Earlier this week, I went to the foundry again, and tried my molds with sand for the first time. I did not yet get to cast more than one sample, but it was "spherical graphite iron" SG 700, containing almost 1% of copper - thus a much harder type of material than the grey iron that I used for the wheels of the 3003.
Upon testing, this stuff proved to be too much for my little mill - even with carbide tools, it would have taken an eternity to mill everything to shape... so I'll return to the foundry in a week or two, when they'll pour a batch of ordinary grey iron - this will be much faster to machine. (And as you know, "Speed" is my middle name... ;-)
Also, the spokes of the wheel pattern tended to stick to the sand -note the nails I've stuck into the sand to prevent this... I've in fact already milled the angle a bit steeper, so the pattern will come out of the sand much easier, next time.
The first metal parts
In the meantime, I've been making the first metal parts for the 0-6-0:
Walschaert gear link hangers, lap & lead levers and union links - a couple or three per day, so I'll not get alienated from the workshop...
(When the whole drawing is colored blue, my loco will be finished! ;-)
The most fiddly parts are the link blocks, which need to be properly radiused on both sides. A little brass bar extension to the small rotary table enabled me to do this - the alu-bronze piece is secured with two screws plus a piece of drill rod through a reamed hole.
The system of links and levers for the Walshaert motion are taking shape! I've used PTFE-coated rings and hardened drill rod axles for all bearings, except the link block, which, being of alu-bronze, functions as its own bearing.
Propane again!
I've decided to go all propane, this time, too! At 159 mm (6") diameter, the 0-6-0 boiler is a bit larger than the boiler of the 3003, so I think I'll try only two larger (52mm, 2" i.d.) flues this time - it's probably easier to get a stable flame and a good radiating body the larger the flues are. As you know, the 39mm (1.5") i.d. of the 3003's flues did make the designing of the burners quite a problem...
The season is ending...
Incidentally, I went to the museum's track in Hyvinge today, with a couple of friends who hadn't seen the 3003 in action, and got a shot of this funny steam mustache on one of my guest engineers...
This was probably the last run of this season - the autumn storms have started, and the probability of warm and sunny weekends is getting smaller all the time. But, this summer I've run the loco approx. 200 kilometers (125 miles) altogether, not too bad, really.
I'll have to exchange a couple of rod bearings this winter; the right-hand rods have started to click a bit when running light, which is a sign of wear, methinks...