Entry posted by 47137 ·
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This post describes my modifications to a Lima coach to lower the chassis onto the bogies and provide for closer coupling. These coaches have various deviations from the prototypes (and really, they are not ‘scale models’), but the changes do improve the general appearance and only take a few hours to do. Nearly all of the work is on the chassis. I also chopped into the body and the interior to let them fit onto the modified chassis, but it will be easy to discard these and fit another body in the future.
Quite a lot of this write-up is for the coupler cams by Symoba. I needed some trial and error here, but when the first cam is in place and you can see how well it works, it is easy to optimise the location for subsequent installations. These cams are too small to provide true close coupling (with the buffer heads touching), but they do make for a big improvement in the overall appearance of a train. The buffers of coupled coaches end up about 3 or 4 mm apart on straight track, with operation still possible on second radius curves.
Parts List
1 x Lima H0 Mk1 coach (these modifications will work for all of the three designs)
4 x 10.5 mm wheels on axles, Steam Era models (these are a drop-in replacement)
2 x M4 plain washers 0.7 or 1.0 mm thick.
2 x Symoba 103 (standard) or 110 (short) NEM-362 pockets
2 x Symoba 111 NEM slider (cam mechanism)
There are two lengths of Symoba NEM-362 pockets, “standard” and “short”; I ended up using one of each.
Special Tools
Symoba 102 NEM-362 height gauge
It is well worthwhile to use the Symoba gauge because it sets up the horizontal location of the NEM pocket (the distance from the front of the pocket to the faces of the buffers) as well as the height.
Tasks
1. Completely dismantle the coach.
2. On the chassis, drill out the original bogie mounts with a hole large enough to let the chassis sit over the bogie boss. I used a 16 mm flat bit. This is the hardest part of the project because you need to support the chassis securely to get a clean cut. I used a screw to hold the chassis onto a block of wood:
3. Use the Symoba gauge to identify the proper location of the cam on the chassis:
The gauge sets up a location for the front of the pocket suitable for these coaches on a modest curve. The buffers of coupled vehicles will be about 2 mm apart on a straight track, and virtually touch on a 720 mm radius curve.
If the coach is to run around a 450 mm radius curve (the usual ‘Radius 2’ Setrack), adjust the buffers or the location of the front of the NEM pocket, or both. There is a compromise between appearance and future flexibility:
- One method is to model the buffers in the retracted position. This produces the closest coupling using the Symoba cams. Essentially, I set up the location of the cam using the gauge on a ‘short’ NEM pocket, and then moved the buffer heads to their retracted position. The standard NEM pocket is too long for this option; it will foul the outermost axle. I did this on the compartment end of the model, the end most likely to couple up to another coach.
- The second method is to use the standard NEM pocket, and install it about 1 mm outwards from the location indicated by the gauge. I did this on the brake end of the model, the end most likely to couple up to an engine or be the trailing end of a train. Some of my engines do not have NEM sockets in close-coupling cams, so a slightly larger gap seems wise.
The standard pocket is better because afterwards you can change the coupler head at will, like any usual NEM installation. For the short pocket, you have to choose the coupler head before assembly and you end up permanently cementing everything together. If you have the presence of mind to bore the two new holes for the bogie pivots a millimetre or so inboard of their original locations, there will be more space for the cams.
After you decide the location of the cam, cut a rectangular hole in the chassis to accept its base. Also trim away the bottom edge of both buffer beams, to make room for the NEM pockets. I removed about 0.7 mm of material here.
4. Cut two rectangles of 2mm styrene and glue them onto the chassis, one rectangle at each end. These form a vertical space to lower the chassis onto the bogies, and make a recess to hold the cams. When the joints have set, cut the large hole from the chassis through the styrene.
5. Cut two more rectangles of 2mm styrene and glue them on top of the first pair. These form the bearing surface for the bogies. When the joints have set, bore 3.5 mm diameter holes through the styrene to make the bogie pivots. It is important to use a 3.5 not 4 mm drill, 4 mm is too big.
6. On the bogies, cut off the couplers and also cut off the two curved ‘eyebrows’ around the pivot. The outer ends of the bogies will foul the NEM pockets on the cams, so cut away a section here too. The piece to remove will be about 14 mm long. Install the new wheels.
7. Fit the bogies onto the chassis. Lightly countersink the tops and bottoms of the 3.5 mm holes, and ease the holes out with a rat-tail file until the bogies fit and turn freely. Add M4 washers onto each of the bogie pivots to set the final ride height of the chassis. I think it is easiest to use washers to fine-tune the ride height but it would be possible to use 1.5 mm styrene for the first layer and omit the washers.
8. Install the cams and couplers. I added the cams one at a time. There is enough friction to hold the NEM-362 pockets while you watch operation on curves, but you do have to trim the cam spigots to clear the sleepers. There is time now to pull the cam off the model and enlarge the rectangular hole in one direction or the other, to get the cam in the best location. When the cam is in is final location it is time to make a final decision about the ride height. If you want to add or remove washers, do this now. Then put the model on some track, apply the Symoba gauge one more time (or, with the short pocket, check the height of your chosen coupler very carefully), and then cement the NEM-362 pocket onto the spigot and cut the spigot flush with the mount.
9. You can now attach the ballast weight test and run the chassis.
10. When you know all is well with the chassis, trim the "floor panels" on the underside of the body moulding to let the body fit over your styrene rectangles. Trim away below the ends of the interior moulding too so it fits, and reassemble the model.
I have wanted a passenger coach for the layout for a while, if only to provide for a stopgap passenger service from Fairport to Creg while I get enough skill to build some kind of railcar. This coach can also be a tool van or a crew coach, or even a brake vehicle to use when something without continues brakes needs to be moved along the railway.
The model sits surprisingly well beside a 'high end' RTR model from LS Models, this is their Type F sleeper:
Running in Great Britain, the Night Ferry train should have a Mk1 brake composite and not a brake second, but a brake second is a lot better than having no brake vehicle at all, and this Mk1 coach looks more authentic than the Bulleid equivalent from Fleischmann.
The coach looks bearable coupled up to Fleischmann Bulleid stock too:
The Fleischmann models sit a little too high on their bogies; this is not very noticeable on their own but if this was a permanent formation I would want to put thicker washers on the bogie pivots.
The final photo is simply a comparison of the original and modified Lima coaches. The modified one looks much more like a model and less like a toy:
The modified model is still clipped together using the Lima fixings. I can alter it into a fresh prototype such as a courier van another day, or even rebuild it using fresh sides. The livery is of course completely wrong, but it is nice to do a modelling project without needing any painting.
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