Are you becoming tyred of waiting on that specific loco to materialize on the market? Why don't you built it yourself?
Anyone wanting to model railways outside the line of the mainstream suppliers will realise that he has to built almost anything by himself. And that is entirely feasible even in N.
A good way to start is by learning something from others who have gone before you. Thus read some books first. A good book is "the 4 mm engine -a scratch builder's guide" by R.Guy Williams, isbn 0906867 70 3, Wild Swan Publications LTD link. Has nothing to do with N gauge but much of the techniques and tools are similar. Another more useful for N gauge is "building an 0-6-0" from the 2 mm Scale Association. This is a step by step account for a simple loco and it works. I made my first loco following this book. Although anyone can buy the book you need to become member if you want any wheels or other loco parts.
There are several ways to scratch built new loco's. The easiest way is to adapt some existing model by cutting, filing and glueing parts. But if you need a different wheel setup things become more serious. Lets have a look at steam locomotives.Broadly speaking we can differentiate 2 ways in building a loco. Let's call it the english way and the german way. What you are probably used to is the german way: an isolated massive chassis with plastic centered wheels with pick up by contact springs. The english way is more prototypical: a chassis with 2 parallel conducting frameplates electrically isolated from each other on metal wheels. This is called a split frame. Both have their pro's and con's between chassis weight, ease of building, reliability of pickup etc.
The 2 mm Scale Association wheels are cast metal with only half of the axle, so called split axle wheels. Two wheels are coupled with a plastic muff. The wheels conduct the current to the chassis, that's why the frameparts need to be insulated. The motorleads are connected with the chassis. The advantage is that you don't need any pickup springs and that you can make all parts such as brake gear, sand pipes, Walschaerts gear etc. from metal and solder them to the chassis. A good thing is that you make a chassis without any need for machine tools. You can can make your frameplates out of 0.5 mm fosforbronze, soldered together and use an archimedean handdrill to drill the holes for the wheels. In that way you have two equal frame plates that can be screwed on either side on a piece of plastic or soldered to some copperclad printplate. In my opinion the main drawback is the splitaxle and thick axlemuff. This severely limits your choice in a high geardrive for a good shunting loco. I therefore have tried several alternatives with turned steel muffs of 2 mm diameter with plastic lining, but isolated axles of 1.5 mm diameter are a better option. No need to say that a lathe is necessary for that.
The alternative is to built an isolated chassis with plastic wheels that you can order as spare parts. Of particular interest are the isolated fiNescale wheels that can be bought from Neil Ballantine as replacement for various english GF loco's. This concerns driving wheels from 9 mm and larger. Raw gears can be bought from Verbeck, but these need considerable work to run smoothly. A better options is gearwheels from various scraploco's which don't run well enough. Axle's can be made from 1.5 mm drills or spring steel. The best option is to set the gear wheels in the middle of your chassis and not such as at least one well known manufacturer does on one side of the frame. And here comes the advantage of fiNe-SCALE, you can easily use a width of 7.25 mm for the frame, making enough room for the gears. A massive frame can be built up from 1 and 2 mm thick brass strip soldered or screwed together. In that way you can leave a slit for the gears in the center without need for machining. The difficult part is to drill parallel holes in the right place for the axles. You need at least a pillar drill for this. The rest can be done by hand with jewellers saw and files.
Between the motor axle and the wheels you need some gears. For a shunting loco with a faulhaber motor one rotation of the motoraxle should give about 0.4 mm movement of your loco. For german loco's with 8.5 mm wheels this comes to about 60 to 1 gearwork. Generally this is easiest done using a worm driving a large wormwheel united with a small gear on the same axle driving one of more wheel axles with gears. Some times you need an extra blind gearwheel to bridge a gap. A normal drive is a 2 or 2.5 mm diameter 0.2 module worm, 0.2 module 35 or 40 teeth wormwheel with an 8-12 teeth 0.4 module soldered to it. On the wheelaxle a gear with 15 or 16 teeth module 0.4 The large module gears are less critical in mounting so that you can have some play in the chassis in order to keep all wheels in contact with the rails. See the page on gears for more information. For large loco's running fast use a smaller gearing, the same as your wheel diameter is smaller. For diesels with 6 mm wheels 25:1 is reasonable drivetrain. Make the geartrain running as light as possible and beware of binds by uncircular gearwheels of a certain german manufacturer. A large gearing in combination with a flywheel results in less free run when powering down due to resistance and rotations. If you want a lot of free run when switched off use a light drive but beware for uncontrolability of your loco. Free running of 2 m isn't that nice at all to ride with, resulting in continuously switching on and off of the powerknob in practice. Not so good for your faulhaber I expect.
The upper part of a loco is a different story. There are many ways to built these. Either the hard way from scratch using plastic or brass sheet or use an etched kit or plastic parts from a manufacturer and lost wax parts for appendages. Count on finishing taking a long time if you follow the scratch method (weeks instead of days). So think before you set out working.
author: Henk Oversloot
date: 17 february 1999