Track Radius

[Howardr]

Thanks all,

Now it's coming back to me...about from 50 years ago in my geometry class. I got a lousy grade in that class.

[cwclark]

what you are doing is not how to measure radius....radius is measured from a central point to the outwards circumference....here's an easy way to do it....take a sheet of plywood and lay it down flat....find a small board preferably a 1/2" x 3/4" and drill a hole about 1 inch from the end...now take a measuring tape and measure from the hole you just created and make a mark at the other end of the board at 18" and 22" ..now drill a hole in both places that a pencil can fit into...now..nail the board down onto the plywood in the first hole you've drilled, and put the pencil in either one of the 2 holes at the other end of the board...make a sweeping motion with the board and mark the plywood with the pencil...this is the centerline of the track and i'll bet you that it will be 18" or 22" from the end of the board that is nailed to the plywood....in other words...it is from a center point outward to the center of the track...so if you are putting down a 22" radius track chances are you are going to use about 4' to 41/2' feet of plywood to create the radius...Chuck[:D]

[Anonymous]

22" refers to the radius (as opposed to the diameter) of the circle, and is measured from the center of the track (midpoint between the rails).

---jps

[Howardr]

I know I should know this but....

I'm getting started with a layout and I'm going to use 22" radius track. However when I put an almost complete circle of 22" Atlas snap track together it sure looked and was more then a 22" circle and measured more then 22" across.

Can anyone of you folks set me straight on how either 18" or 22" track is measured. Thanks.