I know many
people were eager to get more news about the CN woodchip cars project. It took
me a while to start assembling the prototypes 3D printed by Bruce Barney last
year due to lack of time, unforeseen professional projects and procrastination.
However, I’m glad to announce the cars have been assembled, detailed, primed
and painted over the last few years.
assembly is not only a way to show people how the models will look, but also to
seek arising issues and find ways to address them so the final product is, as
possible as I can, flawless, sturdy and easy to assemble.
assembling procedure was quite smooth, I found out a few things that I’d rather
change if I were to sell the models to others who want to build a fleet. I see
a significant difference between what we can live with when scratchbuilding a
single model for ourselves and what we find intolerable when trying to work
with a “commercial” kit.
found are various but not deal-breaking. They will be easy to fix and yet
provide a great finished model. I must admit once painted, these two cars could
pass easily for good quality RTR models.
purely technical perspective, I’ll probably add some thickness to the parts,
going from 1mm to 1.2 mm to lessen risk of warping. Straightening resin or 3D
printed parts is an easy process, but it can be tedious and I quickly found
myself annoyed. It must be improved. Also, while trying to keep the underframe
structural members within prototypical dimensions and minimum 3D print design
guidelines, I feel they must be sturdier. No a lot, but just enough to make
sure breaking is unlikely under normal handling conditions.
In terms of
assembly, I felt the grooves and tongues I designed to make for easy alignment
of parts are inadequate. First, they are too shallow. Second, they lack tabs to
make sure everything is perfectly square and aligned together. It shouldn’t
have a major impact on the model, but expect some kind of tabs under the car. I’ve
yet to figure out how to do it but it must be done.
underframe, I 3D printed the brake apparatus (valve, reservoir, etc.) directly
on the underframe. They look good, but I’ve yet to decide if it is a good
decision. I feel it works well for most modellers and that it can be upgraded
with pipes, wire and other such for prototype modellers. I’ve yet to decide on
the level of details. Should I locate brackets and levers? I don’t know and I’m
not sure if it matters. I feel the ones who will want these details are better
equipped than I am to model these and I suspect a large share of modellers won’t
care. However, I think the model must have provision for people wanting to go
to the next step. It means, I’ll try to provide holes in the underframe to
insert air lines. I’m not interested in cast-on details that can be seen from a
normal point of view. They will be of no consequence for casual modellers and
be a hindrance for people with high standards.
In terms of
details, I found out some parts are better 3D printed while others should be
photo-etched. Brakewheel platforms and end of car platforms should all be
photo-etched for the sake of sturdiness. They can be printed in great details
and be strong enough, but they are still fragile and can be broken during
assembly. Photo-etched parts would be easier and faster to install while
surviving nicely normal handling condition and providing a great level of
ladders, I thought the 3D printed versions would be flimsy and they are not.
Better, they look like the real thing, are easy to glue and the profiles are
quite close the prototype. I believe using photo-etched ladder would remove a
level of detail while performing minimally better.
I also plan to include a notch in the fulcrum so the brake rigging can be easily cemented and stay in place.
Another point is related to performance and NMRA standard. I design the car
using correct model truck dimension and Kadee coupler pockets. On one car, I
kind of tweaked the bolster height to fit the truck and it seems I made a
mistake. To get the coupler at the correct height, I must add 3 Kadee red
washers. This means my first bolster version was the right one. I’ll go back to
it. The other car only requires 1 red washer, meaning the bolster height is
quite right. I’m reluctant to make a change because I know various trucks may
have different height due to manufacturer’s preference. At this point, better
leave the fine tuning to the end user, like we all do with most of our RTR
thing I found out was the height on the coupler pocket hole is slightly too high.
About 0.2mm at most… It may seem trivial, but it causes the coupler to drop
instead of being perfectly horizontal, impeding coupling performances. It will
the screw holes for the couplers and trucks are not right. Trucks have pegs too
thick and need to be sanded to accept a standard truck. On the other hand, the
coupler pegs are too small, inducing unwanted wiggling and exaggerating the
drop I mentioned before. All these are easy fix.
that, I figured out one could easily assemble the model in an afternoon when
all parts are cleaned and prepped. Doing an assembly line would significantly
speed up the process, particularly if the locating pins and tabs are better
the car on the layout yesterday and they are sturdy and track well. Weight can
be added between the underframe members or inside the cars if one is not afraid
of seeing steel or lead from the top.
As for availability, I can pronunce myself on a date. I will have to address the few issues and print a new pair of "final" prototype before launching production and taking order. I've yet to figure out details about sale and distribution. All that with an extremely busy professional schedule in the upcoming months. Stay tuned!