Society Gauge Widening Tool

[Martin Wynne]

Hi Julian,

So, similarly, the yellow line (after it is corrected, which I still await!! )

What is this "correction" you are waiting for?

I'm guessing that you want to find a gauge length which gives a closer approximation to the prototype steps? You are not going to find such a thing because of the shape of the curves. You would need to devise some other method than using a 3-point gauge.

The best method is surely to follow the prototype and use a set of fixed gauges?

p.s. note that the track gauge plays no part in the 3-point gauge calculations. The 00 and EM gauges give the same widening as P4 for the same gauge length.

p.s. this is now on page 8!

regards,

Martin.

[Julian Roberts]

Hi Martin

What is this "correction" you are waiting for?

The following figures are what I was asking Les for yesterday, and you -

The length of tool required to give 0.1666mm widening at 1452mm. The widening such a tool would give at 1848 and 2640mm, and the radii at which the widening would be 0.22mm and 0.25mm.





Cheers
Julian

[Martin Wynne]

Hi Julian,

The length of tool required to give 0.1666mm widening at 1452mm.

43.999mm, say 44mm.

The widening such a tool would give at 1848mm

0.131mm

and 2640mm

0.092mm

and the radii at which the widening would be 0.22mm

1099.94mm

and 0.25mm.

968.07mm

Hope this helps.

regards,

Martin.

[John Palmer]

I would be interested to see what Mr Ward-Platt had to say in the article Philip referred to, because I have a greater difficulty eliminating skewed wheels than I do in getting an acceptable degree of gauge widening. Sorry, Julian, but whilst I commend you for subjecting received wisdom about gauge widening to critical reappraisal, that's where my priority lies.

For me, Allan Goodwillie's reproduction of that North British data table was a taster indeed - more please, or, where I can I get access to the book from which it was extracted? I noted with interest that, although the table lists several species of guard rail/check chairs, it isn't clear that these make any provision for incremental gauge widening. The remarks in the table about Chair 5 do, however, imply a significant difference between check chairs and chairs for guard rails which may (or may not) affect the gauging of the adjacent running rails.

[Martin Wynne]

Hi Julian,

I have made a 5-minute calculator program for you (and anyone else interested).

For Windows, or Linux+Wine, or Mac+CrossOver. Download from: http://85a.uk/gauge_widening.exe

Click and drag the sliders. Click on each side of the slider for precise setting. Or use the keyboard arrow keys. Here is a screenshot:

gw_calc.png

And here is a bit of scruffy video showing it in use:

https://flashbackconnect.com/Default.as ... VvuYbZlbQ2

regards,

Martin.

[Julian Roberts]

Hi Martin

Thanks for all this. 'Fraid I am off on travels in a moment with just a mobile phone. So I am sorry to not take in the programme you just sent right now to work out this question:

You said

The 00 and EM gauges give the same widening as P4 for the same gauge length.

My EMGS standards say that they get 0.2mm widening at 610mm

2016-08-16 22.43.28.jpg

So is their gauge the wrong dimension?

Thanks
Julian

[Paul Townsend]

p.s. note that the track gauge plays no part in the 3-point gauge calculations. The 00 and EM gauges give the same widening as P4 for the same gauge length.

Martin.

Is that a first approxiamation statement or does it also apply to 4mm 7 ft Broad gauge and large scale models?

PS.
Thanks for the GW calculation program

Now all we need to know is how to make our own triangular gauges to give the results we want

[dal-t]

Is that a first approxiamation statement or does it also apply to 4mm 7 ft Broad gauge and large scale models?

While we await the authoritative answer from Martin, my take as a statistician who denies all knowledge (or truth!) of trigonometry would be that for a given base to the triangle, you will get the same amount of widening for gauge, but that will be a diminishing proportion as the gauge increases - won't you?

[Philip Hall]

John, If you would like a copy of the Ward - Platt article, you are welcome to pm me and I will scan mine for you. He actually doesn't say that much, merely that in assembling a wheelset virtually dead true, over a period of time it had moved out on one side and in the other, and that track should accommodate this. Nonetheless, it is four pages of sound common sense well worth reading. As for getting wheels true on axles, the best advice I have seen so far are the articles Chris Pendlenton wrote for MRJ a little while ago. I have my own methods based on his.

Julian, I don't understand why the EM standards allow for gauge widening - at 18.2mm there is quite enough slop to get a Pacific around the edge of a dinner plate as it is. Maybe it seemed a good idea at the time, along with the fact that a three point gauge is a practical way of holding a rail during assembly.

Philip

[Julian Roberts]

Watsappd my son in NZ who replied

"Off the top of my head the widening would change but only proportionally to the gauge change, so for such a small change in gauge the extra widening would be minimal"

He is the one who made the spreadsheet and graph for me

[Martin Wynne]

Julian, I don't understand why the EM standards allow for gauge widening - at 18.2mm there is quite enough slop to get a Pacific around the edge of a dinner plate as it is.

Hi Philip,

Possibly using the EMGS wheel profile*. But with Romford/Markits wheels at 16.5mm back-to-back, or modern RTR wheels at 16.4mm back-to-back, you do need some widening at train-set radii in EM.

*optimally set at 16.6mm back-to-back.

The EMGS standards are years out-of-date and were cobbled together on the back of an envelope in the first place. But they do work well, so EM modellers haven't seen any reason to change them.

Go here and add 2.0mm to all the figures: http://4-sf.uk/dimensions.htm

regards,

Martin.

[Martin Wynne]

Hi Julian,

I don't know where you got this from, but the Check Gauge dimension is wrong. It should be 17.20mm, not 17.25mm:



With the figures shown there the flangeway gaps are asymmetric, which leads to problems with parallel-wing crossings in complex formations such as tandem turnouts (and often found in ordinary crossovers too).

For the correct EM track dimensions see:

emgs_standards_booklet_1970_1.jpg

emgs_standards_booklet_1970_2.jpg

Ignore the BRMSB wheel dimensions there which specify thin 0.5mm flanges. It was because no such wheels were available that the EM track gauge was increased from 18.0mm to 18.2mm to avoid changing the back-to-back on existing wheels.

p.s. Julian there is a note about gauge widening in the small print on the left, which may help your investigations, or not. (0.25mm at 528mm radius.) Is this where the 528mm dimension originated?

regards,

Martin.

[Noel]

Martin, I am no longer an EMGS member, but I have the same sheet from their manual. As Julian's image shows the date of issue was September 1983. Up until I left, not many years ago, it had not been reissued. Its reverse shows P4 standards "as recommended by the MRSG". Whereas the EM standards show gauge widening as 0.20mm at 610mm radius, the P4 figure is shown as 0.22mm, but with the radius figure omitted, although the rest of the wording is present. The 1970 booklet would have been issued when the EM gauge was 18mm, not 18.2.

[Martin Wynne]

Thanks Noel. But regardless of the origin, the 17.25mm check gauge is wrong and should be ignored by EM track builders. Especially those wishing to run modern RTR models with the original wheels widened to 16.4mm back-to-back. Make the check gauge 17.20mm (min).

regards,

Martin.

[Philip Hall]

Martin,

Thanks for the clarification - I had somehow forgotten about the thicker flanges on Markits/Romford wheels. I am still quite jet lagged after our return from Alaska! Peter Denny once wrote that he thought the wheels were a bit tight in the track when he started in EM and he increased his gauge to 18.25mm (I think). I also had to fit some new Markits wheels to a chassis the late Martin Brent had built recently, and they came out at 16.4mm B-B which was never going to work on my customer's railway, so I put them in the lathe and turned a bit off the back of each wheel which gave me 16.65 or thereabouts.

Philip

[Martin Wynne]

I also had to fit some new Markits wheels to a chassis the late Martin Brent had built recently, and they came out at 16.4mm B-B which was never going to work on my customer's railway

Hi Philip,

Why not? The minimum back-to-back for EM Gauge is 16.3mm. Presumably this railway was built to some other standard?

16.4mm back-to-back is the optimum setting for RP25/110 wheels on EM (i.e. modern RTR wheels).

regards,

Martin.

[Julian Roberts]

Martin, I am no longer an EMGS member, but I have the same sheet from their manual. As Julian's image shows the date of issue was September 1983. Up until I left, not many years ago, it had not been reissued. Its reverse shows P4 standards "as recommended by the MRSG". Whereas the EM standards show gauge widening as 0.20mm at 610mm radius, the P4 figure is shown as 0.22mm, but with the radius figure omitted, although the rest of the wording is present. The 1970 booklet would have been issued when the EM gauge was 18mm, not 18.2.

Noel Martin
I will send pic of page Noel is talking about. No mention of 528mm. When I have enough signal.
But another coincidence will be found if you look on this thread at April 21 or thereabouts tbhat may also add sometjing to the 528mm question

[Julian Roberts]

Here it is

[Julian Roberts]

Follow this thread from this post

[Martin Wynne]

My EMGS standards say that they get 0.2mm widening at 610mm ..... So is their gauge the wrong dimension?

Hi Julian,

As I said, there isn't a right dimension. However if the EM gauge is 31mm long, it does indeed provide 0.2mm widening at 610mm radius:

em_widening.png

regards,

Martin.

[Julian Roberts]

If you follow the thread till my reply to Alan at the top of Page 3 obviously you are just seeing a "minor error" being corrected. The 31mm gauge we now have is what gives us 0.22 @ 528mm

Only putting this into the mix as just one of a multiplicity of possible reasons why we have this length gauge, another having just been unearthed by you, Martin

[Julian Roberts]

If you follow the thread till my reply to Alan at the top of Page 3 obviously you are just seeing a "minor error" being corrected. The 31mm gauge we now have is what gives us 0.22 @ 528mm

Only putting this into the mix as just one of a multiplicity of possible reasons why we have this length gauge, another having just been unearthed by you, Martin

By "just" I mean at 1138 this morning

[Philip Hall]

Martin,

Yes, you're quite right, the railway is built to finer EM standards with flangeways set for a b-b of 16.6mm to accommodate wheels by Ultrascale, Gibson or Sharman which work with this. It is just the odd Romford or Markits wheel that has given trouble, as they have a much thicker flange. But for most of my modelling life, when I have never looked at the dimensions for EM beyond what I 'always knew', the 'standard' b-b has been 16.5mm. I always made customers models to this dimension or a loose sliding fit as it were.

However, we are now discussing EM standards on the Scalefour Forum, which perhaps is not quite the thing!

Philip

[Julian Roberts]

Hi Martin
Re your post yesterday morning at 1138 (I can't get quote thingys to work on this mobile phone )

I am sure this is "the answer", but am surprised the date is 1970.

Surely what happened was that in August 1966 the MRSG couldn't agree what the Gauge Widening Factor should be?

So the first article where Protofour was born has no mention of 528. It just says GW will be 0.22, the prototype minus 12% and that the track gauge incorporates a gauge widening factor (unspecified).

Between then and January 1967 they compromise on this hopelessly inadequate figure of 528, completely out of kilter with the whole ethos of the new scale standard of everything being prototypical but with 12% leeway.

I thought the BRSMB was something to do with 00 gauge and had been around since long before.

Could it be that the 528 was a figure that was around already in 1966?

By the second article in

[Martin Wynne]

I thought the BRSMB was something to do with 00 gauge and had been around since long before.

Hi Julian,

The BRMSB panel was set up after WW2 to set out updated standards for all model railway scales and gauges. They published the final results of their deliberations in July 1951. The whole history of the origin of H0, 00 and EM is far too complex to go into here and has been published elsewhere.

When the EM Gauge Society was founded on 10th September 1955 they agreed to adopt the current BRMSB standards for EM, which was a foregone conclusion because no other established standards existed at that time.

Could it be that the 528 was a figure that was around already in 1966?

Almost certainly. Page 1 of that booklet describes itself as Revised Edition (1970). It is a compilation of EMGS "Technical Notes" which had been published previously and articles in the then EMGS newsletter "Marshalling Yard". That edition was the first EMGS publication to show the revised gauge of 18.2mm in the diagrams, but there is no mention of it in the text which continues to refer to 18.0mm and is clearly therefore simply a reprint of earlier material. Including no doubt the 528mm figure, which even by 1970 must have looked very odd as a recommended minimum radius, unless it was intended to be an absolute minimum, even for the sidings round the back of the gasworks. My recollections of the time are that 750mm/30" was (and still is?) regarded as the boundary between train-set curves and finescale modelling.

regards,

Martin.