Help on cutting out part of layout

[wilson44512]

I need to cut out a oval pattern with 2 straights on plywood so i could elevate my second train. I need it 3 inches wide all the way around with the ez track in the middle. what im having trouble with is messuering the curvse to cut. can any one tell me how to measure it si i get perfect curves?

[mabloodhound]

That's not a true oval because you have two straight sections.   Use your grid to obtain Radii measurements for the curves and then plot the radius center on your plywood.   Use a string with a pin in one end and a pencil tied to the other end, set the length of the radius and swing the arc.   re-set the pin for the second radius and swing it again.
Connect the two radii with straight lines.
Cut to your lines and you're done.

[Doneldon]

wilson-

This is very easy with sectional track: Lay out your track on the plywood and trace around it with the clearance you want. Then just cut it out. You don't have to worry about laying out grids or finding centerpoints.

If you do want to draw it out (I can't imagine why you would), use mabloodhound's technique. The centers of your two curves should be in the exact middle of your board side-to-side and the radius of your curves plus 1.5 inches from the ends. Such a layout will leave you with very narrow areas along the outside of the track, meaning that trains are likely to hit the floor with any kind of a problem like a derailment. I suggest that you allow a little bit more room along your edges for safety. Also, the corners can be useful space for scenery or a spur track. Last, consider a longer layout. It's really neat to watch your trains heading down a straightaway and the extra length will make it easy to use turnouts to add some tracks in the middle.

Good luck with your layout and welcome to our hobby!
                                                                                    -- D

[Jim Banner]

That's not a true oval because you have two straight sections.

If you define an oval as two pairs of arcs with two different radii, then then the oval of which wilson44512 speaks is one where one of the pairs of arcs has an infinite radius.  But it may not be an oval by several other definitions.  This begets the questions "which definition is correct?" and "what exactly is a 'true' oval?"  All I can say for sure is that an oval is not an ellipse and vice versa.

Jim

[Terry Toenges]

So these are not ovals? Then what are they? I'm confused.
http://www.thortrains.net/4holay4.html

http://www.tiny-trains.net/product/4X7
http://www.scale-modelers-handbook.com/support-files/modelrailroaddesignsecrets.pdf
http://www.model-train-tips.com/blog/model-railroad-layouts/the-c-g-rr-layout/

http://benchnotes.com/Laying%20out%20an%20oval/laving_out_an_oval.htm


As an aside - How many of you have beards?
http://www.csmonitor.com/2004/1221/p16s02-bogn.html

[Doneldon]

So these are not ovals? Then what are they?

Terry-

Colloquially, they are ovals. More precisely, they are oblongs.

                                                                                  -- D

[electrical whiz kid]

Don;
They're known technically as "oblongs"?  Hmm...  I do learn something new every day.
PS:  I have had a beard since I was two...
Rich