Radius of an arc or segment

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cp4449
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Radius of an arc or segment

Post by cp4449 » Tue Jun 25, 2019 4:42 pm

Anyone have a chart for laying out curve track that I can reference for bending rail? I would be for a 1" scale layout. Or point me to one on the internet

Thanks
Christopher P. Mahony
Los Angeles Live Steamers
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rkcarguy
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Re: Radius of an arc or segment

Post by rkcarguy » Tue Jun 25, 2019 6:46 pm

I ended up drawing some examples in CAD and then had a router guide for turnouts laser cut which can double as a 40' radius gage, I couldn't find anything online but maybe I wasn't using the right terms when I was google searching.

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makinsmoke
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Re: Radius of an arc or segment

Post by makinsmoke » Wed Jun 26, 2019 7:42 am

When I put my track in Ponca City I needed to bend rail. I laid a 4 x 8 sheet of plywood in the yard, took my 50 Ft tape, found my center point and made a 35 foot radius arc. I moved the plywood so it was under the tape/arc, and marked the plywood with a Sharpie.

I set the plywood on horses, and bent the rail to match my Sharpie line. I had an old wire rope reel and used one side, hand bending the rail every six inches and constabtly checking against my gauge.

Yeah, it’s caveman railroading but it got the job done.

Glenn Brooks
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Re: Radius of an arc or segment

Post by Glenn Brooks » Wed Jun 26, 2019 3:54 pm

Somewhere on line I found a simple formula to measure (establish) the radius of a curve, by determining the height of the chord between two designated points on an arc. Alter the cord length to change then radius.

Of course now I can’t remember where I found this. Try googling how to determine radius from chord length, of some such...

Glenn
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Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

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nabob
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Re: Radius of an arc or segment

Post by nabob » Wed Jun 26, 2019 6:08 pm

google 1728,choose geometry, then plane geometry then circle calculator. Many other sites, of course; this one is good

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Harlock
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Re: Radius of an arc or segment

Post by Harlock » Wed Jun 26, 2019 10:32 pm

From a 1960s era Engineering Handbook produced by Railroad Supply:
curve-chart.png
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PRR5406
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Re: Radius of an arc or segment

Post by PRR5406 » Thu Jun 27, 2019 6:15 am

Thank you for posting the chart. I've been looking for this information since, like, forever!
"Always stopping my train, and risking my ankles, with American made, New Balance sneakers."

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makinsmoke
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Re: Radius of an arc or segment

Post by makinsmoke » Thu Jun 27, 2019 6:39 am

That book is still for sale by Railroad Supply.

You should get a copy. They are handy,

BillF
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Re: Radius of an arc or segment

Post by BillF » Thu Jun 27, 2019 10:21 am

On this topic, let me ask: Is there a recommended technique for hand-bending rail? I suspect that clamping in a vise and forcing will likely result in a
tight bend at the edge of the vise and an otherwise straight section.

I purchased a disassembled layout a few years ago, and have been able to select usable bent rails from the collection, but I am now down to the point that I have to modify (i.e. tighten) some of the bends to fit my layout. This is aluminum west coast rail.

- Bill F

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Bill Shields
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Re: Radius of an arc or segment

Post by Bill Shields » Thu Jun 27, 2019 11:43 am

make yourself a rail roller / bender....the same RRSC book has a quickie design for one.

you will never be sorry you have it...

I am sure that even from some pictures you can Jinn one up...
Too many things going on to bother listing them.

cp4449
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Re: Radius of an arc or segment

Post by cp4449 » Thu Jun 27, 2019 11:53 am

THANK YOU HARLOCK!!!!!
Christopher P. Mahony
Los Angeles Live Steamers
1 inch scale member

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