EZ Track Curve Radius

[rogertra]

People are making a rather simple thing overly complicated.

The radius is always the centre line.  Always! 

I don't buy set track but IIRC, the radius is always shown on the packaging.

Why is this so difficult?

[GG1onFordsDTandI]

All of the above mentioned methods are o.k. if your layout is HO (& Bachmann EZ). Other scales/brands will have different measurements on roadbed widths. I think Bachmann has always measured from center between rails. Note: Some companys in the past measured outside/inside rails or even outer/inner tie ends, but I believe the centerline is the most common method overall. Without a "safety lip" fascia even some of the old cast metal trains would sustain damage off a table, but the newer stuff doesn't seem to travel as far in a high speed derail due to accidental un-couplings. Guess the plastic weight vs metal, plastic just doesn't have the momentum the metal does. They flop but don't slide 5 inches anymore. But then again horns, railings, and such, didn't break when you breathed to hard on them either.

[GG1onFordsDTandI]

My only HO-ez (right loco, right price) has a plastic black bed and steel 18r" is exactly a 36"dia = 18" radius
The bed width, measured with a cheap but accurate to 64ths caliper, done at the center and ends of a curve was, <1&15/16" (it will drop into a 1&15/16" gap.)  Outside edge diameter is <37&15/16"

I don't usually measure track close, I like to "lay track by eye, and modify". Like l'm a big kid with a puzzle. "The railroad must go through!". Manufacturing differences, grades and stuff, have an effect on exact length measurements originally taken on a flat surface any how, ie: a grade adds length to a measurement originally taken on a flat surface.  I can do the math, the visual is funner than math  . The industry, scenery, towns, The Automobiles, Semi trucks? Like in life, they come and go with time. For my self enjoyment I have "seriously" modeled many other things. My trains? I like to concentrate on running um, first and foremost! (But the modeling has always snuck into my "yards" over time .
What I do check more carefully are the outside boiler overhang, and cab kick-out of my steam locos, -vs- the inside cut of my longest cars, and space double track curves accordingly, to avoid the loco "ghost knocking" on the doors and sides of the cars on the opposing track when trains pass each other in curves. 

[Doneldon]

GG1-

Galileo showed us that plastic and metal fall at the same speed, all other things being equal. Of course, the metal releases more energy than the plastic when it hits the floor. But then it's stronger in most cases, too. The one thing we can all count on is that whatever makes the dive off of the edge of the layout will be in worse shape when we pick it up than it was when it was still on the rails. This is true even if our train table is not as high as the Leaning Tower of Pisa.
                                                                                                                                     -- D

[phxpsd]

I would like to aplogize for not having thought out my original post.  I came close to answering my question myself in the second sentence of my reply (Reply #2). In my current layout I took liberties with the slight flex at the track to track connections this resulted in slight bellmouthing of the half circles at each edge of the layout.  So the radius stated on the EZ Track IS CORRECT!

Thanks to all that took interest.

[Doneldon]

phx-

It's best to connect track as closely and smoothly as possible. That tiny kink that we can barely see or feel is much larger to those little wheels we run on our rails. Even slight kinks or spreads can cause reliability problems. It's true that we may want to build in some slight looseness to allow for environmental changes over the course of a year, but the junctions where we put those little gaps need to be absolutely straight, with the end faces of the rails perfectly parallel to one another and perfectly aligned. The rail ends also need to be held firmly in place by either the manufacturer's spike heads or our own added spikes.

Which makes me think. (No, this is not a novel experience for me.) Could we have rail joints with tapered rails, with one end tapering from one rail into the next on one side of the rail, say the inner edge, and the other tapering in a complimentary way on the outer edge? Or would that be a whole lot of work for little benefit and make "custom" rail sections almost impossible to do?

                                                                                                                                          -- D

[jward]

personally, I think the rail ends are fine just as they are.   I don't think that tapered ends are a good idea, and may cause more alignment problems than they solve. but if you want a taper, it is easy to do with a small file.

[GG1onFordsDTandI]

Which makes me think. (No, this is not a novel experience for me.) Could we have rail joints with tapered rails, with one end tapering from one rail into the next on one side of the rail, say the inner edge, and the other tapering in a complimentary way on the outer edge? Or would that be a whole lot of work for little benefit and make "custom" rail sections almost impossible to do?
                                                                                                                                        -- D

I think keeping the thin edges on the taper from bending would be an issue over time. Rail expansion or shifting could cause gauge changes. I also think some sharper worn flanges would be more likely to find that groove and ride up it. If you only run one direction maybe. One direction, thick to thin mating at a 90 might work out also. It all would make an interesting test section if someone had the inclination.
I think file work might be of more value on rounding a peak kink.(than a valley kink too).
Not trying to bash, but issues like these are one reason I like traditional tubular 3-rail O a bit more. I avoid grades with PW Super-O too(non tubular,{almost}) But I guess pilot(cow catcher) shorts to the center rail, or full O rollers falling off 0-27r curves, etc. are really just "different train gremlins".

[Doneldon]

I think keeping the thin edges on the taper from bending would be an issue over time. Rail expansion or shifting could cause gauge changes. I also think some sharper worn flanges would be more likely to find that groove and ride up it. If you only run one direction maybe.

GG1-

Rail joiners should prevent gauge changes but I can sure agree that some wheels would likely find a way to pick the joint and derail. I might try this on a stretch next time I'm building some track. It could be an interesting demonstration.
                                                                                                                                                                     -- D

[GG1onFordsDTandI]

I think keeping the thin edges on the taper from bending would be an issue over time.

GG1-
Rail joiners should prevent gauge changes                                                                                                                                                                    -- D

I love to debate the pros and cons of creating anything mechanical! Please note: I want to hear Im wrong as much as I wanna be right on stuff like this! I always tend to lean to the worst case scenario, but could flip flop on you to pros if you start to agree I love physics but wont do the math I prefer to EYEBALL it (it is a joke son {another post, use search for now, maybe I'll link it soon}) but can manage to throw monkey wrenches at an aerospace engineer, and more than a few to many a mechanical, or automotive engineer. (But would never question a boiler operator, still or moving )

Mostly, but over time I don't know if the metal would "pressure meld" smooth or be picked outwards by the flanges, I would guess weight, the flange edge contact factors would have to be taken seriously. I saw a kid tap his way halfway through a school desk with his fingers and finger nails, over time tiny stresses add up! Museums/stores/malls, or a high hour, heavy consist, "caboose chasing" layout, (axles per min)x(time)=?, that's when I think you'll get a real test answer.