Runner with the Acme products ?? :avatar::avatar:

    Cheers, Gary.
     

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