# Curve / radius



## billboquet (Feb 15, 2012)

Hello, I'm a complete beginner in model train, and want to build a layout in 8 x 4', with Atlas code 100. I want a DCC. (HO)
I went to a shop and the guy told me if I will use big locomotive (3 axles) I will need to use maximum 22° maximum.
When I try to use for example Anyrail software to have an idea of kind of layout I could create (with Atlas piece 153 - 558.8 mm 22.5°) the result is huge, I mean just one half of the loop is the half of my layout. 

So I'm little confused because all layout I see on the web are apparently not compatible on what I need or I misunderstood few things in radius / curve definition or restriction

If some of you could bring me little help, or some link to learn more, it would be very appreciated
Thanks
Joel


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## Brakeman Jake (Mar 8, 2009)

There can't be a maximum curve radius,so the numbers manufacturers come up with are minimum radius...a world of difference.I'm in N,but 22 in. as a MINIMUM radius makes sense to me for a six axle HO locomotive,wich doesn't leave much margin for a 4X8 layout.

A radius of 22" means a 44" diameter circle and,as you said,a simple oval will need your whole 4X8,and that is running pretty close to the edge.Hope the confusion is cleared.....


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## billboquet (Feb 15, 2012)

Thank you for your comment.

It's exactly what I though, so when I see such layout that are very nice but not applicable for me
http://mrr.trains.com/How%20To/Track%20Plan%20Database/2010/12/Rosston%20Joelberg%20Holly%20RR%20-CSX%20branch%20line.aspx

And the problem, it's rare to find example that are not just straight lines


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## Davidfd85 (Jul 4, 2011)

I'm not sure if these will help you with what kind of a layout you want to build. This is my first ever layout and it is 4 X 8, now the outside line I could run 3 axle engines it is 22" Rad but the inside is 19" on one end and 18" on the other so I run 2 axle engines only and cars that are 57' or less with no problems. I just took the Falls Mill plan and changed it up some.


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## billboquet (Feb 15, 2012)

Very interesting and good compromise to have different radius to save space and work with smaller locomotive.
I will definitely keep this in mind for the my project
Thanks a lot.
When we start from nothing, a little rock is a mountain for me 
Joel


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## mopac (Feb 24, 2011)

Joel, your hobby shop guy is telling you right about 6 axles need 22'' radius min.
I have a test track that is pretty much a circle of 18" track. I do run 6 axles on
it but I think I am just lucky they don't derail. Its not right and the hard part for 
me is to get the engines on the rails. The trucks are turned to their max. Absolutely
no room for error.

Nice layout Davidd85


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## tjcruiser (Jan 10, 2010)

Joel,

Consider using a sheet of MDF (rather than plywood) as your sublayout board. Standard MDF is 49" x 97" ... a precious extra inch in both directions. A very helpful extra cushion of margin when dealing with 22" radius track loops.

TJ


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## Davidfd85 (Jul 4, 2011)

Yes, I agree with TJ that extra inch would have made my long edges allot easier to work with. Here is a ruff drawing of the layout with and addition I'm planning to start on soon.


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## mr_x_ite_ment (Jun 22, 2009)

Joel...I don't know if you have the space for an around-the-walls-style layout, but if you could swing it, they offer an opportunity for big-radius plans. If you only have space for a 4 X 8, then I would shoot for that 22" radius. You could take tj's idea, and go with MDF board. The extra inch can be nice. Best of luck! 

Chad


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## billboquet (Feb 15, 2012)

Thank you to all for your advices. I will check with MDF as I have enough space (will do it on mezzanine in my job warehouse, so have plenty of space).
But don't want start too big for a beginning
Joel


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## waltr (Aug 15, 2011)

Before committing to a 4x8 foot layout take a look here:
http://www.layoutvision.com/id28.html

It is as Chad suggested.


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## mr_x_ite_ment (Jun 22, 2009)

walt...that was an interesting read! They are pointing out that a 4 X 8 might not always be the best use of space. They state that a 4 X 8 really takes up more room than one thinks when you consider the reach/access you need to have. Thanks for the link!

Chad


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