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HO radius width

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  • Member since
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  • 225 posts
HO radius width
Posted by fender777 on Monday, July 17, 2017 7:46 AM

Anyone know how wide one needs to do a 30 radius. What is the largest radius turn one can do on a 4by8ft sheet of plywood' that is on the 4ft wide side. Is their a scale that tell how wide each radius needs. Thanks

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Posted by carl425 on Monday, July 17, 2017 7:55 AM

fender777
Anyone know how wide one needs to do a 30 radius.

66" will allow 3" from the edge of the benchwork to the track centerline.  This is usually considered the minimum to keep trains off the floor.  More is better.

fender777
What is the largest radius turn one can do on a 4by8ft sheet of plywood' that is on the 4ft wide side.

The 22" radius sectional track curve was invented for just this application.  It does put the track dangerously close to the edge though.

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by slammin on Monday, July 17, 2017 7:55 AM

Multiply the radius by two. That will get you the diameter of you circler at the center line of the track. Add about an inch and you will have the outside diameter of the circle of track. You can use 22" radius track on a 4 x 8 sheet of plywood. Most layouts that have larger radius are around the wall layouts.

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Posted by cuyama on Monday, July 17, 2017 9:23 AM
Tags: radius , Diameter
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Posted by fender777 on Monday, July 17, 2017 9:56 AM
Wow thanks guys for the info and links. Those were great. So far a 30in radius ones really needs 70in wide to look good have room around the edge.
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Posted by peahrens on Monday, July 17, 2017 10:13 AM

In planning your layout, if getting the track close to the layout edge, consider a rollover (off the table) barrier. 

As an example, my small layout has track center just 2-1/2" from the edge, but I have a masonite fascia that extends down about 1', but also extends 1-1/4" upward past the table surface.  If a loco rolled off the track and towards the edge, the fascia edge hopefully would stop it from diving to the floor.

Paul

Modeling HO with a transition era UP bent

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Posted by ROBERT PETRICK on Monday, July 17, 2017 10:24 AM

peahrens

As an example, my small layout has track center just 2-1/2" from the edge, but I have a masonite fascia that extends down about 1', but also extends 1-1/4" upward past the table surface.  If a loco rolled off the track and towards the edge, the fascia edge hopefully would stop it from diving to the floor.

I do the same thing, but my fascia only extends about 1/4" or so above the edge. Not much protection, but some. I run a small fillet of lightweight plaster along the triangular ridge and form up a trackside drainage swale.

Robert 

LINK to SNSR Blog

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Posted by doctorwayne on Monday, July 17, 2017 11:10 AM

This is roughly a 33" radius, with no restraining wall.

The slope of the trackside bank is designed variably, so that no matter at which point on the grade a car or locomotive derails, it will execute a 360° roll, allowing it to land perfectly on its wheels when it hits the floor.
The drop to the floor varies from 49" to 55". Stick out tongue

Wayne

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Posted by riogrande5761 on Monday, July 17, 2017 12:39 PM

Eek, no guard rails makes me nervous with that drop!  Of course, it's your trains.

Rio Grande.  The Action Road

Contrarian's contrarian
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Posted by tomikawaTT on Monday, July 17, 2017 1:29 PM

A few comments from the peanut gallery.

If you want spiral transitions into your curves (See John Armstrong's Coefficient of Lurch sidebar) add an inch to Cuyama's width diagram.

Doctor Wayne is demonstrating what you can get away with if your tracklaying is absolutely bulletproof.

For those of us less talented, it is possible to incorporate scenery elements that act as disaster preventers.  A three-cable right-of-way fence, #24 wire soldered to straight nail fenceposts, will keep ANYTHING on the right-of-way.  Likewise foliage that incorporates structural elements (screen wire, solid 'trunks,') can be planted in the drainage below a bridge to make a gentle catch out of a potential springboard bounce to oblivion.  All without having the fascia intrude into the model space.

For a situation like Doctor Wayne's, the JNR thought highly of guard rails - and not just on curves.  I think that idea is one I'll emulate.

Chuck (Modeling Central Japan in September, 1964)

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Posted by 7j43k on Monday, July 17, 2017 2:13 PM

You can also make a "wall" out of clear acrylic.

 

Ed

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Posted by Jeff1952 on Monday, July 24, 2017 11:23 PM

I went Ed's way also, with a plexiglass "wall" along the edge of the layout. Not only does it keep the rolling stock from disaster, it also protects my scenery from the arms and elbows of guests and grandkids!

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Posted by cowman on Monday, July 24, 2017 11:40 PM

On my 4x6 I have a spot where the tie ends are at the edge of the layout.  Jeff's words are just about what I was going to say before I read his.  Mine goes several inches above the layout surface.

Good luck,

Richard

 

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Posted by joe323 on Tuesday, July 25, 2017 6:38 AM

On the old SIW I put a stack of containers (actually a picture glued to hard board and cut  to shape to act as a back stop if a train derailed if you looked at eye level as an n a picture you would not know the difference in that one area.

Joe Staten Island West 

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