Anthony -- See embedded comments below.
Dick Karnes ============= Anthony Isaacs wrote: >Question: When making up trackwork does one bend the >rails first? > Depends on the tightness of the radius. I handlay my track (all of it!), and I almost never pre-bend my rail. >How do you get smooth bends, for a constant radius? > Ed Loizeaux's recommendation for soldering straight rails together works well. (Use a rail joiner!) This avoids kinks at joints once the rails are curved. But don't overdo! You need expansion joints, so don't solder more than two meter-length rails together. There is a company that makes "sweeps" for S scale in various radii. I forget who, but someone else on this e-list can tell you. These fit between the rails and let you gradually spike your rails in gauge and to a fixed radius as you progress around a curve. For myself, I lay out my track centerlines, then lay my Homabed roadbed, which comes in split halves. I glue it down such that the center edge is against the centerline, then tack it in place with brads, then pull the brads when the glue is set. Then I do the same with the mating split half. The roadbed thus still contains the track centerline. Whether or not I have used roadbed everywhere, I next lay my ties on the centerline. I do this by placing loose ties in a piano-key tie jig that has the centerline drawn on it. I use 1/2" masking tape to tape the ties together, lining up one edge of the tape with the jig's centerline. When I glue the ties to the track bed, I align the tape edge with the centerline. For laying the rails on the ties, I use a combination of "eyeballing" and the natural ability of a straight uniform-cross-section rail to assume a perfect circle or a spiral easement, depending on how its ends are constrained. More on this below. >And for easements? > I lay out easements when I draw my centerlines. For constant-curves, I use a trammel bar (large homemade compass). But I lay out my curves such that they miss the straight tangents by about a quarter to a half inch; i.e., the straight lines are outside the circular arc by that much. A quarter inch is enough for large radii (over 48"). I'd use 1/2" for curves less that 30". My own minumum is 36", for which I use a 3/8" (1 cm) offset. Now place a three-foot or meter length of rail (straight and rather stiff, such as a code 125 or code 148) such that the approximate meeting of the curve with the straight is at about the midpoint of the rail. Now spike each end of the rail to the track bed such that one edge of the rail base is against the drawn centerline. Three spike locations (spike both sides of the rail) about 1-1/2" or 40 mm apart are enough. The end of the rail on the curve is of course spiked to the curve alignment. The unspiked portion of the rail will have assumed a smooth spiral easement between the spiked ends. Draw the easement centerline by holding a pencil against the rail base, being careful not to move the rail as you draw. Extra spikes can be useful here, as can plain old fingers. The same technique works for laying out transitions between curves of different radii. If, despite the care you will have taken, your curves have kinks, remove the spikes about 6" or so in the vicinity of the kink. The rail will instantly assume a "least-energy" smooth curve in the unspiked area. Re-spike one of the two rails here, then re-spike the opposite rail using your track gauge against the first rail. Best way to detect curve kinks is not the naked eye. Instead, couple two 80' passenger cars, push them around your curve, and watch the adjacent car ends. If one car end shifts laterally with respect to the other, that demonstrates a kink, which is really just a locally non-constant radius. >For closure rails and then a Straight frog? > I don't use/build turnouts smaller than #6. As Michael Eldridge says, an approximate bend is sufficient. Then use offsets from turnout tables to spike the closure rail in its proper place. Or eyeball it. For turnouts #8 or larger, pre-curving the closure rail is not necessary -- The spikes are more than sufficient to hold the rail alignment. For details on how I build my turnouts, see my article in "1:64 Modeling Guide," Vol. 8 Issues #5 and #6. >I love the >look of British trackwork, are curved frogs US prototypical? > > No, except in special cases. The poll results are in....... To REPLY to the list, use REPLY ALL, to reply to the sender, use REPLY. I do NOT know if this works on all e-mail software, but it works on some of the most common ones. For those of you on DIGEST mode, all REPLY messages go to the list. Change your membership, change your message settings, use our CALENDAR, view shared files or photos, view the list archives, GO TO http://groups.yahoo.com/group/S-Scale/ Yahoo! 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