So here we are in Build an Eyebar Bridge 2.0, and I’m applying some of those lessons and new information I’ve picked up since 1.0. Setting out, I am bound and determined above all else to keep things consistent: consistent widths for the panels, heights for the box girders.
The bottom eyebars themselves, as always, are a bit of a challenge. As mentioned, the first time I attempted these devils I tried doing individual styrene strips – two on the outsides of the box girders, two on the inside. However the problem of manipulating and gluing these tiny strips became readily apparent: the glue easily pulls them together, and of course getting them into place in the first place is a nightmare. So that’s where I went to casting, first just doing it for the inner eyebars and then deciding to do it for all four. Now doing it for a second time, I really wanted to get the eyebars closer to prototype look. On the prototype, the inner eyebars are close together, the outer eyebars are further away from the inner. Last time I tried that I didn’t like the look of it. With n-scale we are dealing in dimensions so small that at times it’s hard to actually see what you’ve got when you’ve scaled it right. Anyway I ended up cutting down my original mold, the intent being to clue the eyebars in between box girders. However after doing two panels (the first panels on each side of the bridge have lace work rather than eyebars) I discovered the width of the panels was too narrow. The bridge is recorded as 174 feet long, including a short tail on the west end that rests on concrete footings. There are 9 panels after that. On site I figured out the tail was about 14 feet, so that gave me 160 feet divided by 9. I don’t know why but my math skills really hurt me here and I ended up with panels that were about 17’ wide and would have left me with the tail end being 25’. So I recalibrated and brought them closer to the 17.7775 feet each my calculator gave me. But that meant having to, for the third time, make a new eyebar mold. And since my first mold positive was now too short to fit between posts, I had to make an all new one, which is challenging. I kept thinking about how I wanted to try to get the eyebars to have a more eyebar shape, like this:
o——o instead of like how I had them in my model ———
The problem is, those round ends make the casting process difficult. I could cast the individual eyebars one at a time, but then I’m in for a world of pain with tiny, extremely fragile parts. The advantage of keeping things square is it means I can assemble a complete section of eyebars as one piece, and cast it as one piece without having to worry about having awkward spaces the alumilite casting mix won’t reach or release from properly. I did do a bit of reading on two piece molds but concluded it would be much too difficult for an amateur like me to master, if it could be done at all. And again, the beauty of n-scale is that everything is so small anyway that you can relieve yourself of having to get that nut and bolt crazy if you want to. Especially in black paint, nobody but the pickiest will notice. So I decided to leave them as rectangular on the ends. Each eyebar casting will be wide enough to be glued into the center lines of the posts at each end. I also made the inner two eyebars closer together to more closely fit the prototype. Now I just have to tear apart, again, the two panels I started on, respace them, and hopefully tomorrow my new eyebar mold will be ready and we can get down to business!