7mm 31/31.5mm gauge widening?

Steph Dale

Western Thunderer
Guys,
Does the 0 finescale/narrow approach usually have gauge-widening applied?
What's the convention?
Cheers,
Steph
 

Dikitriki

Flying Squad
Hi Steph

I don't know what the convention is - even if there is one - so all I can say is that I did not gauge widen on any of the curved points I built, which went down to 5'6'' in the yard, and 5' on the inside road of the 3 throw point.

Where I built my own plain curved trackwork as part of a formation, I did not gauge widen, but obviously, where I used RTP, that was 32mm so had widening built in.

I would have thought with 31.5mm, which is my experience, no widening is necessary where curves are, say 5'6'' plus. At 31mm, I suspect widening would be necessary, since there is no 'slop' at all, but I have no experience of that gauge.

Cheers

Richard
 

Steph Dale

Western Thunderer
Thanks for that Richard!
I must confess I'd either forgotten or was otherwise unaware that Heyside was 'narrow gauge'. Your info will help with establishing clearances on a chassis I'm working up at the moment.
Cheers,
Steph
 

Debs.

Western Thunderer
I produce O-MF+ gauge-widened track gauges for 7mm. scale layouts containing tight radii (i.e: generally at, or less than 1200 mm.) to a specification recommended by Martin Wynne (Templot), whom recommended that modellers include a gauge-widening of 0.25mm. in such circumstances.

Thus meaning that the appropriate gauge-widened roller gauge has to offer the following dimensions:
- track gauge 31.75mm
- crossing flangeway 1.5mm
- running rail to check rail gauge 1.75mm (i.e. check gauge stays the same at 30.0mm.)


0MF+ Gauges (Large).JPG
 

Steph Dale

Western Thunderer
Debs,

Gottit. Thanks for the clarification - I can load that info in to CAD and get the clearances worked through very easily now.

Very many thanks,

Steph
 

Overseer

Western Thunderer
I wasn't going to comment on this subject as I have no knowledge of it but this thread has me confused. I thought the idea of narrowing the gauge was to improve the appearance of crossing Vs and flangeways while retaining standard O 'finescale' standards on locomotives and rolling stock, so the stock would be interchangeable with other modellers using finescale standards. If you need to design the loco specially to suit the narrower gauge doesn't that negate the interchangeability? And wouldn't you just use 32mm gauge flextrack for the sharper curves, or all the plain track for that matter? Or have I missed something?
 

Osgood

Western Thunderer
It is primarily a means of getting rid of the excessive side play in finescale track without changing the back-to-back of wheel sets and also reducing the tendency of wheel sets to drop as they pass through point frogs, thereby providing better running qualities with stock wheel sets.

I am shortly to experiment with doing more or less the opposite with an existing finescale layout - by increasing back-to-back of all wheel sets and looking at ways of reducing flange way at point frogs. As the layout will have dedicated stock the lack of interchangeability is not an issue for me.
 

Steph Dale

Western Thunderer
Fraser,
The short answer is 'I'm not sure', but want to check. I do like the idea of building my stuff to run on either 32mm or narrow gauge, if it's not too much trouble to do so.
The reduction in flange-track clearance implies to me that the chassis clearances (sideplay) may have to be more carefully thought out. I'm just trying to establish what/whether/how. After all it's possible to build many locos without side play in f/s and they'll go round bends because of the flange-rail clearance. So, if that clearance is reduced, then the sideplay must increase to compensate. Or so my thinking goes.
That's what I want to check. I'm working on a couple of 4-4-0 locos with very restricted bogie swing, so feel the need to do some quick sketches in CAD and make sure I'm on the right lines. It'd be a bit of a pain to have to take a near-complete chassis apart to remedy a problem with the frame spacers!
Steph
 

Dikitriki

Flying Squad
Fraser,
The short answer is 'I'm not sure', but want to check. I do like the idea of building my stuff to run on either 32mm or narrow gauge, if it's not too much trouble to do so.

It isn't.

The reduction in flange-track clearance implies to me that the chassis clearances (sideplay) may have to be more carefully thought out. I'm just trying to establish what/whether/how. After all it's possible to build many locos without side play in f/s and they'll go round bends because of the flange-rail clearance. So, if that clearance is reduced, then the sideplay must increase to compensate. Or so my thinking goes.

Most of the time, normal working sideplay is quite sufficient. In fact with trucks/bogies, it's better as there isn't so much slop movement.

That's what I want to check. I'm working on a couple of 4-4-0 locos with very restricted bogie swing, so feel the need to do some quick sketches in CAD and make sure I'm on the right lines. It'd be a bit of a pain to have to take a near-complete chassis apart to remedy a problem with the frame spacers!

Take a trip up the M5 to check:)

Richard
 

Osgood

Western Thunderer
Surely if you reduce the flange/rail clearances to something approaching S7 tolerances you have to apply the same gauge widening / side play criteria that S7 requires. The only difference is the actual gauge measurement.

I can't cope with side slop. Much of this can be taken up by careful positioning of bearings in axleboxes to restrict axle side play. To what extent this will satisfy my fussiness I will not know until I try it. I certainly like the idea of narrowing the gauge but felt that on a finished layout with only 6 points it would be a disruptive task to alter all of the plain track, hence my idea to do it the other way round.

I would hope that the side play required on a 6 wheel chassis could be accommodated by the centre axle only - so minimal movement of outer axles would reduce slop to a minimum, likewise an 8 wheel chassis would have play on 1st and 3rd axles?

Or have I got this all wrong and folk are in fact looking at the narrow gauge primarily for the visual improvement?

Until I start actually doing something I guess I will not be able to add constructively to the discussion!
 

Steph Dale

Western Thunderer
Tony,
I'm looking at it only to ensure my locos are compatible with a wide set of track standards!
It will also help to be able to talk about it in a meaningful way as part of the Guild Technical Committee.
Unfortunately sideplay doesn't always work out as you describe, inside cylinder locos with working motion have no sideplay on their middle axles. In the case of what you're doing be aware that with over-scale-width wheels you're increasing the chances of a coupling rod-step/running page foul and building a loco with outside motion will be very tricky.
One advantage with the f/s approach is that the wheel faces tend to come out very close to scale width.
Steph
 

Steph Dale

Western Thunderer
Richard,
Thanks for the reply, once again you've added some clarity to my thought processes.

Tony,
FYI, 32mm gauge f/s has about 1mm total slop, so 31.5mm has about half a mm. 31mm would result in the flanges running on the rail head all the time, which is not prototype practise.

Steph
 

Osgood

Western Thunderer
Maybe it's time for some one to make a three point track gauge for 31.5mm.

OzzyO.

Peartree Engineering at Pulham Market Suffolk do some nice three point gauges, also an adjustable one (which might even do the job). I spoke with him at Reading about the possibility of one for Scale7 and he said he was working on it. Seemed the kind of gentleman who would be prepared to make up one for 31.5.

I imagine a three point would complement Debs's roller gauges nicely.
 

Dog Star

Western Thunderer
Peartree Engineering at Pulham Market Suffolk do some nice three point gauges, also an adjustable one (which might even do the job). I spoke with him at Reading about the possibility of one for Scale7.
I think that the S7 Group Stores has a three-point gauge in the list.
 
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