Wednesday, March 25, 2009

Chassis with waggly bits

Yesterday I got some goodies in the post - the proper wheels for the Barclay steam locomotive. OK, I had a set of wheels already and they were the right size but the number of spokes was wrong apparently. Since the person this model is destined for will know about these things I'd better get this right.

Barclay loco wheels are unusual, the spokes have a flat face and look very different from the delicate thin ones found on most engines. Apparently there is a shortage of the model versions at present so I assume that a lot of you out there have Barclays on your own workbench - if that's the case I hope these notes are helping you !

Anyway, the wheels went in easily enough as did the motion bracket after laminating and a little filing where it passes through the chassis, much easier than opening up the slots.

Too allow for prototype variations the kit includes two sets of cylinders, 3 sets of con rods (although I couldn't tell the difference between them) and 3 sets of slide bars. I also had 3 sets of cross heads to work with - this choice was easy as the cast nickel ones are the nearest to the right colour.

Having picked the nearest cylinder etch and decided it didn't seem to matter a jot which slide bars I went for, construction started. The cylinder folds up and the bars are doubled and fitted making sure the crosshead slides all the way (I've been caught out with this bit before) without falling out. Mating the unit up with the bracket showed that the cylinder needs to be packed 1.5mm from the chassis side - unsurprising as this is a OO model, EM gaugers wouldn't need to do this although where they would get the clearance behind the crosshead is a mystery to me.

At this point I found an old problem reared it's ugly head - Romford crank throws. The scale rods are fine if you have scale throw. On these wheels the crossheads try to exit through the bracket. Normally (engineers and finescale modellers look away now) I just open the hole at the driving wheel end up a bit to allow some slop but here I think I'll do the job properly and use up some of the spare rods and make new ones.

No comments: