Is the frog number or angle of a frog in a curved turnout even relevant? I figured the minimum implied radius is the constraint. Implied radius of the diverging route is sort of the same issue with straight turnout but that's traditionally explained by the frog # when talking about straight turnouts.
- Douglas
It is directly related.
But it's more correctly (I think) the cotangent of the angle.
Ed
rrinkeryou need to draw straight lines from the frog to determine the frog number.
do you? Isn't the frog number ultimately the angle that the rails intersect at?
greg - Philadelphia & Reading / Reading
Likely true, remember the number for the frog is derived from the separation per unit distance for the FROG, not the whole turnout. Curve the rails past the frog to some radius and you may get a number completely different from the frog - you need to draw straight lines from the frog to determine the frog number.
--Randy
Modeling the Reading Railroad in the 1950's
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gregc i see no need to "straighten" the rails around the frog (which I did with other turnouts i laid). I believe the guard rail should guide the truck, maybe widen the gauge a little.
i see no need to "straighten" the rails around the frog (which I did with other turnouts i laid). I believe the guard rail should guide the truck, maybe widen the gauge a little.
Re: the prototype
I suspect the reason the rails are straight while running through the frog is that the designer/builder of that switch was using an off-the-shelf frog. Which is based on two intersecting straight lines.
A custom curved frog would likely cost much more than a standard one.
So, ya pays yer money and takes yer choice.
selectorA curved turnout will be a much better fit into a curve than a standard NMRA type
That's exactly what I said -- or meant to say.
A curved turnout will fit better, but not perfectly, into a circular curve. I see that I accidentally typed "that" instead of "than", which may have created confusion.
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cuyama selector You can't practically insert a true NMRA-compliant #6 turnout into a 44" radius curve without a compromise at the turnout, a kink if you will, but that's not true for a curved turnout with the same frog number. I don't think that is correct for most (if not all) commercial curved turnouts. There is still a small amount of difference from a true curve radius owing to the points and frog. Much closer that a straight turnout -- but not exactly a circular curve.
selector You can't practically insert a true NMRA-compliant #6 turnout into a 44" radius curve without a compromise at the turnout, a kink if you will, but that's not true for a curved turnout with the same frog number.
I don't think that is correct for most (if not all) commercial curved turnouts. There is still a small amount of difference from a true curve radius owing to the points and frog. Much closer that a straight turnout -- but not exactly a circular curve.
i think selector referring to closure radius
i don't believe this is suggesting that such a turnout can fit cleaning into a curve of the same radius
i do believe it is indicating what the tightest radius is for purpose of determining if a locomotive can handle the turnout. Locomotives have maximum track curvature limits
i'm planning on laying a curved turnout. I plan on making the frog match the inner/outer curve radii, which will be tight (hence the ? about frog #).
Byron, don't you have that ackwards? A curved turnout will be a much better fit into a curve than a standard NMRA type. The diverging route past the frog is straight for an inch or more. If one chooses to mangle the turnout and clip the rails almost immediately after the frog, then you could add curved rails from that point on. Personally, I'd just use a curved turnout.
selectorYou can't practically insert a true NMRA-compliant #6 turnout into a 44" radius curve without a compromise at the turnout, a kink if you will, but that's not true for a curved turnout with the same frog number.
I don't think that is correct for most (if not all) commercial curved turnouts. There is still a small amount of difference from a true curve radius owing to the points and frog. Much closer ̶t̶h̶a̶t̶ than a straight turnout -- but not exactly a circular curve.
carl425If you get your hands on the turnout, which I highly recommend, you'll find that it's the radius they lie about rather than the frog.
if the commercial 20"/24" curved turnout is not really 20"/24" then any comparison is invalid.
My guess is that in the case of curved turnouts, the term 'substitution radius' has more application and meaning because of the twin curved routes, something a conventional turnout won't offer the user. You can't practically insert a true NMRA-compliant #6 turnout into a 44" radius curve without a compromise at the turnout, a kink if you will, but that's not true for a curved turnout with the same frog number. At least, it 'should be' true for a curved turnout with the appropriate twin curved paths.
Look at your drawing. You show the whole turnout being more than 15 inches long. It is not. If you get your hands on the turnout, which I highly recommend, you'll find that it's the radius they lie about rather than the frog.
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Model track manufacturers seem to use their own terminology when labeling curved turnouts. If you are measuring the ratio of the distance to width, is that how you came up with 10.5 for your Walthers #6.5?
Using commercial turnouts, we pretty much have to make a "best-fit" for whatever are available on the market; either that or custom build your own using FastTracks.
Rio Grande. The Action Road - Focus 1977-1983
Walthers states that their 20"/24" curved turnout has a #6.5 frog. I figure it to be a #10.5.
i'm working on laying out a curved turnout and I come up with larger frog numbers than the commercial turnouts of the same sizes. Do commercial turnouts use stock frogs?
Knowing the intercept of where the frog is located and the centers of the curves, I calculate the angle of the line between the curve center and intercept. The lines tangents to these are parallel to the corresponding frog rails. The difference between the angles is the frog angle from which the frog number can be calculated.
why are the frog numbers different?