Flexi Track Curves

[GNRi1959]

When laying flexi track in a run around layout do I have to follow the Peco curve radius as is published for their pointwork?

 

[Broithe]

With flexi-track, you can largely do what you want, as long as your vehicles will cope with the radii that you end up with.

It is worth, though, carefully 'flaring' things together.

[GNRi1959]

Broithe, thanks for that.

I am setting out curves using a trammel on a layout that will be primarily all goods wagons during the steam era. The curves are of a  radius of 550mm and upwards.

[Broithe]

The transition from straight to curved shouldn't be just straight into the final radius - it needs to be staged, or flared, in a 'French curve" manner - it looks and runs much better if you do that. You can create virtually the same effect by having a series of short circular curves running on from one another. Flexi-track can give you a much better arrangement than set-track will.

https://en.wikipedia.org/wiki/French_curve

[Broithe]

Like this - each time the radius reduces as you move away from the straight, you move the centre up the radius line at the end of the preceding circle, and draw the new part of the curve - and then repeat, until you are happy.

Edited July 24, 2018 by Broithe

[David Holman]

Excellent advice by Broithe. 550mm is fairly tight as a minimum radius. 600 better, 750, indeed 900 or more ideal, but then few are blessed with such luxuries.

 Seem to remember mainline diesels could do 12 chains = 66x12= approx 800 feet or 3.2 metres minimum radius!! In dockyards, things got down to 3 chains or less, so maybe 750mm, but certainly not for mainline locos or bogie stock.

 Transition curves not only help with running, but visually too. Hence you might go down to 450mm radius at the tightest points, but hopefully, these can be hidden behind buildings, scenic features etc, allowing transition points to be more generous - hopefully towards 750mm.

 Another advantage you have is observing trains from inside the curve, where sharpness is less pronounced that the outside. Likewise, avoiding over long bogie vehicles will be better too. 50' coaches better than 60+, while short, four wheel wagons will be fine.

[GNRi1959]

10 hours ago, Broithe said:

Like this - each time the radius reduces as you move away from the straight, you move the centre up the radius line at the end of the preceding circle, and draw the new part of the curve - and then repeat, until you are happy.

Broithe, that is exactly what I done using a piece of ply across the width of the shed with a centre line drawn in it. I started the curve at the centre of the trackwork and as I started the arc I moved along the centre line until the curve found its place on the baseboard.

As I said already, it’s all wagons on this layout.

[DiveController]

I do something similar to Jim with the largest radius curve transitioning from the straight and tightening around the curve with the same at the other end. Obviously this needs some additional space but avoids the sudden lateral (centrifugal) thrust on the rolling stock which looks as odd visually with the train as it does with the aesthetics of the railway, This is most pronounced at higher speeds such as on the main line and with longer rolling stock.  The tightening curve also looks odd with longer coaches overhanging the track but sometimes that can be concealed in a tunnel etc. It may be worth while just have ing a few pieces of set track of different radii to help diode things and discourage one from tightening the flexitrack more than minimum curvatures 

[GNRi1959]

Thanks DiveController.

Some two months on from that post I am wiring my point motors!