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Discussion Starter #1 (Edited)
I'm just planning out my first layout with Tomy/AFX HO track and I have a question about curve radius. If I have this right, a 9" radius turn fits perfectly inside a 12" radius turn. But I also see that Tomy makes an 18" radius turn. Does the 12" fit correctly inside the 18"?

I guess I just don' understand the math. Where is the radius of a curve measured? The inside edge of the curve? The center?

The pieces I'm looking at now are banked turns and as I mentioned, I see a 9", 12" and an 18" available. I'm wondering if this means for a 4 lane track I can do either a 9 inside of a 12 or a 12 inside of an 18. Am I on the right "track" here?

Thanks for the help
Brian A
 

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The standard width of HO track is 3". Depending on the brand of track, there will be everything from 6", 9", 12" 15", and lastly 18" curves. This is measured from the center of a circle to the outside of the curve. This way, the next curve larger can nest properly with the next smaller sized curve. You can think of it this way, the track width stays 3" wide through the turn. You are close with your guess. You just missed the 15" curve. Hope this helps!! :)
 

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The only banked turns are 9" and 12". The 9" bank is marginally usable with cars that do not have traction magnets of some sort.

The flat turns all nest in 3" radius increments as expected with some minor gaps due to manufacturing tolerances (or lack thereof):

6->9->12->15->18

A 10-lane flat track is very doable. There's also a 3" hairpin. Kind of a freaky piece, but if you are willing to compromise on driveability, it's technically feasible to get a 12 lane Tomy track.
 

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I would like to see the link to the 18" banked turn. As far as I've seen, they only make the 9 and 12 in banked turns, the rest are flat. Tomy/AFX measures the outside radius of the turn, so there is a 15" radius in between the 12 and 18. THEORETICALLY, the 9" banked turn fits perfectly inside the 12" banked turn. If it's permanently mounted, I guess it could, with some work. But the reality is all this track is made in China, and has some quality issues. The other issue is how big of a track you are going to make. I mounted mine on a 16x4. It was too much straightaway for these tight radius turns. The bottom lane wasn't competitive with the top three. On a smaller layout, it might work better.
I built my track here..... http://www.hobbytalk.com/bbs1/showthread.php?t=220632

and tore it down here..... http://www.hobbytalk.com/bbs1/showthread.php?t=250705

I would still like to build another banked oval track. It would be a lot better if Tomy would make a 15" banked turn, or if lifelike would make a matching 9" radius turn for there less radically banked 12" turn. I hope this wasn't discouraging, just thought the info might be helpful.
Maybe you can pioneer some technic that might make it all work?

Rich
www.myspace.com/northtexasslotcars :thumbsup:
 

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Discussion Starter #6
The other issue is how big of a track you are going to make.
Hi Rich, I'm planning a 4x8 layout. Sounding like a 4 lane banked turn might not be a good idea. I was thinking of doing something like a 120 degree turn at the end of the main straight like you find on a tri-oval.

Brian A
 

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I would try it anyway. With a much shorter straight, it might work just fine, for magnet cars.
If you're planning to run tjets, or even magnatractions, the banking is too steep for them.
Some guys on this board have successfully put a slight bank in flat track, that's another thought.

Rich
 

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...or if lifelike would make a matching 9" radius turn for there less radically banked 12" turn.
Little known fact - Lifelike did make a 9" 1/8" banked curve. It was found, as far as I can tell, only in the Disney Test Track set. They never marketed it seperately. The only loose pieces of Lifelike curves available are 9" 1/4 curves and 12" 1/8 banks (with molded outside wall).

This is one of two useful pieces of track that were made for a set but never made generally available. The other is a 3" straight made by Mattel and found only in the Harry Potter set.

Joe
 

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I've got some of those 9" 1/8 banked turns. The banking on them is the same as the Tyco and Tomy tracks,
much steeper, so they don't fit inside the 12s right. It's almost like they designed the 12s to fit around the flat 9s.
My first track build was a LifeLike 4 laner with the 12" banked turns.

 

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And a choking hazard to boot !

CPSC Information /!\ WARNING: CHOKING HAZARD ... Something tells me that running with a pair of these in your hand is trouble too. ;) nd
 

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These curves can be banked as follows:

1) Get a couple of your friends over to help you lift one side of your track table off the floor approximately 6-10 inches.

2) Place blocks of wood or one week's supply of free yellow pages phone books under each of the raised table legs.

There you have it.

CPSC Information! WARNING: CHOCKING HAZARD

Do not use your own or others' body parts, live pets, blocks of ice, or mattresses with the tags removed to bank your race track. And oh yeah, avoid raw shellfish.
 

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Discussion Starter #14
For what its worth I heard back from Oakridge Hobbies and they say it is an 18" banked curve...

Hello Brian,
That is correct.
The item is:
TMY-8997
Thank you.

Regards,
Jim
Oakridge Hobbies
800/594-5115
630/435-8657
 

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Discussion Starter #17
Not actually planing to buy it right now so don't wait for me!

I brought it up it my original post just to try to understand how the different radius fit together.

Don't let it stop anyone else from experimenting. I'd love to know how it looks myself!
 

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How many here have Life Like tracks ?

I have a ton of Life Like I've been thinking of building a track with to sell complete at the flea market rather than toss it out .

It's decent track but lacks the radii to be creative.

Gonzo
 

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Discussion Starter #20
Not yet NT. Still working on a new table. If my plans work out right its going to be a hinged two layer with a 1/43 track over an HO.

Brian
 
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