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Peter's Model Railroading | The Layout | Stops | The Hazel Mine Complex | Hazel Mine Tipple
Module Construction

Construction of the very first module of my new layout officially started on March 19, 2021, with the arrival of ten sheets of 24" x 36" Gatorfoam board. These sheets are 3/16" thick. I would have preferred 1/2"-thick sheets, but for the same price that I'd get ten of the thinner sheets, I would only get three 1/2" sheets. What I need more is quantity of sheets rather than thickness of sheets, for the structural integrity of the module. So, the Design page shows how I designed the module using 3/16"-thick sheets. The sheets were extremely well packaged. There was an outer shipping box, and what you see here are the sheets in their inner shipping box. They used regular foamboard material to protect each of the corners. I experienced no damage and am very happy with my purchase.
(external link: Artgraphics)

Here are the ten sheets. They are nice and straight and flat. As far as stiffness is concerned, I would say they are about the same as 1/4" plywood; pretty tough.

After spending time completing the design diagrams, I officially started the construction of the first module on March 27, 2021. The first step was to create the 48" long side panels. Since the sheets I bought are only 36" long, I had to cut a second piece. What you are seeing in this photo is my actual set-up for cutting the second piece to the correct length. The side panels fit in between the front and back panel. So, I have those two panels leaning up against the tablesaw fence, then placed against those is the second piece, and the full 36" piece. The tablesaw fence is set at 48", so that I could then use the sawblade to mark off where the long piece is to be cut.

One thing I learned very quickly about working with this material is that the wood veneer layers stick out ever so slightly from the foam layer itself. So, if you want good, solid glue connections, be sure to trim all of the factory edges a tiny bit.

One other thing I learned was to use gloves while sliding this stuff through the table saw. The veneer edge can leave some pretty serious paper-cuts on your fingers (ask me how I know, and why it is painful for me to sit here and type on the keyboard!).

With the long side pieces cut to length, and then glued end-to-end, and letting that dry overnight, I set about to cut the two handles I had designed into the side panels. I used a 1-inch Forstner bit to drill the two holes very carefully at the ends of the handle opening, and then cut the material in between away with a couple of extra passes of the bit. The remaining material was removed with a knife.

The lesson learned here is that the veneer layer really is made out of resin-impregnated wood (it looks like cardboard paper, but it definitely isn't). It is quite difficult to cut with a knife. A jigsaw is a better tool to use. The hole is not perfect, but I'll fix that later with a file.

Mostly for my own reference, this is the set-up I cobbled together to use the drillpress with the 1" Forstner bit to cut the holes for the handles. I clamped a piece of plywood to the drillpress, and then clamped a vertical piece to the back, so that I could push the Gatorfoam board against that and get a consistent location for the holes. The trick is to make sure the clamps stay out of the way of the long side panels. I need to use this set-up for the long side panels, and also to cut out the slots in the grab handle reinforcement pieces later on.

The clearing for the creek must also be cut while the side panels are still loose. I put the glue joint for the two pieces making up the long sides near the back. This wound up being right where the creek cut-out needed to be. For one of the side panels, the end-to-end glue joint failed (not surprisingly), so I glued a scrap piece to the inside of both of the side panels, to reinforce that joint. The key here is that the scrap piece must clear the bottom by at least 3/16th of an inch, as the bottom sheet will be inset into the vertical walls later on, and it needs to be clear of the top of the creek cut-out, of course.

The next step was to glue each long side panel to either the front panel or the back panel. I placed them into the inside corner of a large metal square, to make sure the glue-up wound up being square. I used blue masking tape as the clamp to hold the pieces together while the glue set. I used the flat surface of my table saw as the assembly table. A piece of wax paper was placed under the joint being glued, so that the glue doesn't damage the tablesaw. I let the two sub-assemblies dry overnight, and the next step is to glue them to each other.

I let that cure for many hours. By the way, I am using regular yellow carpenter's glue, and it works great. The assembly is, of course, quite weak still, but the glue joints on these 4" tall vertical sections are holding up pretty well. I was able to carefully move the outer frame around. With the outer frame built, I could then take an accurate measurement of the interior width. The 3/16" Gatorfoam board sheets are just a touch thicker than that, so that is why actual measurements must be taken where material thickness is to be taken into account. I cut a full 36" sheet to the needed width. Since the side panels' joint was in the rear, I decided to place the bottom sheet's joint toward the front. Eventually, the top sheet will be the full sheet from the front; you want to stagger joints as much as possible, for maximum overall structural integrity. I glued the sheet into the outer frame, and again used masking tape as the clamps. Where to apply the glue to make this connection was actually something that required a bit of thought. If I applied the glue to the bottom sheet's edges, due to the tight fit, the glue would scrap off as I inserted it from the bottom into the outer frame. This would leave very little actual glue in the joints, and leave a big mess on my tablesaw. So, instead, I applied a thin bead of glue along the bottom edge of the vertical outer frame, and used my finger to smear it out a bit. When I, then, insert the bottom sheet from the bottom of the frame (I actually had the frame sitting on one of its long edges to be able to do that), the glue would be pushed up into the inside of the box, which is much better. When the whole thing was dry, only one small spot stuck to the table (snapped loose easily), so this approach is the best one for me.

Once the one full sheet was dry, I could then take the actual interior measurement for what the second piece would be, which I then cut and glued in to the module.

Here is a view of the bottom of the completed core box. I am leaving the masking tape on the module until the whole thing is built, so as to help the glue joints stay strong while I do more work on this.

With the basic box done, it is now time to focus on the interior bracing. I have decided to build a honeycomb/eggcrate assembly, for its structural integrity. This means that I need to be very accurate with my cuts. First up are the three pieces that go down the depth of the module, which consist of two pieces each, cut to fit the interior of the box. Again, using masking tape to hold the end-to-end joints together while the glue sets.

By the way, the tape comes off easily and cleanly, much like it would if it was used to glue two pieces of wood together. Further evidence that the veneer is not some sort of cardboard paper. Again, wax paper is used to protect the tablesaw.

I love my new GluBot bottle; boy, does that make glue-ups easier; I should have bought one years ago.

Here's a photo of all the pieces that are going to make up the interior honeycomb assembly. Three long ones to go the depth of the module, and seven shorter ones to go across the width of the module. Two of those are skinnier because they fall under the creek area. All will be placed 6" apart in both directions.

After cutting out the clearance for the creek in the long pieces, I carefully cut out the grooves that allow the honeycomb construction. This was probably the hardest part of this whole construction. I cut all the related pieces together, so that the grooves would all line up accurately. I cut the grooves on the long pieces such that they fall at their top edge. This is because of how I plan on gluing the assembly into the box. Trying to glue the whole honeycomb would take too long and the first bit of glue would likely have already hardened by the time I finish applying the glue to the whole assembly. So, knowing that, I am going to first glue the long pieces to the interior of the box, using the other pieces as their guides. Once that glue has set, I can then take my time to glue each of the shorter, "width", pieces in their position. That is why the grooves need to be at the tops of the pieces that are glued in first. Planning the construction of this first module wasn't trivial. But, part of the reason for why I document things on this web site, is so that I leave notes to myself for when it is time to build the next module.

Speaking of planning... In addition to creating the 3D CAD design, I also spent about a day of hobby time creating my own step-by-step instruction sheet for how to actually build this module. I printed that off and kept it in the garage. I took notes and created another revision. I am currently at about the bottom fifth of the middle page!

I then dry-fitted the interior honeycomb bracing on the tablesaw, to make sure all my cuts were accurate. They were! One of the things you learn in woodworking is to test- or dry-fit your assembly before applying glue. So, I decided to do that by placing this honeycomb into the box, and it fit but it wasn't as smooth as I thought it should be. When I then took this honeycomb out and put it on its side on a flat surface, I noticed that two of the vertical ("width") boards weren't even with the others. After taking measurements, I realized that somewhere along the way I had flipped those around end-for-end, and so the grooves weren't quite matching. Flipping them around fixed the problem, and the assembly slipped into the box perfectly. If I had already applied glue, it would have been really bad. Always dry-fit first. I also forgot to account for the scrap pieces I had glued on the inside of the side panels in the creek area, but that was easy enough to fix by trimming one of the "width" boards in the creek area.

The interior has been installed into the box.

As indicated in the design, I wanted to reinforce the grab-handle area, to make sure that the weight is properly distributed when the module is lifted up. For each side panel, I cut three sheets measuring 5-1/2" x 3-1/4". I then grouped three together and held them under the drillpress while I cut out the opening.

It was then just a matter of applying glue between each of these and the side panel, and then clamping them down. I used wood to protect the Gatorfoam board from the clamps.

To reinforce the corners of the module, I decided to cut a strip of 3/4" plywood to 1-1/2" wide, glue them together, and, when dry, cut them into the appropriately-sized blocks to fit within the corners. I marked off their centers.

I then drilled a 1/4" hole into the center of these blocks, about 2" deep, so that, in the future, I can insert a bolt to act as a module leveling device. For now, they'll be hidden, but I know that they are there, should I decide to use them.

After the blocks were glued into place, I filed the grab handle openings nice and smooth, lightly sanded the exterior, and then painted the outside vertical panels of the module. The manufacturer recommends painting the opposite side as well, so I also painted the inside of those panels. It took two coats of my favorite Lowes paint to get good coverage.

The next issue to resolve was "sound". My past experiences with foam left me with the conclusion that foam board amplifies the noise of a train running over it. So, thanks to battery-powered engines, I was able to put an engine on a leftover sheet on top of the module, and, much to my surprise, it was only barely louder than the mechanical noise that the engine itself makes. My previous plywood-based modular layout was louder than this. The difference is that the plywood version had an open bottom. Here, I will wind up with a closed system.

If you remember my previous layout, which sat on a collection of cabinets I had built many years ago, those cabinets are now no longer in the room that holds my model railroad. That is because I am in the process of building new cabinets that are more space-efficient. In the meantime, though, I still have to store all the stuff that was in those cabinets, so I bought a bunch of these Bankers boxes. These are then great for supporting my new layout.

So, with the sound issue not being an issue, it was time to permanently seal up the interior of the module. I used whatever heavy stuff I could find to hold the sheets down while the glue set.

All-in-all, I used 6 sheets of 2'x3' Gatorfoam board to build this 2'x4' module. There are some usable scrap sections left over. So, that means two orders of ten sheets will allow me to build a total of three of these modules (noted here for future reference). Now we just need to see if time causes the module to warp, or if my construction was strong enough to keep it in its intended shape.

For the past two layouts I have used 24" square sheets of ceiling tile that I bought at Lowes. This material is 1/2" thick and is used for office building ceilings. It is very similar to Homasote, but much easier to obtain. The sheets are about 23-3/4" wide, so I had to cut two sheets to 12" wide and then glue them down to the top of the module. The ceiling tile serves two purposes; namely, to dampen any remaining train noise, and to allow for scenery dips (1/2" in S-scale is equal to a scale 32", so enough for a gully or ditch).

A third piece was added at the back, so that there is an even foundation for the tipple building itself. The back of the module will be all scenery, so it doesn't matter there. And so, with this photo, I officially declare the construction of the base module finished.

The entire module, as shown in this photo, measuring 2' wide x 4' deep x 4-1/2" tall, weighs 9lbs 5oz (4.1kg). A significant improvement over the 40+lbs (18+kg) of the previous plywood-based modules! I find it easy to move around, I can carry it with one hand, and should make moving it with delicate track and structures a lot easier and safer. I am very pleased with how this turned out.