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

Andy is that a shower tray you've added between the buffers on that diesel shunter ?

 

Ah I see now... yes of course these little engines were always great performers on the rally circuit

 

i knew those unusable side rod etches from this kit would be good for something... and their new role is to strengthen the truck frame which is again a very flimsy affair. After a lot of work modifying the rear truck pony by adding details such as the lateral coil spring assembly I finally finished this one this evening, now I have the front one to do but that will come latter after the cylinder block build. The rear pony truck is quite a substantial item now... it just needs cleaning up a bit and then I'll add a sliding spring assembly to hold it correctly in the frames.

 

Rear pony truck fitted in the mainframe and I'm happy because there is no confliction with the mainframe in swing radial movement, the wheels have been shimmed and won't "hunt" across the truck bushes so that's good too. Also another package containing frame detailing items arrived today from Laurie Griffin so the correct shape real sandboxes are now fitted, these are whitemetal ones but are very sharp castings. I'll go back to reshaping the guard irons following the shape on the GA drawings, this model will be 41244 which was shedded at Bangor and Rhyl later going to Bank Hall and finally Aintree before scrapping in 1967. From archive records 41244 always had the unmodified LMS Ivatt pattern guard irons and also the short chimney which is a bonus because I have one of those in stock.

 

And the side profile view, later on in the build I'll add in the sand pipes and valves.

 

As I understand the issue with snagging wheels with insufficient frame clearance is down to a couple of things, firstly the tyre flange is oversize on models and secondly the radii of curves are often too sharp, both resulting in a need to increase clearances for bogie swing. For example if we were to upsize a model train wheel set and track work to full size then the problem would become visually obvious to see, even the medium size points made by Peco would be way too short a radius and potentially only any use in an internal industrial set up, so compromises have to be found and the trade off in overcoming wheel snag is to find non authentic modifications and solutions which work, such a move may not be totally acceptable to the pedantic purist. On my Elton Crossing layout the main line point is B9 which at 24 inches long is even too short for passenger line use which requires at minimum a C10 with continuous wing rails or a D12 on low speed lines. Most modellers cannot afford such spacious settings (including me) for long points even if someone like C&L even made them which they don't. Again the trade off with using tight curves is to accept the fact that end throw and over throw on passenger bogie stock will happen, but with having over scale wheel flange derailments will be reduced.

 

So this is how I decided to construct the cylinder block in order to keep things reasonably straight forward. The block sits against the mainframes at an angle of 1 in 20 and is held in position by two 10BA screws, in order to keep the front and rear faces of the block parallel I squared and marked up four holes just inside of where the frame inserts will go, drilled at 2mm dia I then soldered a length of 2mm rod into each hole on the rear face ensuring a true fit. Once satisfied the front plate was aligned to give the correct width and that soldered too, it was just a matter of checking everything for square and filing the rod ends flush then fitting to the mainframe. I can now confidently cut the front frame portions and solder the insert into place, then it will be a matter of soldering the front mainframe spacer... remember this is still only tack soldered. Still a bit more fabricating work to do on the block before i can move onto the front frames and buffer beam.

 

I've already pressed out the rivet detail on both the front and rear buffer beams, the front one has been soldered to the front footplate in readiness, but before I can solder the front frames back on I need to scratch the two lifting ring collars around the holes in the etch... this detail is not included in the kit, then it will be a case of dressing the front footplate with lamp irons, grab handles and of course the corner gusset strengtheners which will come from LGM. I think I may also have discovered a way to make the buffers "spring" without having the nut and thread... in other words make a self contained buffer. The gusset plates are an important feature on the Mickey mouse and need to be included but to do that the buffer back piece will have to be chopped. The two central holes at the front of the block allow a small screwdriver to be inserted tightening or releasing the 10BA holding screws.

 

Here's the result of tonights efforts, I was determined to complete fabrication of the cylinder block and add the last bit of the cut off mainframe with buffer beam. So welcome to 41244 ... smokebox number and build plates to come from Chris at Severn Mill.

 

And this is how I put the cylinder block together... it looks a bit crooked but this really is just the camera angle, the block sits as it was intended in the reconnected mainframes and the whole fabrication is quite square and solid.

 

With the running footplate temporarily in position it shows that I got the cylinder block positioned in te right place and that there is sufficient clearance for the con rod to pass unhindered when the side rods are fitted, side rod fitting is the next job and I'll order the outside motion pack from Laurie in the morning... gosh its morning now . Once the slidebars and valve gear is fitted I'll form the cylinder wrappers and dress them with new lost wax drain cocks and excess pressure valves which are already to hand, the stretcher beam which located the front truck will also be fitted along with the front footplate. That's all work for this weekend though, making up the front truck will be a big move forward to having a completed rolling chassis. At last this is starting to look like an engine and hopefully we have progressed past the one step forward and two steps backward stage. At this rate I'll have to scout around for another kit to build over the Festive Season... I quite fancy doing one of Jim's 4F kits.

 

Oh yes they are Toto... not a criticism but hand drawn etches are not so hot and in 16 thou thickness are in need of additional strengthening. This kit has no compensation incorporated and certain etch items such as cab bulkhead fitments were not included plus the con rod is 4mm too long, the firebox is of the old fashioned design which means you have to fashion the curved flairs with a file and pack the inside face with copper so as not to file holes into the corners.

My advice is only get one of these kits if a) such a model you want is unavailable elsewhere or b) (like myself) want to use the etches as a start point and chuck everything else away replacing with new and better quality components.

Have a great holiday in Prague Toto and hopefully Skype when you return.

 

Over this weekend bench work focused on getting the cylinder block and front footplate assembly aligned finally and then seam soldered as a removable assembly. The buffer height position is correct when compared to the Standard 4 tender.

 

The front truck has been made up too and fitted to the pivot stretcher beam on the main frame... I've also started to solder the boiler seam having pushed out the top clothing sheet rivets, I need to make an internal disc former which will add strength and assist in forming the boiler shape evenly.

 

So things were going swimmingly until it suddenly occurred that I hadn't cross checked the width of the cylinder block, so I now have an assembly which will have to be taken apart again for the sake of 2.5mm excess width on each side. The cylinder block is just noticeably wide and that won't do... moral of the story here is never trust etches of dubious origin, I should have heard the fire bell ringing when I discovered the con rods were 4 mm too long. Only one thing for it now and that is to slice the cylinders off on each side and reduce the width accordingly... luckily I inserted those 2mm dia brass rods for strength as they will keep the things intact when I start dissecting. The problem is the original cylinder outline was drawn like this and even had I not made a removable block assembly the same problem would still have arisen because whoever drew these components only ever intended to produce something which loosely looked like an Ivatt loco. I'll wait until the outside motion bits arrive from Laurie to then check widths again so I'll know exactly how much metal to remove.

On a more positive note the front truck differs from the rear one because this has the swing link and damper assembly fitted where as the rear truck has secondary coil springs, the reason was on the real thing it was to aid the stability of the loco and increase riding quality, so this model must have the same feature represented.

 

Here is the full side profile view... even at this angle it will not be possible to get away with not dealing with the cylinder issue as I feel it is way too noticeable and I'm much too much a stickler for allowing sub standard design features affect what I want to achieve. But hey ho onwards and upwards at least we can see all the bits coming together now... I'll drill the wheelsets next week and fit the new 10BA crank pins and the new side rods. Also of note are the generous rivet marking detail on the cylinder wrappers, this of course is most definitely not correct and I put down to artistic license by Mr Acme, my solution was simple... fit the half etch wrappers the other way round and cover the offending rivet press marks with a fine banding strip which I'll fashion from phosphor bronze strip.