7mm MOK Ivatt 4MT in S7

[richard carr]

The next bit is the firebox itself, its quite a bit thicker but rolls in just the same fashion.








The boiler is then done in just the same way.

 

[adrian]

The next bit is the firebox

Isn't this still the smokebox? The inner tube for the wrapper unless there's a variant I don't know of with a round top firebox!

 

[oldravendale]

Richard - when using the GW rollers do you lead the metal you are rolling with a piece of scrap to ensure that the roll starts correctly? (I have a set of GW bars as yet unused, but have been told that unless you lead with a piece of metal you'll get a flat at the start of the roll).

Brian

 

[richard carr]

Adrian

Sorry for the confusion all the photos are of the smokebox and its wrapper.

Richard

 

[richard carr]

Brian

That's true you can't roll them right to the very edge. I hadn't thought of trying to lead it with another piece of metal but I will try it on the next one.

Once you use the formers everything turns into the right shape. There is though quite a defined seam on both the smoke box and boiler.

Richard

 

[mickoo]

Richard,

Leading in the work piece with a sacrificial backing piece greatly reduces the flats at the start and end of the work piece and gives a smoother joint.

I use a piece that is wider and longer than the work piece, that way you get an even roll throughout the whole work piece, a piece just at the start will then drop clear as the rest of the work piece goes through and your rolling radius will alter. Scrap 10 or 15thou is usually fine.

Mick D

 

[Steph Dale]

A layer of cereal box card on each side of the etch and extending a cm or so ahead of it (if you see what I mean) works just as well - that's how I formed the boiler on my Finney7 Radial tank. It also helps protect any formed rivets should that be important to the build (not necessary for this purpose on the Radial or this, as far as I can see)

Steph

 

[oldravendale]

Thanks, Richard and Mick. It was you who taught me about this, Mick. Even though the work room/man cave has been set up for a while now I can't get out there because a little thing called Finney7 intervenes! I'd like to test out the rolling bars and promise I will do so. I have been rumbling to SWMBO that some time needs to be spent in the isolation ward as otherwise, what's the point in having spent £lots in having it built?

I wondered whether Richard had found a way of overcoming the flats at the start situation by some wonderful new method about which we do not know. Apparently not!

Even before buying the rolling bars I spoke to George (of GW Models) who described and demonstrated how to use them in exactly the way you have described, Mick. As the proud owner of most of the kit George has produced I cannot speak too highly of his engineering prowess or helpfulness, once you are past his rather gruff exterior. (His BA nut spinners are a joy!)

B

 

[richard carr]

Brian

No no miracles from me on rolling bars.

I made some more progress today. I had feared that forming the firebox would be a nightmare and end up ruining an otherwise excellent model.

In the end it has not proved too difficult to achieve, I followed the instructions exactly as they are written and it worked.



Here is the firebox in the flat.

The instructions say to use a 6-7mm bar for the corner bends and 20mm for the side bends, so I did her it is after the first corner



Then when you have done the bends you use the tabs to fit it to the front of the cab, this works really well



Its just held in place with the twisted tabs



Then you solder on the front plate that is a brass casting.



And there is the finished firebox, at least before all the detailing that is required.

 

[adrian]

And there is the finished firebox, at least before all the detailing that is required.

That has gone together rather nicely - I always have trouble with the large holes right on the bend not being uniform along the bend but that looks to work out well.

 

[Peter Cross]

To get over the flat at the start and finish, it is the gap between rollers that cause it so if it can be bridged it helps. Use a carrier something like an over length heavy card. Or roll a curve on ends against a ruler or such to start with.

 

[john lewsey]

Superb Richard strange isn't it an apparently ugly prototype makes such a compelling model
John

 

[dibateg]

Good progress Richard - one thing to watch is that when you attach the boiler to the firebox, make sure that it and the attached front platform are sitting in the same horizontal plane as the cab. As you can guess, it was a mistake that I made... and had to undo..
Regards
Tony

 

[richard carr]

I have been out on a train most of today but a little more progress has been made. The cab, boiler, firebox and smokebox now fit together quite well.





Its not quite as good on this side though.





I'm quite pleased and will progress from here.

Richard

 

[oldravendale]

Thanks for your advice, Peter. I'll try ways of leading the flat sheet when I make some tests.

I'd not considered card previously - that sounds like an inexpensive first option!

Brian

 

[Yorkshire Dave]

Is this of any use? One of my dad's slides taken at Peterborough.

 

[Wagonman]

They do have a certain brutish charm...



Richard

 

[Steve Cook]

I've always found the models to be more appealing than the prototype, this 3.5" version was caught running round the track today and if you'll forgive the cliche, it really did run like a sewing machine.

 

[warren haywood]

And here's one I had the pleasure to paint last year, MOK version

 

[richard carr]

It's a little while since I last posted an update, I have been busy building the cylinders, valve gear and rest of the bits that go with it. To say the least there is a lot of detail, all in beautiful cast parts.

This is how far I have got



It's starting to come together, the slide bars are not attached to the cylinder at the moment.

This is how I got here.

I started with the slide bars.



You need to use some 0.7mm nickel silver wire to to pin the upper and lower slide bars to the cylinder front.


You remove the bits of wire between the slide bars by cutting them in the middle first and then working up to the ends.

I opened up the main cylinder castings with a large taper reamer



If you don't have one of these I can highly recommend getting one they come in handy for all sorts of things.



Here are all the bits to make up the J hangers and die blocks, the parts in the top right are for the weigh shaft.



Here they are going together.