to find out my turn radius do i just measure the oval in width in inches and thats my turn ratio. i used tubular track that the hobby shop guy sold me but i had no idea what a turn ratio was till i got here. thanks
Good to see that you are trying to hone your skills. In order to determine the ratio or “radius” of your track simply use the formula r = d/2 .
Tex
Tubular track is customarily identified by the diameter (twice the radius) of a circle of track, measured to the outside ends of the ties. If you have a complete circle of track, you can put it together and measure this directly. However, tubular track is flexible enough that you can get quite a range of numbers this way. A good way to avoid this problem is to measure your circle twice, once in the north-south direction and once in the east-west direction, so to speak, and average the numbers. Be sure that the circle doesn’t move between measurements.
The radius that is useful for layout-planning purposes is not half this diameter, but half the diameter measured between the center rails. That diameter is shorter by exactly the length of one tie. Ties are normally 2 inches or 2 1/4 inches long, depending on which of the two common styles of tubular track you’re using. Of course, you can measure this smaller center-rail diameter on your track circle too, then just divide it by 2 to get the radius.
The commonest diameters are those that the two styles of track are named for, O27 and (nowadays) O31. O27 track is 27 inches in diameter measured to the ends of the ties and 25 inches measured to the center rails. This makes its radius 12 1/2 inches. O31 is about 30 1/2 inches measured to the ends of the ties, 28 1/4 measured between the center rails, and about 14 1/8 inches radius (14.142 inches exactly). It is sometimes called O30 instead of O31. Originally Lionel called it just “O”.
If you don’t have a circle of track but can figure out how many of the curved sections would make up a complete circle, you can in fact calculate the radius from a measurement of just one of them. Measure the chord length (the straight-line distance) between the ends of the center rail, excluding any track pins. Then multiply it by 1.307 for 8
Bob: Thanks for another lesson. (Luv this hobby [:)])
thanks for the explanation, the other one that was left did me no good and was useless… i did that and i got 54 inches. i hope there is a 54 track or i am doing something wrong. i heard of 72 but never a 54. is there one??
In tubular track, 027, 031, 042, 054 and 072 are common sizes, marx also made 034 diameter track.
Atlas O also offers in their solid rail line, 027, 036, 045, 063, 072, 081, 090, 099 and I forget how many larger diameters, but as I recall they use a consistant 9 inch diameter difference throughout the line.
MTH RealTrax offers 031, 042, 054, 072 and probably others I don’t remeber off the top of my head.
Lionel Fastrack offers 036, 048, 060(I think) 072 and again probably more that I didn’t list/remember.
Doug
Yes, there are 27, 31, 34, 42, 54, and 72. If you can tell me the style and brand, I may be able to give you fairly precise measurements. O27-stiyle track is 7/16-inch high and has 2-inch ties. O31-style track is 9/16-inch high and has 2 1/4-inch ties. The brand may be stamped into the ties.
hi, i already have the track down and ballasted. it is a lionel track. made in china. unreal. but yea its 54. thanks for the help.
What kind of ballast did you use? Would love to see some pictures.