Model Forum / General / Railroads / June 2004

 "Digital Railroader LLC" <unpublished@unpublished.com>,
 In a message on Sat, 26 Jun 2004 12:46:29 GMT, wrote :

"RL> The 2" extruded foam sheets seem very strong - if I had a 2' wide grid of
"RL> benchwork, would I need a plywood subroadbed, or would the foam be
"RL> sufficient with an frame of wood and stringers every 2' or so?

Generally yes.  You might want make your 'stringers' as upside down L
(or right-side up T) girders (made from 1x3s or 1x4s) to spread the
support under the foam sheets.  Note that you might NOT want to stand
or jump on this benchwork, but it will be quite happy to support your
trains, buildings, and scenery (esp. if the scenery is itself mostly
more chunks of foam).

"RL>
"RL> --
"RL> Frank Eva
"RL> http://www.digitalrailroader.org
"RL>
"RL>
"RL>                                                                                                                      

                                    \/
Robert Heller                        ||InterNet:   heller@cs.umass.edu
http://vis-www.cs.umass.edu/~heller  ||            heller@deepsoft.com
http://www.deepsoft.com              /\FidoNet:    1:321/153

       

Quite... in fact, you don't even need 2" foam for that. Lots of N-Trak
modules are being built now with 1" foam. You _will_ want to make a
_mechanical_ attachment to the foam, because while construction adhesives
are fine for just holding it in place, I've found that if there's any kind
of flex in the frame they'll let go over time. I use deck screws into the
wood frame, putting them through 1/4" fender washers and snugging them
down into the foam, then covering them with lightweight spackling.

--
Joe Ellis

The Flint Hills Northern is built on 2" foam, supported by 3/4"x3"
slats every 18-20", and a 1x4" (equivalent) outside frame.  No
problems.  I could have gone for 2', but chickened out.  The biggest
issue I've run up against is the problem of mounting switch machines
under the layout to the foam.  You can't use mechanical fasteners,
since the foam is far too soft to hold.  I have used two methods, both
of which use latex foam adhesive to mount the machines.  One choice is
to mount the machine on wood, and then glue the assembly to the base.
This works well when the machine design won't allow direct glueing
(the other method).

When glueing anything to the foam from undeneath, you do need to rig
some method of holding the item (switch machine, whatever) firmly up
against the bottom of the layout until the glue sets up.  I just use a
couple of sticks clamped together and wedged between the item to be
glued and the floor.

Good luck!
---
Gary M. Collins
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Fifteen years ago I started building modules for a portable layout that were
2' x 8' in size.  The board frame is 4" wide x 1" thick pine on the four
sides, glued and screwed together with 2" x 2"  x 3 1/2" lg. blocks in the
corners.   1 1/2" down from the top I glued and screwed on the inside of the
frame, mounted vertically, 1" x 2" boards for 1 1/2" foams to sit on.   32"
in from each end I pit a cross piece of 1" x 2" pine, mounted horizontally,
to help support the foam.   These were notched into the 1" x  2" vertical
side members to make a flat frame surface to support the foam.   All wood
joints are glued and screwed  together.   Elmers wood glue  is fine and cheap
for this.   The foam is glued in place with Liquid Nails for Projects.   This
will stal somewhat flexible since it is a latex adhesive.

In the period of time since construction, these modules have live in a house
for a short time, and spent a lot of time in the trailer that is used to take
the layout to shows.   This trailer sits in the sun in the summer, at times
well over 120 degrees F and at 30 degrees below zero in the winter with no
ill effect.

As some one has pointed  out, this is only a model railroad.   How heavy is
it?   For practical purposes only build a layout a wide as you can easily
reach.   For most people 24" is good.   If you can get to both side of the
layout like a 4' x 8' table, put two 2' x 8' modules together.

The trrack is glued to the subroadbed, which is foamcore.   The foamcore is
easily cut with a sharp utility knife, with curves and bevels.   The foamcore
is  glue to the foam.   I use Future Floor Wax as a glue for the track and
subroadbed.   The subroadbed is glued down first and dried in place.   Then
the track and ballast are next, in one operation.   I use round head pins to
keep the track aligned until the wax is dry.   Can goods make good weights to
put ontop of the track while it dries.

This all has stood the test of time in Ohio.   We have traveled over 9000
miles so far without failure.

Dave Decker

Fifteen years ago I started building modules for a portable layout that
were
2' x 8' in size.  The board frame is 4" wide x 1" thick pine on the four
sides, glued and screwed together with 2" x 2"  x 3 1/2" lg. blocks in
the
corners.   1 1/2" down from the top I glued and screwed on the inside of
the
frame, mounted vertically, 1" x 2" boards for 1 1/2" foams to sit on.  
32"
in from each end I pit a cross piece of 1" x 2" pine, mounted
horizontally,
to help support the foam.   These were notched into the 1" x  2"
vertical
side members to make a flat frame surface to support the foam.   All
wood
joints are glued and screwed  together.   Elmers wood glue  is fine and
cheap
for this.   The foam is glued in place with Liquid Nails for Projects.  
This
will stal somewhat flexible since it is a latex adhesive.

In the period of time since construction, these modules have live in a
house
for a short time, and spent a lot of time in the trailer that is used to
take
the layout to shows.   This trailer sits in the sun in the summer, at
times
well over 120 degrees F and at 30 degrees below zero in the winter with
no
ill effect.

As some one has pointed  out, this is only a model railroad.   How heavy
is
it?   For practical purposes only build a layout a wide as you can
easily
reach.   For most people 24" is good.   If you can get to both side of
the
layout like a 4' x 8' table, put two 2' x 8' modules together.

The trrack is glued to the subroadbed, which is foamcore.   The foamcore
is
easily cut with a sharp utility knife, with curves and bevels.   The
foamcore
is  glue to the foam.   I use Future Floor Wax as a glue for the track
and
subroadbed.   The subroadbed is glued down first and dried in place.  
Then
the track and ballast are next, in one operation.   I use round head
pins to
keep the track aligned until the wax is dry.   Can goods make good
weights to
put ontop of the track while it dries.

This all has stood the test of time in Ohio.   We have traveled over
9000
miles so far without failure.

Dave Decker