Re: Some thoughts on resin warping & shrinkage


Walter M. Clark
 

--- In STMFC@yahoogroups.com, "Tom Madden" <tgmadden@...> wrote:

Can't offer much in the way of solutions to this very interesting
set of problems, but if you'd care to consider some possibly useful
insights, read on….. (Most of you know a lot of this already, but
it's good to get it all down in one place.)<SNIP>.

Thanks for your attention!

Tom Madden
So, Tom and the rest who have commented on this topic, it seems there
are two additional things I need to do to the resin kits before I
build them.

First, at least for the larger pieces such as roof, ends, side, doors
(maybe) and floors/underframes, heat to about 150 F and hold at that
temperature for a couple of hours before matching/adjusting major
dimensions at the start of assembly (which is a problem because I
don't have an oven that will hold that low a temperature. Would it
work to get the oven up to that temperature, established with an oven
thermometer, turn off the gas and put the kit pieces on a sheet of
glass slid into the oven on the bottom rack, then watch the
temperature and when it drops too low turn on the oven for a little
while to bring the temperature back up? Or would that take a chance
on igniting the resin castings? I don't need a resin smoke bomb in
the oven; my wife's patience only stretches so far).

Second, glue braces inside the sides to remind the sides they are
supposed to stay flat. How about if I use a heavier brass H or
channel along the lower portion of the side and a lighter brass angle
near the top? Would that both keep the sides flat and add weight,
concentrated near the bottom so the car doesn't get top heavy? Of
course I need to be sure the final assembly including trucks, couplers
etc. isn't too heavy, but that is easy to handle.

Of course open top cars wouldn't receive the inner bracing. Would
that really matter too much since hoppers and gondolas don't get too
far from the erecting floor before becoming bent, battered and abused
in service (just don't let it get so bad that it becomes a caricature
and not a representation).

So, what am I missing/where did I go wrong/what suggestions for
improvement can you give me?

Walter M. Clark
Time stopped in November 1941
Riverside, California

Join main@RealSTMFC.groups.io to automatically receive all group messages.