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TT120 Track Standards.

Martin,

Have you found out what the PECO track and wheel standards are for TT120? I've had a look at the NMRA and MOROP standards for TT and there appear to be coarse and fine standards from both organisations. The publicity picture of the turnout seems to show quite fine standards around the crossing nose.

Jim.
 
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Martin Wynne

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@Jim Guthrie

Hi Jim,

In the Peco launch video it was briefly mentioned that they were using the MOROP NEM TT:120 standards.

I can find only one MOROP standard showing dimensions for 12mm gauge:

https://www.morop.org/images/NEM_register/NEM_E/nem110_en_2009_20111116.pdf

which shows a flangeway of 0.9mm min , 1.0mm max and check gauge 11.0mm min.

In Templot I currently have the flangeway at 0.85mm. I must have got that from somewhere 25 years ago when I first compiled the list, but I can't remember where. I will change it to 1.0mm in the next update.

(MOROP seem to have made the same mistake as NMRA and mixed up a compliance standard with a manufacturing drawing.)

Are you planning a TT-120 layout?



From Wikipedia:

"Commercial support for British outline TT:120 was introduced in June 2022. It has a scale of 2.54mm to the foot or one tenth of an inch to the foot and uses 12mm gauge track, just like the TT scale used both in the USA and continental Europe. The new scale was announced in June 2022 by the UK manufacturere PECO. The company launched its new TT:120 scale 12mm gauge code 55 track and UK prototype accessories. Writing in the Peco Publications & Publicity magazine, Railway Modeller, editor Craig Tiley stated, 'To explain: rather than perpetuating the hybrid combination of 3mm:1ft scale and 12mm gauge track that was adopted by Tri-ang for its TT range during the 1950s and '60s, Peco has instead chosen the accurate scale and gauge combination of 2.54mm:1ft on 12mm track. This equates to a ratio of 1:120 (hence the term TT:120) which represents a brand new scale for commercial items in British outline.
On the same date UK-based manufacturer Gaugemaster announced plans to introduce a new range of products for TT:120 scale, which could include Class 66 locomotives, subject to demand.​
A few days later Danish model railway manufacturer Heljan announced plans to produce a British Rail Class 31 locomotive with possible future developments of a British Rail Class 08 locomotive and a Hunslet Austerity 0-6-0ST locomotive, all in TT:120 scale."​


cheers,

Martin.
 
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Jim Guthrie

Member
Thread starter
Martin,

I found the same NEM 110 and and also NEM 310 for wheels :-

https://morop.org/images/NEM_register/NEM_E/nem310_en_2009_20111116.pdf

I also dug out the NMRA standards and it looks as though that might be where you got your settings - i.e. they state a flangeway of 0.85mm

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/standard_3.2_corrected_hmin.pdf

So Peco have probably applied a wee bit of a fudge to satisfy both standards. :)

These days we always hope for finer standards but I dare say Peco has to go with the accepted standards. I note that the NMRA spec shows a tolerance of -0.13mm for the flangeway in TT, so working down to that would give a flangeway of 0.72mm.

The MOROP spec gives a wheel width of 2.5mm but the NMRA spec gives a wheel width of 2.01mm but with quite heavy flange dimensions. But it might be possible to use the NMRA RP25 Code 79 wheel spec which gives finer flange specs.

https://www.nmra.org/sites/default/files/standards/sandrp/pdf/RP-25 2009.07.pdf

There's a whole load of fudging going on here. :) If I can get the flange dimensions down a natz further I could use my S scale form tool where the flange is 0.45mm x 0.45mm :)

I might be tempted to build something in the scale - it would give me some space to run decent lengths of passenger trains which my present house won't allow in S scale. I had a quick experiment with a CNC machined Drummond Caledonian 28ft coach. :)

CalTTCoach-07.jpg


CalTTCoach-09.jpg


Don't need no steenkin wishlists. :)

Jim.
 
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Nigel Brown

Member
Location
Wales
@Jim Guthrie

Hi Jim,

In the Peco launch video it was briefly mentioned that they were using the MOROP NEM TT:120 standards.

I can find only one MOROP standard showing dimensions for 12mm gauge:

https://www.morop.org/images/NEM_register/NEM_E/nem110_en_2009_20111116.pdf

which shows a flangeway of 0.9mm min , 1.0mm max and check gauge 11.0mm min.

In Templot I currently have the flangeway at 0.85mm. I must have got that from somewhere 25 years ago when I first compiled the list, but I can't remember where. I will change it to 1.0mm.

Are you planning a TT-120 layout?



From Wikipedia:

"Commercial support for British outline TT:120 was introduced in June 2022. It has a scale of 2.54mm to the foot or one tenth of an inch to the foot and uses 12mm gauge track, just like the TT scale used both in the USA and continental Europe. The new scale was announced in June 2022 by the UK manufacturere PECO. The company launched its new TT:120 scale 12mm gauge code 55 track and UK prototype accessories. Writing in the Peco Publications & Publicity magazine, Railway Modeller, editor Craig Tiley stated, 'To explain: rather than perpetuating the hybrid combination of 3mm:1ft scale and 12mm gauge track that was adopted by Tri-ang for its TT range during the 1950s and '60s, Peco has instead chosen the accurate scale and gauge combination of 2.54mm:1ft on 12mm track. This equates to a ratio of 1:120 (hence the term TT:120) which represents a brand new scale for commercial items in British outline.
On the same date UK-based manufacturer Gaugemaster announced plans to introduce a new range of products for TT:120 scale, which could include Class 66 locomotives, subject to demand.​
A few days later Danish model railway manufacturer Heljan announced plans to produce a British Rail Class 31 locomotive with possible future developments of a British Rail Class 08 locomotive and a Hunslet Austerity 0-6-0ST locomotive, all in TT:120 scale."​


cheers,

Martin.
For what it's worth, those standards seem spot on for 3mm Society Intermediate standard.
 
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Martin Wynne

Admin
Location
West of the Severn UK
Info
.
Enjoy using Templot?
Thanks.

Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add
helpful replies.
Any source for the wheel standards they might have in mind?
@Nigel Brown

Hi Nigel,

The Peco launch video mentioned MOROP NEM for the track, so presumably they are expecting the MOROP NEM 310 wheel dimensions at:

https://morop.org/images/NEM_register/NEM_E/nem310_en_2009_20111116.pdf

But it would be wise to do some trial and error before making any assumptions about what will or won't run. No doubt anything you can buy RTR off the shelf in a model shop will be ok, Peco know their market.

cheers,

Martin.
 
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Jim Guthrie

Member
Thread starter
I suspect that a finer version might have to come about if modellers want to scratchbuild steam locomotives or other models where the distance over wheel faces is important - in typical British fashion as has happened with most other popular scale/gauges. :) I dare say we could adopt the 3mm Society fine standards which contain a set for 12mm gauge to avoid yet another set of standards.

Jim.
 
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Nigel Brown

Member
Location
Wales
@Nigel Brown

Hi Nigel,

The Peco launch video mentioned MOROP NEM for the track, so presumably they are expecting the MOROP NEM 310 wheel dimensions at:

https://morop.org/images/NEM_register/NEM_E/nem310_en_2009_20111116.pdf

But it would be wise to do some trial and error before making any assumptions about what will or won't run. No doubt anything you can buy RTR off the shelf in a model shop will be ok, Peco know their market.

cheers,

Martin.
Thanks, Martin. 3mm Society Intermediate wheels mostly meet MN 310 (but not vice versa); the exception is wheel width. 2.0 - 2.3 versus 2.3 - 2.5 (2.0 min allowed with a fudge). IMHO Peco et al need the fudge to come anywhere near catering for UK prototypes. I'd go further; I think 3mm fine standards are the minimum needed. We shall see.
 
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