Fast Tracks

Hi all, I'm looking for a little info/advice to decide whether to buy completed turnouts, Fast Tracks products, or a combination:

I'm working on a trackplan for the East Broad Top in HOn3. I don't want to run my Mikados on a turn much tighter than 18" radius, but space is limited. If I'm reading the HOn3 NMRA standards right, is the radius at which the turnout curves away 16" for a #5 and 27" for a #6? Might I squeeze out the #5?

As for the main, I have 2 turnouts on curves, so the "siding" is coming off as the tangent of the curve and the main is departing it. Would placing a #6 turnout (made from one of the assembly fixtures) work ok, or should I make a custom turnout from TwistTies? It looks like the assembly fixtures straighten the turnout, making a "kink" if I want a constant-radius turn.

Or does anyone know if MicroEngineering's turnouts are constant-radius?

Thanks!
Ray

For HOn3 Mikados - I' d strongly suggest working your space for number 6 minimums. While you might 'squeeze' a number 5, that would depend on absolute perfect curvature though the closure and that's not really practical. Even then the Mikados would not likely negotiate 16" reliably - especially older brass versions.

Your chosen 18" minimum radius is acceptable - but may require some slow speed operations for the larger equipment, note that some older equipment may not work well even at 18" minimums. With the larger equipment - make sure your side clearances are generous.

The Micro engineering turnouts do not use a constant curved frog radius. I'm unaware of any commercial HOn3 turnouts that do. Building a curved turnout with the Flexties would maximize your space compression, but I'd shoot for something close to minimum 20" or 22" radius even then at the turnout point to allow for points and frog transitions and inevitable irregularities (though irregularities will be very minor). Using transitions either side of the turnout location will not take a lot of offset to incorporate a slightly larger radius through the turnout, and having reliability is and will be far more important as time goes by - especially with the use of larger equipment.

_________________
-ed mccamey-
COSLAR RR - http://www.coslar.us/
NMRA Standards and Conformance Department
PROTO & FINE Scale Coordinator
I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.

Thanks for the suggestions. And it is an old brass model (Hallmark's import of #15). The 4 middle drivers are "blind" like the prototype, but I can imagine they still wouldn't have great contact when sliding off the top of the rail in a turn. I do intend to keep the speed down, hopefully 15-30 scale mph, since the prototype rarely went much faster than that.

I also found the printable layouts of the various turnouts earlier today. Since I already have the benchwork, I may print several copies and use them with HOn3 flex track I already purchased to make a sort of mockup of the trackplan. I'm basically reusing the benchwork from a standard gauge layout I had when I was a kid...a 4'x4' circle that grew into a 4'x8' oval, then narrow perpendicular extensions for a roundhouse and industry.