End Plates, Side Pieces & Middle Members - "In" and "Out", "Top" and "Bottom"

Middle Cross Member
Now that we've got those triangular corner gussets marked up and the T-nuts installed, let's next take a look at that 1"x 2"x 22 1/2" middle cross member.

I love that cross member! For a number of reasons. The module (and its mate) is going to be lifted in the middle, carted from one end of the set-up hall to the other, set on its side with heavy stuff stacked on top, rolled over, bolted, and upended on some dollies. It's going to be thrown into the back seat (or trunk) of your car, thumped and bumped downstairs into the basement, kept out in the cold garage, to say nothing of being man-handled by a bunch of guys who don't treat any modules with "kid gloves". That middle cross member is going to provide extra ruggedness to withstand that kind of rough treatment.
While we build the module, you'll find the sides are going to bend in or bend out so that the middle may be 22 3/8" wide or 22 5/8" wide. Try pushing or pulling those sides apart or together while inserting a piece of Styrofoam loaded with glue into the module frame!  It can get a bit messy.  The cross member keeps the middle of the module at 22 1/2". For a 4' module, I use one cross member. For a 6' module, I might use two cross members.

If you look under some modules, you'll see a whole bunch of wires hanging loosely down just waiting to be yanked out as they're loaded and unloaded into cars, basements, and set-up halls. With the notch in the middle, we now have a place to hang the track power buss and the LocoNet cables that will go from one end of the module to the other (more on the wiring later on).

The notch in the middle of the cross member is simply two cuts 1/2" wide and 1/4" deep that we cut with a saw (hack saw, hand saw, table saw, etc) and chisel out (saw out, router out, cut out) so that we have the notch. It will go next to the Styrofoam. To make sure that we don't forget, mark the side that has the notch as "Top" with a pencil or pen.

Here's a photo of that middle cross member to give you a better idea of what we've been talking about.
 /(Before you go rushing off to the lumber store, hold off for a minute. I've got one more saw cutting trick to show you.)

Mark The Wood - "In", "Out", "Top", "Bottom"!
I can't stress enough the importance of marking each piece of wood.  I've screwed and glued too many pieces of wood together only to find that they were glued on wrong.  With wood glue, there's no second chance.  A few minutes spent marking each piece is going to save us grief later on.  As we've moved along, we've marked our pieces "In", "Out", "Top" and "Bottom". 

Getting The Best 3/4" Edge On "Top"And Worst Edge On The "Bottom"
The idea here is to make sure you've got the best 3/4" edge on the top.  Once you've decided, mark each of the 3/4" sides of each piece of wood as "Top" and "Bottom".  

If both of the 3/4" edges are nice and straight, it's a simple matter of flipping a coin and marking that edge as "Top" (on both sides) and the other edge (on both sides) as "Bottom".  If one of the 3/4" edges bows up and the other edge bows down, then the edge that bows up (carpenters call it the crown) is the "Top".  If things are impossible and you have access, you can always run the wood through the jointer-planer.  Or we should be more careful when we select our wood.

Getting the Best 4 1/2" Side "Out" And The Worst Side "In"
We next want to make sure that the straightest 4 1/2" side is on the outside.  If both sides are straight, flip a coin as to which side will be "Out" (as in "Outside") and which side will be "In" (as in "Inside"). 

We want any curves to be swinging into the middle of the module so that our middle cross member and the gussets can "push" the curve out.

Your wood might have had a tendency to "cup" or "crown" along the wood grain as shown in the exxagerated graphic below.  We want the "cups" marked "Out" and the "crowns" marked "In".
It may also be the case that the wood has got blemishes, gouges, or knots, in which case we want these to be on the inside if we can't cover them up with plastic wood and/or paint.

Once you've decided, mark each  4 1/2" side of each piece of wood as "In" (as in "Inside") and "Out" (as in "Outside"). We've already marked the corner gussets and middle cross pieces as to "Top" and "Bottom".  Using the criteria outlined above, mark the end plates and side pieces "Top", "Bottom", "In" and "Out".  
The end plates will be butted up against other modules in a setup so it's very important that we get the "best" sides on the top and on the outside.  For the side pieces, we don't want to have to use pipe clamps when we fasten the middle cross member or glue the Styrofoam into place.

Next up, we locate and drill the holes for the screws.

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