Under-gauge flexi-track

[John CutlerParticipant]

Whilst making a track-mounted AJ coupling gauge, I discovered that my C&L flexi test track was 18.1mm and not 18.2mm gauge. This may or may not have been bought via the EMGS. Sure enough I then found that some of my sidings were the same. I used a mint gauge to check; why is it so expensive (£26.00)? I am not aware of any issues with straight track lengths but am now concerned that some curves may not have sufficient gauge widening. It will be a pain to tear up and replace ballasted track so should I worry?

The lesson here is to check critical dimensions immediately after purchase. If you buy from the EMGS, do not expect the poor Trade Officer to exercise quality control; he just does not have the resources. Incidentally, never rely on the stated widths of axle spacing washers; over many years of using them I find that few conform, though newer ones are better. Always measure before committing them to your prize loco!

[Nick RidgwayParticipant]

0.1mm represents 1/40 of a foot in 4mm scale, which is a little over 1/4 of an inch. This is within the normally-experienced tolerances on prototype track: “1/4 tight” has been deployed on tube lines to stop the motor bogies from thrashing about when accelerating, for example. “5/8 wide” is sometimes deployed on sharp curves to reduce the prospects of flange and rail wearing each other out; I’ve done it myself in 12in scale.

Bear also in mind that EM gauge track is a scale 2&1/2in narrow compared to the prototype. Where does it end (rhetorical question – NNTR)?

[John CutlerParticipant]

Thanks, Nick.

It is reassuring to know I should not worry. Reading some comments on trackwork tolerances elsewhere made me despondent!

 

[Geoff StennerParticipant]

A bit late to the show, but please remember EM standards (Denny, Pendon etc.) were originally 18mm gauge. The extra .2mm was added when Stephen Poole wheels appeared in the ’70s, when we all had to use only Hamblings (see Guy Williams first book) or Romfords and the Poole wheels were a useful alternative. The latter had thick flanges and are long defunct and meanwhile, proprietary wheel standards have improved hugely so along with that and the fine standards of wheels from Gibson and Ultrascale, I doubt that he extra .2mm is needed in the 21st century. Sharman standard wheels worked ok in P4, too, and were revolutionary with their fine profile when they first appeared, so another example of the redundancy of the extra gauge.

[Bob AllisonParticipant]

Totally agree with Geoff on this one.  There is a lot of unwanted sideways slop when using Gibson wheels on 18.2mm track, so a bit of gauge narrowing is actually quite useful (except, maybe, on really sharp curves.)

Bob

[Mike BakerParticipant]

The EM track and points supplied by Peco to the EMGS are18mm gauge.

I only noticed this when laying a British finescale point up to a EMGS (Peco), there is a noticeable difference in the gauge.

Some of my locos are not too happy on the 18mm gauge points.

[John CutlerParticipant]

Oh Dear!

I should follow my own advice!

I installed a pair of EMGS B6 turnouts to replace some troublesome home-made ones.

Did I check the gauges beforehand?

 

Following Mike Baker’s post (Thanks, Mike!), I checked these with an 18.2mm mint gauge.

Then with a Vernier gauge.

Yes, the darned things are under-gauge, by between 0.1 and 0.2mm.

 

This may not matter much if you use a strict (Good Luck with that!) 16.5mm Back-to-Back with the usual wheel slop of AG wheels. This 18mm gauge is not desirable where the switch rails (point blades) meet the stock rails. There is no set in the Peco stock rails. However, Peco or the EMGS designer have wisely widened the  gauge here at the blades; my mint gauge freely moved through both sets of switches. This is the only part of the turnout where the mint gauge does not encounter friction.

 

My BB standard is 16.5-16.7mm. Coach and rolling stock wheels are left at the standard 16.5mm but locos get wheels built to an acceptable range using a 16.7mm Back-to-Back tool tightly. I find the wheels usually spring back to 16.6mm or sometimes even 16.5mm. When I used a standard 16.5mm BB jig, I discovered the wheels almost always ended up at less than 16.5mm apart; I guess the plastic in the loco wheels springs back after being set. So yes, some of my locos suffer a bit going through the EMGS/Peco B6 turnouts.

 

Not happy.

I will start keeping records of problems to decide on possible loco modifications or if I should rip the darned things out. It seems I might have to go back to hand-built wonky track!

 

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