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For Layout Planners Who Like Math

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  • Member since
    December 2008
  • From: Heart of Georgia
  • 5,022 posts
Posted by Doughless on Thursday, August 4, 2022 5:49 AM

ATLANTIC CENTRAL

  So I am assuming the storage tracks run the long dimension? That may seem obvious to you, but not out here with us.

Once you get the first one right, the rest are parellel lines.

A chalk line is not eaxpensive, can I send you one?

Sheldon

 

Having a chalk line for this purpose would expand my layout building tools from 3 to 4, and that would be overkill for the hobby. Big Smile

And I want to make sure I get the lengths correct before I fill the benchwork with lines.  I'm not a carpenter by trade so laying lines is usually an iterative process for me, resulting in a lot of lines being laid. 

BTW, I was quick to see the diagram last night. 

Ray's diagram has the long and short sides flipped from the final plan and shows two long ladder tracks, where as the short sides will run from SW to NE and the long sides will run from E to W.  Geometry tells me that swapping the long sides with the short sides will change the shape of the runaround, but won't change the mathematically determined lengths. 

So the short sides will run from SW to NE and will be the ladders.  Only two storage tracks per ladder resulting in shorter storage tracks, but they will abutt the backdrops on the E and W, to give the impression they are long and go into the horizon.  Storage capacity is minimal because of this shape, but, its plenty for the 20 to 25 cars I need to hold in the yard.  About 10 to 12 on each side, each side will make up one or two (about) 68 inch trains that will fit on the runaround.

- Douglas

  • Member since
    December 2008
  • From: Heart of Georgia
  • 5,022 posts
Posted by Doughless on Thursday, August 4, 2022 9:09 AM

ROBERT PETRICK

 

 
Doughless

Now we can adjust the height a bit to see what it does to the length.  If anybody wanted to play along.  I understand if people have better things to do.

 

 

For every inch you increase the "height", you increase the length 8 inches. That's kinda where the No 8 turnout designation comes from. Exactly fits the 7.15 degree angle offset.

 

Ah, yes, of course.  Thanks Robert.

- Douglas

  • Member since
    September 2003
  • From: Omaha, NE
  • 10,325 posts
Posted by dehusman on Thursday, August 4, 2022 9:17 AM

Doughless
The exercise was to understand what the lengths of the pair of sides would be before I started laying out lines or track.

Draw a center line for one ladder, draw the diverging center line.  Then just draw the centerline for the other ladder wherever you want it.  I guess I'm not seeing why it needs to be so precise or one needs all the math.  Laying it out should be fairly straight forward.

Dave H. Painted side goes up. My website : wnbranch.com

  • Member since
    January 2007
  • 268 posts
Posted by Lee 1234 on Thursday, August 4, 2022 9:28 AM

Peco #8

If you lay out 4 of these in a row that's more than 4 feet long.  I did a quick lay out in XTrackCAD and 4 lefts are like 15 inches wide with a diverging angle on the last track 4 times the frog angle.  

L

  • Member since
    December 2008
  • From: Heart of Georgia
  • 5,022 posts
Posted by Doughless on Thursday, August 4, 2022 11:09 AM

dehusman

 

 
Doughless
The exercise was to understand what the lengths of the pair of sides would be before I started laying out lines or track.

 

Draw a center line for one ladder, draw the diverging center line.  Then just draw the centerline for the other ladder wherever you want it.  I guess I'm not seeing why it needs to be so precise or one needs all the math.  Laying it out should be fairly straight forward.

 

This is getting into personal layout situations which I avoided to limit confusion, but i already have the layout built and I wanted to know the runaround length there would be by reconfiguring the runaround.  I wanted to reconfigure to have more straight tracks towards the backdrop over any thing else, but wanted to see if it also increased the runaround lengths.  It does, as expected, but not by very much.

I called it a yard because that's where most folks do the angles and straight line thingy so I thought that it would help them relate.  It appears to have added to the confusion rather than subtracted.  I actually don't care about the placement of the yard tracks, in that they will fill in wherever later.  There is only a need for one or two on each side and they can originate off of any track, frankly.

I can't lay it out and measure accurately because there is already roadbed, track, and caulked and wired.  I want more straight tracks towards the back of the layout than what I have now.  That is the reason for this entire project.

So I'm redesigning on paper before I plunge into making lines that I can't make anyway, especially useful because this situation is dictated by geometric angles and absolutely no curves anywhere to adjust any errors.

Also, I am impressed by the number of comments on this forum that appear to design layouts by understanding the angles and the math of it all, where I never had much need to ever do that.  I thought there would be plenty of responses eager to use calculations.  Frankly, I'm a bit surprised by the number of comments that suggest to just lay it out with templates or draw out lines on the bench before even fashioning a diagram.  Oh well.

- Douglas

DrW
  • Member since
    January 2008
  • From: Lubbock, TX
  • 302 posts
Posted by DrW on Thursday, August 4, 2022 11:23 AM

Much of the confusion arose because the OP called it a rhombus. A rhombus has four sides of equal length. What he wanted was a parallelogram, as has been figured out by now.

JW

  • Member since
    January 2014
  • 1,416 posts
Posted by ROBERT PETRICK on Thursday, August 4, 2022 11:37 AM

DrW

Much of the confusion arose because the OP called it a rhombus. A rhombus has four sides of equal length. What he wanted was a parallelogram, as has been figured out by now.

JW

Yes, exactly.

LINK to SNSR Blog


  • Member since
    December 2008
  • From: Heart of Georgia
  • 5,022 posts
Posted by Doughless on Thursday, August 4, 2022 12:58 PM

ROBERT PETRICK
My question is why a rhombus?

I guess you knew the term was wrong back then but said nothing.  Thanks.

ROBERT PETRICK
You suggested this simple solution a few posts earlier where this could be solved to a pretty close tolerance by carefully laying out two parallel lines 9" apart and slicing another line across at a 7.15 degree angle and then measuring the results

As revealed in my post to Dave, there is existing track in the way preventing any sort of straight lines being drawn.  I did not reveal this early because I know the habit of members to devise alternative plans or alternative methods...like iterating lines or downloading software ...and just wanted to stick with the mathematical answer to the question because that answer was all that I needed before I started.

 But, if I were to draw lines on the bench first, what tool do I use to make sure the angle is 7.15 and not 7.0 or 7.25?

- Douglas

  • Member since
    January 2014
  • 1,416 posts
Posted by ROBERT PETRICK on Thursday, August 4, 2022 1:50 PM

Doughless

But, if I were to draw lines on the bench first, what tool do I use to make sure the angle is 7.15 and not 7.0 or 7.25?

Here's how I would do it:

Measure horizontally 8 inches and then vertically 1 inch and put a small mark. Or 16 inches horizontally and 2 inches vertically. Or 24 inches and 3 inches. And so forth. This is the analog solution to a trigonometric calculation. You would be marking out the sine and cosine of 7.15 degrees. This could also be done easily using a 24" framing square.

Sheldon started out life as a draftsman. So did I.

Hope this helps.

Robert 

LINK to SNSR Blog


  • Member since
    December 2008
  • From: Heart of Georgia
  • 5,022 posts
Posted by Doughless on Thursday, August 4, 2022 2:04 PM

ROBERT PETRICK

 

 
Doughless

But, if I were to draw lines on the bench first, what tool do I use to make sure the angle is 7.15 and not 7.0 or 7.25?

 

 

Here's how I would do it:

Measure horizontally 8 inches and then vertically 1 inch and put a small mark. Or 16 inches horizontally and 2 inches vertically. Or 24 inches and 3 inches. And so forth. This is the analog solution to a trigonometric calculation. You would be marking out the sine and cosine of 7.15 degrees. This could also be done easily using a 24" framing square.

Sheldon started out life as a draftsman. So did I.

Hope this helps.

Robert 

 

Duh, ok.  It goes back to the basis of the #8 frog.  1 for every 8, another way to think of it.

- Douglas

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