I know I’ve seen some pictures of how to convert turnouts to spring switches using some piano wire. I’ve been searching to find these pictures, but I’m not having any luck.
Can anyone give me some info ?
I don’t have a ready pictorial or website link handy, but essentially you want a non-overcenter spring turnout like Atlas or Walthers/Shinohara (and unlike the Peco unless you remove the spring in one). IOW, the points must slide easily with finger-tip pressure.
Then, you fashion an L-shaped piano wire where the small length fits up into the hole in the throwbar, or you could just have a pivoting bellcrank-type mechanism with a short length of wire sticking up through a hole under the throwbar and into the hole in it. Either way, think it through, and the idea is to have the pivoting mechanism connected to a weak spring that works to keep the points to the one side. This has to be clean and reliable so that the points really do come back to the closed side desired, but also so that the wheel flanges can relatively easily force the points open.
Bottom line, you want a pivoting arm or a sliding block held inside a tube or horizontal shaft of a sort, clean lubed, easily moved, and the spring action must be only sufficiently strong to force the points over to the side where you want them as a default.
I hope our hosts will excuse this link to a discussion on another forum, but it will be helfpul in some small way to you:
http://www.trainboard.com/grapevine/showthread.php?79722-How-can-I-Model-a-Spring-Switch
Crandell
Ach… Glue a thin nail in the throw-bar hole, and then connect it to a rubber band under the table.
LIONS like things simple.
I discovered that my most recently installed turnouts are unintentional spring switches. They are connected to the under-table throwing linkage by an Anderson link, a Z-shaped vertical wire in a tube. The top of the Z drives the throwbar, bottom is powered by the throw mechanism. Points are held in normal position by a light weight hanging from a cable (fishing line) connected to that lower arm, with the cable to the point throwing device* slack. In that configuration, the points are held against the stock rail but can easily be pushed aside by the flange of a wheel moving trailing point through the turnout.
Like most prototype spring switches,throwing the points to the reverse position locks them firmly against the stock rail. Attempting a trailing point move from the (usually) favored track will absolutely, positively put something on the ties rather than the rails. That’s because the cable connecting the switch machine (or manual electrical switch) to the Anderson link is under tension - a lot more tension than that of a light (fraction of an ounce) weight.
Chuck (Modeling Central Japan in September, 1964 - with spring switches, intentional and unintentional)