Midland Railway 0-4-0ST (Burton Tank)

This ABS Zero Zephyrs kit was the first loco kit I bought when I made my first steps in 7mm, in 2005. Its the sort of thing that IMHO is just too small to work in 4mm but should be ideal in the bigger scale.

I didn't actually start building it until 2016 when I came up with the scheme shown below for powering it. This uses an ABC gearbox with a Maxon 2W motor in the firebox, in place of the suggested 1620 Mashima and worm drive.

So here are the frames being prepared. I've got the rear axle rigid in the chassis and the front axle able to slide up and down. At this stage I'd worked out that I needed to have the axles slightly higher in the frames in order to get the buffer beams at the right height - photos show that the buffers should be at the top of the buffer beams so that they are almost level with the footplate (see diagram above).

Very interesting, and of course it's quite an attractive prototype - like o-4-4 tanks there aren't many ugly inside cylindered 0-4-0 tanks. It always surprises me how often 7mm builders make locos with rigid chassis, in general.

I'm sure that it's a matter of taste, but I'm not quite sure what you mean about too small to work in 4mm (Keyer, for one, would not have agreed with you since they made a kit!). I say this as someone who's made several perfectly good, reliable, 0-4-0s in that scale. With modern gearboxes and small motors this is quite practical (and discreet). Iain Rice's North Cornwall Minerals stud shows that it was in the '70s when you couldn't get such things. 2mm would be more of a challenge but someone will have tried and I've seen a - working - Ruston 48DS in 2mm Finescale and that is minute.

Look forward to seeing more.

Adam

I've got one in the box waiting to be built so I will be watching with interest
Marc

With some frame spacers (but not all) soldered in, the motor in, and the wheels on, it looked like this:



The gearbox looks a bit obvious here but it can be cut down and is mostly contained within the ashpan.
From underneath:

The tubular frame spacers were temporary, using the holes for the cast sandboxes. Not being exactly certain where vertical spacers would be, I just put stretchers at each end of the chassis. The coupling hooks go though holes in these stretchers - they have also turned out to be a useful way to fix the body to the chassis.

I'd made a new rear buffer-beam from 15thou nickel-silver so that I could add the kit part for the rear buffer beam to the parts for the front buffer-beam to get it to be the correct thickness. The bolts on the front buffer beam were represented by bits of 0.8mm wire fitted into holes drilled all the way though the layers. The drilling was done by hand as I didn't then have a drill stand; consequently they aren't as well lined up as I'd like but you can waste a lot of time waiting for the perfect moment to do something (and then find out it was no big deal). The bases of the buffer casings seemed to me to be a bit on the large size (as are some of the other whitemetal castings in this kit - beautifully cast, but too big) so I replaced them with Slaters Kirtley buffers; these have the additional advantage of being cast brass rather than white-metal.

Here's a recent photo of the front buffer beam to illustrate the last paragraph in the previous post.

The new firebox was built on a rectangle of nickel silver. The bolts that attach it to the footplate are still in use to attach the boiler/saddle-tank/firebox unit to the footplate.


Then front and back formers were added, spaced out with lengths of bullhead rail. Shades of KeilKraft. A wrapper formed from 12 thou brass was then added. You may notice that there's a square hole in the front former - this is to ensure that there enough room for the motor. The hole in the back former is to allow a screwdriver to get to the screw that goes through a similar hole in the front former, that attaches the firebox to the boiler.

At this stage I'd fitted backs to the splashers but had left in place the (non-prototypical) footplate inside the splashers - this part of the footplate was later removed (which made fitting the cosmetic springs a bit tricky, but that will hopefully be covered in a later post). It isn't immediately obvious (I hope) that I've also filled in some holes in the footplate between the splashers - there do need to be some holes here, but much smaller than in the kit.

I've just remembered that (well before this stage) I moved the splasher fronts out slightly, which wasn't too difficult as the footplate is formed of two layers and the splasher fronts fold up from the lower layer. There's about 3/4 mm of clearance at the wheel rims, which is quite tight given that the front wheels need to be able to rock to make the compensation work.