ATLANTIC CENTRAL Rich, are you asking why an Atlas #4 is really a #4-1/2?
Rich, are you asking why an Atlas #4 is really a #4-1/2?
For example, using the chart provided by greg, if the frog angle on an Atlas #4 is actually 12.40 degrees, then it is a #4.5, not a #4.
Further, if Peco advertises a turnout as a #5, is the frog angle 11.26 degrees or something more or less than 11.26 degrees?
Rich
Alton Junction
If you don't have a chart handy you can use these formulas:
Frog-1 by Edmund, on Flickr
Frog_0001 by Edmund, on Flickr
Frog_fig9 by Edmund, on Flickr
More fun than a Sudoku.
Regards, Ed
richhotrain ATLANTIC CENTRAL Rich, are you asking why an Atlas #4 is really a #4-1/2? No, I understand the difference, but when I asked earlier if someone could post a list of frog angles on Atlas Code 83 Custom Line turnouts and Peco Code 83 turnouts, I am interested in such a list to determine if the various turnout manufacturers are not accurately stating the number of frog units on their packaging. For example, using the chart provided by greg, if the frog angle on an Atlas #4 is actually 12.40 degrees, then it is a #4.5, not a #4. Further, if Peco advertises a turnout as a #5, is the frog angle 11.26 degrees or something more or less than 11.26 degrees? Rich
No, I understand the difference, but when I asked earlier if someone could post a list of frog angles on Atlas Code 83 Custom Line turnouts and Peco Code 83 turnouts, I am interested in such a list to determine if the various turnout manufacturers are not accurately stating the number of frog units on their packaging.
What you're asking is, do the manufacturers deviate from Greg's chart when they design and build their turnouts?
Would an Atlas #6, Peco #6, and Walthers (shinohara) #6 each have the exact same angle as what is listed in Greg's chart? If not, what is the exact angle of each?
We know that the Atlas #4 is off by enough that it would be better to call it a 4.5.
- Douglas
Yes, Douglas. Unfortunately, I don't have a Peco #5 turnout to measure the frog angle, so I am asking if anyone knows the frog angle on a Peco #5 turnout.
Rich, Atlas rounded off their "#4-1/2" to 12.5 degrees.
They also rounded off the #6 to 9.5 degrees, but that is almost not measureable compared to 9 degrees, 32 min.
I can't speak for PECO, I don't own any and have never worked with them.
But I did print out their full sized diagram of the #5 and layed an Atlas #4-1/2 on top, the PECO is clearly a lessor angle asa #5 would be.
I suspect no other manufacturer has taken as big a liberity as Atlas did with their #4
Sheldon
DoughlessWhat you're asking is, do the manufacturers deviate from Greg's chart when they design and build their turnouts?
they may have the correct frog angle, but they may deviate from the "lead length" or "frog distance" from the chart. the curved rail is in blue and straight in red. the curved rail radius is on the left (e.g. 47.9") the and lead-lenght in thr middle
and even the NMRA "RPs" are inconsistent
greg - Philadelphia & Reading / Reading
gregc Doughless What you're asking is, do the manufacturers deviate from Greg's chart when they design and build their turnouts? they may have the correct frog angle, but they may deviate from the "lead length" or "frog distance" from the chart. and even the NMRA "RPs" are inconsistent
Doughless What you're asking is, do the manufacturers deviate from Greg's chart when they design and build their turnouts?
they may have the correct frog angle, but they may deviate from the "lead length" or "frog distance" from the chart.
That is a whole other topic, like the fact that the Atlas #6 has the longest lead length as #6's go.
ATLANTIC CENTRALThat is a whole other topic,
it addresses the "equivalence" of turnouts -- if one can be replaced with one from a different manufacturer
I'm not a big fan of the side throw fitting on the Atlas switch. It takes room and it needs to be burried to look realistic. I only bought Peco (sprung) for my current layout and I did not regret it.
Simon
Well, I have to admit that is not an issue for me. I'm just a little too OCD to use a bunch of different brands of turnouts - two or three is about my limit.
Atlas for most stuff, Walthers for slips, scratch built when need be.
YoHo1975At the risk of wading into some sort of pre-existing argument, Let's be clear about a few things here. When we talk about a Frog, that number literally ONLY applies to the frog itself, the geometry of the adjoining track is NOT involved in that number. Only the geometry of the frog itself. When asking about Peco, We must first verify if we are talking Code 100 or Code 83. In code 83, Peco follows the Frog geometry they specify 5,6,8. BUT, in code 100, Peco uses Small, medium and Large. they do this, because in Code 100 all 3 switches use the exact same frog. angle of 12 degrees. But the geometry of the Turnout including the track is very different for each different model. So again, when talking about turnouts, the frog is only a part of it, it's also about the track geometry around it.
Well, there is no argument really about that. There are those of us who understand and those that don't, and that's Okay.
As you know, if all producers made frogs that were exactly the same as Greg's chart, then the angle of the diverging track post-frog would be the same for each similarly numbered frog no matter who produced it.
But that would still not mean that the turnouts themselves are interchangeable, since the length and curvature of the closure rail plus points could be longer or shorter based upon the geometry......if there are easments built into the curved closure rail, essentially.
Atlas has those easments. Peco does not. And that's why the Peco turnout is shorter, but why the Atlas is better for longer equipment. Some other aspects of the Atlas are not better, so pick the turnout that suits your needs the best and learn to live with its shortcomings in other areas.
The length of the Atlas geometry, as well as the #4.5 frog angle, provides better performance than "comparable" #4 turnouts made by others, and it may compete with Peco #5 pertaning to certain locomotives that might benefit from a longer closure rail with easements.
YoHo1975 When asking about Peco, We must first verify if we are talking Code 100 or Code 83. In code 83, Peco follows the Frog geometry they specify 5,6,8. BUT, in code 100, Peco uses Small, medium and Large.
When asking about Peco, We must first verify if we are talking Code 100 or Code 83. In code 83, Peco follows the Frog geometry they specify 5,6,8. BUT, in code 100, Peco uses Small, medium and Large.
But, even if I had simply referred to the turnout as Peco #5, isn't Code 83 implied since Peco Code 100 turnouts aren't referred to by number but rather by size and Peco Code 83 turnouts are referred to by number, not size?
Earlier in this thread, you simply made reference to Peco #5.
YoHo1975 I personally would prefer Peco #5s
I personally would prefer Peco #5s
Doughlesssince the length and curvature of the closure rail plus points could be longer or shorter based upon the geometry......if there are easments built into the curved closure rail, essentially.
not sure the "easement" is the correct term to describe the curve of the closure rail.
you may have noticed that there is a unique "Turnout Radius" for each frog number in the chart i posted. that is the radius that matches the frog angle when it crosses the opposite rail. that radius is 339' for a prototypical #6 which is 46.7 scale inches. that value is comparable to the top drawing in the diagram below.
that radius can be reduced but will not reach the opposite rail when the angle matches the frog angle when it crosses the opposite rail. a section of straight track (red) or combinations of larger radius track are needed to reach the opposite rail. a shorter lead-length results.
of course the lead-length can be shortened requiring a tighter radius curve
presumably the reason for using a larger turnout is to maximize the closure rail radius for longer wheel base equipment.
it seems an ironic compromise to use a larger turnout frog number but with a compomised length resulting in a tighter radius section of the closure rail.
Greg, most turnouts, model or prototype, have points that are straight and at a low angle in relationship to the straight route, then the closure radius, then the straight frog.
The "effective" curve of the points is almost always a larger radius than the closure radius, so there is very much an "easment" effect, even if it is more in one direction than the other.
As I suggested to you once before, your drawing does not take this into account.
Do some turnouts have a curved diverging point rail? Yes.
But again, on many turnouts you can clearly see the "kink" in the diverging stock rail at the tip of the points, then the straight section the length of the points, then the closure radius, then the straight section parallel to the frog, not a continious curve.
Honestly I still don't see the point of your drawing, it is inaccurate as it applies to most turnouts.
YES, when you reduce the lenght of the turnout, you decrease the closure radius.
BUT I will say again for the 100th time, not in the way your drawing shows becuase it does not account for how the points are made on most turnouts - model or prototype.
And I don't have time draw a bunch of correct drawings to show you.
I will try to explain more. When you make the turnout shorter, rather the the increased straight near the frog that you show, the length and angle of the points changes.
This reduces the easement effect of the points and in extreme cases then requires the diverging point to be curved.
One day, maybe I will have time for some drawings......
What's the point of all of this?
Using the number on the package that the turnout comes in, will a #4 turnout work in a yard or won't it work?
I say, it will work.
the closure rail has to match the frog angle when it crosses the opposite angle. the values i've come up with are comparable to those in the chart from the prototype.
any shortening of the lead length or broadening of any section of the closure rail requires some section of the closure rail to be a tighter radius than that in the chart. making the points straighter requires tightening the radius elsewhere
ATLANTIC CENTRALBut again, on many turnouts you can clearly see the "kink" in the diverging stock rail at the tip of the points, then the straight section the length of the points, then the closure radius, then the straight section parallel to the frog, not a continious curve
yes, that "closure radius" section is tighter than if the entire closure rail were of constant radius
do the math
gregc any shortening of the lead length or broadening of any section of the closure rail requires some section of the closure rail to be a tighter radius than that in the chart. making the points straighter requires tightening the radius elsewhere
richhotrainWhat's the point of all of this?
understanding why frog number does not fully describe a turnout.
why turnouts from different manufactures are not interchangeable.
and why #4 turnouts from one manufacturer may fit better in a yard than others
richhotrainSo what?
your long wheel base loco rides fine (no derailments) over a #6 turnout from one manufacturer. so you think it will do fine with a #6 fom another.
but that lead length from the other manufactures is shorter, which you think is great. but it requires a smaller radius closure rail which your long wheel base loco has a problem with.
richhotrain What's the point of all of this? Using the number on the package that the turnout comes in, will a #4 turnout work in a yard or won't it work? I say, it will work. Rich
Rich, I tried using Atlas #4's in my yard years ago, but my operational plans call for mainline steam to pull trains in andout of randomly assigned arrival and departure tracks.
My steam roster is pretty conservative size wise, but my 4-8-2's did not like the Atlas "#4-1/2", a true #4 would be a disaster, and I doubt #5's would be reliable either.
gregc richhotrain What's the point of all of this? understanding why frog number does not fully describe a turnout. why turnouts from different manufactures are not interchangeable. and why #4 turnouts from one manufacturer may fit better in a yard than others
richhotrain What's the point of all of this?
If you are referring to crossovers, I will agree that an Atlas Custom Line Code 83 #6 turnout and a Peco Insulfrog Code 83 turnout will not fit well together to form a crossover. But, in terms of mixing those same Atlas and Peco single turnouts in a yard, I don't do it but what would be the problem for those that might?
ATLANTIC CENTRAL richhotrain What's the point of all of this? Using the number on the package that the turnout comes in, will a #4 turnout work in a yard or won't it work? I say, it will work. Rich Rich, I tried using Atlas #4's in my yard years ago, but my operational plans call for mainline steam to pull trains in andout of randomly assigned arrival and departure tracks. My steam roster is pretty conservative size wise, but my 4-8-2's did not like the Atlas "#4-1/2", a true #4 would be a disaster, and I doubt #5's would be reliable either. Sheldon
My reasoning was the same as yours. Whether or not in practice larger steam engines would use the yard, I was determined to make it possible, and I did.
Later, I replaced the Atlas Custom Line Code 83 #6 turnouts with Peco Insulfrog Code 83 #6 turnouts because I decided to give up Tortoise powered control for spring controlled point rails.
richhotrainInterchangeable in what sense?
two ways
on the mainline, replacing a longer #6 turnout with a smaller #6 that has a tigher closure rail radius may lead to more derailments with longer wheel base locos. and it's also possible a turnout is the same length, because of the length of rail before the points and after the frogs, but the lead-length and closure rail radius are smaller
i don't know whether your atlas or pecos are shorter. but presumably it's obvious that if you used one as a template for locating yard switches but use a mix of the two in the ladder, the longer one may not fit in the same space nor line up the same as the other because of the position of the frog relative to the points. (and i assume you wouldn't mix)
i'm guessing that it's far easier for even long diesels to negotiate tigher turnouts than even moderate size steam locomotives. so you may not be concerned with these issues if you don't operate steam.
gregc the closure rail has to match the frog angle when it crosses the opposite angle. the values i've come up with are comparable to those in the chart from the prototype. any shortening of the lead length or broadening of any section of the closure rail requires some section of the closure rail to be a tighter radius than that in the chart. making the points straighter requires tightening the radius elsewhere ATLANTIC CENTRAL But again, on many turnouts you can clearly see the "kink" in the diverging stock rail at the tip of the points, then the straight section the length of the points, then the closure radius, then the straight section parallel to the frog, not a continious curve yes, that "closure radius" section is tighter than if the entire closure rail were of constant radius do the math
ATLANTIC CENTRAL But again, on many turnouts you can clearly see the "kink" in the diverging stock rail at the tip of the points, then the straight section the length of the points, then the closure radius, then the straight section parallel to the frog, not a continious curve
I've done the math, decades ago, built plenty of turnouts from scratch, and understand the subtleties of the geometry. And I understand the differences between the various commercial turnouts on the market.
Your drawing does not take any of that into account.
So to me it seems a pointless exercise.
I don't expect one brand of commercial model turnout to exactly interchange with a different brand. That is folly as well.
PECO makes great track, Atlas make great track, Walthers makes great track. They each have advantages and disadvantages. Pick what works for you or build your own.
Busy now,
gregcany shortening of the lead length or broadening of any section of the closure rail requires some section of the closure rail to be a tighter radius than that in the chart. making the points straighter requires tightening the radius elsewhere
Not if you purposely lengthen or shorten the entire turnout. Or adjust the angle of the striaght point rails diverging from tangent.
Your chart shows length of the turnout determined solely by a constant closure radius. Varying the radii of the closure rail and adding or shortening the straight components (the red line and the (undrawn) point rails) as well as how severe the points angle away from tangent is how the model manufacturers make their turnouts longer or shorter than the others....all the while keeping the tightest part of the closure radius the same as other producers.
Its impossible to do the math (without having a geometric goal in mind) because there are three different sections of rail between the frog and the point. The closure rail itself could have an easement on either side that feathers the curve into the straight parts.
Its not infinite of course. There will be a point where you run out of lateral space to keep going, but playing with the length of the three sections and the angle of the points is why different model turnouts have different geometries.
Atlas generally having the longest turnout, IOW, the longest length of rail between the frog and the point, as any other manufacturer.
And the sections all have to closely match the shape of outside stock rail to keep the train on the track, so the differences are minimal.
Edit: keeping in mind that the radius of the curved closure rail, or the "closure radius" is not the same thing as the (estimated) "embedded radius" of a turnout. The embedded radius is essentially the radius of the closure and the straight sections (red line and points). Atlas being the longest turnout, it has the broadest embedded radius of any turnout, but the actual radius of the closure rail at its tighest point is no tighter or broader than any other turnout (IMO, not having micrometered the different turnouts).
By observation only, the PECO #6 is a shorter turnout because the points diverge from tangent at a more severe angle than Atlas.
gregc richhotrain Interchangeable in what sense? two ways on the mainline, replacing a longer #6 turnout with a smaller #6 that has a tigher closure rail radius may lead to more derailments with longer wheel base locos. and it's also possible a turnout is the same length, because of the length of rail before the points and after the frogs, but the lead-length and closure rail radius are smaller i don't know whether your atlas or pecos are shorter. but presumably it's obvious that if you used one as a template for locating yard switches but use a mix of the two in the ladder, the longer one may not fit in the same space nor line up the same as the other because of the position of the frog relative to the points. (and i assume you wouldn't mix)
richhotrain Interchangeable in what sense?
ATLANTIC CENTRALYour drawing does not take any of that into account.
the red straight sections on the shorter turnouts account for any combination of straighter sections in the closure rail.
the blue curved section can be rotated and the red section split to account for straigher points and a straighter section near the frog
DoughlessIts impossible to do the math
the Catskill Archive Frogs and Switches page does
DoughlessYour chart shows length of the turnout determined solely by a constant closure radius.
the chart does not show total turnout length.
it shows the "Frog distance", what i've been calling lead-length and the maximum closure rail radius. the total turnout length needs to include the rail lengths before the points and after the frog.
presumably it shows the dimensions for a standard turnout of varying frog number. i wouldn't doubt there are exceptions