Stupid question

[Sir Clothem Cap]

I have heard is said that if you don't ask stupid questions you never learn anything so here is mine.

Having just avidly read the new 16mm Handbook I find that reverse curves are to be avoided. What is a reverse curve

[invicta280]

An S bend

btw Isn't that 16mm handbook a work of art. Can't put it down!

[IrishPeter]

Having just avidly read the new 16mm Handbook I find that reverse curves are to be avoided.

LOLROFLAO!!!

That's another rule I have broken, then! Actually when I cannot avoid a reverse curve I always put a short stretch - at least a foot - of straight track between the two componants of the curve. I think what you are actually meant to avoid is going straight from a right-hander into a left-hander (or left to right) as it causes problems with buffer interlock and stuff like that.

Peter in AZ

[Keith S]

What is this 16mm handbook you speak of? (another stupid question) Is there some way to get a copy in Canada?

[invicta280]

The association of 16mm narrow guage modellers

www.16mm.org.uk

issue a quarterly magazine called 16mm today and once a year you get a handbook as well. Good value IMHO.

[DLRdan]

Not quite, you get the handbook when you join. This year though as a new one was made a copy was sent to exisitng members. In the past there has been wagon kits, brass etchings and one year a book.

[Sir Clothem Cap]

Thanks for clearing that up, it's worth asking stupid questions

[METHSSNIFFER]

If reverse curves are to be avoided why do they have them on the prototype are we talking set track here of some tight radius or something. They wouldnt of built narrow gauge if this was the case!

[IrishPeter]

I am thinking that they are problematic when using tight radii. My curves tend to be 10' radius, so with a short straight section between I do not have problems with my reverse curves. However, imagine doing that with R1 or R2, and I think you can see why they tell you to avoid reverse curves.

Peter in AZ

[invicta280]

I think the problem arises because most model rail track curves are
to a constant radius and when you go from say 3' rad one way abruptly to 3' rad the other you will get a pretty savage swing and maybe buffer lock and all that malarkey.

On a full size railway ( and some models) the curves are transitional
( mathematically known as a clothoid- or euler spiral).
This is where the curve starts imperceptably from straight and the curve gets tighter before flattening out into a straight line again.

If you've got the space its not difficult to plot a transitional curve but probably easier on an indoor layout on a baseboard.

[Jerm]

This is a lesson I've personally learned several times in the smaller, indoor gauges/scales. I do now have quite a good size S curve in my garden - 3.25' radius, I think. I have a 1' straight piece between them and I haven't had a problem on that stretch, ever.