Just for fun, I decided to get really picky and try to use some sections of track to make some portable corners. So I started with a real tight circle using aristo "2 foot" radius track. 3 pieces and you go 90 degrees...right? Well mostly, kind of, sort of. Except the rail ends are not really square with a 2 foot radius center line. Also I'm just remembering what I was getting frustrated with in the garage so maybe it wasn't really 2 foot? The real question here is: Does anyone know the actual radius of the outside rail, the center line and the inside rail? And I know that there of course would be a difference if I'm measuring at the center of the rail or not. Wouldn't it be cool to scribe a perfect circle that matched the outside of the rail base and match the rail to that line for a perfect loop of track? What would that radius be? Twelve pieces and I should be able to measure it...ha ha...right? What could be simpler, says this old fool, knowing full well that it's the seemingly simple things that can drive you nuts.
Track Radius, Inside Rail, Center, Outside Rail
- Thread starter DVS4G
- Start date
This will drive you mad! 
Some manufacturers give measurements to centre, some to (Aristo?) inner-rail..
My biggest gripe:
I have a fair bit of Aristo. track, including curves and points (turnouts) and none of 'em have a part number, so I have no idea if they are' as designed' or have been tweaked in a previous existence.
Good luck! - I think you will need it?
PhilP
Some manufacturers give measurements to centre, some to (Aristo?) inner-rail..
My biggest gripe:
I have a fair bit of Aristo. track, including curves and points (turnouts) and none of 'em have a part number, so I have no idea if they are' as designed' or have been tweaked in a previous existence.
Good luck! - I think you will need it?
PhilP
Remember, different makes, although using the same code 332 rail type and 45 mm gauge, can use different track geometry, if only in detail sometimes. All my line, outdoor and on the ground, is made up of flexi' track and all curves are "transitional". My "perfect loop" of track is quite random in its included radii. Might I suggest a more flexible (pun intended) approach to your portable corners. As a result of my looser approach to track design these small trifles have proved to be of little concern and stress to me 
Honestly, good luck and all the best with your endeavors. Max
Honestly, good luck and all the best with your endeavors. Max
Is that to the outside of the outside track, inside of the out side track, or centre of the outside track, also is the to the outside of the inside track ........................................................
The only way to compare one brand, to another, is to go by centre-line..
But for this, we need someone to have taken the physical measurements, or done the calculations..
There is some information out there, but I am not sure anyone has pulled it all together, in one table / place?
PhilP
But for this, we need someone to have taken the physical measurements, or done the calculations..
There is some information out there, but I am not sure anyone has pulled it all together, in one table / place?
PhilP
According to the diagram in the Aristo catalogue the radius is measured from the centre of the track.
definitely the center line is the standard. You can easily calculate the radius of the outer rail, just add 1/2 of 45 mm and then 1/2 of the thickness of the rail itself. that is the outer rail... for the inner rail radius, subtract these two items.
Of course, while I have technically answered what you asked, the centerline of the rail would be hard to see with the rail above it.
so, just do the 1/2 of 45mm and that is the INSIDE edge of the rail (add to radius and you have inside edge of outer rail.... subtract from radius you have the inside edge of the inner rail)
very easy, but I will caution you, your statement about the ends not matching, this is typical, and some trimming is often needed to minimize gaps.
Better: lay the curves out as you want, making them as broad as you can, most sectional track has some five, making them EXACTLY a particular size serves no practical purpose in most cases.
Greg
Of course, while I have technically answered what you asked, the centerline of the rail would be hard to see with the rail above it.
so, just do the 1/2 of 45mm and that is the INSIDE edge of the rail (add to radius and you have inside edge of outer rail.... subtract from radius you have the inside edge of the inner rail)
very easy, but I will caution you, your statement about the ends not matching, this is typical, and some trimming is often needed to minimize gaps.
Better: lay the curves out as you want, making them as broad as you can, most sectional track has some five, making them EXACTLY a particular size serves no practical purpose in most cases.
Greg
Well, I agree with a few things here, ha ha.
Centerline of the track in general (where the mounting/nailing/ screwing holes are!) is what the measurements, when given, refer to. (except when they are not - noted at the end)
And, 45mm is, of course our inside rail head to inside rail head measurement. So Gregs "half of 45mm" certainly makes sense. Now I will need to go look at the track harder to determine if the edge of the rail head is in the same vertical plane as the edge of the rail base. My bet is no, because that would make it too easy.
Also, I agree that when you build a circle and try to get the curves all matched at the ends, you seem to always end up with a gap somewhere and then end up averaging out the gap by splitting it between all the sections so you have only tiny gaps everywhere and by then you are frustrated to the point of "it's close enough".
And, who in their right mind ever just builds a circle anyhow? (oh wait, that Christmas tree thing, huh)
So, where I got into trouble was trying to build four identical, swap-able 90 degree corners which caused me to want to know where my mark was at each side of the 90 degree corner. This was my practical purpose for wanting a particular size. As I originally jokingly posted, I did actually let my OCD completely out of the box by putting together those twelve sections on a flat tabletop. The sections I picked were surprisingly well matched and had very little gap anywhere when snugged up fully. Then I measured across the circle from nail hole to opposing nail hole (centerline diameter...right?). Would you be surprised to know that in those twelve measurements, there was a large variety of diameters? So I added them all up and divided by twelve to get an average. 47.315 inches. Funny how none of my large measuring sticks are graduated in millimetres. But a quick conversion yielded the interesting fact that 47.315 inches is 1201.8 mm.
At this point I had that moment we have all probably come to on occasion. That "wait just a darn minute. That sure sounds familiar" moment. Dead silence as I go find the LGB track chart and wake up to the fact that this is Aristocrafts version of LGB R1 1200 mm track. Duh and double duh......
For the non millimetre crowd: 1200.15 mm = 47 1/4 inches. Close enough for my dull pencil.
For those following Gregs logic: the inside edge of the outside rail would be at 1222.5 mm or 48.1299 inches. (1/8 inch = .125 so 48 1/8 for the American carpenters)
And when you go to, well, any supplier that sells track, and you buy a "curved track, four foot circle".....you can be reasonably sure that it sure ain't the centerline they are referring to!
All you machinists with your thousandths are on your own. I'm tired and my caliper is not 48 inches long anyhow.
Centerline of the track in general (where the mounting/nailing/ screwing holes are!) is what the measurements, when given, refer to. (except when they are not - noted at the end)
And, 45mm is, of course our inside rail head to inside rail head measurement. So Gregs "half of 45mm" certainly makes sense. Now I will need to go look at the track harder to determine if the edge of the rail head is in the same vertical plane as the edge of the rail base. My bet is no, because that would make it too easy.
Also, I agree that when you build a circle and try to get the curves all matched at the ends, you seem to always end up with a gap somewhere and then end up averaging out the gap by splitting it between all the sections so you have only tiny gaps everywhere and by then you are frustrated to the point of "it's close enough".
And, who in their right mind ever just builds a circle anyhow? (oh wait, that Christmas tree thing, huh)
So, where I got into trouble was trying to build four identical, swap-able 90 degree corners which caused me to want to know where my mark was at each side of the 90 degree corner. This was my practical purpose for wanting a particular size. As I originally jokingly posted, I did actually let my OCD completely out of the box by putting together those twelve sections on a flat tabletop. The sections I picked were surprisingly well matched and had very little gap anywhere when snugged up fully. Then I measured across the circle from nail hole to opposing nail hole (centerline diameter...right?). Would you be surprised to know that in those twelve measurements, there was a large variety of diameters? So I added them all up and divided by twelve to get an average. 47.315 inches. Funny how none of my large measuring sticks are graduated in millimetres. But a quick conversion yielded the interesting fact that 47.315 inches is 1201.8 mm.
At this point I had that moment we have all probably come to on occasion. That "wait just a darn minute. That sure sounds familiar" moment. Dead silence as I go find the LGB track chart and wake up to the fact that this is Aristocrafts version of LGB R1 1200 mm track. Duh and double duh......
For the non millimetre crowd: 1200.15 mm = 47 1/4 inches. Close enough for my dull pencil.
For those following Gregs logic: the inside edge of the outside rail would be at 1222.5 mm or 48.1299 inches. (1/8 inch = .125 so 48 1/8 for the American carpenters)
And when you go to, well, any supplier that sells track, and you buy a "curved track, four foot circle".....you can be reasonably sure that it sure ain't the centerline they are referring to!
All you machinists with your thousandths are on your own. I'm tired and my caliper is not 48 inches long anyhow.
Making modular components with track on them is another world. We do with in Z scale, and it depends on if your modules are mirrored around the center of the module, or just one set of tracks.
The important thing is locating the track centerlines in reference to an edge or center of a module. We made huge layouts from many modules (like 10 scale miles or more) in Z scale.
If you are trying to make modules, look at HO module specifications, or perhaps our Z scale (Z_bend) specifications. Also you don't really want to bring the track to the edge of the module.
A whole discussion in of itself.
Greg
The important thing is locating the track centerlines in reference to an edge or center of a module. We made huge layouts from many modules (like 10 scale miles or more) in Z scale.
If you are trying to make modules, look at HO module specifications, or perhaps our Z scale (Z_bend) specifications. Also you don't really want to bring the track to the edge of the module.
A whole discussion in of itself.
Greg
I spent more of my younger days than I care to remember setting up and tearing down HO scale modular railroads. It was a thing in our group for a good long while. So if anyone wants to have a long and probably boring (cause you might have to listen to a few of my "in the old days" stories) conversation, I do speak "module". I can for sure tell you a whole bunch of stuff NOT to do. Module owners are known for being able to shift time and space in at least 6 dimensions. There's no other explanation for how a 9 inch gap is NEVER 9 inches long.
But I have found my way to a reasonable answer to my original question. Along the way I learned a few things. I hope I remember some of them tomorrow. Things like NO the rail head is not the same width as the web base. So you can throw out the notion of dividing 45mm in half. But to keep it short, a 24 1/2 inch radius circle will line up with the inside edge of the bottom web of the outside rail. Close enough for my purposes at least to get a reasonable repeatable standard to work with. And then, you make it fit.....always.
But I have found my way to a reasonable answer to my original question. Along the way I learned a few things. I hope I remember some of them tomorrow. Things like NO the rail head is not the same width as the web base. So you can throw out the notion of dividing 45mm in half. But to keep it short, a 24 1/2 inch radius circle will line up with the inside edge of the bottom web of the outside rail. Close enough for my purposes at least to get a reasonable repeatable standard to work with. And then, you make it fit.....always.
Well, clearly you can measure the width of the rail foot, and compensate for the difference between the extra width over the rail head...
What pray tell needs this absolute precision in G scale? If it's for modules, and you are as experienced as you have stated, you know you have a reference point on the module and put the centerline of the rail where it needs to be.
You imply you are making 4 corners... how about letting us in on the secret project?
Greg
What pray tell needs this absolute precision in G scale? If it's for modules, and you are as experienced as you have stated, you know you have a reference point on the module and put the centerline of the rail where it needs to be.
You imply you are making 4 corners... how about letting us in on the secret project?
Greg
Yep. Where to put the centerline. That's where this all started. That and a box of track I was given. Easily identified by the joiners with those slots and little screws. Not so easy to find data on where that centerline should be for a curve. The absolute precision comes from a desire to do it "right" while I fully understand that "perfect is the enemy of good enough". After working in HO and N scale for the bulk of my modeling years, I find that G scale is very forgiving.
Alas, the secret project would not be secret if I told you all. But wait! Those were Gregs words. I never called it secret, ha ha. In truth, it is no more than a test track that fits in my repairs trailer that I drag around the countryside when I am called to go make repairs. There are thoughts of cutting some holes in the trailer sides to allow portals to the outer world for broader curves and pure entertainment of the public. Pull up to the curb, drop the shelf on the side of the trailer, out comes a train! Might spark some conversation, eh?
Alas, the secret project would not be secret if I told you all. But wait! Those were Gregs words. I never called it secret, ha ha. In truth, it is no more than a test track that fits in my repairs trailer that I drag around the countryside when I am called to go make repairs. There are thoughts of cutting some holes in the trailer sides to allow portals to the outer world for broader curves and pure entertainment of the public. Pull up to the curb, drop the shelf on the side of the trailer, out comes a train! Might spark some conversation, eh?
Hmmm..... only do it in a neighbourhood with a high literacy rate. Spelling conversation could be mispelt conversion.... that's the last you see of your train.
Now if we are talking about 45 mm gauged "G" layouts in trailers..........where is Trammayo when you need him, never mind Greg (no offence meant. Greg) I have sent up a distress flare. Max