So I want to draw a perfect curve on some Homasote to cut it, and to mark the track center. How should I go about doing this? I was thinking about using a compass, but 13" might be too big for that. I was also thinking about string around a nail method, but I don’t know how accurate that will be.
I use a piece of plexiglass that I cut 36" x 2" and marked and drilled a hole every 1" (1 hole and then start your 1" holes, hole-1"-2"etc). Slip one end over a finish nail and your pencil in the hole the is the radius of your curve. Make your mark and you should have it.
A similair method to Bob’s would be to use a wood yard stick. Your “zero” or pivot point would start at the 1" mark then drill a 1/4" hole at each inch mark.
I use a set of curved templates that I made years ago from plywood. First I drew the arcs, using a compass made from a yard stick. Then I cut them out, using my jig saw. Being an inch wide, I get two radii from one template. Don’t forget to label the radius.
Nick
A “perfect” curve in model railroading would include an easement, to many members here. In that sense, use a thin lath or strip of flexible material that will deflect tangentially to get an easement (called a tramel). Then, finish your curve as instructed above. You can use string and a nail, cut-out curve templates made beforehand, a compass, or just add a piece of flextrack to the previously fixed end and bend it around to the direction you want. That curve should be as good as any you’ll need.
If you can find a 40" long piece of 1/4" X 3/4" cedar or stripwood of some kind, you can drill a hole very close to one end and place a short screw or nail there so that the tip projects about 3/8" past the other side of the tramel. Then, drill holes starting at 18" from that nail hole, and drill one every inch, or two, until you reach the last possible hole. Countersink each hole surface so that you can put a pen into it and just let the tip come out the other end of the hole. Label each hole for its associated radius.
Now, when you want to draw a circle or curve, you place the nail at its centre, and use a pen in the appropriate hole further out to draw your curve. If you want to ease the curve (preferrably on both ends of it), turn the thin tramel on its side, fix it with several nails or screws for about 8" from the nail end down toward the start of the curve, and then deflect the tramel toward the direction that the track will curve. That resultant curve is eased…essentially. Draw a line along one side of the tramel, and you have a reference for your centre line until you feel you need to tighten the curve to get it around to the end of it and the next tangent (straight). So, you should only extend the easement centre line for about 6", at most, and then get down to your desired radius or you will not meet the rest of your track on the other side. This will take some practise…so d
Thanks for the responses guys, hopefully this weekend I can get some time to make my templates.
Cheers…