A few posts ago, I wrote about making the glazing carriers from plasticard and the etched drop-light frames, mashed up in a jig. After that, there was a long hiatus while I was away from my modelling materials and then the arrival of that ultimate diversion-activity, a home resin-printer. The printer has a learning curve that needs ice axes and pitons, but to save a little time I choose to practise on a printed version of the glazing carriers.
The story of the printed window frames
is on RMweb where many members helped with good advice and Mike Trice really rallied round and sorted out the support issues. Mike's final approach to the problem looks like this:
The morals seem to be
- use the ordinary grey resin and don't try to be clever with special kinds coz they don't do;
- more supports, always ...
- ...but don't put the "trunks" of the supports so close to the part that resin gets trapped in between;
- avoid any horizontal ledges where the excess resin can get hung up and cure in clumps;
- be thorough, to the point of obsession, about cleaning the prints lest stray resin form warts and carbuncles.
I get 10-12 units per print run, enough for one and bit of the 27' coaches. They look like this after washing:
(this one is not quite washed enough), and like this after removal of supports:
Minor sanding to remove the support nubs is to follow.
The left hand one is showing its cosmetic face. The glazing for the fixed lights is to be glued to the arms of the "I" shape and the central well represents the visible frame of the droplight. The membrane of resin here is 0.5mm thick, which is about the thinnest that survives the cleaning process. The droplight is stood back from the etched side a little. The left-hand unit in the photo shows the face inside the coach and the channel carries the glazing of the drop light.
This seems a lot of faff to avoid making up a few dozen plasticard units, but I consider the learning time well spent for other printing projects. It now takes 4.5 hours elapsed, about 20 minutes labour, and pennies in consumables to make a batch of frames when I need them. Further, they will all be accurate (or else visibly bad), which is not so sure with my plasticard work.
While the glazing units were being sorted out, I draw and printed a set of spring mountings, since the axlebox/spring/shackle castings in the kit don't include the mounts and the coaches look odd with the shackles waving in the breeze. These are an easier target for the home printer and worked pretty much first time (sorry, no photos available). When I came to fit the spring mounts, however, I found that they fouled the fasteners holding the body to the underframe. Therefore, I'll have to make up new body-securing plates and fit them to the already-painted body. Further, the fastening points on the frame need to be where big holes were etched out, so I'll need bridging strips. None of this is very hard, but it needs workbench time which is in short supply at present. I plan to make the securing bars in the coach from decently-thick strip that can be tapped 12BA for studs and then epoxy'd into the coach. The bridges for the frame will be 0.5mm strip, soldered in. If I make these in matched sets, they should be self jigging.