Suggestions on cutting out track bed from plywood?

Radius's for my raised track were marked using a 1/4" x 4" x 6' long strip of plywood to make your own version of a yardstick compass.  Drill proper size holes down the center of the 4" wide strip and lay flat on on the material to be cut with a sabre saw.  (one hole for circle center and other holes for outside radius marker)

Yard Stick Compass

The helix base structure is 1" thick GatorFoam (light weight).

The rising track at edge of table to the helix has a 1/4" plywood track base with custom supports.

What are the scribes you show in the picture? One with a point the other with a marker?  Do the slide over the yard stick?

Get these https://www.amazon.com/Taytool...x=tramel+&sr=8-2

, a straight 1x2, and a jigsaw.

Someone makes a circle guide for a router but it’s hundreds of dollars. I’ve used the above setup with good success. Just mark the curve radius on the stick and measure on both sides of that radius mark however much you want I overhang beside the track.  Cut it out and there you go. Plywood is a good medium to use, I’m sure there are other choices too.

I used an old freight truck with a 3" piece of flat aluminum bolted to the hole, where it would have mounted  to the boxcar, gondola etc...and coming out at a 90 degree angle to the truck.   Drilled a hole in the aluminum piece to fit a pencil, placed the track down on the sheet of plywood, and "drove" it around.  Set it to the width of elevated roadbed I wanted, worked great.  No further measuring, no variation,  no math.  

Tom

Great suggestions

@Windy City posted:

I want to support my elevated layout with a plywood (or other support) base to minimize the need for trestles in some areas. Is plywood the best substrate?

Plywood is OK, but you may want to get a better grade with more plys and less voids than run of the mill construction grade.

@FlyPlanes-PlayTrains posted:

I used an old freight truck with a 3" piece of flat aluminum bolted to the hole, where it would have mounted  to the boxcar, gondola etc...and coming out at a 90 degree angle to the truck.   Drilled a hole in the aluminum piece to fit a pencil, placed the track down on the sheet of plywood, and "drove" it around.  Set it to the width of elevated roadbed I wanted, worked great.  No further measuring, no variation,  no math.  

Tom

I like it! Great practical solution!

Went back to my elementary school days and dug up my old compass. Stuck one leg in a surplus freight car truck and a pencil in the other. Place your track down and spread the compass out  to the width on either side of the outer rail you want. Push the truck so the pencil registers on the surface below. Flip the truck around to scribe the other side. Can use to mark path of roadbed also.

@Cape Cod Northern posted:

Went back to my elementary school days and dug up my old compass. Stuck one leg in a surplus freight car truck and a pencil in the other. Place your track down and spread the compass out  to the width on either side of the outer rail you want. Push the truck so the pencil registers on the surface below. Flip the truck around to scribe the other side. Can use to mark path of roadbed also.

Simple but fantastic idea!

I second the use of higher grade plywood than the normal construction. I use baltic birch 9-13 ply. It won't warp or give. Stronger and straighter than normal plywood and no voids and sands to a nice finish.

     https://kingsfinewoodworking.c...-it-why-is-it-better

Windy City asked, "What are the scribes you show in the picture?"

They are trammel points on Micromark's site for $14.95.  Yes, they slide up and down your yard stick and the knobs on top snug them in place.

I built my whole layout with eleven ply 1/2" Baltic Birch, it was great to work with and gave great results.  Forget about the home supply store cheap plywood, it's truly not that much more expensive to use quality wood.

@Cape Cod Northern posted:

Went back to my elementary school days and dug up my old compass. Stuck one leg in a surplus freight car truck and a pencil in the other. Place your track down and spread the compass out  to the width on either side of the outer rail you want. Push the truck so the pencil registers on the surface below. Flip the truck around to scribe the other side. Can use to mark path of roadbed also.

Too clever Al!  

Great time saver for drawing  guide lines for parallel tracks too. 

The problem here is finding someone who stocks sheets of quality plywood. So far all I’ve been able to find are 24x30” panels of Baltic Birch from Rockler for $13 each and I’d need 13 panels vs 3 sheets of 4x8 Birch at Home Depot for $46 each. It’s not the dollar difference, it’s having to basically piecemeal the decking. Maybe I’ll email 84Lumber and see if they can special order it. They said they could order Advantech, but that’s heavy stuff.