Flymo748 wrote:It's not conclusive proof that split chassis work for me, as I still see a number of problems with them that need to be solved, but it certainly surprised me that it worked first time.
Would you care to elaborate as I am about to start one?
Certainly... I'll start by saying I'm not permanently anti- the idea of split chassis, it's just I'd need convincing there are better ways of doing things than I've used this time round.
The main thing is I'm not convinced about the best method for shorting out the wheels. This time, I used etched brass shorting strips.
I initially had problems soldering the strips onto the tyre. These are Alan Gibson steel tyred wheels, and despite using the ultra-aggressive Carrs brown label flux and a very hot iron, they took several attempts to bond securely. Some of them pinged off when I pushed the wheels onto the axles, which was annoying as the wheels were painted at that point. Obviously you can't linger with the iron whilst soldering them as because of the plastic centres to the wheels. Perhaps the answer will lie in using nickel silver tyred wheels, as I understand Ultrascales are.
The second problem is setting the back-to-back accurately - because you now have a soldered strip which makes a 0.xx mm packing piece between the backs of the tyres. So you are reduced to trying to set the BtB on the edge of the wheel, rather than across the whole face of it.
That is compounded when wheelsets develop a wobble. Despite using a GW Models quartering jig to set the quartering, and press the wheels on square, there is still a noticeable wobble in the centre wheelset. I spent quite a bit of time this weekend trying to chase the wobble out of this pair of wheels, but only being able to apply the gauge at one point on the tyre meant it turned into an exercise of chasing yourself around in circles.
Some things have been no problem - the use of PCB spacers rather than the etched ones in the kit was absolutely fine. Likewise the insulating of the various bits which span the chassis has gone well enough. There will be more on that to come soon in writing up what I did at Missenden. And the making and using of the split axles was all very problem free.
So the main thing is being able to use the wheels as a normal insulated set. I have a couple of ideas on how I could do things differently.
- don't use mechanically added shorting, but use the conductive silver paint which is available. I have some of this, which I used to flood the joint between the shorting strip and the axle, to make sure it conducted well. I will experiment with how well it works to short out the wheel by painting the whole of the back and sides of the spokes with the paint. This will be my preferred route.
- alternatively, try the approach of using fine fuse wire for the shorting. I'm thinking this could be soldered to the inside edge of the tyre so it doesn't protrude, and gently melted into the back of a spoke to achieve the same result. The main thing will be to produce a wheel which doesn't have anything sticking out to mess up using it.
Of course, there'll be an engineer along in a moment to tell me to bloody well shut up moaning and just mill the whole thing from solid brass
Hope this helps,