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What wheel and track standards are manufacturers following for TT:120?


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PECO claim that their new TT:120 track follows NEM standards, but their website does not provide further detail. Presumably that is because there are multiple standards that apply. There are also the NMRA standards for TT and of course there are the 3mm Society's standards for 12mm gauge track, two of them in fact.

 

Additionally there are standards for wheel profile, covering width of tread and the width and depth of flange, plus the adjustables such as wheel back to back.

 

What these standards are will have an impact on how well TT:120 runs and how good it looks

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The Peco TT-120 thread has certainly produced a lot of discussion however I believe Peco already produce HOm track of 12mm gauge.  The question surely is what is the difference between the two?

 

Clearances, rail code, sleeper spacing, crossing angle, etc.

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Since the vast majority of TT scale product available to date is Continental, I'd be shocked if they'd follow anything other than NEM standards.

 

That said, RP25 wheels work just fine with Tillig track, I do believe Modmüller and maybe others produce RP25 wheelsets... I've yet to see TT track built to RP25 though. Anything can be made to work, I've seen successful experiments (done for the sake of experimentation only) with Proto:120 and even Proto:160 standards, but universality is key.

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I'd have thought it'd be similar if not the same as Tillig, Arnold, Piko, etc use as I'm pretty certain the Peco track will have been designed to allow their stock to run otherwise, as said on the other thread, there'd be no point in them launching it.

 

When Heljan produce their 31  or we see Peco's wagon we'll know, won't we, until then I'm sure people will fill the thread with speculation as usual!

Edited by Hobby
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2 minutes ago, Jeff Smith said:

The Peco TT-120 thread has certainly produced a lot of discussion however I believe Peco already produce HOm track of 12mm gauge.  The question surely is what is the difference between the two?

 

Clearances, rail code, sleeper spacing, crossing angle, etc.

 

A lot, the H0m track is for people modelling metre gauge in H0 scale, so heavier rail and different sleeper spacing. Code 75 vs 55 rail I think? Very different in appearance.

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I have summarised the four 12mm gauge standards - two TT:120 and two 3mm scale - into a table for comparison. The various standards bodies have different ways of presenting the standards, some do max and min and others a preferred value with a tolerance. For the purposes of discussion I have averaged that all out. I have also left out measures that only one standards body thought important. So I stress, this is a summary, don't use these figures to check actual stock against.

 

image.png.e5c56408da2930f3c61382d6b7b128fe.png

 

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3 hours ago, Hobby said:

 

A lot, the H0m track is for people modelling metre gauge in H0 scale, so heavier rail and different sleeper spacing. Code 75 vs 55 rail I think? Very different in appearance.

Different appearance but the critical dimensions of crossing and checkrail clearances etc. will be the same for TT and H0m. The relevant track and wheel NEMs refer only to track gauge not to the scale of what is on it. That's no accident as MOROP's approach was always to use the same track and wheel standards for both SG and NG so as to enable NG modellers to use commercially available wheelsets, chassis etc. (Tri-ang's TT-3 led to a lot of 00n3 layouts and the arrival of N gauge triggered an explosion in both 009 and H0e)

Making the rail look relatively lighter with more appropriate sleeper sizes and spacing would make the difference but I've seen a number of 3mm scale 12mm gauge layouts built using Peco H0m track.

Most of my H0m stock started life as TT from Berliner Bahn etc. though I do now have some actual Tillig H0m items. All seem happy with both Tillig and Peco H0m but I still have some Tri-ang TT-3 items left over from my youth and they really don't like any of my H0m (I was thinking of using a Tri-ang motor bogie for a  metre gauge railcar but gave up on the idea. 

Edited by Pacific231G
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5 hours ago, NCB said:

 

 

Link seems to be dead, so leaving us none the wiser.

 

Since Peco are likely to want plenty of sales in Germany and Eastern Europe, I'd expect them to go with NEM standards. After all RTR TT-120 exists on the Continent, in reasonable quantities, but not in North America

 

The track standards are pretty close , it's the wheel standards that have most of the variation. So we will have to wat for the first items of stock to see where things really are

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14 hours ago, Pacific231G said:

Different appearance...

 

Which is all I said! You can go into the detail of construction all you wish but I was just commenting on the appearance, which, if my previous use of Ratio TT track in 00n3 modelling is anything to go by, Peco's use of code 55 will make it look "lighter" in appearance than their H0m track. Which is what i thought Jeff was asking - I think it was more a question of why they would bother having already made 12mm gauge track, the answer is in the looks!

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1 hour ago, Hobby said:

 

Which is all I said! You can go into the detail of construction all you wish but I was just commenting on the appearance, which, if my previous use of Ratio TT track in 00n3 modelling is anything to go by, Peco's use of code 55 will make it look "lighter" in appearance than their H0m track. Which is what i thought Jeff was asking - I think it was more a question of why they would bother having already made 12mm gauge track, the answer is in the looks!

 

It's also VERY noticable if you look at the HOM track and the new tt1:120 track, the difference in clearance on point blades and checkrails is obvious.  Peco have categorically stated that the track is to UK sleeper spacing and is as close to finescale clearances as they can manage (Railway Modeller)  given mass production with a rail size (code 55 in effect) which is scale size for UK prototype. (Actually, I could have an argument on that, but won't for now :)  ) 

 

We are about 10 days into this...  we have a range of track and one new manufacturer already signed up and various 3D printing groups almost falling over themselves to rescale a lot of their products for a whole new market and other companies such as Worsley Works happy to resize their etches etc....   I have my personal suspicions (and they can only be that) that more announcements are coming.    I can't help feeling that perhaps Kato and Hornby/Arnold/Corgi and litterally waiting in the wings to announce, but over time to keep the hype up :)

 

In the meantime, I'm building my first Scalescenes building to TT1:120 to look at the size by doing a simple scaling from the 4mm one.   So far, I have found that little extra in size is making this a lot easier than the N-gauge version :)

 

Graham

 

 

Edited by Moria15
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11 minutes ago, Hobby said:

I agree Graham, it would be nice for someone at Peco to do  a side by side photo.

 

Agreed

 

Side by side would be good, but simply looking at the video or the website and comparing it to the plans you can print off for HoM show the differences very clearly :)

 

Also the fact that a medium radius TT1:120 is 36" radius with an exit angle of11.25 degrees rather than a radius on HoM mediums of 20" radius with an angle off of 10 degrees speaks volumes :)

 

Now, being completely obtuse in my own way, I now have to experiment to see if 18mm wheelsets for EM will run on a 17.83 gauge track rather than 18mm gauge track (and fit the TT1:120 clearances) to get Broad gauge working and see how it looks and if it's worth reducing the broad gauge down by a mil or so ...  but I'm probably out on my own on that one :)  If the 18mm wheelsets work on 17.83 mm gauge without needing adjustment with a lump hammer , then doing the 3d printed baulk road will be easy and just slot the rail in for whichever gauge is best :)

 

Graham

Edited by Moria15
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3 hours ago, Hobby said:

 

Which is all I said! You can go into the detail of construction all you wish but I was just commenting on the appearance, which, if my previous use of Ratio TT track in 00n3 modelling is anything to go by, Peco's use of code 55 will make it look "lighter" in appearance than their H0m track. Which is what i thought Jeff was asking - I think it was more a question of why they would bother having already made 12mm gauge track, the answer is in the looks!

I agree about appearance, NG track does simply look different. On 009/H0e layouts N gauge trackwork (usually because a particular formation wasn't available for NG) always stuck out like a sore thumb.

 

Geoff specifically asked about "Clearances, rail code, sleeper spacing, crossing angle, etc." so not just appearance and I wanted to answer that part of his query.  It's interesting if Peco are using tighter clearances for TT than they did with H0m but perhaps not surprising. A lot of "heritage" rolliing stock from Berliner Bahn etc. was being used for H0m (including by me) simply because,  with TT itself having largely died out as a RTR product in the west, that was what was affordably available .  Since then Tillig (and others?) have been producing TT stock to finer scale so Peco can presumably afford to produce track for TT that's less "universal" and, to a large extent, start with a clean slate. 

 

I've always though of TT as the ideal compromise size but, unfortunately for me, TT never took root in France, even before N gauge appeared  so, as that's what I model, almost nothing is available.  

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On 17/06/2022 at 00:57, Ravenser said:

 

 

Link seems to be dead, so leaving us none the wiser.

 

Since Peco are likely to want plenty of sales in Germany and Eastern Europe, I'd expect them to go with NEM standards. After all RTR TT-120 exists on the Continent, in reasonable quantities, but not in North America

 

The track standards are pretty close , it's the wheel standards that have most of the variation. So we will have to wat for the first items of stock to see where things really are

Link seems fine for me.

 

By the way, these are the MOROP/NEM standards. it'll be interesting to see what actually turns up; to me the pointwork looks finer than those standards.

Edited by NCB
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On 17/06/2022 at 04:50, Pacific231G said:

Since then Tillig (and others?) have been producing TT stock to finer scale

 

Tillig... and Roco, Piko, and more recently Arnold, amongst the well-known western manufacturers; there are a few other TT scale manufacturers of note (Kuehn, MTB) and a plethora of small ones specialising in their local subjects.

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On 16/06/2022 at 12:37, whart57 said:

I have summarised the four 12mm gauge standards - two TT:120 and two 3mm scale - into a table for comparison. The various standards bodies have different ways of presenting the standards, some do max and min and others a preferred value with a tolerance. For the purposes of discussion I have averaged that all out. I have also left out measures that only one standards body thought important. So I stress, this is a summary, don't use these figures to check actual stock against.

 

image.png.e5c56408da2930f3c61382d6b7b128fe.png

 

This is interesting and brings out how overscale the wheels will be.   Almost twice the wheel width in NEM and three times the flange depth and width.  Unfortunately P2.5 will require compensation and tighter check rail gaps!

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7 minutes ago, Jeff Smith said:

Unfortunately P2.5 will require compensation and tighter check rail gaps!

A friend of mine who normally works in 1:160 did a bit of P:120 as an experiment and it worked fine... so long as the trackwork is near perfect. 

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