Obviously, some kind of new doors were needed.
My requirements were as follows:
- The doors should open far enough to admit a standard
Athearn boxcar.*
- The area just inside and just outside the doors
could be occupied by railroad equipment
at the time the doors need to be opened or closed,
so swinging doors would be inconvenient.
(Besides, they're old-fashioned. After all,
this is the twentieth century!)
- There is a large window above every door, which
ruled out having the doors slide straight up.
- I knew I would to have to reach down to
access couplers just inside the doorway, so doors that
swung up (like the garage door on the old Aurora
Colonial House, now made by
International Hobby Corp.) wouldn't work for this application.
- Due to the limitations of my workshop,
precision or delicate parts were to be avoided.
- I wanted the doors to be at least somewhat light-tight,
in case I ever illuminated the buildings for night operations.
After sketching and rejecting several ideas, I developed a design
for a manually operated rolling door
that met my requirements. There
are two main assemblies in this design.
- The
door assembly
consists of individual strips of plastic glued
to a backing of a very supple fabric. This is wound
around a roller which rests on two inclined support arms
above the doorway. The door is counterbalanced by weights
suspended from cables (thread)
wrapped the opposite direction around the roller. The
weights apply
torque to the roller to take up the slack as the door is raised,
and their weight also helps keep the roller
from climbing the support arms when the door is raised.
- The
support arms and guide tracks
are mounted on the walls. The support arms
hold the door roller up and help keep it near the wall. The
guide tracks hold the door against the inside of the doorway.
The design of the support arms and guides permits the door
assemblies to be installed or removed in a few seconds.
To install the door,
roll the door onto the roller until about one half inch is
hanging down. Then wind the counterweight thread so it
hangs down on the side opposite the door, allowing
about an inch of slack above the weights. Holding the roller
above the supports,
and feed the end of the door into the door guides
until the bottom panel reaches the doorway. The
roller can then rest on the support arms. After
making sure the counterweight threads are outside
the support arms, work the door up and down by hand
until it runs smoothly.
When working properly, it is possible to work the door up and down
with the point of a bamboo skewer, the kind
that works so well as an uncoupling tool.
Troubleshooting:
Some of the things which tended to cause problems after
assembly are:
- Loose threads from the fabric bunching up
and causing friction in the door guides. Remove
the door assembly and gently
trim off all loose threads with a sharp hobby knife.
- Counterweight threads on the inside of the
support arms. Once these are
on the outside, and the door has been up and down a few times,
the threads stay were they belongs.
- Door panels on the bottom of the roller getting tangled
with the door as it slides down. Try adding weight to the
counterweights.
During final assembly of the building, check for interference
between the ends of the door rollers and the
steel columns that go in the corners. You may
have to remove some material from one or the other.
* If the door not been able to open far enough
with the 2¾ inch high doorways of the kit,
I would have
simply added a ¼ inch stone foundation to the bottom
of the walls to make the doorways taller.