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Track geometry


rue_d_etropal

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I have been trying to work out geometry of some track I have. It was a Fleischmann point, so I did a google search and found this very useful website, with radius and lengths.

https://www.enigon.com/raily/modules/en/index.html

 

And then noticed it had most, if not all manufacturers so checked out Peco, having been struggling to work out the OO large curved point. It was all there and looks correct, certainly good enough for me.

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And then noticed it had most, if not all manufacturers so checked out Peco, having been struggling to work out the OO large curved point. It was all there and looks correct, certainly good enough for me.

 

Hmm...if you mean the SL-86/87 curved point then it doesn't show the radii of either road.  I believe the inner road is quite tight, I've seen less than 600mm suggested.

 

The 12° angle it quotes is the angle between the two roads at the heel.  I believe the angle subtended by the individual roads is 18° for the inner and 6° for the outer.

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Hmm...if you mean the SL-86/87 curved point then it doesn't show the radii of either road.  I believe the inner road is quite tight, I've seen less than 600mm suggested.

 

The 12° angle it quotes is the angle between the two roads at the heel.  I believe the angle subtended by the individual roads is 18° for the inner and 6° for the outer.

It shows the radius of the inner road as 762mm and the outer as 2100mm and the angle as 18.81° for the inner and 6.85° for the outer

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Hmm...if you mean the SL-86/87 curved point then it doesn't show the radii of either road.  I believe the inner road is quite tight, I've seen less than 600mm suggested.

 

The 12° angle it quotes is the angle between the two roads at the heel.  I believe the angle subtended by the individual roads is 18° for the inner and 6° for the outer.

 

Peco points always look right to 99% of modellers & work straight out of the box.  600mm radius is luxury to many modellers.  Anyone who is disastified with Peco points, build your own!

 

Peter

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Peco points always look right to 99% of modellers & work straight out of the box.  600mm radius is luxury to many modellers.  Anyone who is disastified with Peco points, build your own!

 

Peter

The OP was not discussing any of the issues you rather bizzarely raised in your rant.

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It shows the radius of the inner road as 762mm and the outer as 2100mm and the angle as 18.81° for the inner and 6.85° for the outer

 

 

My apologies, you're correct that it does show that when you click on the track element.  I hadn't noticed that feature (the text that tells you about it is rather small and easy to miss).

 

The SL-84 and SL-85 are shown as 96mm long.  I've got an SL-84 in front of me now and it's 104mm long (this is the figure that AnyRail uses).  Strangely, Peco's own website says it's 98mm!

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My apologies, you're correct that it does show that when you click on the track element.  I hadn't noticed that feature (the text that tells you about it is rather small and easy to miss).

 

The SL-84 and SL-85 are shown as 96mm long.  I've got an SL-84 in front of me now and it's 104mm long (this is the figure that AnyRail uses).  Strangely, Peco's own website says it's 98mm!

My pile of Peco points waiting forlornly for me to take them to a wonderful new life on the loft layout show discrepancies of 4 to 5 mm length between similar points of different vintages. You just can't be that precise when planning CAD style.   The Streamline curved point was always 5ft / 2foot 6 radius but can be curved down to around 600 mm on the sharp radius by cutting webs etc and one of mine is around 18" radius after web cutting surgery and a replacement point blade.  There is a post on here somewhere.   These CAD programs are great for a back of a cigarette packet sketch but like the old 1960s CJ Freezer plans  allow 10% extra baseboard area for 2017 track to be sure it fits.  Alternatively take a hacksaw (A manual 19th century  alternative to a Dremel cutting disc) to your points and you can easily save 10% of your pointwork length

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I did my own full sized outline design of the large radius curved point, based on the angles and radii , and it is pretty near damn spot on compared to the Peco template. I had used Gaugemaster as a reference in the past, but their nominal radius is way out of the true value.  It does seem an odd angle for both curves, but then it does not have to match up with any other points. In fact I still think it might be a combination of curved and straight sections, as that is what it looks like to the eye. For my design it is far closer thany all the tries I had at working it out, and that is what matters. Someone asked if I could do an inset design, probably because they had a similar problem working it out.

 

Most of the code 75 points share geometry with the code 100, just a pity they don't do an asymetric code 100 3 way point, or non electrofrog version of the code 75 one. As far as I know the code 83 range is based on USA geometry. They do have the code 83 on the online list as well.

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  • 2 weeks later...

in addition to rue_d_etropal's ​post I agree that code 100 & code 75 share the same geometry, code 83 is a different kettle of fish

 

code 83 was made for the US market & it follows their geometry and naming system i.e. They are described by a number .

A #8 point is a very long point , the number relates to the angle of the frog, a #8 point frog angle is a ratio of 8 to 1 (8 units out from the frog it diverges by 1 unit)

 

With code100 & code75 the diverging rails are a constant radius from the point blade to the end of the point

 

Whereas with code83 points the curve starts at the point blade & only continues far enough to get the required angle, from there on it is straight

Because of the geometry of number points(part straight & part curved) it is difficult to give an equivalent radius

The following drawing should help to explain the different geometries

 

post-28417-0-08444500-1491137985_thumb.jpg

 

The top point is a Medium Radius Peco

The lower point is a #5 code83 point

These points are about the same size but the frog angles are slightly different

Templates for Peco points can be downloaded from their website

 

John

 

 

 

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