Yesterday morning I worked on shimming and positioning the trestle, trying to find the sweet spot where most of the bents were centered on their piers, with the rails lining up. It’s as bad as I feared; but nothing a load of gravel can’t cover. 
There’s a 1/2" thick base block for each pier, and yesterday I thought I’d be diving into sanding them to deal with the vertical tolerances of the pier concrete. What I didn’t expect to see was that all the end piers were like 1/4" to 5/16" too high, making me think there were flaws in the plywood spine used to set the heights for those.
Regardless of the cause, and long story short, I didn’t want to have 3/16" cedar as the base for bents, so I lasered a bunch of little boxes out of acrylic, and cut a bunch of varying-thickness styrene sheet for shims to be placed in them.
These boxes took the place of the intended 1/2" thick base blocks for 4 end bents where the piers were too high.
For both ends of the bottom sill if these bents I fiddled with the shims until the bent was solidly rested. Then I took the boxes loose shims out, glued the shims into the box, applied cement to the bottom of the box, and slid the box under the bent’s lower sill. Here’s two of the nicer outcomes.
All the in-between bents were within range for Plan A. For each of these, I sanded the base block if needed, sometimes several times, until all of the bents were seated firmly on their piers.
I removed those base blocks and stained them. They (and eventually the bottom sills of the other bents) will get a coat of marine epoxy. They’ll be locked laterally onto their piers with little plex L pieces.
I’m waiting on marine epoxy and more acrylic cement. And there’s rain tomorrow, so I’ll pick up during the week or next weekend.
After all this is done, it’s a (hopefully!) only matter of tying in of the rails, and placing a couple anchors. But it’s been cold out (just above freezing this morning). So I’ve decided to push certain related cosmetic issues until the spring or later, and call this project done once I get the rails connected and make a video of a loco running across the thang.
Cheers,
Cliff





















