PRR Chartiers Branch: Hazel Mine - Framework
As described in the design, these three modules making up the Hazel Mine diorama are going to be made from 3/4" plywood. This photo shows the core materials I bought to get that process started. There are two 4'x8' sheets of 3/4" plywood, and one 4'x8' sheet of Masonite hardboard. In the foreground is a box of 24"-square ceiling tile, which will be used as the roadbed. I needed to buy the ceiling tile at the same time, so that I can cut the width of the front boards such that they account for the actual thicknesses of the plywood sub-roadbed and the ceiling tile roadbed. I want the top of the front frame board to match up with the top of the ceiling tile. That way the ceiling tile's edges are protected, and it looks nice and finished. It has been 8 years since I last bought materials for a new layout, and the increase in prices was staggering (inflation is definitely real!). The ceiling tile I had bought for my previous S-scale switching layout was no longer available. To cover the entire 4'x8' space of the diorama, I need 32 square feet of ceiling tile. This box provides twice that amount, and it was cheaper than the equivalent 12"-square ceiling tiles. So, I have enough for the next diorama I am going to build!
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At the local Lowes they only had oak plywood ($54) and white-birch plywood ($40). Both looked really nice, and both had 10-plies and both had some visible voids. I had planned on getting the oak one, but seeing the price difference and seeing that they were about the same in quality, then the price started to be more important. The white-birch is pre-primed on the backside only.
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This photo, and the next one, are mostly just for my own reference. They are of the details of the Armstrong ceiling tiles that I bought for the roadbed material. These are 2-foot-square tile with no grooves, so I can butt them up against each other, which will also eliminate the need to fill the gaps that the 12" pieces I had used before created.
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The first order of business was to convert the "car-and-a-half" garage into a woodworking shop. Full 4'x8' sheets can be cut width-wise or length-wise in the garage, but it requires the moving of the table saw. My table saw sits on a movable frame, so that is easy to do. My dust-collection system is also on wheels. What you have to account for in a situation like this is that an 8-foot board needs 8 feet of clearance in front of the table saw and 8 feet of clearance in the back of the table saw, to properly feed it and cut it. The garage is the standard 20 feet deep, so it all just fits. Both ends need to properly support this heavy board. In the photo below, you'll see a stained cabinet in the background, which provides the support of the board when it is being fed into the table saw. In the foreground you'll see one of the two roller stands I have to handle the outfeed. If you look at the table saw's fence, I have extended the fence by another 4 feet. The original one I had built 15 years ago has disappeared (see link above, right), so I had to build a new one for this project. By the way, I don't have a circular saw and an 8-foot straight-edge, so I have to do this to be able to cut an 8-foot sheet length-wise.

(As an amusing side story; talking about making sure you have enough clearance, when I was cutting the first strip, I didn't account for the trim around the door frame for the door that leads from the house to the garage, and sure enough, in the middle of that long cut, I hit the door frame, and I had to move the table saw over by at least a half an inch before I could finish that cut!)
After all of that set-up (and building the fence extension), I am finally ready to make that dreaded first cut! Actually, it went well. The first two cuts were the 4"-wide support braces. I then cut the 6"-wide strips for the side and back panels.
The front panels are next. To be able to fit them to the actual materials, I put one ceiling tile on the plywood, lightly-clamped them together, and measured their combined thickness (a bit over 1-1/4"). The front panel strip was then cut to a bit over 7-1/4".
The next step was to trim each of these strips down to their final dimensions for the individual boards that make up the frameworks of the modules. These, and the ceiling tiles, are shown in the next photo on my work table.
Before starting the assembly process of the frameworks, I wanted to cut the "ground" plywood sheet up first. Those big 4'x8' sheets are hard to manipulate in such a small space, so by cutting them up, they are easier to move. I managed to get all of that work done in one day. The next day I was going to start by trimming 3/4" off of the depth of these sheets, since the front panels had their height raised from 6" to 7-1/4" in my design. However, I went bike riding first, and during that time I had the idea of cutting a groove all around the perimeter of this "ground" plywood to support the 1/8" hardboard. My reason for going this route was that cutting the backdrops to a height of 24", and bolting them to the sides of the modules would lead to two problems. One was that the bolts might cause interference in a future layout, and, two, the backdrops would only be 16-3/4" above the ground surface of the layout. I plan on putting lights on top of the backdrops (design to follow later), but that put the lights right at my forehead (I'm 6'4"), which would be annoying. By placing the backdrop in a groove, I regain the 6" of the height of the modules back in the backdrop height, and I don't have to mess with bolts for attaching the backdrop panels. So, what you see in the photo below are the three modules' "ground" plywood sheets cut to size and having their grooves cut in them (I cut them with the table saw).
It may be hard to make out in this photo, but I took the X-Y coordinates of where the creek is in the design diagram, and marked those out on the "ground" plywood. I then free-handed a fitting line between those marks to sketch out the creek. My work table is just big enough to handle all three sheets, and the clamps are necessary to keep the end pieces from possibly falling off.
Here's a close-up to show the lines drawn. There is an area where the creek goes off the layout/diorama in the back. Since the creek will be dropped down by 2 inches, the backdrop panels will have account for that. So, essentially my backdrop panels will be cut to 22 inches tall, but there will be a lip of an additional 2 inches to reach the "creek" plywood.
I used the jigsaw to free-hand the cuts along the lines I had drawn. The next step is to make those 2"-minus-the-ceiling-tile-thickness cut-outs into the framework pieces. I loosely placed the front panel and the two side panels in place on the work table, and then carefully placed the "front ground" plywood sheet on top of that.
I could then mark off on the side panels where the edges of the creek were. For those modules where the back of the creek is at "ground" level, I also marked those off.
I thought about how to carefully and accurately cut these cut-outs. At first I figured the jigsaw would be good for that, but I was concerned about not getting the bottoms of the cut-outs to be smooth and even. If they weren't, then the "creek" pieces of plywood might not be flat, and might not line up between the three modules. In the end I decided to use the table saw. I first cut the vertical cuts based on the marks I had made. I then set up the table saw such that it would cut the cut-outs to be the same depth. I put two marks on the table saw's fence to indicate to where the blade cut. I could then run the piece through until the marks on the wood lined up with the marks on the table saw. For the cut-outs that don't end at the end of the piece, I carefully lowered the plywood directly on top of the rotating blade, and pushed and pulled the piece until both pencil lines on the board lined up with both marks on the table saw. This went well. I then flipped the boards over and made the cut again from the other side. That leaves a small triangular-shaped piece where the table saw blade can't cut, but that was easily done with the jigsaw. The framework pieces are now ready for assembly.
In my design page, I mentioned that I was going to use biscuits to reinforce the butt-joints that I am using to assemble these modules. This makes for a plenty-strong joint, unless you are going to throw them around or drop them. Under normal handling conditions, these modules should last a life-time. A normal butt-joint connected with glue without the use of dowels, biscuits, or screws would not be strong enough. However, when you assemble a frame using biscuits, a bit of planning is required. The general set-up is shown in the photo below. The two cross braces are to be attached to the inside of the long side panels. The back panel is to be attached to the ends of the long side panels. This means that the cross braces must be attached first. I carefully lined up each of the pieces and put a mark across their joints of where I want to cut slots for the biscuits. Note that in the photo, the pieces are set right-side up, but when I actually started marking them, I flipped them all over, because the top of the framework needs to be on the flat work table surface.
I cut their biscuit slots first and then glued and assembled the sub-frame. After letting that cure for at least 30 minutes, I came back and started cutting the slots for the back panel.
For cutting slots in the ends of boards, it is a simple matter of lining up the biscuit cutter's mark with the line I drew on the piece.
For surface slots, like the ones shown in the next photo, I have to extend the mark up the board.
The way I cut these is I put the board up vertically on the work table (which is perfectly smooth, flat, and even), then put a framing square against the side that is not being cut (which guarantees that I am getting a parallel slot), and then I put the biscuit cutter on the work table and against the other side of the board. It is then just a matter of lining up the cutter with the line on the board, and making the cut.
I put the framework upside-down on the work table so that I was guaranteed that the top of the framework was even during assembly. Flipping it right-side up again, I could then mark off on the back of the front panel where to apply the glue to glue that board to the framework. No need for biscuits here, because there is plenty of glue surface.
After the basic framework was done, it was now time to start attaching the "ground" and "creek" plywood sheets. The module that is shown in these photos is the skinniest middle module. I figured that was the easiest one to build first. The other two are built the same way, but they are just larger. The back side of the horizontal pieces have the groove cut into them for supporting the hardboard backdrops later on. As I am placing these horizontal plywood pieces, I want to make absolutely sure that their grooves line up. The backside backdrop is going to be a single sheet spanning all three modules, so the grooves must line up along all three modules. So, the idea I had was to make two alignment jigs out of the hardboard. They need to be mirror image of each other. The alignment section at the top of these jigs is a bit delicate, so I glued some pieces of oak quarterround to their fronts to reinforce that. It also keeps the hardboard from flexing, which is what I want to prevent as well.
For this middle module, there is one small piece in the back behind the creek. It has the groove in it, so that is a good example of how these two alignment jigs are to be used. The groove is to sit outside the back vertical frame member of the framework. So, the hardboard jigs sit flush up against that vertical frame member, and then the groove is guaranteed to align with that perfectly. I could then glue and screw this plywood piece in place.
The creek is next, and it is done in the same way. The two jigs are used to line it up, and then it is glued in place. I don't want to mar the top surface of the creek, so I am not using screws here, just glue.
Up until now, the big horizontal piece of plywood was just loose on top of the framework. I used it as a work space for placing my tools. However, it is now glued and screwed to the framework. I first glue it in place. As you've heard woodworkers say, "You can never have enough clamps". Well, this glue-up required nearly all of my clamps. When the glue had set for about 30 minutes, I came back and installed screws where I could.
The final step was to apply the ceiling tiles. These are applied to fit the module. This one required two full tiles and the left-over from the creek space was used to fill the remaining gaps. I used the blade, only, from a coping saw to carefully cut the ceiling tile to the profile of the creek. I then came back and cut it again, but this time with a bit of a sloped profile. The ceiling tile is very loose material, so it crumbles easily and I wasn't able to cut it with a utility knife. It is also messy. I didn't bother applying ceiling tile to the small piece in the back of the module, because that is where Buffalo Hill is and so that will be covered by a sloping rise later on when I start building the scenery base.
This photo was taken from the actual front-view of this module. The creek area is hard to see, but still worth modeling. It is more pronounced and to the foreground in the other modules. All-in-all it took me 5 days of hobby-time work sessions to cut and prepare all the framework pieces, ignoring the initial garage set-up time. Then it took me two days to assemble this first middle module. It is fun and relaxing work.
The next module I built also took me two days. It was the right-hand one. When I built the first module, I was being real careful, and double-checking everything, so it went flawlessly. For the second one, my confidence was high, and I didn't bother doing all the double-checking, and sure enough, I messed up. I put the board that was supposed to be at the back end on the front end. This meant that I had to fix the back piece, which was now a 4" piece instead of the 6" piece. It also messed up the overall orientation of the boards on the sides. Not fun when I discovered all of that. All-in-all, though, it came out OK.
So, having learned my lesson from the second one, the left-hand module was the last one to build, and I was very careful. It also took me two days to put together. Unfortunately, I had messed up in the cutting of the back panel for this one when I was cutting the cut-outs for it. I cut it backwards, which meant that the "pretty" face of the board is now facing inward, instead of outward. Since that is the back panel, it isn't that big of a deal. However, when I started attaching the creek piece, I realized that I also didn't make the cut-out for it long enough, so I had to cut the back panel while it was attached to the module, which made it much more difficult. However, as you can see in the next photo, it came out well. This is the module that will hold the tipple itself and the power house.
My workbench is only about 63" wide, so I could only put two of the modules up there at a time. The left-hand one lined up well the middle module. No adjusting needed.
I took the left-hand one down, and moved the middle module over, so that I could put the right-hand module on the workbench. In general, for the critical areas (the front panel and the top surfaces of the ceiling tile), the modules lined up well.
However, for some reason the back didn't line up. I still don't quite know how that happened. As you can see, the backdrop Masonite hardboard panel is supposed to sit in the groove that I cut, but the groove of the right-hand module doesn't line up with the middle one. There is also a bit of a vertical difference, but that can be resolved with bolts. After a bit of a set-up on the tablesaw, I ran the entire right-hand module, upside-down, through the table saw, to cut another groove where it now needs to be.
I had put the three modules on the floor, when I noticed that the left-hand module didn't look all that nice from its side. For the current set-up in my room, that is the side that I will see the most, other than the front. Mere painting this side isn't going to make it look more attractive.
So, I cut a piece of leftover 1/4" oak plywood to size, and shaped it such that the creek opening was matched up. On the front corner, I cut a small piece of 3/4" oak quarterround to the same thickness as the oak plywood sheet, and glued them both to the exposed side of the module.
And so, after 13 days, I went from picking up the supplies at Lowes, to having three built modules. Just for fun, I decided to weigh the individual modules. The left module (on the right in the photo) weighs 45lbs (20.5kg), the middle one weighs 33lbs (15kg), and the right one (on the left in the photo) weighs 44lbs (20kg). They are quite a challenge to lift up on the workbench.
I applied two coats of white paint to the underside of each of the modules. The main purpose for painting these modules is to protect them from humidity, and from water spillage when I get to the scenery stage.
I also applied that same white to the top surfaces of the modules, i.e. the creek, the wood, and the ceiling tile. Especially the ceiling tile edges are very important because that material is very fragile. On the sides (all four of them) of the modules, I applied two coats of my favorite dark green color that I've been using for almost 15 years now for my layouts. I didn't bother with buying an earth-toned paint for the top surface, because over the years I have learned that by the time all the scenery base materials are applied, none of that surface paint is visible anymore, so it is kind of a wasted step/expense. This completes the construction phase of the modular framework.
These modules were a bear to get on top of the cabinets, which top out at 50" from the floor. However, with some creative use of dollies and other means, I was finally able to get them up there.
Next, I pulled the modules about 6 to 8 inches to the front off of the cabinets, lined up them, and put clamps between them. This then allowed me to drill holes and insert 1/4" bolts with washers and nuts to hold them together.
I then pushed the modules back so that they overhung the cabinets in the back by 6 to 8" and installed bolts in the back too. Then, I pushed them into their normal position. Not an easy task, because I estimate these three to now weigh 125lbs (~57kg) together. Here's a view of the creek, taken from the left side.