Irish 3ft in 4mm scale

[Guest Lyonesse]

I'm thinking of having a go at some Irish 3ft gauge, in 4mm finescale (P4 equivalent).  I know this has been done before, at least on Adavoyle, but what I can't find is any published standards.  Irish 3ft also doesn't seem to be one of the preset standards on Templot.

 

Broad gauge in P4 standards is fairly straightforward, crossing flangeways are the same as standard gauge P4 and other dimensions increase with the increase in gauge.  At least that seems to be the case for Irish broad gauge and it's what I did for Indian 5ft 6in gauge.  But although the S4 web site mentions a narrow gauge group (now defunct?) there doesn't seem to be anything published.

 

Can anybody point me where I should look?

 

Thanks

[martin_wynne]

Hi,

 

On Adavoyle we did exactly the same as your broad gauge. Everything is the same as P4 with an appropriate reduction in gauge. This means the wheels are to 4mm scale, having P4 width and profile. This matches the prototype and is essential if you intend any mixed-gauge tracks as we had on Adavoyle.

 

The reduction in track gauge, check gauge, and back-to-back is 1ft-8.5in scale = 6.83mm.

 

This differs from the popular narrow-gauge modelling idea of using mechanisms from a smaller scale, such as 009 using N gauge wheels and mechs in 4mm scale, or 0n16.5 using 00 gauge wheels and mechs in 7mm scale.

 

There are no narrow-gauge pre-sets in Templot because there are far too many of them to list them all, and it is next to impossible to get definitive dimensions. But it is very easy to set up a custom gauge/scale setting -- once you know what you actually want.

 

cheers,

 

Martin.

[Guest Lyonesse]

Martin,

 

Thanks for that.  I did see that it's fairly easy to set custom parameters in Templot.  I just wasn't sure what values to use, other than for the track gauge.

 

Having been involved with Adavoyle you probably know more than me.  But are wheels to mainline profile representative of the standards used on the Irish 3ft gauge lines?  It makes life easier if that is the case.

 

I plan on taking a good look at the NG exhibits at Cultra on our next holiday to NI.

 

 

[martin_wynne]

18 minutes ago, Lyonesse said:

But are wheels to mainline profile representative of the standards used on the Irish 3ft gauge lines?  It makes life easier if that is the case.

I plan on taking a good look at the NG exhibits at Cultra on our next holiday to NI.

 

Hi,

 

You will find that they vary. Generally the flange profile is the same as for standard-gauge, but overall wheel widths vary. For Adavoyle, Tony made all the wheels 5" wide (1.67mm), i.e. the same as standard-gauge carriage and wagon wheels.

 

Bear in mind that P4 uses overscale flangeway gaps (0.67mm instead of 0.58mm). So if you use correct blunt-nose vees you wouldn't want to make the wheels much narrower than 5" otherwise you will be risking some wheel drop in the crossings.

 

cheers,

 

Martin.

[Guest Lyonesse]

Thanks for that, Martin.

[ianb3174]

Interesting. So this would work using EM standards minus 6.2mm? 

[Andy Reichert]

If you plan to have any dual gauge turnouts, then it would be wise to use the same standard for both narrow and standard gauges.  Mixing P4 and EM-6.2 at the crossings would cause issues.

 

Andy

[ianb3174]

Andy

I wouldn't be doing mixed gauge, just using EM standards at 12mm gauge