Model Railroading > No 6 Turnout radius

What radius is the section of track that curves away from the straight portion on an Atlas No. 6 Mark III Customline turnout? I inserted one coming off of a 30-inch radius curve (the points are in the opposite direct of traffic flow) and it appears to have a much wider ratio. Any suggestions?

The curve between point and frog is roughly a 48" radius. If you didn't modify the diverging tangent past the frog, the apparent radius will be even wider.

Unfortunately, the only switches with circular geometry are Walther's curved, and Atlas Snap switches. You're going to have to mess with the alignments to get it to fit.

VunderBob

ajcassatt wrote:
>
> What radius is the section of track that curves away from the
> straight portion on an Atlas No. 6 Mark III Customline turnout?
> I inserted one coming off of a 30-inch radius curve (the points
> are in the opposite direct of traffic flow) and it appears to
> have a much wider ratio. Any suggestions?

If you use a turnout that has a wider raduis than the curved track attached to it, in effect you have an easement. That's not bad if can manage it. But, it sounds like you have a space problem.

Also on some prefab turnouts, it's possible to curve the straight section on the outside of the branch, if you don't get carried away.

"Straight" legs of prefab switches can be curved by cutting thru the plastic strips under the rails & between the ties. Then gently bend, not force, them into position.

Only the straight legs can be curved, but can the entire turnout also be curved in the same manner to achieve a 30-inch radius on the "curved" portion? What about a different switch maybe a No. 5? it the radius of that switch closer to a 30-inch radius, or dare I say it, a No. 4?

Rob Gross

ajcassatt wrote:
>
> Only the straight legs can be curved, but can the entire
> turnout also be curved in the same manner to achieve a 30-inch
> radius on the "curved" portion? What about a different switch
> maybe a No. 5? it the radius of that switch closer to a 30-inch
> radius, or dare I say it, a No. 4?
>
> Rob Gross

There are too many pieces that can't move to flex a turnout into position. I suppose you could disassemble it, and use the points and frog to build a curved one in place, but if you go to that much trouble, you might as well build a custom one to begin with.

A #4 is about 16", a #4.5 is a hair over 18 (that's why Atlas #4s are really #4.5s). A #5 might do better, as you suggested, but I don't know if it maps out to 30". There is not a linear correlation between frog number and effective radius, IIRC.

VB

Aren't the Peco brand of switches curved throughout the diverging leg? The Small has a radius of 24", Medium turnout has a radius of 36", and the curved has an inside of 30" and an outside of 60". All this info from a walthers catalog.

bTW, according to Joh Armstrong in Track Planning for Realistic Operartion, a #4.5 (the Atlas "#4") has a closure radius of 22" and a substitution radius of 36". Which means in the area between the hinge of the points and the frog, the radius is 22", but the whole turnout will replace a 36" radius portion.

A #5 as a closure of 26" and a substituion of 44". A #6 has a closure of 43" and a substituion of 56". Perhaps a #5 will work a little better, though I believe a Peco Medium will be the best bet.

Hey,
In reality TURNOUTS don't have a radius on the diverging route. That is why they have a number, #4, #5, #6 etc. There is no "Radius" per-say. Sounds like you need a number #7 or #7.5 CURVED turnout. Shinohara makes them for Code 100 track and for Code 83 but the code 83 ones come in a Walthers package. There is not any radius track that will be the same as the diverging route of a straight turnout. You have to experiment with different ones to find the one that works the best. The diverging route of a TURNOUT only curves a little and comes off straight. No Radius!! Now an Atlas SNAP SWITCH is not a TURNOUT, and has an 18" Radius. It comes off curved.
If it has a number it has no radius!

Hope this helps everyone!

Rio Grande Fan

PECO do left and right hand curved tunouts in OO/HO. I don't know the radius of inner and outer curve, but I can post a fullsize scan if it will help.
Shortliner