Bow Works: Locomotives for the North London Railway

[garethashenden]

I don't know why I didn't start this thread earlier, but I didn't. The North London Railway has three principle types of locomotives. There are two 4-4-0T passenger engines, one with inside cylinders and one with outside cylinders, both designed by Adams. The best known class is the 0-6-0T goods tanks, credit for which is usually given to Mr. Parks, although I believe they were a collaboration between him and Adams. There is also the very adorable Crane Tank, originally built as a 0-4-0ST and converted into a 0-4-2ST with a crane on the back in the 1870s. It's also notable as the oldest locomotive taken into BR stock at nationalisation.

In 4mm there are a couple of options for the Goods tank. The GEM whitemetal kit is the only currently produced version, but the Blacksmith etched brass kit can sometimes be found secondhand. Branchlines offer an etched nickel silver chassis for the GEM kit and will supply everything as a complete kit, including a detailing pack, motor, gearbox, and wheels. One of these followed me home following last year's Scaleforum. As for the 4-4-0Ts things are a bit more difficult. The compound curves of the smokebox on the 1-10 class outside cylinder engines has apparently defeated all kitmakers who attempt it. There are rumours, but not kits. The inside cylinder class 51s are a bit better off in that there is at least a kit. Well, there's a sheet of etches drawn by Peter K and available from Kemilay, if you're willing to pay now and get them when they have enough orders to fill the sheet. Luckily for me a fellow club member was selling a pair of these etches, so I snatched them up.

So there's the state of play, three kits to be built into their early 20th century condition, painted black with yellow and red lining.
One of the 4-4-0Ts was started first, eventually to be number 109. This is the number assigned to the first in the class, 51, after it was moved to the duplicate list in 1885. Originally built in 1865, rebuilt in 1886 with a cab and withdrawn in 1925. I started this in EM, as that is what I was working to at the time. The body and chassis went together pretty well, aside from the bogie which needs considerable reengineering. At some point in the process, around the time I was realising that the bogie needed more work, I came to the conclusion that it would be better for the securing bolt to go up rather than down. In other words, I had put a bolt through the footplate inside the smokebox and soldered it in place thinking that I could hold the bogie in place with a nut or two and shorten the bolt as needed. After reaching that conclusion and thinking about it for a few days I did that thing we sometimes have to do and reduced the locomotive to its component parts. It has remained pretty much untouched since then (January), awaiting P4 wheels and renewed enthusiasm. The wheels are a problem though. They should be 5'11" 16 spoke pin-between-spoke, the closest that are available are 5'8" 16 spoke, unless I want to go with 6'0" 18 spoke. I'm undecided on which option is best, which makes it somewhat easier to put off ordering the wheels. I do quite like this class though, and I'd like to get the kit reassembled, so thoughts/suggestions would be welcome.
Here is 109 on Empire Mills before its disassembly.

And here is the offending bogie

The recent article in Scalefour News about building a Brighton Atlantic has given me some thoughts on it, so there may be progress soon.

[garethashenden]

The other current project is one of Park's 0-6-0T Goods Tanks. I haven't yet settled on a number, but it will have H-spoke wheels and probably not have vacuum brakes. 78 (the second 78) and 111 are candidates at the moment.
The Branchlines chassis went together quite well. I went the CSB route first drilling holes for handrail knob fucrums. I used a home made jig consisting of three correctly spaced holes drilled into a piece of plywood with a drill press. I put the London Road models axle alignment jigs into the holes and, one axle at a time, replaced the rigid bearings with High Level hornblocks. I also used this jig to assemble the two frames with their spacers.
Here is one frame on the jig with the other next to it, ready to assemble.

And the assembled frames with the cast footplate on top.


I decided against the Branchlines gearbox, I'm not really sure why. I'm sure it's good, but I went with a High Level RoadRunner+ in 54:1 instead. I did use the supplied flywheel and I do notice its effect. I'm not sure I will still notice it once the other wheels are connected, we shall have to wait and see.

The only problem I have with the chassis is that the guard irons are too long. They can either be at 90 degrees to the frames, which is wrong, or resting on the rails, which is also wrong. They will be shortened in due course.

Recently I have been working more on the body. Mostly I have been dry fitting parts and cleaning up the castings. I have run into a problem however with the tank top casting. This is one piece for both tank tops and the top of the boiler. Comparing it to the prototype, it looks as if the boiler doesn't curve high enough.
Compare the model:

With the prototype:


Various solutions involving brass tube are being considered. In the meantime I decided I was unhappy with the pockmarked appearance of the tank sides and have fretted out a pair from nickel silver. These have been joined by a new tank front as the casting for that keeps bending in the middle. I will also make a new front and back for the cab out of nickel silver, as the castings are far too thick for what was only ever sheet metal.
The two sides, still tacked together, and the tank fronts.

I have a feeling that the footplate may not stay whitemetal for long...

[David Knight]

So you would classify the kit as an "aid to scratchbuilding"? I think the N/S cab will look much better.

Cheers,

David

[garethashenden]

So you would classify the kit as an "aid to scratchbuilding"? I think the N/S cab will look much better.

Cheers,

David

I rather depends on whether or not you like white metal locomotive kits. I tend not to like them and that may be colouring my views on the kit. Having the kit has at least got me to the point where I feel the need to upgrade some components. If I had started out to scratchbuild the engine I don't think I would have ever actually started. I think for the next one I'll see if I can get all the little castings without the big ones, but I suspect not. In that case, the kit is worth getting for the detail castings.

[garethashenden]

Progress has been made with the new body for the Goods Engine. I had previously cut out the tank/cab sides and tank front. Most of two months have passed in which I did some 2mm Finescale modelling, some American N scale modelling, and bought another Goods tank kit. This one however is the Mallard etched kit. The chassis is quite rudimentary but the body looks pretty straight forward and will be quite a bit faster than cutting each piece by hand. That said, given the amount I have invested in these two kits, I would like to end up with two locomotives. So I shall persevere with the scratchbuilding. To that end I have now cut out the footplate and cab back, both from 20 thou nickel silver. These five pieces have since been assembled into a box. There's not a lot of detail yet, but they already look better than their whitemetal predecessors. The next step will be chassis fixings followed by the valances and buffer beams. The valances have been cut out although they are still over length. I'm contemplating using the white metal buffer beams as they seem to be well cast and the correct size, but I may fabricate them as well. We shall see.
In the meantime, here is the current state of play.

[garethashenden]

Following the struggle with the mechanism, I have now fitted better pickups. These are the coil style made from 0.25mm phosphor bronze rubbing against the flange. They were quite straight forward once I got the hang of it and I think I'll use them in future as well.

[garethashenden]

Shortly after I made the new tank sides I made a pair of valances. These have remained stuck together until last night when they were parted and attached to the footplate. I have reached the conclusion that in order to actually get anything done on my layout I need to be able to "play trains". With that goal I need to get this engine completed enough that it can be used for shunting. At a bare minimum that is 1 bufferbeam, 1 coupling hook, and two buffer housings. I decided however to do both ends while I was at it. I'm using the kit's whitemetal bufferbeams, the thickness of the material is good here. I'm still waffling on the buffers. Both whitemetal solid buffers and brass/steel sprung buffers came with the kit. I feel that the detail is a little better on the wm ones and I'm kinda ambivalent about sprung buffers in general. I'll think it over for another day or so before fitting either. I am also expecting the postal service to deliver a new motor today. It is a Maxon coreless and should be a good addition to the mechanism.

[garethashenden]

Well it's been a while, but more work has been made on the Park tank. I started by making the cab front. I fitted it to the model, then realised that none of the body pieces were square to the footplate, so everything came off the footplate before being reattached in the proper position. After that I cut a rectangular piece to form the tank tops and fitted it. The most laborious step so far was in creating the top of the boiler between the tanks. I used 3/4" brass tube, a length of which was cut slightly longer than needed. I then cut a 1/3rd or so section out of the tube lengthwise, so that I had something with the correct curvature, but too high and too long. I cleaned up the edges with a file, then set about reducing the height of the section to fit the model. I used a piece of course (80 grit) wet and dry sandpaper on a piece of glass. This resulted in a nice flat bottom for the boiler, which is what I wanted. After a bit of sanding I realised that I was still well over a millimeter away, so I trimmed most of that from one side with a piecing saw. Then I went back to sanding, checking the fit against the model as I went. Once that was done I drilled a small hole in the cab front for the safety valve handle. I think I'm going to have to replace the dome though, it's a bit big. The diameter is fine, but the flare at the base it overdone and it's too tall. But that can wait for now. The last thing I've done is I've turned a smokebox inner from the same tube as the boiler. I will make a front and back for the smokebox that will fit to this ring, then it will get wrapped to form the correct shape. The smokebox is sitting too high at the moment, held in place by blutack...

[garethashenden]

I never can seem to work one project through to completion. I'm always jumping around from one to another. So it's back to 4-4-0T number 109. I had disassembled most of the locomotive so that I could replace the screw in the smokebox with a nut. Well, I got it taken apart and then got distracted by some other project.

A year and a half later...

I haven't found a good way of ordering Alan Gibson wheels from the "wrong" side of the pond, so I had a friend collect a few at Scaleforum and send them on. These included P4 wheels for 109. The correct size is 5'11", 16 spoke. No one makes these, so the choices are 5'8" 16 spoke or 6'0" 18 spoke. I had gone with 5'8" 16 spoke with the EM version, because I thought that the wider flange would make up the difference and there were the right number of spokes. For the P4 version however, I have decided to go with the 6'0" 18 spoke option. I rebuilt the chassis with leftover P4 spacers from a RT Austerity kit. I then reassembled the body with the crucial nut in place. After that, I attacked the troublesome bogie. The prototype's bogie is an outside framed affair. The kit contained what I consider to be an odd way of constructing the bogie. There are two cosmetic outside frames, two functional inside frames, and a cross piece. All in all it's quite a flimsy design with virtually no bearing surface. It looked like this:


What I came up with a design that is far simpler and stronger. I kept the outside frames, but got rid of the rest. I took a piece of fairly thick brass flat stock, about 1mm thick. I drilled two holes and joined them to make a slot with a piecing saw. This would let the bogie move from side to side, rather than just pivot around the mounting. I chose to use the pinpoint axles, rather than inside frames. Unfortunately, the outside frames have rectangular openings for the axleboxes, not round ones for bearings. I dug around in the spares box for a while and came up with some bearing carriers from some Bill Beford sprung w-irons. Bearings were fitted, but the hard part was lining up the bearings in the openings. The first one was easy, the other one on that side was measured 6' away and fitted. After this I stuck the sideframe to the crossmember. I added two pieces of rectangular brass tube to the ends of the crossmember to reinforce things a bit. The side with the bearings was fitted and a pair of wheels fitted. Predictably, the wheel hit the crossmember, so out came the piercing saw and the file. Once the wheels fit, I attached the other sideframe, making sure to keep the axles square with the sideframes. The bogie is square and doesn't rock on a glass surface, so I'm optimistic. Right now I have fitted a short length of brass tube between the bogie and the footplate to set the ride height. This isn't an ideal solution and is putting the front of the locomotive lower than it should be. I intend to fit both vertical and lateral springs, probably just lengths of phosphor bronze wire, to control the movement of the bogie, hopefully these can help regulate the height as well.

Here is the underside of the bogie, hopefully it all makes sense.


And the rest of the model:





And with the Goods Tank


Lots more to do. Bogie springs are probably first, then the cab interior.

[garethashenden]

At the beginning of January I bought a 3D printer and have been printing all sorts of things since then, mostly in N scale. I’ve had trouble making the short section of exposed boiler on the Goods Tank, it’s either the right length or the right diameter, and never round enough, so I thought I’d try printing it. The design is quite straight forward and it’s far more repeatable than my attempts to roll metal. The only thing I’m not satisfied with is the chimney. The flare to the sides of the smokebox isn’t big enough and it’s not as well defined as I’d like. I’ll try to fix it, but I may end up using the cast kit chimney.