I’ll have 2% grades on my first layout ( L-girder construction). I’m currently cutting the subroadbed from 1/2" birch plywood. I assume I should start the incline at a joint–but if I splice the joint, am I not defeating my purpose? Perhaps it’s a non-issue at 2%–but I’d appreciate your advice before I’m committed. Thanks. Rick Krall
I personally would start the incline away from the joint so the transition from flat to slope is smoother. I also make sure the next joint on the incline is in the same plane of the slope. My opinion is if you start the incline at a joint, it will be very likely to a) not be a smooth transition and b) it will be very obvious where your incline starts and c) it will put extra stress on your plywood joint that may cause trouble for you.
Don Z.
I faced this question on my last layout- I hope you can learn from my mistake! I started the incline at the joint (I was using 3/8" AC sanded plywood for the subroadbed (N Scale Atlas code 80 track on cork) and this was nothing but trouble. When the plywood joint & the start of the incline were in the same place, the subroadbed would not make a gradual start to the incline- instead it was a sharp rise. This caused endless frustration with derailments on longer trails & long passenger cars I finally fixed the problems by making scab-splices in the plywood (with a nailer block below the seam) at least 1’ before the incline was to start. This allowed the plywood to “flex” into the start of the grade.
[2c]You might try an cookie cutter start on your grade. Cut into your plywood top at the start of the grade for about 6" to 8" in an u shape the longer the better and rase it up a little then start the grade,that makes for an nice smooth transition !!
JIM
Start a section of sub-roadbed a foot or so before the first part of the grade transition, and fasten down the first six to nine inches solidly. Screws and glue here, it’s going to get torqued otherwise. Then after it sets, drive precut door shims ($2 per bundle at any HI store) under the loose, uphill end. This will flex ther subroadbed into a gentle curve.
Now you have a foot of the lower end of the subroadbed fixed with screws and glue, and the rest of the section floating free, resting on the shims at the end. Place, but do not drive, closely spaced shims under the subroadbed along it’s entire length, and fasten it down. This will preserve the gentle curve you created when driving the first set of shims into place.
Make sure your track joints don’t fall anywhere within the vertically curved section, put them as far away, on both ends, as possible. Otherwise there will be a sharper kink at the joint, not the smooth curve you’re looking for.
I laid the entire grade of subroadbed, then dressed all the joints with a belt sander. If you skip this step, then any imperfections you have in the angle at the top of the risers which fall on splices in the subroadbed will put kinks, dips, or bumps in the vertical grade, which should be as linear as possible between the transitions. A torpedo level, two foot level, and another bundle of door shims will really help you get this nice and straight. A train will see any bump as being a steeper grade, even if it’s only for a very short distance. Then your grade effects, slowing down and speeding up, will be much more pronounced than they need to be, up to and including stopping the train, though probably not this extreme on a 2 percenter.
A smooth, skinny brad through each end of adjoining subroadbed sections into the appropriate riser, and a brad into any risers under “floating” sections of subroadbed, will still allow you to shim the joints to your straight-edge, and then