Tightest radius for HO

Discussion in 'FAQs' started by MasonJar, Oct 24, 2003.

  1. MasonJar

    MasonJar It's not rocket surgery

    What is the tightest radius for HO Atlas Code 100 flex? I am hoping to make a little diorama, but would still like the trains to run contiuously. I have a little HO docksider (0-4-0) that I presume can take a pretty tight corner.

    How far can I bend the flex track? I was hoping to keep the diorama no more than 18x18.

    I was inspired by Micro Layouts for Model Railroads. Lots of neat little (literally) stuff there.

  2. jon-monon

    jon-monon Active Member

    You can bend it about as tight as you would want to. And the 0-4-0 will run around a tight curve too. Experiment on scrap.
  3. MasonJar

    MasonJar It's not rocket surgery

    Thanks Jon... Even though it is pretty flexible, I didn't want to find out that suddenly at 10" radius, it snaps... :eek:

  4. jon-monon

    jon-monon Active Member

    I think you could bend it further than that even, eventually, I guess the rails will pop out of the ties. I don't think they will break, and I don't think there will be a problem until it's bent to the extreme. If it's the type where the rail slides in the ties at only one side, it would be best to have that side on the outside of the curve.

    You might get out of gauge before you get to the point of breaking anything too. 0-4-0's like to pop wheelies, and I guess would get sensitive to derailment when accelerating on a very tight curve, or any curve for that matter. I have several, differing brands and they all behave this way. Front wheels jump track easy. ADHD kids of model rail.

    I would get one, try it, and consider it a sacrificial lamb.
  5. interurban

    interurban Active Member

    Andrew,, I have used curved set track 18'' radius.
    then cut out alternate plastic spacers underneath the rail, and curved it right tight then cut the excess track off the ends.
    SW 15 will go round it and frieght if you do some fixing:D
    My traction loop is 20'' wide

    How tight do you want it:eek: :confused: :D
  6. jon-monon

    jon-monon Active Member

    Geeze, Chris, they make flex track ya know! :D :D :D
  7. interurban

    interurban Active Member

    :D Hi jon, the flexy track wants to flex back on that tight curve also you will lose the gauge.
    where as set track will keep the tight curve with out fighting back and the gauge seems to stay:p
  8. Roger Hensley

    Roger Hensley Member

    Atlas still makes 15 inch radius track. I really wouldn't want to take flex tighter than that because the ties will start to skew and you'll lose gauge.

    Now, that said, you can always hand lay just about any radius you want if you use a 3 point track gauge in construction.
  9. brakie

    brakie Active Member

    I would not use anything less then 15" curve if you are using 40' cars.The shorter 36' cars should be ok down to 14" curve.However I would not go less then 14" on my curves.
  10. Pete

    Pete Member

    That's going to be a really tight circle in HO, having a radius of slightly less than 9". Remember, R=½D with D being the width of the platform (18"). You'd be looking at using just over 1&frac12 3-foot sections of flextrack.
    I'd tack up a 'test track' and try that first before committing to the 18" square.

  11. jim currie

    jim currie Active Member

    how bought trying your hand at hand laid track,code 55 hand laid.
    this is up your alley:D :D
  12. jon-monon

    jon-monon Active Member

    Another neat old piccy, Jim. How much do ya s'pose fair is for a lap around? :D :D :D
  13. shaygetz

    shaygetz Active Member

    My Christmas layout uses C100 Atlas flex track turned to 12 and 3/4" radius. It has been this way for 7 years now and shows no sign of fatigue. I run an Athearn GP35 on it as well as a Rivarossi 4-4-0 Genoa, a Spectrum 44 ton switcher and a AHM 0-4-0 Docksider. All regular length cars I own run on it with no problem.
  14. jim currie

    jim currie Active Member

    Jon one way or round trip?:D :p
  15. rcwatkins

    rcwatkins Member

    I'm no expert at this, but I would go with 18" curves.
  16. CN1

    CN1 Active Member

    I'm no expert either but I would say no less then 16"
  17. Lighthorseman

    Lighthorseman Active Member

    From My Planet...

    While I was asking about On30, (that is still HO gauge) a fellow named Jim Favre, a guru from the On30 Conspiracy, wrote back to me about how he makes super, super sharp radii in HO gauge track.

    He handlays...and starts with a basic template of the curve he wants. He then puts on a pair of work gloves, and bends the rail to a close match by running the rail many times through the gloves he's wearing. This puts a gentle, even curve in the track without big bent kinks. He stressed that it must be done gradually. He used HO scale Atlas code 100 to create a Gn15 loop around a tree. The radius? TWO INCHES. :eek: A modified Bachmann On30 Porter makes the rounds.

    Is this REALLY any help to you? Somehow, I doubt it.:D
  18. MasonJar

    MasonJar It's not rocket surgery

    Thanks for all the tips and suggestions!

    I think I will try to tack the flex track down to foam or something first, and see how tight I can make it go...

    Stay tuned!

  19. 60103

    60103 Pooh Bah

    back when Peco streamline was new (1960 ish) they had pictures of it tied in knots, twisted lengthwise and otherwise tortured. I had a traction layout on a small piece of plywood that had curves muchless than 12" radius -- using streetcars, small locos and Roundhouse old-timer cars.
  20. marc gast

    marc gast Member


    I have 15 and 16.5 inch radius on my logging module. MDC shays and also the Mantua 2-6-6-2 logger will negociate these curves, also the new Bachmann 3 truck shay. My module is 36 inches wide and has a continous loop.
    I wouldn't suggest going any sharper than 15 inch on the radius.
    A 9 inch radius is out of the question.
    An 18 x 18 would work in "N", however, a pipe dream in HO unless it was a small point to point.
    Hope this helps out.

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