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Peco Turnout Angles


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Hi David,

 

You have lost me there. Here is the Templot screenshot with the ruler tool placed along the splice rail. To the nearest mm it is 48mm, as you say it should be:

 

2_221157_410000000.png

 

The V-crossing (frog) is curviform pattern, meaning that the turnout radius runs through, to give a total swing of 12 degrees at the end of the splice rail (exit). The actual angle of the V-crossing at the gauge intersection is 1:5.93 RAM = 9.57 degrees.

 

1 in 5.93 RAM  ( 1 in 5.97 CLM ) curviform V-crossing

 

By comparing the splice rail with the straight edge of the ruler you can see that the splice rail is curved.

 

p.s. this is the Peco Large-Radius Turnout. Are you confusing it with the Medium-Radius Turnout (not shown)? The turnout radius shown (1138mm / 44.8") is correct for the large-radius turnout.

 

For more about Peco geometry, see 8 pages of recent topic: http://www.rmweb.co.uk/community/index.php?/topic/103006-peco-ooho-large-radius-point-measurement-query/&do=findComment&comment=2019037

 

regards,

 

Martin.

The drawing is curved but the actual hard copy plastic and metal point has two straight rails, If you put a ruler along them they are straight. combining at the frog, the insulfrog has a tiny sliver of plastic between and a vestigial plastic frog, the electro frog vary but also have two separate rails, none are like the drawing above.

The real world large radius point does not curve beyond the gauge intersection so a frog angle of 9.57 degrees is about right.  You can cut some sleeper webs and tweak the end into a curve but that is not how they come from the factory

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Any more on the difference between code 100 and code 75 points?

 

Ed

 

Martin-how did the Peco points get into Templot, did you measure them or did Peco give you the info.?

Comparing some of mine I can't see any difference apart from the rail section. Apart from the plastic check rails, the sleeper mouldings also appears to be identical. The only other difference I can find is that the wipers welded to the code 100 switch blades to improve electrical contact are missing in code 75. Peco presumably assume (or have found) that modellers choosing code 75 are advanced enough to switch frog polarity.

That applies to simple turnouts but the code 75 three way point is asymetrical so different from Code 100.

 

Peco's templates for Streamline are photographic or possibly scanned images of the relevant track items; that does show a difference between code 100 and 75 and the termplates ARE different. The 83 line templates are drawings rather than actual images so presumably were prepared before production items were available.

 

David: 

The large radius points are curved beyond the frog  though I had to scan one and print out the enlarged frog end to see it clearly. Martin's figures are correct, the angle at the V is about 9 1/2 degrees and the final divergence angle is 12 degrees. The short and medium turnouts are straight between the V and the end and the geometry of that end of them is identical. 

Edited by Pacific231G
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Martin-how did the Peco points get into Templot, did you measure them or did Peco give you the info.?

 

Hi Ed,

 

I calculated them from the published template drawings and the published data.

 

The 3 significant published dimensions are swing 12 degrees to offset 25.4mm, and the length.

 

regards,

 

Martin.

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Some batches of Code 100 streamline points lacked the wipers, Peco told us the were un necessary when we complained, the points were entirely useless but we got some damaged ones for £1 each and after some repairs used them instead.   The tags subsequently returned

 

I have measured several Peco long radius points against a steel ruler within the last ten minutes, none of them new, but left and right, electrofrog and insulfrog and the divergence angle is the frog angle on all of them. All the frog rails are dead straight measured against a ruler and the last 40mm or so or the "Curved rail" is also straight.  I cut the webs between sleepers and curve the ends of these points to increase or decrease the angle and save a  millimetre or two when tracklaying.

 

The medium and short radius also have straight frog rails but the short has a slightly shorter rail and a slightly wider divergence angle.  (See my previous pictures)  Nonel of the points have "Frogs" as a separate piece, though from a separate thread about electro frog conversions, you can replace the plastic frog nose moulded into the base of old insulfrog points with a piece of NS rail filed to shape to convert them to electrofrog

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I have measured several Peco long radius points against a steel ruler within the last ten minutes, none of them new, but left and right, electrofrog and insulfrog and the divergence angle is the frog angle on all of them. All the frog rails are dead straight measured against a ruler and the last 40mm or so or the "Curved rail" is also straight.

 

Hi David,

 

You seem to be saying that your Peco turnouts are faulty and not as described by Peco. In which case I think you should return them to the supplier for replacement.

 

Here is part of Peco's published drawing for these turnouts. I have added some yellow straight lines along the rails, which clearly show that both the point rail and the stock rail are curved.

 

I have also added some red lines across the rail ends, and measured the angle by rotating the image. It is 12 degrees as specified by Peco.

 

2_230756_220000000.png

 

If production turnouts do not match this drawing they are clearly faulty, and need to be returned to Peco so that they are aware of the problem.

 

regards,

 

Martin.

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Some batches of Code 100 streamline points lacked the wipers, Peco told us the were un necessary when we complained, the points were entirely useless but we got some damaged ones for £1 each and after some repairs used them instead.   The tags subsequently returned

 

I have measured several Peco long radius points against a steel ruler within the last ten minutes, none of them new, but left and right, electrofrog and insulfrog and the divergence angle is the frog angle on all of them. All the frog rails are dead straight measured against a ruler and the last 40mm or so or the "Curved rail" is also straight.  I cut the webs between sleepers and curve the ends of these points to increase or decrease the angle and save a  millimetre or two when tracklaying.

 

The medium and short radius also have straight frog rails but the short has a slightly shorter rail and a slightly wider divergence angle.  (See my previous pictures)  Nonel of the points have "Frogs" as a separate piece, though from a separate thread about electro frog conversions, you can replace the plastic frog nose moulded into the base of old insulfrog points with a piece of NS rail filed to shape to convert them to electrofrog

Hi David

Despite the Peco template I half convinced myself that a Peco large radius turnout I was looking at last night had straight rails from the crossing V to the heel. When  I put it on the scanner and blew up my own image I was easily able to detect the curvature.

post-6882-0-33369000-1445605739_thumb.jpg

You should be able to see the slight curvature on the oriignal image but drawing a straight line along the gauge corner should make it clearer.

post-6882-0-89843600-1445606267_thumb.jpg

measuring the crossing angle from this with a protractor gave about 9 1/2 degrees and a final divergence angle of 12 degrees.

 

I also managed to half convince myself by eye that there was a slight curvature in the point rail of a couple of Code 75 medium points but this was an optical illusion.

I've been looking at several small and medium radius points and though there are slight differences between those manufactured at different times, those from about the same time are identical from the throat to the heel end as this scan of two code 75 points of similar age should show

post-6882-0-00881800-1445608263_thumb.jpg

. If you look closely at Streamline points you'll also notice a surpisingly large commonality of components. On these two points everything including the first few timbers, apart of course from the curvature and position of the diverging switch and stock rails, is identical from the throat end to just before the loose heel (where the switch rails are hinged)  as is everything from the diverging end to the crossing (frog) throat, it's in the middle that they differ. 

 

By the way. looking at your collection of old points I too have a box of these I use for trying out track plans (and for reminding myself not to use slips !!). Don't assume that they're as they were originally supplied.

Edited by Pacific231G
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Er as I said many posts ago  "The Medium and Small radius points look fine and work fine but there are issues with the long radius points.   They use the same track spacing but a shallower frog angle in plastic and metal compared to the small and medium, even if the spec sheet says otherwise."

 

All my long radius points are between 48 and 52 mm from the frog to the heel of the point,  The small and medium 40mm to 44mm.  In hard copy nickel silver and plastic if you line up the diverging rails of a large radius with a small or medium radius to lay a crossover then the "straight" tracks are not parallel.  If the straights are parallel then there is a kink where the points join. The divergence angles are different, the frog angles have to be different, you can clearly see this in my photos but the software programs don't show this, in fact if you do it with the software it fits beautifully.  

 

My 2ft radius point is clearly different to my 3ft as can be seen from the photo, Peco may well have commonised the frog assembly between 2ft and 3ft radius for recent production but it seems unlikely that they could use the same frog for the large radius as well    

 

Could someone post a photograph of a new code 75 large radius point so we can pore over it in 2 1/2 times magnification? 

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Er as I said many posts ago  "The Medium and Small radius points look fine and work fine but there are issues with the long radius points.   They use the same track spacing but a shallower frog angle in plastic and metal compared to the small and medium, even if the spec sheet says otherwise."

Which everyone has agreed, the frog angle is approximately 9.5 degrees and the curve beyond the frog brings the turnout divergence angle to 12 degrees. The spec sheet only gives the turnout divergence angle not the frog angle.

 

Could someone post a photograph of a new code 75 large radius point so we can pore over it in 2 1/2 times magnification? 

Is that not exactly what Pacific231G has just done, and the curve concerned is clearly visible?

Regards

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Er as I said many posts ago  "The Medium and Small radius points look fine and work fine but there are issues with the long radius points.   They use the same track spacing but a shallower frog angle in plastic and metal compared to the small and medium, even if the spec sheet says otherwise."

 

All my long radius points are between 48 and 52 mm from the frog to the heel of the point,  The small and medium 40mm to 44mm.  In hard copy nickel silver and plastic if you line up the diverging rails of a large radius with a small or medium radius to lay a crossover then the "straight" tracks are not parallel.  If the straights are parallel then there is a kink where the points join. The divergence angles are different, the frog angles have to be different, you can clearly see this in my photos but the software programs don't show this, in fact if you do it with the software it fits beautifully.  

 

My 2ft radius point is clearly different to my 3ft as can be seen from the photo, Peco may well have commonised the frog assembly between 2ft and 3ft radius for recent production but it seems unlikely that they could use the same frog for the large radius as well    

 

Could someone post a photograph of a new code 75 large radius point so we can pore over it in 2 1/2 times magnification? 

David

Your small and medium radius points appear to be from different periods and are both fairly old and from a time when the crossing clearances were far greater than they are now (I've got a few of those in the planning box and the crossings/frogs look horrible) 

You should also be aware that on old points, especially if they'e been bashed around a bit, the stock rails can creep a little and that, possibly combined with slight manufacturing differences may explain why you're getting kinks on straight crossovers. Current production is completely in line with the printable templates they offer so I'd suggest that rather than just looking at the spec. sheets you print those off  and compare the older points you've got with them.

 

Which everyone has agreed, the frog angle is approximately 9.5 degrees and the curve beyond the frog brings the turnout divergence angle to 12 degrees. The spec sheet only gives the turnout divergence angle not the frog angle.

 Is that not exactly what Pacific231G has just done, and the curve concerned is clearly visible?

Regards

 

The large radius point I scanned for post 31 was actually a Code 100 electrofrog but it did confirm what I already knew about the shallower frog and the curved rail beyond it. I don't have a code 75 large radius point but For all three radii Peco use the same base mouldings for both rail sizes so only the rail section, possibly the crossing clearance  and the height of the plastic check rails are different. To check that I've just printed off the code 75 large radius template and laid a code 100 point over it and it lines up perfectly.

 

Apart from those for the 83 line, the templates on Peco's site are scans of actual production items and their mass production now seems to be very consistent with the same final divergence angles. If you're using older examples to make crossovers and they're not lining up properly I'd suggest checking the stock rail position and if necesssary a few strokes of the file to square them up. You'll need to cut the rail ends anyway if you want to create a narrower six foot way (2 metre way nowadays) between parallel tracks.

Edited by Pacific231G
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Not being into peco, or any other 4mm track, I could make a couple of points.

 

Martin's image, post #30, should the red line at the end of the curved branch be at 90 degrees to the yellow lines? Having loaded the image into my cad program and done a quick check, it looks more like an angle of 87 degrees. If it were 90 degress, then the 12 degrees would be about 9 degrees.

 

David's post #15,  the image showing the 'kink' with the long and short points, said kink would be more significant if the straight tracks were exactly parallel.

 

Trying not to be to critical, but when the small differences that we are looking at is not easy to see in images, I tend to notice odd things, that probably don't matter.

 

Best wishes,

 

Ray

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Martin's image, post #30, should the red line at the end of the curved branch be at 90 degrees to the yellow lines?

 

Hi Ray,

 

No. The red line is at 12 degrees across the rail ends. The yellow lines are chords along the curved rails to demonstrate that they are curved -- you can see the versine gap at the centre between the chord line and the curved arc.

 

Here it is again with blue lines at 90 degrees to the red line, i.e. the blue lines are tangential to the curve exit at 12 degrees.

 

post-1103-0-70138400-1445691657.png

 

The blue lines should align smoothly with the rail ends and connect to the next track. Although this is true for the stock rail, the point rail appears to be not quite tangential at the rail end. It might need bending a fraction more at the end when fitting the rail joiners to make a smooth connection. It might also be a good idea to file across both rail ends to make sure they are in line, using the 12 degree angle on the end timber as a guide.

 

regards,

 

Martin.

Edited by martin_wynne
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Paicific 231G

 

The points in post 31 are a small radius and a medium    The Small radius is 25 sleepers long, Medium is 30 sleepers long and the large 35 sleepers long.

 

The large radius in my hand is 52 mm from the point of the frog to the heel and the medium 44mm.  We are comparing apples with aubergines here.

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I think Ian's question was answered quite early on. All this techy stuff is interesting but I don't believe that it will improve any layout planning. The best thing to do with Peco track is to print off a set of their templates. Along with some wallpaper (use the back not the pretty side) a pencil, something long and straight guide the pencil and a tube of pritstick have some fun doing your track plan.

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Paicific 231G

 

The points in post 31 are a small radius and a medium    The Small radius is 25 sleepers long, Medium is 30 sleepers long and the large 35 sleepers long.

 

The large radius in my hand is 52 mm from the point of the frog to the heel and the medium 44mm.  We are comparing apples with aubergines here.

Hi David

The two points in the lowest picture in post 31 are small and medium but the scan of the frog end in the first two images are of the same large radius point with lines added to the second image to clarify the curvature. 

 I never suggested that the frog end of the large radius point WAS the same as the small and medium, quite the opposite in fact. What makes comparing all three of them not apples and aubergines is that the large radius ends up with exactly the same final divergence angle as the small and medium but uses a curved crossing and curved rails beyond the nose to achieve that. I think that does have some effect on the movement of vehicles passing over pointwork. 

 

You were asking for a scan of the code 75 large radius point and I've now found that I do have a couple of them so here they are. The timbering and overall geometry is identical with the Code 100 equivalent. The crossing gaps (though not the check rail gaps) appear to be slightly finer with code 75 but that may be an optical illusoon because when I've actually measured them I've been able to find very little actual difference and they seems to be using a 1.25 mm gap

post-6882-0-44421200-1445771081_thumb.jpg

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I think Ian's question was answered quite early on. All this techy stuff is interesting but I don't believe that it will improve any layout planning. The best thing to do with Peco track is to print off a set of their templates. Along with some wallpaper (use the back not the pretty side) a pencil, something long and straight guide the pencil and a tube of pritstick have some fun doing your track plan.

 

Indeed it was. However, I seem to have started a bit of a discussion on this issue! What I can't get my head around is that the basic geometry of the Peco turnouts does not seem to be 'cast in stone'. Clearly I can live with the odd mis-alignment, because a bit of 'fettling' here and there will get the alignment back. However, my plan will be relying on a layout drawn up in software and I really don't want to end up with any 'surprises' once I get around to actually building it. But, like I said, I'm sure most of these can be worked around with a bit of 'cutting and bending' at the heel of the turnout crossing.

 

The main issue is to be able to get good reliable running through the turnouts, without any obvious 'jumps'.Such things just don't look good.

 

Ian

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Indeed it was. However, I seem to have started a bit of a discussion on this issue! What I can't get my head around is that the basic geometry of the Peco turnouts does not seem to be 'cast in stone'.

The main issue is to be able to get good reliable running through the turnouts, without any obvious 'jumps'.Such things just don't look good.

 

Ian

Hi Ian

So far the comparisons I've made with relatively recent examples indicate a far greater degree of consistency than I'd expected. For instance, I've just stacked six assorted (left right and code 100 & 75) large radius points on top of one another and they line up perfectly.  as do the divergence angles of a mixture of all three radii.

There have been changes in manufacturing over the past fifty years or more and If you use second hand points made some time ago and possibly a bit distorted in service then there probably will be differences. However, anything reasonably new and straight out of the box does seems to be spot on with their full size planning templates (something that I'm not aware any other manufacturer provides). I've also planned out trackwork using XtrkCad and AnyRail and not noticed any real differences when setting them out physically.

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Sorry to resurrect this this thread (and change the Gauge) but I have just tried to use a code 55 long crossing with code 55 large radius points and they don't line up very well for some reason. The crossing seems to have a shallower angle than the points. I'm assuming that N gauge is the same template for OO when using streamline track?

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  • 3 years later...
  • 1 year later...

 

yeah - surely all this PECO frog angle & radius of curve would be sorted if Peco had the sense & courtesy to publish PROPER engineering drawings instead of photographs with pathetic rulers?
Radius? - DEFINE your AXIS
Frog angle? DEFINE your AXIS
I cannot comprehend how a supposedly reputed Manufactuter is determined to be so recalcitrant!!!!

 

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39 minutes ago, Bebbspoke said:

 

yeah - surely all this PECO frog angle & radius of curve would be sorted if Peco had the sense & courtesy to publish PROPER engineering drawings instead of photographs with pathetic rulers?
Radius? - DEFINE your AXIS
Frog angle? DEFINE your AXIS
I cannot comprehend how a supposedly reputed Manufactuter is determined to be so recalcitrant!!!!

 

I doubt that it would make any difference. How many millions of points have they sold over the decades? The vast majority of customers have no idea that they aren't technically accurate and even those that do, most still buy them.

There are other choices.

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Having read through this resurrected thread, and the discussions

contained therein,I 'm reminded of a phrase my father used:

 

Near enough isn't good enough, When it's exact, that's near enough.

 

In this case though, I do think some of the arguments are a little extreme.

 

We're modelling railways, not laying 1:1 track for 100+mph running.

Does a difference of a few thou (sorry, fractions of a mm)

here or there,really matter?

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FWIW: More recent Peco templates are not photographs - they are computer generated images, presumably derived from the CAD designs in some way. In those cases, since we know that PDFs hold dimensions accurately we can be sure that the template are reasonably precise.

 

They are still not engineering drawings but I'm not sure that's really needed when many people have successfully derived working geometries for these parts from the information we do have.

 

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10 hours ago, kevinlms said:

I doubt that it would make any difference. How many millions of points have they sold over the decades? The vast majority of customers have no idea that they aren't technically accurate and even those that do, most still buy them.

There are other choices.

 

 

I agree whilst Peco sell a few track building parts they are in the business of selling RTR track and all the different parts should easily connect together

 

As for listing data, anyone building their own track is highly likely to obtain better quality plans, where Peco's track plans are for layout planning, not track building

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7 hours ago, Harlequin said:

FWIW: More recent Peco templates are not photographs - they are computer generated images, presumably derived from the CAD designs in some way. In those cases, since we know that PDFs hold dimensions accurately we can be sure that the template are reasonably precise.

 

They are still not engineering drawings but I'm not sure that's really needed when many people have successfully derived working geometries for these parts from the information we do have.

 

I'd noticed that with the 83 line templates but assumed it was just to get the templates out at the same time as the product. It's interesting that people are complaining about Peco's full size templates when, AFAIK, they're the only manufacturer to supply them at all. The only point of an engineering drawing would be to enable you to build points wih the same geometry yourself and that's obviously not  what Peco want you to do. 

The question of the actual radius is interesting because just about every turnout quoted as three foot radius, that I've been able to get hold of, including SMP, has a very similar if not identical curve to Peco's medium radius.  I assume that it's the notional radius of a constant curve from the end of the switch to the crossing but, as the actual curve is more of a transition, then the minmum radius would be less. 

 

I also notice that Bebbspoke's post on this is his first on RMWEB despite having joined almost a year ago. We may choose to draw a conclusion  from that.

 

Edited by Pacific231G
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