Hi Kev,
each part is printed separately. Easiest way to explain is a picture…
the chassis has gone in two halves as the axleboxes are trapped by the retainers which are printed as part of the W irons. Because of this, the boxes go in from the top, which means that the ends of the W irons have to be connected by a stiff loop that goes around the back of the wheel. That pretty much drives the shape of the two chassis blocks.
There are 3 screw holes to retain the block to the wagon, but they could be glued, of course, and I put two transverse 2mm holes so I can use a bit of cocktail stick to pin the halves together, in alignment.
it would be possible to make the W irons open at the bottom, but then the retainer would need to be glued on. The axleboxes wouldn’t fall out because the spring wire retains them, so this would be possible. Might try it.
The axleboxes are printed with a pair of legs that rise up to solebar level behind the W iron, so they are pretty much invisible. On top of this, there is a lump through which the spring wire passes. These are more or less a 3DP version of the Exactoscale etched brass ones, iirc, though of course, I’ve moulded the axlebox as one piece, which eliminates the risk of gluing it all up solid. The axleboxes are printed with a 2.5mm hole for a Slaters bush, this needs a twiddle with a drill to clear it to diameter, and the bushes just push in.
The brake shoes, rocker, pushrods and inner V hanger are printed as one piece, I’ve only done one hand so far, but it’s easy to mirror for 4-shoe brakes (or not for single or either side, as required). The brake assy simply pushes into the slot in the chassis block, add a drop of cyano to fix. I will add the holes for the brake safety loops next time I print some.
Springs are also printed separately. I’ve done several, these are RCH pattern 3’6” for wooden solebars.
The funny bushes with two holes allow use of a single spring on the couplings. See pic in post 503. I’m not being stingy, it means the wagon is pulled along by the rearmost buffer beam in compression, rather than the front buffer beam being pulled off. It also effectively doubles the rate of the springs, which, when I’ve converted more stock will prevent the “strangled chicken” appearance when all the couplings are stretched beyond belief…. This seems to be a particular issue with RTR stock, Chinese springs are rather wimpish (Or, more likely, underspecified)
the outer V-hanger, lever and rack are also a separate print, as they fit the outside of the solebar. They need to be a bit thicker too, far too fragile at present.
The Saturn printer is fairly large, so I can get two wagons’ worth of bits on the build plate at one go, it takes just less than three hours to print, and the slicer reckons it uses about two quids’ worth of resin. That doesn’t allow for the wastage when clearing up, though.
hope that answers your question.
atb
Simon