Hi Gareth and Le Corbusier,
You will find a simple adaption of one of my jigs in the "Livingston starters Group" section 3 which allows you to use it as a test rig for testing your chassis running upside down and the other way up allows you to see how best to load your chassis and trial it on track. The original construction of the jig which is also used to make your coupling rods accurately you will find in the first section of the "West Scotland Group Build a loco" section.viewtopic.php?f=39&t=666
what you are asking about can also be found on this thread - in fact if you follow the threads you will be able to build accurate models straight off after a small investment both in time and cash. The Livingston lads have all made the jigs and are using them. The cost per person has been about £12 and a couple of evenings work each to make the jigs. It is worth looking at the Livingston Starters Group thread as it covers the use of basic tools and some basic information on how to use them.
It also has a look at various common types of motor and gearbox combination and what they are best for as well as how to put them together accurately, also what advantages each has as well as some disadvantages. This is not stuff to do with the two localities, it is more to do with using a system of construction which has been worked out logically. There is a lot to take in, but if you start at the beginning it leads on to an organised way of building, in this case from scratch - all the way through to building the bodies and painting - everything in fact. There are three "West Group" threads altogether which can be found in the section for beginners - but more widely used as can be seen by the number of hits for each section - clearly there are a lot of people using the information.
What Tim has mentioned in his latest post gets eliminated as well in the process.
You will realise when you look at the thread, that I have put many hours into the posts as I realised that when I was doing the courses it was possible to photograph each stage and write it up as we went along. It allowed the others who were building the locos to look up what we covered at home, so that they could come along to the next meeting a stage further on.
I am now running the second course and using the same thread for the Livingston starters group so they too may have a good loco working within a reasonable time. This group are not scratch building locos, but are building kits and finding that the equipment and the system works with a wide range of locomotives. Some of their questions also appear as I have been trying to get them into doing this - there is no such thing as a stupid question from my point of view, for a beginner it may all seem that building an accurate model is like some sort of alchemy, whereas it is simply logic, some common sense and years of experience building many models that has led to a system that gets good results and eliminates problems as you go along.
Although there is some theory - everything is by example and can be seen just how it works.
We have had a short discussion about building a working chassis in a day elsewhere on the forum and it is possible using the simple jigs which I use.