Re: Project update: the Petrolia & Erie

"Greg Procter" <procter@xxxxxxxxxx> wrote in message
news:46097E41.2DC261A@xxxxxxxxxxxxx
Dan Merkel wrote:

<pawlowsk002@xxxxxxxxxx> wrote in message
news:1174938792.150066.182460@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Folks:

Two 2 x 4 grid sections have been completed. The
2 x 4 L-girders made earlier were joined by short L-girders into a
grid. After finding that the first, which
had yellow glue and wood screws at all joints, made
distressing cracking noises when 'tested', I switched
to Liquid Nails for the small-area joints, and started
using drywall screws at all joints, having run out
of wood screws. Both units seem extremely rigid
against bending and racking stresses; twisting is
decent but not perfect. There has to be a way
to make a light model RR frame that won't twist!
Maybe I could try some 1 x 2 cross-bridging...

Having put aside the question of legs, I am now
pondering my options for topping these units. I
want a flat top, lightweight yet rigid, cheap to
build, with all fasteners from below, and of course
/quiet/. What does everybody think about:

-1/4" plywood or masonite glue-laminated to 2"
foam- the board holds the screws; the foam provides
rigidity, and can be sculpted. Track would be
laid on cork roadbed. Cost, probably .75
per square foot. I could also use just foam, at
.50 per square foot, but would have to glue this,
which I'm trying to avoid.

-3/8" or 1/2" plywood or waferboard with
1/2" Homasote glue-laminated to it. Track would
be directly laid on the Homasote. Not so easy
to sculpt, perhaps, and a bit more expensive,
at $1 per square foot, but perhaps quieter and
stronger? Certainly it would hold nails better.

For this section of board, since it's going to
be a flattish industrial area with a number of
spurs, I'm not going to bother with open-grid
work. If I use the Homasote-plywood method
I may well space the board out 1" or so, though.

Has anybody some suggestions or favored
methods I might try here?

Cordially yours:
Gerard P.
President, a box of track and some grids.

GP (and others),

What I did was the following... I went to the lumber yard and bought some
good one side 3/4" plywood. I had them cut it into strips that were
three
and four inches wide by the length of the material. I estimated how many
of
each I would need.

I had a pretty detailed plan that I worked off of for the frame. I
carefully used thin long nails and wood glue to build the framework; I
used
the three inch strips on their edge. I tried to consider section joints
and
having some longer strips for added strength & rigidity. I made smaller
sections in the garage then assembled them in my train room due to
doorway
considerations.

Once I had the entire frame completed on the floor in my train room, I
added
the four inch strips on the outside so that the bottoms were even with
the
framework. This made the framework recessed an inch inside of the
outside
framing. I also added some simple metal 90° angles in strategic corners
for
extra strength & rigidity. Now comes the hard part... I raised the
entire
grid up on some boxes that looked like milk crates to attach the legs. I
was careful to keep the tops of the legs level with the tops of the
framework. I attached the 2x4 legs with wood screws & bracing.

Next, I laid sheets of 1/4" luan plywood on the framework. Where
necessary,
I simply marked them from below to fit then cut them out. I used wood
glue
and an electric brad gun to secure the plywood to the framework. When
the
framework was completely covered, I did the same ting with 3/4" blue foam
insulation board. I tried to stagger the joints for extra strength.
After
the parts were cut to fit, I glued them in place with Liquid Nails that
was
compatible with foam. The 3/4" foam and 1/4" plywood made up the extra
inch
so that when I was done, the deck of the layout was even with the boards
I
used on the outside of the layout.

My layout kind of looks like a big capital "E" and it is strong enough
that
a relatively light tap on the one end can be felt all the way around to
the
other end. The layout is in a climate-controlled area (heat & A/C) but I
have not seen any issues with moisture causing warping or anything along
those lines. The boards on edge give you plenty of space to run wiring
in
such a way that it doesn't hang down in the way. All in all, I'm pretty
satisfied with the way it turned out.

What I would do differently would probably only be to use 1/2" plywood
instead of the 3/4" There isn't a whole lot of difference in price, but
it
would be lighter and probably about as strong. But the 3/4" foam glued
to
the 1/4" plywood seems to be plenty strong.

By the way, cork roadbed is glued to the foam; track is glued to the cork
roadbed. That makes it pretty quiet. If you use any kine of nails that
run
into the plywood, that will allow the sound to resonate from the bottom
of
the layout like one large speaker. The only problem with this
track-laying
technique is that you need to be pretty sure where you want your track to
be
laid; the glue isn't easy to remove from the track and nearly impossible
to
remove from the foam & cork roadbed.

If anyone wants a more detailed description, please contact me outside of
the group & I'll try to explain in more detail what I did.

dlm
-------------
Dan Merkel

I would go with the 1/2" plywood sides to the frame rather than 3/4" or
even lighter. (we've been metric in NZ for the last 30 years) I've used
9mm ply.
For the top surface I use 9mm Chipboard (coarse MDF) plus 12mm Pinex
(compressed soft fiber) and on the outside faces I use 3mm or 5mm brown
Hardboard. 3mm where the edge stops at baseboard level and 5mm where it
forms the backscene and boxes in the structure'

My reasoning is that the trackbed needs mass to dampen train noise.
Where the track rises or falls within the baseboard I make sure the
corners in particular are gussetted with the 9mm chipboard and also
areas between tracks that aren't required to be open for access are
filled.
I think the depth of the sideframes is important for rigidity but the
thickness needs only be sufficient to stop them buckling from weight
(people leaning on layout) so possibly a single 1/4" thickness might do
the job.
I keep meaning to try making the backscene the rear frame structure, but
baseboard construction always seems to be hurried as I always seem to be
focussed on the layout to come. ;-)

The other two factors I now try to keep to are total weight (moveable by
two people, one being my wife) and baseboard (module) size small enough
to fit through a standard doorway.

One I built was so precise that it jammed going through the doorway
because I hadn't taken account of the vinyl to carpet floor covering
transition.

Regards,
Greg.P.


Hadn't really noticed, but I guess we have more than one "GP" on the group.

dlm


.

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