John Palecki Structures Kit O2

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KIT O2:
On3/On30 D&RGW 120' Pin-Connected
Light Through Truss in Cast Resin and
Laser Cut Plastic

Price: $240
Availability: In Progress, see below

A BOU T

Q &A

PURCHASE

This is a lightweight
bridge perfect for
branchlines and
older eras. Scale
will be O narrow
gauge but prototype
(and model) is wide
enough for small
standard gauge.

Here is a bridge that
could be called a
standard. It is an 8-panel
design of 120' length that
was used in various
places on the D&RGW
narrow gauge system.
Plus they were moved and
re-erected at times. And,
of course, an iron pin-
connected truss could be
used on any railroad
setting from the later
1800's to near the
present time. Add a wood
deck and you would have
an attractive highway
bridge.

The kit captures the
simple elegance of pin-
connected bridge. The
eye bars and pins will
work under tension as on
the prototype. It
assembles with just a few
gusset plates, with only
the pins holding the
structure together.

Model Features:

O narrow gauge
but wide for some
standard gauge
equipment
Resin castings
for ease of
assembly
Laser cut eyebars
for strength
Floor structure
uses steel bars
for reinforcement
Assembly with
ACC adhesive
Alignment aids
built-in to parts
Hundreds of
rivets in correct
patterns
NMRA clearance
Real pin-
connected
assembly
Shorter version
will be available

ABOVE: Prototype bridge in Colorado from B. Lund

RIGHT: Click on the thumbnail to the right for a clearance drawing taken
from my working CAD drawing. I have drawn the NMRA clearance
templates per their standards for each scale. The On30 is the same for
On3. The On3 Wide uses the side clearances for O Standard Gauge. The
rail-to-upper-brace model height matches the prototype, which is plenty of
room for the tallest narrow gauge stack. It is a bit shy of the 5 1/2" O
Standard height, but should allow enough room for lighter steam
locomotives and anything 40' with a roofwalk (no hicubes or multilevels).

S gauge fans should note the bridge would not be unreasonable for a
layout in that scale!

RIGHT: Here is a little of the inside
story.

This is the mold for a floor
crossbeam. The aluminum frame
fixes the rubber in place with
minimized dimensional variation. The
pins align the mold surface.

The master is shown built-up on a
styrene plate. This technique was
developed in-house. It has allowed
me to build-up a stable master with
all the thin sections and small details
I wanted. Because this part is
identical on both sides, I was able to
flip over the master to mold both
sides. Other masters have different
sides but are precision aligned so the
casting is correct.

At the bottom is a casting with the
resin entry "sprue" cut off. That was
all the prep needed- no flash to clean
due to the accurate, stable mold
design.

I use the latest in commercial
industrial resins for maximum
strength. The parts are post-cured to
bring them to maximum performance.

Casting is a slow process involving much model work to make the
masters, mold them in RTV and then to hand cast every model piece.
The results are worth it, and gives the modeler a special and unique
product - from one railroad bridge fan to another.

ABOVE: Prototype bridge end view in Colorado from Nathan Holmes
www.drgw.net

Here is a table of D&RGW bridges that are the same or similar to this model:

VERY CLOSE:

Almont
Gunnison
Chama (2 spans)
Navajo
Elk Park (old span)

SLIGHT DIFFERENCES:

Pagosa (east of): small truss, portal bracing
Durango: portal bracing, vertical beams turned

TYPICAL TRUSS SIMILAR:

Florida River
Teft
Bondad
Juanita
Pagosa Jct
Hendrix

The bridge can be shortened for some of these prototypes. I would like to include the
portal braces with the neat four-leaf clover design if possible.

For photos of D&RGW
bridges, try:
www.drgw.net
http://davesriogrande.home.
att.net/index.htm
www.drgw.org/features/ocpe
rry/index.htm

LEFT: This is the complete 30" long floor
assembly. There are 9 floor cross beams. In
the inset photo you can see the floor
construction. The outer two stringers are cut
styrene I-beams. The center stringers are
continuous .125" x .375" semi-hardened
steel strips. They are capped with styrene to
model an I-beam shape. The steel stringers
add tremendous strength and rigidity to the
bridge.

ABOVE: Here is a close up of an intermediated floor section. I have included all the connection
details of this typical pin-connected bridge. You can see that the plates, angles and rivets are all
at different levels. This gives the model an extremely realistic look. They are as close to
prototype thickness as possible. Also, the parts come in one piece; all you need to do is fit the
stringers into their sockets on the floor beams and apply ACC. The parts are strong but still
flexible with none of the brittleness sometimes associated with older castings.

LEFT: Here is a detail photo
of the shoe casting and end
floor beam. This part is rarely
correctly modeled but is very
important - all the thrust of the
bridge is translated to the
ground via the four shoes.
For this O-scale model I
added heavy inner plates for
the pin to rest on. This will be
one reason why the model will
look good and function like a
real bridge.

LEFT: This is a laser cut sheet of
eyebars. Each truss gets one
sheet. The material is scale
thickness, and are dimensional
accurate for easy alignment and
good pin fit.

KIT INFO AND PROGRESS PHOTOS
See the newest developments here as I master and mold the parts for this great bridge.

RIGHT: I recently added
stained basswood ties and
code 70 rail to my first bridge
floor. I will include drawings of
the tie layout in the
instructions. My On30 locos
look great crossing the bridge
deck spanning a great
plywood chasm on my layout.

LEFT: This is a complete assembly of the first
laced beam I have cast. The beam is made of two
side castings, four lacing sections and eight
plates. The plates drop into place on alignment
tabs in the correct position and holding the sides
in alignment. The lacing tacks down on the beam
flange rivet spots. It goes together quickly and
easily. The remaining beams will be built similarly.

RIGHT: Here is a drawing of how the
bridge fits. It is 30 5/8" total length. Plan
to leave a gap between the bridge and
the abutment. The height from
abutment top to bridge stringer top
(where the ties sit) is 1". Build your
abutment with adjustments for bridge tie
thickness, track tie thickness and
roadbed thickness.