Well, I must have missed your earlier post, 'cause I don't remember seeing any of this before. But I'm not sure I completely understand it all, anyway (I didn't pay much attention in math class). So maybe I'll just try to build myself a large version of an old drafter's tool called a "French Curve" (http://mathworld.wolfram.com/FrenchCurve.html) out of a thin sheet of plywood or a thick sheet of styrene, and cut out the curve starting with a wider radius and gradually tighten it to the desired 40" (or smaller) radius... then just lay it where I want it on the layout and trace around it for placing the center-line for the track/roadbed.
HECK with all the math...how's that for simple!? John Degnan ----- Original Message ----- From: Richard Karnes To: [email protected] Sent: Saturday, December 09, 2006 1:02 PM Subject: {S-Scale List} Re: NASG/AM Heavyweight Operation John -- I have already posted how to create spiral easements without math. Here's a repeat of that message: The key to good performance with any body-mounted coupler is your trackage alignment. There is no real minimum radius for body-mounted couplers IF you design curve transitions (spiral easements) into your alignment. You can do this without math simply by using a length of rail as a spline to plot your track centerline. First draw your circular arc offset by about a half inch from your straight track centerline. (Use a larger offset for very small radii, a smaller one for very large radii.) Then place your rail spline so that its center is approximately where the straight track should join the curve. Then spike one end of the spline aling the straight-track line and the other end along the circular arc. Spike each end in three places to ensure conformance to both the straight line and the circular arc. Then use the location of the spline as a template to draw your transition centerline. If you wish to have gently undulating alignment instead of perfectly straight track, connect three lengths of rail (code 125 or heavier) with rail joiners and solder them together so you have a perfectly straight 9-foot length. Spike this down in just four or five places and let the rail take its natural shape between the spiked locations, then draw your line along the edge of the rail. There is a scientific/mathematical foundation for this based on minimum-energy configurations of splines. Four our purposes, it's enough to know that such an alignment for trackage minimized lateral offset between the ends of railroad cars. Dick Karnes Yahoo! Groups Links [Non-text portions of this message have been removed] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/S-Scale/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/S-Scale/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
