the values of "X" and "L" for easements leading onto a 36"radius curve?
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RayG8 the values of "X" and "L" for easements leading onto a 36"radius curve?
If do these - IIRC, L is the length of easement so L/2 = around 10 or 11 inches roughly for 36 inch curves. My L/2 is about 9 inches (distance to the mid-point where the offset is) for my 32 inch curves.
My copy of John Armstrong book is at home so thats from memory. I use L/2=9 inches for around 30 or 32 inch curves. X is the offset, it should be approximately a half inch or a bit more, again per JA's table. If someone has the book handy maybe they can offer the values.
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riogrande5761 If someone has the book handy maybe they can offer the values.
Armstrong's table doesn't list 36" radius, but it's an easy extrapolation.
For 30" curves, X=1/2 and L=18
For 42" curves, X=5/8 and L=25
So for 36" curves, X=9/16 and L=21.5
Note that scale is not relevant in the table.
edit: Bear caught my mistake. 9/16"
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My copy of Track Planning is somewhere in the basement and haven't looked at it since I finished laying out my curves. (fixed the formula mistakes in my earlier post - memory is the first thing to go!) JA's book was written back when 30-inch curves were considered broad, and 24-inch as conventional so the table doesn't really go higher - extrapolation is necessary but you can estimate it like Carl did.
I am using 32-inch minimum curves and just tweaking the 9 inches to the center of the easement and 9 more to the end of the other side so if L is the total length, 18 inches is about right and a half inch for the offset. As my wife would say, Geordie style.
Since I use springy Atlas code 83, it naturally springs into the easement like the "bent stick" method so I don't need a bent stick. Corks springs too for mainline. All of my curves have easements including staging:
I use the low-tech approach. I run the (straight) tangent track to be 1/4" to 1/2" outside of the radius curve, then bend the cork to find its path between the two. Bingo... instant easement!
Jim
Jim, thats pretty much what I do, although I still approximate the distance of the easement using John Armstrongs measurements for length of easement based on the radius. So low tech but based on the numbers still.
Years ago there were some templates. I don't recall where, but I printed them off and use those. But really, if you use about 1/2" and 12 to 18" you shouldn't have any trouble unless closed coupled full length passenger cars with diaphragms are your thing.
I have found that when I set up HO sectional track with 15" radius, that 4-4-0 locomotives and 40 ft cars go aound it just fine. For 24" in S scale 2-8-0's and 50 ft cars do just fine. I'm not really interested in getting a Big Boy around 18" curves in HO, so I do easements more for the appearance than operational necessity and shorten them up if necessary to get the curve in.
What's really important is doing a good job laying the track so there are no kinks, bumps, etc.
Paul
riogrande5761 RayG8 the values of "X" and "L" for easements leading onto a 36"radius curve? If do these - IIRC, L is the length of easement so L/2 = around 10 or 11 inches roughly for 36 inch curves. My L/2 is about 9 inches (distance to the mid-point where the offset is) for my 32 inch curves. My copy of John Armstrong book is at home so thats from memory. I use L/2=9 inches for around 30 or 32 inch curves. X is the offset, it should be approximately a half inch or a bit more, again per JA's table. If someone has the book handy maybe they can offer the values.
What page is that chart on? I looked at my 3rd edition and could only find X offset, no reference to L.