M7 Etchings

Now that I was happy the motor unit was working I could finally turn to the rest of the model. These are the Railmotor etchings as supplied from Worsley Works.

Soldering up the solebars

So the first bit was to solder on the solebars, this was done on a glass plate to try to keep it as flat as possible.

Rolling a bit of scrap as a test

The next stage was to form the curve in the cab end plates. I thought I ought to have a practice first so on a bit of scrap sheet, a nice lump of 5/8″ brass bar rolled across it on the cutting board. It seemed to work ok so I pressed on with doing the cab ends.

Cab ends rolled to shape

Tumblehome formed on the sides.

Once that was done it was then on to forming the tumblehome on the coach sides. I left the etches in the supporting frame as there is a cutout in the middle of the sides for a recessed doorway to be soldered in once the sides have been curved. The supporting frame is keeping the 2 halves aligned – so they are formed attached to the frame. I can then solder in the door etchings before removing them from the frame.

Tack solder the sides together.

I’ve tack soldered the bodywork together but it’s rather flimsy as it is. The sides are anything but straight! The half etch is extremely thin in places and so great care is required in handling it. When soldering the recessed doors in I managed to put a ding in the side with the soldering iron, which needed a bit of careful work to remove.

Fitting baseplate to the bodywork.

The sides by themselves were very fragile, even with the tumblehome and I kept bending them. So I decided to make a baseplate to solder in the bottom to try and keep them as straight and square as I could. The holes are cut out in the middle because I have decided to solder the roof on for strength and I will need some method to add glazing and seating when it is all done. In the corners I have drilled and tapped the baseplate 12BA so that I can bolt the bodywork to the footplate after painting.

The next big challenge was going to be the roof as there isn’t one supplied in the kit. There are  various options from the trade with resin and plastic roofs. Although I wasn’t sure if they were the right shape and would be difficult to solder so I thought I’d have a go at making my own roof.

First attempt at forming the roof

As it is only a small model it’s only a small bit of nickel-silver wasted if it goes wrong. To begin with it was just a quick job to see if I could produce something acceptable. It sort of worked, I managed to get a representative profile.

However it was too narrow and didn’t overlap the sides very well.

Not to give up I thought I better make MkII, taking a little more care this time. Also knowing that it would probably work I thought I’d run through the steps to making the roof in case any one else wants to try.

Cutting out the roof

First job was cutting out a rectangle of 10thou nickel-silver. I have a large sheet of half-hard n/s which was suitable for the job. I mark out with a pair of odd leg callipers and cut out with a piercing saw and then file down to the edge. I’ve included this shot as it shows something I’ve tried to explain before but it’s difficult without the photo. Basically as I file down to the line if you watch carefully you know when you have reached the scribed line as a small sliver of material will curl off from the surface.

Forming the first curve on the roof

One edge is then clamped in the vice against a tube of suitable diameter for the large radius, I then just used finger pressure to curve the roof around the tube. Make sure the tube or bar is clean of any blemishes or indentations. Any markings will probably indent or mark the nickel silver. The roof is turned around and curved from the other side.

Get the major arc correct

With a bit of work experimenting with different size tubes gets the major arc correct.

Forming the minor arc

Next is forming the minor arc at the edges. For this I used a couple of lengths of silver steel bar and a rawhide mallet. Holding the roof over the silver steel bar with a small overhang just go along the roof and tap over the edge.

Smoothing out the roof

It took a little going backwards and forwards to get something looking right. Final finishing involves just rubbing the mallet up and down the roof to try to smooth out any undulations.

Roof MK II

It still needed a bit of tweaking to get it straight, it was just slow and steady with the rawhide mallet tweaking the bends against a few different sized bars. This time it’s wide enough!

Roof MK II

The roof still needs to be soldered on and trimmed to length but as it was getting late I thought that better be left for another day. Also I need to check it again with a fresh pair of eyes to make sure it’s all straight before I solder it in place.