Right. I'm about to put this thing back in its box as I'm after flight testing it.
I am very close to being able to fit the motion. I found I needed to file the angled end of the bottom slide bar so it didn't get struck by the connecting rod on the upswing. Both slidebars now just get kissed, in the luvvie "mwah, mwah" style, which is about as far as I'm happy with.
One of the problems with building working scale models is tiny working dimensions on the real thing don't translate to tiny working dimensions at 7mm to the foot. Compromises have to be made, and it helps if the manufacturers design for the compromises and don't expect it to be ALTRT.
I thought it would be an idea to trial fit the rest of the waggly bits to check for fit.
Nothing is permanently fixed at this stage. The rear part of the motion bracket is a good interference fit, which helps the slotted link stay in place. I've not fitted the eccentric cranks - which are incidentally cast to accept a suitable tap so they screw on the crankpin, which is nice - in this view as I think the cast eccentric rod may have to be substituted for the etched version. I'm not happy that it has to negotiate several angles at once in several planes, so a thinner specimen may help.
Several things are awry in this picture. First, the radius rod is back to front. Look at any photo of the real thing and you'll see the big forked end has the scalloped side outward. Sadly, as I found out early on, this is impossible to do with this model because the whole thing would seize up on the motion bracket. It barely misses the bracket as it is. It strikes me - ho-ho - the radius rod isn't long enough because the valve crosshead is sticking out the back of its slide.
Now, obviously the radius rod will be held up by the reverser link. It really does seem the radius rod isn't long enough. I know I moved the motion bracket back a small amount, but I wouldn't have thought it would have caused this much discrepancy. Can anyone give me dimension for the length the rod ought to be?
I'm open to injections of wisdom. I am not lugging the object to Kettering tomorrow, though. While it's fairly robust, I don't want to risk damage in transit at this stage.
I'm seriously thinking I'm better off sticking with building rolling stock and inside-cylinder locos! I reckon this monstrosity will be stuffed in its box to stew, and I'll either carry on work with the above decks detailing, or pick up something else for a bit. If I don't seem to be smiling much at Kettering, you'll know why!
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