The Jigs Up
After my first trial, I did some internet searching to find other designs. I had seen one in Garden Railways magazine that I liked with the track on an open ladder and held up by poles. So when I stumbled upon O Scale Trains By Ron on YouTube, and he had instructional videos, I knew I had my new approach. Ron also has some instructions and photos on his website. We'd see if this worked out.
I tend to be a little impatient when starting a new project so once I had the idea of how the ladder railbed would go together, I dived right in. The basic design would have two pieces of PVC lattice board forming the supports (girders) with PVC trim cut down to be spacers. Holding the whole thing up I would screw the ladder railbed to a plumbing tee (mount) attached to a 1" PVC pipe which would telescope out of a 1.25" PVC pipe which is sunk into the ground.
Since I was using track pieces with known radii, I thought I could calculate the inner and outer radii of the ladder structure and attach the spacers appropriately. To make sure this held up to the weight of the trains I wanted to put the girders under the rails. So for my 4' radius track (600 mm) with a 45 mm gauge, that made the inner and outer radii 577.5 mm and 622.5 mm. Measuring out an equal angle, I would attach spacers at 303 mm on the inner and 326 mm on the outer. So I measured them out, and attached spacers. That wasn't too hard. Unfortunately, it turned out to not be very right either. The curve of the railbed didn't match the curve of the track very well. It was much shallower.
I know... I didn't account for the thickness of the lattice boards. Nope (I didn't but that wasn't the problem)
My calculations were off. Nope (actually they were as I mistook the radius for the diameter the first time but that didn't really solve the problem.)
So I tried physically measuring the length of the inner and outer rail on the piece of track with a measuring tape. Still didn't help. Probably too hard to hold the tape tight but still following the shape of the rails.
It seemed that no matter how I tried to clamp and hold the pieces, the girders, while flexible, had too much resistance and I couldn't quite get things in the right spot. My wife suggested building a jig to hold the pieces in place. I made a couple of jigs out of some old boards and then tried clamping them down to my work table (actually just a piece of plywood resting on a few saw horses). But the girders would twist the jigs leaving me with the wrong curvature. So I tried screwing the jigs in to the plywood. My thought was that if I made a jig for every standard curvature I used, I could just look at the plans, line up the girders in the right jigs and build the railbed. I adjusted them a few times so that I could layout four sizes of curves on one board.
I labeled each one with the rail description.
The upright parts of the jig hold the girders to the right curvature while I am attaching the spacers to hold it permanently in shape. Only, this didn't quite work either. For just one curve (piece of track) it's close, but putting two consecutively reveals that the error is always in the same direction and so it really adds up. Possibly it's because the springy lattice-board pieces, girders, still straighten out a little bit in the part between the two jigs. Or maybe it's because the jig necessarily adds a little straight segment at the join between each curve, because the space between the jig uprights is the width of the track, but straight instead of curved like the track.
After some more research and some helpful hints from Ron, thanks, I found a new method that is almost what I'm using now. That'll be the next segment.
I tend to be a little impatient when starting a new project so once I had the idea of how the ladder railbed would go together, I dived right in. The basic design would have two pieces of PVC lattice board forming the supports (girders) with PVC trim cut down to be spacers. Holding the whole thing up I would screw the ladder railbed to a plumbing tee (mount) attached to a 1" PVC pipe which would telescope out of a 1.25" PVC pipe which is sunk into the ground.
Since I was using track pieces with known radii, I thought I could calculate the inner and outer radii of the ladder structure and attach the spacers appropriately. To make sure this held up to the weight of the trains I wanted to put the girders under the rails. So for my 4' radius track (600 mm) with a 45 mm gauge, that made the inner and outer radii 577.5 mm and 622.5 mm. Measuring out an equal angle, I would attach spacers at 303 mm on the inner and 326 mm on the outer. So I measured them out, and attached spacers. That wasn't too hard. Unfortunately, it turned out to not be very right either. The curve of the railbed didn't match the curve of the track very well. It was much shallower.
I know... I didn't account for the thickness of the lattice boards. Nope (I didn't but that wasn't the problem)
My calculations were off. Nope (actually they were as I mistook the radius for the diameter the first time but that didn't really solve the problem.)
So I tried physically measuring the length of the inner and outer rail on the piece of track with a measuring tape. Still didn't help. Probably too hard to hold the tape tight but still following the shape of the rails.
It seemed that no matter how I tried to clamp and hold the pieces, the girders, while flexible, had too much resistance and I couldn't quite get things in the right spot. My wife suggested building a jig to hold the pieces in place. I made a couple of jigs out of some old boards and then tried clamping them down to my work table (actually just a piece of plywood resting on a few saw horses). But the girders would twist the jigs leaving me with the wrong curvature. So I tried screwing the jigs in to the plywood. My thought was that if I made a jig for every standard curvature I used, I could just look at the plans, line up the girders in the right jigs and build the railbed. I adjusted them a few times so that I could layout four sizes of curves on one board.
I labeled each one with the rail description.
The upright parts of the jig hold the girders to the right curvature while I am attaching the spacers to hold it permanently in shape. Only, this didn't quite work either. For just one curve (piece of track) it's close, but putting two consecutively reveals that the error is always in the same direction and so it really adds up. Possibly it's because the springy lattice-board pieces, girders, still straighten out a little bit in the part between the two jigs. Or maybe it's because the jig necessarily adds a little straight segment at the join between each curve, because the space between the jig uprights is the width of the track, but straight instead of curved like the track.
After some more research and some helpful hints from Ron, thanks, I found a new method that is almost what I'm using now. That'll be the next segment.
Comments
Post a Comment