Simon Moore wrote:I really like the idea of csb's & I've just ordered some gubbins from high level to have a play with. I'm planning on having a go with a rt models austerity chassis.
I will pop to the local model shop on saturday morning to see what they have for the beam compensator.
I started by chassis suspension journey in much the same way as you are. In my case I was doing it to 00 tank locos to improve their electrical pickup for reliable exhibition running, but once you've got there you don't want to go back. I now thing its harder to build a properly flat rigid chassis!!
There is something to be said for getting used to working with hornblock assemblies on a simple compensated chassis before having a go at making all the axles mobile. Once you are confident you can get the two rocking axles sorted reliably, doing all of them and fitting CSBs isn't a very big step further.
I think Phil is entirely right to say that the spec of the compensation bars isn't critical. Any wire that can bear its share of the loco's weight without bending will do. I'm sure Peter's 1mm wire is perfectly adequate though I will admit I used thicker stuff than that. Using the cross brake wire, if it is central between the wheels, is a perfectly valid choice, but, as the wire used to make these can be reactively thin, a tube to go over and reinforce the wire is wise. It isn't the the only solution e.g. a bar with a hole drilled through it with stops solder to the cross wire to keep it central. Hopefully your local model shop (you lucky boy) will provide. In any event I think you will find a stock of tube sizes is a very useful modelling resource. (preferably telescopic (i.e. thin walled tubes which will fit one with another). Very handy when modelling assorted plumbing under loco.
One thing to keep in mind is the weight distribution of your model. When the loco's centre of gravity (CofG) is directly above the centre of the chassis, your plan will produce a desirable equal weight distribution across all the driving wheels, and the best pulling performance. Letting the CogG wonder too far backward will reduce the pulling power of your loco and letting it wonder forward, close to the compensation pivot point, and some very odd things can start happening. The Scalefour Digest 41.0 - The principles of model locomotive suspension
explains it all, at some length. It can be a bit off putting when you first meet it I know, but it is worth study if you want to understand what is keeping your stock on the track. The relevant sections on our current topic are here