Can you believe it!....just started laying track,(temporarily) and an immediate problem. What's the radius of this bend?? Is it too small? what the heck size is this? Well, I had some Hobby Lobby foam/plastic/kinda like real good cardboard stuff in the leftover pile. Got out the beam compass and made some curve templates. 10' 11" 12"etc. to about 15" when finished. Pretty easy to do, even if you have no beam compass. A beam compass can be made from......well heck even a tomato stake, two sharp pencils and some tape or those paper clamps that take a superman to squeeze open. Use that Hobby Lobby material or really good cardboard. They ain't that pretty, but they do work Al
Remember that track radius is measured from the CENTER of the track. To many people scribe a radius and put either the outer or inner edge of the track/trackbed to that line....
If the templates are narrow enough to slip-fit in between the rails, they can be used to form flex track to the right radius. Assuming their material is still strong enough, when cut that narrow, to control the desired radius. Radii in 1" increments would lay out curves too closely spaced to be adjacent, unless maybe you're in Z scale. For example, N scale Unitrack double track spacing (c-c) is 33mm, so their curves' radii are also in increments of 33mm.
Why make a template? Just use a beam compass to lay out the centerline and use that as the center of the cork roadbed. Then use the center dividing line of the cork and use that to lay the track. I always use a curve radius 1 inch smaller than what I want. That allows me to use a section of cork to lay out a gradual easement between the straight track and the center of the curve.
Sometimes the center of curvature for a curve is a point in space (or even behind a wall,) not on a surface the same level as the track that can serve as the pivot point for a compass. Also, the templates themselves can be laid in place temporarily, just to see how they look and connect at scale. Of course, a good track layout app (I use XTrackCAD, which is free) can make experimentation with a layout much easier. And such apps can print the track plan 1:1 on multiple sheets of paper that can be used to place and form your flex track. The one thing templates cannot do is create a true easement (of continuously varying radius to tangent), unless you created such templates for every radius transitioning to tangent track. For sectional track, I just use longer radius curve section(s) at the ends of the curve, to eliminate the worst-case curve transition to/from tangent track. You could do the same with your templates. You can compensate for the extra space with a shorter radius section (template) at the apex of the curve. Ever notice how race car drivers do that on the race track?
I use the templates all the time laying out the centerline for the track or experimenting. Use the compass that can be 3D printed and the beam with holes spaced 1/4" apart when I can but often you can't. A number of times I find that I can't swing the compass as it would be off the layout (have done that by attaching a temporary board out there). Also the back end of the beam can run into things making it hard to swing. Works great at times but often not as more and more things get in the way as the layout progresses. Since the inside of one template is the same radius as the next one I can put them against each other and slide them to extend the curve. Often like with the compass an inside curve might be easier to use than the radius on the outside or the other way around. The templates were easy to make. A huge benefit of the compass when laying track is ....... ... click ( HERE )... .. how easy it is to bend flex track (especially ME track) into shape. Also one can use a tool that is similar to the end of the compass to bend track to other shapes that aren't a simple radius. ... click ( HERE )... You can find more info and links to the print files on my site here..... https://1fatgmc.com/RailRoad/Trackwork/Trackwork-Index.htmlhttps://1fatgmc.com/RailRoad/Trackwork/Trackwork-Index.html Sumner
No problem, use a temporary filler section clamped to the inside of the curve to anchor the compass then draw the curve. If the pivot point would be behind a wall then do that section before installing it against the wall. Of course, if using sectional track or Kato Unitrack, your radii are predetermined. You can then just lay the track or with sectional track and using a marker, mark the center lines with a dot and connect the dots.
