figure 8

[Highfiver]

How much Bachmann ez HO track do I need for a figure 8 using the 45 degree and the 90 degree crossovers ?    Can I make the figure 8 smaller or larger by not using as many track ? I know that I need 22 curved track to use the 30 degree layout but I don't have that much room.

[jward]

using a 30 degree crossing gives the most compact figure 8 you can build with available components. if you don't have room for that one, you won't be able to build any of the others....

dimensions taken from the book "atlas HO layouts for every space".......since the standard atlas and ez track straights and 18" radius curves have the same geometry, these dimensions should apply to ez track as well.....

30 degree crossing......42" x 78"....22 curves, 1 30 degree crossing
60 degree crossing......42" x 84"....20 curves, 4 9" straights, 1 60 degree crossing
90 degree crossing......42" x 90"....18 curves, 4 9" straights, 4 6" straights, 1 90 degree crossing

[Highfiver]

Thank you !  Those dimensions were very helpful.
If I have 40" x 90"  - can I just use 4 short straight track instead of the 9" straight to make it a bit shorter

[jward]

no. the radius of the curves determines the width of the table.  as such, you can't shorten the straights as they are all used in the center of the layout to connect the curves to the crossing....the dimensions given in the atlas book  give a little breathing room along the edges. you should be able to squeeze an 18" radius circle into 40" but your track is goiing to be very close to the edge.

[ACY]

I found on another website a person asked a similar question, as it turns out, you need about 40.5" without having any overhang with the track extending over the table, so it will be close depending on how wide your space actually is. The only way to find out is to try it, but I would not recommend it because it is pretty risky running that close to the edge without anything like Plexiglas keep it from falling, but because there may be a slight overhang you may not have room for that.

[pjsdad]

EZtrack is 2 inches wide so an 18 inch circle (the end of your figure needs 38 inches without overhang. I don't know where those other numbers come from. With 40 you should have plenty of room for a guard of some sort, or if one side is against a wall run the track against the wall and have 2 inches in front.

[ACY]

EZtrack is 2 inches wide so an 18 inch circle (the end of your figure needs 38 inches without overhang. I don't know where those other numbers come from. With 40 you should have plenty of room for a guard of some sort, or if one side is against a wall run the track against the wall and have 2 inches in front.

I think you are the one that is a bit confused, we are talking about a figure 8 layout, which supposedly requires about 40.5", you are talking about a basic circle/oval with 18" radius curves, also known as 36" diameter/wide, and that would afford sufficient space, as I believe it is 36" diameter center line to center line and the track base isn't more than 2.5" wide, so that makes the total width about 38-39" with .5 to 1 inch on either side. But if the track goes a little over then he can't build an guards.

[jward]

acy forgive me if i am wrong, but wouldn't a figure 8 layout be the same width as a circle of whatever radius track you are using? only the length of the layout should change based upon the degree of the crossing.

without testing out the configuration, just working with the numbers, if you have a circle of 18" radius track and you want to add another one on  a 2 1/4" centerline from the first track, your radius for the second track would be 20 1/4" making your diameter 40 1/2"......given that you could lay a second track on this centerline, and run trains  on both tracks without sideswiping, i'd say 40 1/2" would be more that enough room. you should actually be able to get that table width down to about 38 1/4" minimum without sidewiping the wall or track hanging over the edge. but it would be very close, and you'd need to have everything precisely centered.

[ACY]

When you add the 30 degree crossing, I think it would add a little bit of extra width to account for, at least it seems but it is entirely possible that the person on the forum I checked, incorrectly stated that it required about 40.5". I'll check it out in any rail...

[pjsdad]

right, i was figuring the width of the "8" is the same as a circle. (2*18+2=38)
Likely the dimensions in the first post are correct with a 2 inch margin all around. If you want I'll break out the trig tables and work out the length of a figure 8..

[ACY]

Went on Anyrail, it appears that it requires some adjusting with 18" radius and a 30 degree crossing, and if it worked out, I measured that it comes to 40" diameter because the track needs to be adjusted a bit to make it work resulting in a larger diameter.

[jward]

interesting......
what is the length of the legs of the ez track 30 degree crossing? the atlas one used in the plans i consulted is 4" long.

[ACY]

It is almost 13" long according to anyrail. The Atlas one, according to anyrail, is about 4" like you said. After doing some figuring if chooses the 30 degree one he will not have enough room because the Bachmann crossings are longer than the Atlas ones used for the dimensions you gave earlier. Here is a pic:

[Doneldon]

I just love math problems, but there isn't one here.

The length or width of the crossing is irrelevant since a figure eight arrangement doesn't have a full circle in the first place. Consequently, an 18" radius "end" of the figure eight can be made with just curved sections and be about 38.5" wide at its widest point. Adding a concentric circle on the outside of this with a 20" diameter plus clearance on the insides and roadbed on the outsides would lead to a grand total of 43.5" in width. It's easiest to understand if you ignore the 18" radius circle and just think of a 20" radius circle plus an extra inch for additional clearance between the two tracks. That's 41", plus we must add half of the width of the track and roadbed twice, which is, of course, the width of the track and roadbed, 2.5". We have a grand total of 43.5" which would leave 2.25" on each side of a 48" panel which is not enough for safety in the event of a table edge derailment. So there needs to be a fence at the edge of the table or a net below it. Twenty-four inch radius curves would also fit, barely, but without enough space for a table-edge fence where the trains swing into or out of a curve.

However, Jim Banner has a dandy way to correct for this: Just screw 1x2 material on flat along each edge of the train table and gain another 1.75" of clearance. This will be plenty of space for fences or walls to contain mishaps at the edges of the table. This is a simple but elegant solution to the problem.

                                                                                                                       -- D

[jward]

that thing is HUGE.....

well the atlas dimensions will work if the atlas crossing is substituted for the ez tracj one. the curves and straights are the same. and the atlas crossing will work if it is shimmed up with cork roadbed or 1/4" flat moulding strip.