# Why can't we just all agree?



## mickey (Jan 28, 2009)

I'm so tired of having engage my brain when reading post about 'radius' or is it 'diameter' ? Can't we just all get together and decide to use one or the other?


----------



## Dr Rivet (Jan 5, 2008)

Because folks who came to large scale from the "toy train" word of Lionel and American Flyer will always use DIAMETER and those of us who came from the smaller scales like N and H0 scale modeling will use radius. It is what we grew up with.

MTH and Lionel [and Atlas 3 rail, Gargraves, and Ross] still market their curved sectional track by diameter [0-27,0-31,0-42,0-54,0-72...].
H0 and N sectional track is marketed by radius.

I find R1/R2/R3/R5 pretty useless except in a relative sense because the large scale vendors are NOT consistent.

Since all my permanent layouts have used flex track, diameter is not very useful for me.

It is purely a personal choice.


----------



## vsmith (Jan 2, 2008)

Most manufactures in LS list by diameter, that's why we still mostly use that designation IMO.


----------



## JPCaputo (Jul 26, 2009)

If everyone adds an r or d to the dimension, as in 5'r or 10'd then it is clear to all, and converting is a simple factor of 2.


----------



## Garratt (Sep 15, 2012)

Two different words with two different meanings. Each has it's place.
LGB track has naming based on radius and other manufacturers use diameter so I think that's where the two terms are sometimes used within one context. 

Andrew


----------



## JPCaputo (Jul 26, 2009)

Maybe add a sticky topic with the conversions & diameters of each brand of track, including switches.
It will be a good reference for everyone.


----------



## Semper Vaporo (Jan 2, 2008)

I think there are also people confused as to which is which... often saying (or typing) one, but meaning the other.


----------



## Peter Eaton (Mar 11, 2015)

I'll go with diameter. I bought some 11.5 diameter curves for a trestle I built years ago, lets see that would be 5.75 radius. I like the idea of a sticky dedicated to the track sizes. Peter


----------



## zubi (May 14, 2009)

It is very simple, talking about diameter is relevant when you want to know if the track will fit in your available space. Radius is usually mentioned when you want to know if a particular locomotive can negotiate the curve. And both are trivially related with each other (factor two). Things get slightly more complicated when one starts using outer diameter of radius to the centre of the track. So to make a long story short, there is nothing to agree about. All that is needed is a complete description of what is meant. And that is usually done. Best wishes from Tokyo, Zubi


----------



## chuck n (Jan 2, 2008)

As long as "d" or "r" follows the length I don't have a problem. Occasionally I have seen posts where someone says, "I'm using 5' curves." That is when we have problems.

Chuck


----------



## Jerry McColgan (Feb 8, 2008)

zubi said:


> It is very simple, talking about diameter is relevant when you want to know if the track will fit in your available space. Radius is usually mentioned when you want to know if a particular locomotive can negotiate the curve. And both are trivially related with each other (factor two). Things get slightly more complicated when one starts using outer diameter of radius to the centre of the track. So to make a long story short, there is nothing to agree about. All that is needed is a complete description of what is meant. And that is usually done. Best wishes from Tokyo, Zubi


Well said,

Explains my viewpoint as well. Neither will go away and it is pretty easy to understand the difference.

Jerry


----------



## Gary Armitstead (Jan 2, 2008)

Actually there is nothing to agree to here. Radius and Diameter are engineering terms. Period. Look at ANY blueprint and you will see features with dimensions as follows: a hole will be noted as DIAMETER. Also the hole location will be noted with a POINT dimension with the centerline of the hole. A feature with curvature on the inside of a part or the outside edges of a part, will be noted as RADIUS with a POINT location for the center of the RADIUS.

The prototype uses degrees of curvature using chords and segments of chords. The curved section in that equation is always RADIUS as used in the equation. 

To note our track curvature as diameter is WRONG.  Learn to deal with the math here. Radius and diameter are third grade math.  End of my rant.


----------



## NTCGRR (Jan 2, 2008)

As I am back to larger scale (1" scale) I agree with Gary.


----------



## Treeman (Jan 6, 2008)

Dealing with radius or diameter is a minor problem. A much bigger problem I see is the letter "R" used by our friends in Germany, all use the letter. But the R1, R2, R3, R4, R7 does not mean the same to any of the three manufactures, LGB, Piko, or Train-Li. This is very confusing to me, let alone a new comer.


----------



## chuck n (Jan 2, 2008)

I agree with Mike! When one manufacturer used the "R" designation it was fine, but more with different meanings for the same "R" numbers muddies everything. It is time to drop the "R" designation and use real numbers.

Using other "R" systems is a major disservice to the hobby! Beginners have enough problems, buying track should not be difficult.

Chuck


----------



## Greg Elmassian (Jan 3, 2008)

Another vote for Mike!

Having R1, R2 implies to newbies that an R2 curve is the same no matter what the manufacturer.

It's a mess. Coming from smaller scales, I never used diameter.

Greg


----------



## JPCaputo (Jul 26, 2009)

I came from ho and n, diameter and radius is no problem. The R1, R2 etc is what took me a while to understand, I still google the actual dimensions for the brands.


----------



## Dick Friedman (Aug 19, 2008)

I much prefer to just refer to curves by degrees of curvature. <G>


----------



## Garratt (Sep 15, 2012)

Dick, the radius can still be different though. 

Andrew


----------



## zubi (May 14, 2009)

Well, actually, it is part of the fun. And I really hope it will stay this way! Almost as bad as scales, couplers and water (for those of us who run 'real' trains;-)..., not toys!). It is not all that difficult, it is just different, inconsistent, individual, requiring some brain and enjoyable and thanks goodness for that - I do hope it will never be like 'that's the way it should be stuff of the smaller scales'. Best wishes from Tokyo, Zubi


----------



## Totalwrecker (Feb 26, 2009)

inches are radius
feet is diameter
Reality is centimeters ........
Oh my.


----------



## Chris Scott (Jan 2, 2008)

Is it radius or diameter will never be resolved or solved as the question of which will never not be and or have to be asked and answered as there will always be need for clarification to deal with the human principle and condition of uncertainty. If this were not the case this topic would never many times over be raised. 

To the question, "Can't we just all get together and decide to use one or the other (radius or diameter)?", the simply obvious answer is, not possible, never going to happen, can't happen. 

Besides, your radius is my diameter and your diameter is my radius. Who knows which is which without the question of which?


----------



## chuck n (Jan 2, 2008)

We've spent a fair amount of time discussing the various R values and what they mean to whom. I've spent a fair amount of time today trying to find a site that compares them, without any luck. It may be there, but I didn't find it. Here is my attempt. Have at it. Any corrections, additions, and suggestions would be very welcome. If we get it right, maybe Greg could add it to his data base. 

The Train-Li ad in the latest GR says that their track goes up to R13. That may be, but their site only goes up to R4.

I've only included Manufacturers that I know use the "R" designation. If there are others, let me know and I'll add them to the table.


Table deleted, because of new information from Cliff, see later post (9/7/15)!

Chuck

I've screwed up already. The train-li values are in centimeters, not millimeters. It's getting late. I'll correct it in the morning. 

It has been corrected and the original table replaced!!


----------



## ntpntpntp (Jan 14, 2008)

I drew this up a few years ago to try and get some sort of overall idea how the curve radii of various manufacturers compared, which items were near equivalent etc. I know it's not complete, but might be of interest?

http://falconer-family.org.uk/images/Track%20radii.gif


----------



## Treeman (Jan 6, 2008)

Dick Friedman said:


> I much prefer to just refer to curves by degrees of curvature. <G>


Degrees don't tell the story, all circles are 360 degrees.


----------



## chuck n (Jan 2, 2008)

Mike, we agree again. We've got to stop meeting like this.

Chuck


----------



## Treeman (Jan 6, 2008)

Trying to avoid a total state of confusion.


----------



## CliffyJ (Apr 29, 2009)

Hi Chuck, 

Nice spreadsheet! 

Just FYI, Train Li carries (as you probably know) the sectional Train Line 45 track, which has 900mm & 1200mm radii. Axel decided to round it to the nearest foot, hence his new designation of R3 & R4. We had an interesting thread here on MLS on that, but unfortunately I can't find it.

http://www.train-line45.de/Gleismat...ainline&SessionId=&a=catalog&t=24&c=119&p=119

Train Li is designating their turnouts in the same fashion, even though the centerline dimensions are in round millimeters. For example, the "R7" turnout is very close to a 7-foot radius, but is actually R2100mm, or R82.7" 

Cliff


----------



## chuck n (Jan 2, 2008)

Thanks Cliff. I guess that I should change the table. I just took the foot and converted it.

I'm off to New England tomorrow morning for three weeks. It may be a while before I can make the changes.

Chuck

Table revised per Cliff.










Thanks, still learning how to format the table. Lines didn't show where I wanted.


----------



## CliffyJ (Apr 29, 2009)

Really interesting to see it all together, thanks Chuck. Wow, quite the jumble!


----------

