Mixing raidiai

[mikec069]

I've heard all about not having and/or limiting 'S' curves.  What about mixing 18 and 22 curved track 'flowing' in the same direction.  I'm trying to replicate a layout from a magazine and the official list calls for the use of flex-track.  There are a few reasons I will not use flex track.  Not the least of which is the whole roadbed issue. 
Anyway, will mixing different radii cause derails and/or other not nicenesses (yes it's a word in the Mikec069 dictionary.  )

Thank you all,
Mikec069

[SteamGene]

Mixed radii is called "easement."  From the straight, use one section of 22", then 18", with the last piece being another 22."  You can do the same thing with other radii.  But DON'T do the reverse. 
So what is the problem with roadbed and flex-track.  The one thing I'll say about flex track is that my experience shows a problem using it with tight radii.  I think that tighter than 24" you may be best off with sectional track.
Gene

[Michigan Railfan]

Gene, why do you say not to mix around the radii from how you put it? Will there be a sure derailment?

[mikec069]

Thanks SteamGene

I'm assuming by 'Don't do the reverse' is start with 22 and  end with 18.  Correct assumption?
And as for flex track, my room for my train allows for a max of 22.  Anyting wider and I run the risk of going off the edge of the table.  I found out that is NOT a good thing to do  

Anyway, thanks again
Mikec069

[Joe Satnik]

Dear All,

In the case of sectional curve track of changing radii, it would more properly be called a "pseudo-easement".  (A spiral easement being the real thing.)

http://www.bachmanntrains.com/home-usa/board/index.php/topic,6564.0.html

Hope this helps. 

Sincerely,

Joe Satnik

[SteamGene]

You are both correct.  In the latter, I was trying to apply the KISS rule. 
Gene

[jward]

the tight radius issue with flex track can be easily resolved with track guages from ribbonrail. these are metal and designed to fit between the rails of your track. they come in a variety of radii, you don't need a whole set just the radii you intend to use. by using these you can be sure that your 18" radius curves are in fact 18" with no kinks.

[boomertom]

I know a lot of published track plans tend to lean towards flex track but then show 18" curves.

If you are going to use 18" radius curves, isn'i it simpler to use sectional
track in the first place? this is something that has puzzled me for quite some time and maybe one reason I have never had much luck with such plans.

Tom

[SteamGene]

It may be the cost, since flex is less expensive than sectional.  Then, how many sections does it take to make a three foot flex track?  How much current is lost from section to section as opposed to flex track?
Gene

[lmackattack]

I use flex track in straight or over 26" radius. All of my curves under 26" are sectional 22" or 18" radius.  I had solder all the joints on my old layout but they started to kink after 2 years of use. My current layout with sectional curved track has ran flawless after 5 years of use. I would agree with everyone that says flex is better left for larger radius. I also have about 6 power pick up points around my layout.



Trent

[rustyrails]

I have successfully built flex-track curves down to 15" R in HO and something like 11"R in N.  There is nothing wrong with using sectional track if you are uncomfortable with flex, but my flex will look better than your sectional because of the necessary "stiffness" required by the sectional track geometry.  Don't limit yourself just because you think flex is hard to work with.  Start by using some to replace several sections of straight track.  Buy a pair of rail nippers and learn to cut, join, and solder the track.  Then try a little bit on a curve.  You'll be amazed at how your track starts to flow.  It's easy, it really is, but you'll never know unless you try.  The kinking issue that Imackattack mentions can be caused by temperature variations or warping benchwork.  Leaving an occasional slip (unsoldered) joint will help prevent it.  Just make sure that all joints on curves are soldered. 
Rusty 

[uncbob]

Mixed radii is called "easement."  From the straight, use one section of 22", then 18", with the last piece being another 22."  You can do the same thing with other radii.  But DON'T do the reverse. 
So what is the problem with roadbed and flex-track.  The one thing I'll say about flex track is that my experience shows a problem using it with tight radii.  I think that tighter than 24" you may be best off with sectional track.
Gene

Do you get a full half circle diameter with parallel tangents that way ?

[Joe Satnik]

Dear uncbob,

If you use an odd number of 18"R 15 degree (half) curves, yes. 22.5 + 30 + 30 + 15 + 30 +30 + 22.5 = 180 degrees. 

A 90 degree corner = 22.5 + 30 + 15 + 22.5 degrees.

These pseudo-easements can be done, however 22"R is not much larger than 18"R, so there wouldn't be as much of an easement effect.

Hope this helps.

Sincerely,

Joe Satnik     

[uncbob]

Never could understand the rational of easements

For example if you are using an 18 inch radius I assume it is because you don't have room for a larger diameter

Using easements takes up more room so why not just go with a larger diameter

[SteamGene]

It doesn't take up as much room.
Gene