Scissors crossover alignment problem

[Frank]

Hello Martin,

In order to understand how to do, I am looking into building a scissors crossover from design to lasercut. So I started to read Archive topic 465 from John Preston. All the steps I have done can you find in the word document. Also I added the box file. When I look to the final result in the figure below, the exercise looks rather okay, I thought, although it just fits because of the minimal adjacent centre distance of 44,67 mm I used. But there is a small problem and I don’t know how to solve this in a proper manner. The problem is that the inner track doesn’t fit exactly inside the pie slice determined by the radius and the angle made by the outer track. The rootcause is of course that all turnouts are the same (N=8) where the inner turnouts should have a bit smaller radius and factor N. ... and this causes again that I cannot put the timbers in both the upper left as right area opposite to each other. Do you have an idea how I can solve this?

 

[Martin Wynne]

@Frank

Hi Frank,

Your result is prototypically correct. The length of a turnout doesn't change when laid in curved track, so on a smaller radius it will turn through a larger angle. The timbers don't need to line up, in fact being staggered helps in arranging the rodding runs.

But topic 465 is 15 years old! There have been a great many updates and new features in Templot since then which make it much easier to create a scissors crossover now. I'm sure I covered the process recently, possibly in a Zoom meeting, but I can't find it. Anyone?

p.s. Frank, your check rails need extending to cover the V-crossings in the turnouts:

cheers,

Martin.

 

[Frank]

@Frank

Hi Frank,

Your result is prototypically correct. The length of a turnout doesn't change when laid in curved track, so on a smaller radius it will turn through a larger angle. The timbers don't need to line up, in fact being staggered helps in arranging the rodding runs.

But topic 465 is 15 years old! There have been a great many updates and new features in Templot since then which make it much easier to create a scissors crossover now. I'm sure I covered the process recently, possibly in a Zoom meeting, but I can't find it. Anyone?

p.s. Frank, your check rails need extending to cover the V-crossings in the turnouts:

View attachment 6822

cheers,

Martin.

Hi Martin,

Thank you for the quick response. You're right: I completely overlooked those check rails to cover the V-crossings. They are far too short now! Your reference to that recent zoom meeting or wherever it was makes me very curious. Hopefully someone can find, has written down, something regarding these new insights, methods, etc. to make this construction in an easier way. I am highly recommended.

Thanks in advance!

Best regards,
Frank

 

[Martin Wynne]

@Frank

Hi Frank,

It's buried somewhere in one of the Zoom recordings.

I will make another video, maybe later today, so that it's easier to find.

cheers,

Martin.

 

[Terry Downes]

some of the answers and useful links can be found within the share and show topic 00-SF Princes Risborough....

 

[Martin Wynne]

@Terry Downes @Frank

Many thanks Terry.

Frank, Terry has found us the Zoom recording I was thinking of -- it's here, with Terry:

SCRUFF ZOOM 20th MARCH 2023

As that's straight and mixed with regular diamonds and maps I should probably make a proper tutorial video for a plain type 2 curved scissors. I will do that soon. Nudge me if I forget.

cheers,

Martin.

 

[Frank]

@Terry Downes @Martin Wynne

Hi Martin,

I will help you not to forget ! In Holland we have a saying: "Een knoop in je zakdoek leggen" translated something like: "Tie a knot in your handkerchief" ....maybe that helps. Many thanks to you and Terry for helping! Iwill take a look what Terry has found!

Best regards,
Frank