Minimum Radius

The Cuckoo · November 30, 2011, 08:22:05 PM

I'm in the final stages of planning my layout, currently the tightest curves are 10 inches, as the layout will not be permanent set up I'm looking into ways of reducing the size to make it easier to store.
I'm now considering 9.5 inch or even 9 inch curves and wondered what other peoples experiences are of using similar size radius curves.
A few of things to mention, the curves will be Peco flexi track, stock will all be modern image (I have heard that some steamers struggle on tight curves) all the curves are in hidden sections going into the fiddle yard so I'm not concerned if they looks unrealistic.
I have seen a few excellent exhibition layouts using 9 inch radius curves but opinons seem to be split on how tight curves can be without any running issues.
I do realise that this subject has been discussed on here before but I really would appreciate peoples opinions on the matter.

Jason

Flakmunky · November 30, 2011, 08:35:32 PM

Hi,

According to Antics, 1st radius curves are 9 inch radius. My advice would be:

1) By a circle of 1st radius track and test what you want to run on that.
2) Use Setrack for curves of this radius as the geometry will be more accurate than you can achieve... Any slight change in radius or a kink in a rail might be enough to cause you problems... Of course, if the curves are going to be seen and you want the Code 55 profile then invest in a Tracksetta tool to ensure it is as accurate as possible.

HTH,

fM

Newportnobby · November 30, 2011, 08:41:30 PM

I totally agree with everything FM has said/suggested. With modern image you won't suffer too much (I have run 3 and 4 axle diesels successfully but am keeping them for larger radius curves), and DMU's seem to have no issues. You've said the 9" radius will be in the hidden entrance to fiddle yards so I would just check they are easily accessible in case you have a derailment. I definitely would not recommend larger steamers on 9" curves - just in case you were thinking of running a steam special

GrahamB · November 30, 2011, 09:25:56 PM

I've had no problem with older Farish steam stock running around 9" curves.

I did have a challenge when it came to the new Dapol Hall. However I was able to resolve that. See http://www.ngaugeforum.co.uk/SMFN/index.php?topic=2755.0 Sadly the thread went off topic but it does show you need to be careful.

If I was planning a new layout I'd now try for a minimum 10" radius curves.

4x2 · November 30, 2011, 09:33:53 PM

What you could try is something i've suggested before, which is to use the peco 1st rad curves as a template and lay your flexitrack on the outside edge. This should give a rad of about 9 3/4".

GrahamB · December 01, 2011, 07:58:28 AM

Quote from: 4x2ybecauseican on November 30, 2011, 09:33:53 PM
What you could try is something i've suggested before, which is to use the peco 1st rad curves as a template and lay your flexitrack on the outside edge. This should give a rad of about 9 3/4".

Doh!
Like all the best ideas, soooooo obvious and blindingly simple - once someone has pointed it out

The Cuckoo · December 02, 2011, 08:13:54 PM

Thanks for the replies eveyone. I have a couple of 9" tracksetta tools so will set to work trialling some 9" curves using code 55 flexi track.
Using Setrack as a template is an excellent idea, I do have an old Graham Farish starter set which has an oval of track which if I remember correctly is around 9 or 10 inch radius.

Flakmunky · December 02, 2011, 08:16:08 PM

Good luck, my friend. Please do come back and let us know the outcomes of your experiments!