Scalefour Forum

I'm about to start my first P4 chassis & I would like some advice on what gauge wire & tube is best for a compensation beam.

The model I'm making is a mercian barclay diesel 0-6-0. I've looked at the chassis trying to decide how to make it work. I think it might be best to beef up one of the brake wires with a tube over it to add my compensation beam to.

Is this a wise way of doing the compensation & what size wire & tube should I use?

No particular size tube really, whatever I have to hand, just a good fit on a suitable wire. I've often used a large stiff paper clip, unbent and straightened, for the beam as it is easily bent to the right shape once it's in the engine. I just 'overbend' it so the chassis rides a little high at the compensated end, and then gently push it down to the right height. I find this easier than fiddling around with stiff brass wire inside the chassis trying to get it right. For a small engine such as the one you are building the paper clip wire will be quite strong enough. It solders easily as well.

Using one of the brake cross beams is OK so long as it's in the right place, generally midway between two axles.

I'm assuming here that you are using a fixed axle at one end and a single beam between the other two axles, which for a beginner is good way to start.

Philip

Morning Philip

Thank you for your reply. The reason for the brake idea was as it was set at half way between the wheels & about the right height to add the beam to it.

I will have a look at paperclip wire I had not thought of using this. I am doing a fixed axle because I feel this is a simple enough way to start.
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.

Morning Simon,

You’ll just need a suitable small tube which will fit in between the frames and be a nice fit over your brake hanger wire. I would blacken the ends of the tube and the inside of the frames where the hanger goes through so there is no chance of getting solder in there.

So far, I’ve only ever used compensation, never felt the need for anything else. Will on here is your man for CSBs.

Philip

I have pretty much consolidated on 1mm brass wire for both the beam and the pin in the tube of suitable internal diameter.

Whether the local modelshop has anything suitable will be seen. I acquire my stock from Eileen's (no connection etc.)

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 and here