A little bit of work over the weekend - ably assisted by Florence & The Machine's new album - saw the chassis essentially finished apart from the leading pony truck.

As reported in the last post, the basic 0-6-0 chassis ran very well, but as always, there is scope for things to go wrong as you start adding cylinders, connecting rods and so on. Although Comet kits are great, I've found that their outside cylinder parts need a lot of fettling before things work... whereas the two DJH kits I've built with cylinders both needed a lot less attention before I had smooth running.

The slidebars are a simple fold-up etch which I sweated together without too much hassle. The crossheads need a lot of material removing from them, though, but the danger is that you go a bit too far and end up with a fit that's sloppy rather than just right. I've done that in the past, and was determined not to do so this time ... but even so it can be tricky to be sure you've eliminated all tight spots between the crosshead, slidebars and cylinder. Compounding the issue, the clearances are very tight. There's not much room between the leading crankpin and the back of the crosshead, but I was prepared for that and filed the crankpin washer down as far as it would go. Also, due to the crankpin throw on the wheels, the connecting rods come very close to the slidebars when the wheels are at 6 0'clock and 12 0'clock ... and some careful tweaking is needed.

Nonetheless I got it all running very sweetly, and then comes the pain of fitting the motion support brackets, or whatever they are - those "C"-shaped brackets that link the slidebars. I've never found these things to be anything other than a flaming nuisance, partly because clearances are tight, partly because you can easily upset the good running you've just struggled to get ... and also because there isn't much of a contact surface to get a really solid soldered bond. All the same, they have to go on! Fitting these took a couple of hours, and at one point I had to walk away and come back because the running had deteriorated so badly, presumably because the brackets were "squeezing" the slidebars a little. It then occurred to me to position the crosshead at the end of the brackets to act as a spacer, and once resoldered, the brackets worked fine, and running was back to how it should have been...

Ah, the joys of even a simple outside cylinder loco.

I fitted the rear pony truck first, as I had the right diameter of wheel for it - I'll have to search the spares box for the leading one. However, so far the pony seems to track pretty reliably, given that it's got no weight on it.

As mentioned earlier, the SE Finecast chassis (correctly) has the rear axle in a fixed frame configuration, as (if I'm not mistaken) the Large Prairies didn't have separate rear pony trucks like the 44xx class. However, I'm not sanguine about the chance of such a rigid chassis making it around my 30" curves, as even the Comet one seems to have the pony truck at quite a deflection on curves ... but we'll see, perhaps I'm being unduly pessimistic!

Anyway, this Comet chassis is nearly done and runs superbly, even without the body on. Top marks to Comet.