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Easement radius from straight to radius track

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Easement radius from straight to radius track
Posted by LOCO NUT on Friday, April 29, 2016 6:01 PM

I'm in the process of planning and building my next model railroad.  I have been doing some research and found that there is actually an easement transition from straight to curved track. I will be using pre made radius tools to lay my flex track curves. I was wondering if there is a standard or at least a recommendation for the radius of the Easement going into the curve. For instance,  if I'm building  a 36" radius curve would I use double the radius at 72"? Triple at 108"? And so on. Any information or insight on this subject would be appreciated. 

Thank you 

Scott 

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Posted by BigDaddy on Friday, April 29, 2016 6:14 PM

My recollection from John Armstrong's Track Planning for Realistic Operation is that an easement allows for a tighter than optimum radius to work.  If you have room for 36" radius, I wouldn't lose much sleep over creating an easement.

Henry

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Posted by ndbprr on Friday, April 29, 2016 6:15 PM
There was an article and templates in MR years ago. I am guessing late 70s if you can find a copy
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Posted by gregc on Friday, April 29, 2016 8:06 PM

LOCO NUT
For instance,  if I'm building  a 36" radius curve would I use double the radius at 72"? Triple at 108"?

In Armstrong's Track Planning for Realistic Operation, he describes two values, x & L, defining an easement.  He lists values of x and L for 3 radii

   3/8"    12"   18"

   7/16"  16"   24"

    1/2"   18"   30"

normally, a curve would meet a straight track at some point P and R is the distance between P and the center of the curve.

Armstrong suggests increasing the distance between P and the center of the curve by x,  1/2" for a 30" radius curve (i.e. 30.5")

But he also suggests changing the point where the curve ends and becomes straight by extending the curve L/2 beyond point P.    and the curve starts deviating from its normal radius of R at roughly L/2 from point P.

So the easement begins ~L/2 from point P and ends L/2 beyond P with the center of the curve R+x perpedicular to P.

google model railroad easement

 

 

greg - Philadelphia & Reading / Reading

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Posted by riogrande5761 on Friday, April 29, 2016 9:34 PM

Greg. Excellent putting John Armstrong info there. Since I go with 30 (or lately 32") minimum radius, I use the half inch offset with approx 9 inch x 2 transition. Have it memorized. As for easement radius, you don't use a much larger constant radius as the op supposes, but rather it is a spiraling radius.  

If you bend springy flex track starting from straight to the half way point and then the rest of the way until it matches the 30 inch curve, the transition is a gradual spiral from straight until it reaches a constant radius at 30 inches.  That method works very well for me.

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Posted by carl425 on Friday, April 29, 2016 9:47 PM

...or you could just use the "bent stick" method.

I put 3 finishing nails into the center line of the curve and 3 more on the tangent (which has been offset by Armstrong's numbers).  Then I use spring clamps to hold an aluminum yard stick against the nails and draw the curve with a sharpie.  The point of the sharpie is about the same size as the nails so the curve lines up with the tangent and radius.

Works great and requires no math.

BTW, Greg mentions it but I think the point needs emphasis - you want the easement to be a spiral, not just a larger curve.  This way the transition from tangent to curve is gradual.

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Posted by selector on Saturday, April 30, 2016 1:33 PM

This is where flex track works so well. Even if you cut and used only 10-12" of it and fashioned your own easement, it works sooooo well!  You nail it down with the tangent line you drew previously, and make it meet your pre-curved portion on the other end.  Draw the outline of the tie ends along that eased portion it makes naturally, and then lift the flex track.  Cut the flext to fit and place its ties within the outline.  There's your easement.

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Posted by riogrande5761 on Saturday, April 30, 2016 1:43 PM

For sure.  Springy flex track works great for forming easements.  Simple and easy.

Rio Grande.  The Action Road  - Focus 1977-1983

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Posted by BobVegas on Saturday, April 30, 2016 1:59 PM

Question,

If I found a layout for lional and it is 8X12 can I take that and make it on a 4X8 layout in HO scale?

 

Rob

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Posted by mobilman44 on Saturday, April 30, 2016 2:10 PM

With all respect for forumulas and templates........

Draw the centerline for your tangent (straight) track.  Draw the centerline for the curved track - so that the two lines cross.

Attach a long piece of flex to the tangent space, perhaps 6 inches or so before where the two center lines cross.

Take the other end of the flex and hand form it so to center on the curved centerline and follow the curve from there.

Where you attach it to the curve centerline will obviously determine if your easement is sharp or gentle.  I've found that "letting the flextrack" flow on its own will give a very nice result.

Yes, I would definitely solder flex track on curves...................

ENJOY  !

 

Mobilman44

 

Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central 

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Posted by Steven S on Saturday, April 30, 2016 3:32 PM

BobVegas
If I found a layout for lional and it is 8X12 can I take that and make it on a 4X8 layout in HO scale?

 

O scale is about 1.8 times as large as HO.  That 8x12 layout would work out to about 4.4'x6.7', so it should fit in a 4x8 layout.  The width may be a little tight.

Steve S

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Posted by BobVegas on Saturday, April 30, 2016 3:34 PM

Thank you so much I don't want to go to N scale for this I hope it works

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Posted by SouthPenn on Saturday, April 30, 2016 3:55 PM

BobVegas

Question,

If I found a layout for lional and it is 8X12 can I take that and make it on a 4X8 layout in HO scale?

 

Rob

 

HO stands for Half O, so it would be 4 X 6. Good to go.

South Penn
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Posted by carl425 on Saturday, April 30, 2016 4:38 PM

SouthPenn
HO stands for Half O, so it would be 4 X 6. Good to go.

Yeah but... Lionel locomotives and rolling stock are designed to run on WAY tighter curves than HO stuff is.  The Lionel plan (did you miss the fact that he said Lionel?) he's working from could have curves as tight as 27" DIAMETER (that's what O-27 means).  Almost NO HO stuff will run on half of that.

Here's an example of an 8X12 Lionel plan I found online.  The inside curves are 36" DIAMETER.  That would come out as a 9" radius if you halved it to fit on a 4x6.

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Posted by cuyama on Saturday, April 30, 2016 7:59 PM

Steven S
O scale is about 1.8 times as large as HO.  That 8x12 layout would work out to about 4.4'x6.7', so it should fit in a 4x8 layout.  The width may be a little tight.

The poster is looking to convert O Gauge (like Lionel), not O scale. The difference is important, as O Gauge trains have compromises to let them go around very tight curves relative to HO (or O scale). Merely scaling does not tell the story.

SouthPenn
HO stands for Half O, so it would be 4 X 6. Good to go

Nope. The actual relationship is 48/87.1 

And even more importantly, again, the O Gauge curves are much tighter relative to scale than are HO curves. See a more-detailed explanation in the poster's other thread.
http://cs.trains.com/mrr/f/11/t/158326.aspx

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Posted by BobVegas on Sunday, May 1, 2016 1:14 PM

So if I did a 5x8 or 5x9 table would I be able to do this layout to HO, i already did the layout and ran large engines on it in the O gauge, so again can it be done and if so can I use 18 inch curves?

Rob

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Posted by carl425 on Sunday, May 1, 2016 2:21 PM

BobVegas
So if I did a 5x8 or 5x9 table would I be able to do this layout to HO

What layout?  Unless you post the actual plan, all we can do is guess.

But, there are thousands of 4x8 and 5x9 HO plans out there.  You'd be far better off if you would just pick one of those.

BTW, why don't you start a new thread so we don't continue taking this one off topic?

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Posted by selector on Sunday, May 1, 2016 5:50 PM

BobVegas

So if I did a 5x8 or 5x9 table would I be able to do this layout to HO, i already did the layout and ran large engines on it in the O gauge, so again can it be done and if so can I use 18 inch curves?

Rob

 

Your rolling stock's manufacturers' stated minimums will be the determining factor.  Large steamers...probably not.  Longer diesels...maybe.  Heavyweight and modern long passenger cars, say those in excess of 75', probably not unless you revise their coupling mechanisms. 

It isn't the track plan so much as the cars and engines....they'll let you know, one way or another.  The best way is to mock it up somewhat and run trains forward and in reverse with the most typical combinations of rolling stock.  If they'll go through the turnouts you have and the curves you are forced to use, you're on the way to the races.

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Posted by BobVegas on Sunday, May 1, 2016 8:25 PM

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Posted by IRONROOSTER on Monday, May 2, 2016 4:58 AM

Easements help when trying to run on curves too sharp for the equipment.  For example running 80-85 ft passenger cars on 24" radius - sure a lot of manufacturers make them to run on this radius, but you're pushing it.  So an easement helps.  For 36" radius you probably won't notice much difference.  Keep in mind that on the model we have much fatter wheels and looser track standards than the prototype (unless you're doing Proto87) so we can get away without the easements in most cases.

Yes, you can use larger fixed radii.  While an easement is a spiral curve, you can use larger radii to mimic that.  For example, a section of 36" radius followed by 30" into 24" curve.  Even better is to use short sections of track with smaller changes, i.e. 36" into 34" into 32" into 30" etc. until reaching 24.

With flex track, an easy way to do spiral easements is with a template.  These have been published over the years or you can make your own.  Draw the track center line and lay roadbed and track to it.

Good luck

Paul

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Posted by riogrande5761 on Monday, May 2, 2016 7:28 AM

IRONROOSTER

Easements help when trying to run on curves too sharp for the equipment.  For example running 80-85 ft passenger cars on 24" radius - sure a lot of manufacturers make them to run on this radius, but you're pushing it.  So an easement helps. 

With flex track, an easy way to do spiral easements is with a template.  These have been published over the years or you can make your own.  Draw the track center line and lay roadbed and track to it.

Paul

Yes, John Armstrong called the affect of easements as reducing the "coefficient of lurch".  In other words, with the spiral easement, two long cars will not have as much offset between them as they enter into the curve, thus reducing the "lurch" into the curve and fewer chances of derailments.

If you use springy flext rack, you don't even need to use a templet.  Just draw the center lines as illustrated in the earlier diagrams with the curve centerline offset by the prescribed amount - such as 1/2 inch for 30 inch curves.  Then at about 9 inches from that point, allow the flex track to spring in where you lay it roughtly half way between the two centerlines at the offset, and for another 9 inches allow the track to spring in until it matches the centerline on the curve.  Done.  I don't even draw the center line because the spring of the track forms the proper spiral in.  Works like a charm.  Of course you could draw the center line after tacking the track down but it isn't necessary and will be covered up as you paint or ballast.

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Posted by cuyama on Monday, May 2, 2016 12:52 PM

BobVegas
So if I did a 5x8 or 5x9 table would I be able to do this layout to HO, i already did the layout and ran large engines on it in the O gauge, so again can it be done and if so can I use 18 inch curves?

Assuming that you are still talking about this plan:
http://ctt.trains.com/how-to/track-plan-database/2014/10/big-steam-in-the-coal-fields

Probably not. A very rough quick sketch suggests that it may not quite fit in 6'X10' in HO using flextrack, even with a very steep grade. With sectional track, it would require even more space. 

The tracks are probably a little closer together in this sketch than they would need to be to incorporate the different tiers of track as in the original O Gauge plan. You'd also need a vertical transition at the other end of the grade, but that would be easy to include. Access would be needed to the center of the benchwork. (oops, and the legend should read 6'X10')

As others have noted, there are lots of HO 5X9 plans on the Internet, although they may not be as packed as the original O Gauge plan for all the reasons noted in this and your other thread.

http://cs.trains.com/mrr/f/11/t/158326.aspx

And as noted multiple times, O Gauge models have compromises that HO scale models don't incorporate -- so O Gauge engines can go around relatively sharper curves than HO scale models of the same engine.

Edit: Also note that the O-31 curves of the O Gauge original are near 15" radius. So moving to 18" radius for HO scale means the curves would actually be larger -- even in the smaller scale. 

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Posted by BobVegas on Monday, May 2, 2016 2:50 PM

I have made a layout on anyrail and it looks good excpt I do have 15 inch curves so I would like someone to look atn this and give me ideas to mak this work with 18 inch curves, i will email you the fine if you reply. I don't know how to attach the file or picture here.


Rob

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Posted by BobVegas on Monday, May 2, 2016 2:57 PM

I understand now, so I want to keep this type of design, so any suggestions on layout plans, I did the work on the anyrail software and it was tight with 15 inch curves but I want this type of yard, don't have to be up and over but it looks nice. Like I said i did this layout in the O scale lionel and had old post war engines run and I used all Ross track, and it looked and worked nice. So I thought if it was a smaller scale it would take less room, i see now that is not true. So I ask all of you here for ideas to build my layout, I have had no lucjk online finiding plans. Someone here can take this design make chnages so it works and post it so i can build it. I am asking for help here, I need my hobby back soon. Thank you all for your help so far. The most I can go is 8 X 6 is the max for work space.

 

Rob

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Posted by BobVegas on Monday, May 2, 2016 5:54 PM

So what if I went to N scale for this layout that would work right?

 

Rob

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Posted by tomikawaTT on Monday, May 2, 2016 6:27 PM

Lionel O Gauge vs scale HO content deleted, repeats earlier posts.

Back to easements.  Some time around 1950, Ed Ravenscroft made 'foobie' easements by using radii R - 3R/2 - 3R - tangent, each larger radius segment as long as a heavyweight passenger car.  He was using Tru-Scale milled roadbed.  At about the same time the club I later joined made 'flex Tru-Scale' by cutting most of the way across tangent and wider-radius pieces, then laid honest logarithmic spiral easements.  I personally use the 'offset the tangent, locate the two ends of the easement and let the flex track do its thing' method, which seems to meet my simple needs.

I won't give dimensions - I work in Metric units, which peeves the 'Loyal Order of English Measurement' squad.

Chuck (Modeling Central Japan in September, 1964 - in 1:80 scale, aka HOj)

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Posted by cuyama on Tuesday, May 3, 2016 1:52 PM

BobVegas
So what if I went to N scale for this layout that would work right?

Yes, but that is a significant change in size of the models from O Gauge to N. You might want to see some N scale in a hobby shop or at a train show before making the shift to be sure that you are happy with the smaller models. (Personally, I model in N scale, but it doesn't suit everyone.)

You seem to be in a hurry to find a plan. If your major requirement is a small yard, there are many published plans from which to choose in HO, including the Atlas HO layouts, many of which are designed for their sectional track and are squashed into a 4X8 or so. (Many of these concepts would be better if relaxed into a larger space, in my opinion).

HO sectional track generally is not as robust as the O Gauge Lionel Fastrack you may have been using. KATO HO Unitrack is an exception and works quite well. 

An Internet search for Unitrack HO track plan yields a lot of results, some of which might fit your space and interests.

But if you wish to duplicate the overall arrangement of the original O Gauge layout in 6'X8' with sectional track, then N scale will work. KATO also makes N scale Unitrack, which works well.

Good luck!

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Posted by riogrande5761 on Tuesday, May 3, 2016 2:33 PM

tomikawaTT

I won't give dimensions - I work in Metric units, which peeves the 'Loyal Order of English Measurement' squad.

Chuck (Modeling Central Japan in September, 1964 - in 1:80 scale, aka HOj)

Sure seems like common sense to give measurements in units most people on the forum can understand.  But what do I know?

Rio Grande.  The Action Road  - Focus 1977-1983

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