00 gauge Standards

[Derekstuart]

I agree with everything everyone has ever said.

 

(trust me- it's easier this way)

[PatB]

I agree with everything everyone has ever said.

 

(trust me- it's easier this way)

 

Nod, smile, check your nearest exit and keep your finger poised over the third 9 .

[Pacific231G]

 

I cannot make out what all the talk about the history of H0 standards used in America, Europe and Australia has to do with the UK's very own 00. Especially as one of the leading track manufacturers in the world, made here in Britain, has their own standard that sticks two fingers up at any self appointed group of modellers say.

 

So what are the current 00 standards

Hi Clive

I know others won't agree with this (and why should they)  but what it has to do with OO is that OO uses a nominal gauge of 16.5mm*, There are two currently widely accepted sets of standards for 16.5mm gauge which, for wheel profiles at least but I suspect more, the manufacturers are using. There is not, so far as I can tell, a widely accepted set of current standards specifically for 16.5mm gauge track when it happens to be used for OO.

 

I don't think Peco have been putting up two fingers. They started out by dutifully following BRMSB standards (I have several original Pecoway points that Romford and other wheelsets run through very smoothly) and even offered EM in kits if not RTL. They then had to also produce OO variants for Hornby, Rovex and Trix.  Had they stuck with BRMSB they'd probably have gone out of business as either most modellers using RTR stock decided that "Peco points don't work" or by having to make too many small batches.Instead it seems (I have no inside knowledge)  they came up with a "universal" compromise that most OO (and therefore H0) wheelsets would negotiate which they've refined to some extent as RTR wheels have tended to converge. 

 

I suspect that the BRMSB got as far as it was capable of before effectively disappearing in the early 1950s and that was that for accepted OO standards. Meanwhile the other main groups of modellers using 16.5mm gauge (who adopted the also the UK's very own H0 scale) set up standard setting bodies. For good or ill, these are still around so current standards for 16.5mm gauge do exist and I think have enough overlap in their tolerances to co-exist. Those standards surely need to at least be taken into account when trying to decide what standards to use for OO. 

 

The manufacturers as always followed the standards just as far as it suited them.

 

*Since "number 00 gauge" (before it became two scales) was originally specified as 5/8" or 16mm I have no more trouble accepting 16.2mm as OO than I do accepting Pendon's 18mm gauge track as EM even though EM is normally 18.2mm

[hayfield]

I agree with everything everyone has ever said.

 

(trust me- it's easier this way)

 

 

What have you downed a bottle of wine already?  

[RichardS]

I personally don't give a stuff what standards a layout is built to; does it work, does it keep the punters at a show entertained? If so, then I'll be happy with it. Which may be why so many stand and watch Hornby Dublo and tinplate train sets, because they work and keeps the punters amused.

Which is a fair comment but even the tin-plate and HD were built to a standard, albeit with generous tolerances, else the bits would not work together. And this applies to every layout that works - the bits need to work together.

 

But I agree the standard used should be irrelevant to the enjoyment the model brings to maker and viewer. And for most broad minded modellers I suspect it is even though they might choose to work themselves to a specific protocol.

[RichardS]

In all seriousness I hope 'Pacific 231G' will be kind enough to publish or share his database. I'm sure it will be interesting to compare the various data.

(Sorry if that sounds a bit geeky)

Regards

Richard

[Pacific231G]

In all seriousness I hope 'Pacific 231G' will be kind enough to publish or share his database. I'm sure it will be interesting to compare the various data.

(Sorry if that sounds a bit geeky)

Regards

Richard

I don't think I can attach a spreadsheet to this but here's a screengrab of it thus far which I hope is readable .

 

I give no guarantee of the accuracy of my information or calculations and I really did this to find out for myself where tolerances overlap or nest to enable a common standard to be derived. I think NMRA and MOROP do overlap (but only just in a few places) as does MOROP and DOGA intermediate. Some of DOGA's dimensions seem to lie completely outside the NMRA standard though I'm not sure why as they relate to the same wheel contour.

[Junctionmad]

Great stuff. ,know just to flesh it out to include doga fine and 00-SF/4 SF

 

NMRA standard S -3.2 should be quoted as the track for reccomended practice RP25, 1.22 nominal flange ways etc. As NMRA S4.2 specifies rp25/110 wheel for S 3.2

 

Edit: doh, you've done that ( face slap )

[Junctionmad]

I personally don't give a stuff what standards a layout is built to; does it work, does it keep the punters at a show entertained? If so, then I'll be happy with it. Which may be why so many stand and watch Hornby Dublo and tinplate train sets, because they work and keeps the punters amused.

The punters sitting in the back of the plane, typically don't give a " stuff" how the aircraft flies , or what standards were followed , as long as it stays up in the air and the in-flight entertainment is passable

 

However to the engineers, designers and builders , it's of great importance what standards apply , how they interact etc,

 

Be happy that unlike you, the people responsible for designing and building things do care. ........

 

The movie is showing terminator 3 by the way , and if you look out the window , you will notice you're not on the ground.

[martin_wynne]

Great stuff. ,know just to flesh it out to include doga fine and 00-SF/4 SF

 

Don't forget Peco, 00-BF, H00-DN and Proto-87.

[Junctionmad]

Don't forget Peco, 00-BF, H00-DN and Proto-87.

You have to love 00 , don't you. It's like that cuddly stray dog, you take in , it's eats everything , sh1ts every where , chews your slippers and snaps at the hand that fed it. But sure, it's lovely and cuddly ..........

 

The P4 people just took it to the vet ...

[RichardS]

What about NMRA 'OO' which is to 19mm gauge or something?

 

Yes, it's 03.45 GMT (near enough for OO anyway).

[nswgr1855]

 

 

The 4-SF (00-SF) dimensions can be found at: http://4-sf.uk

 

Terry Flynn doesn't agree with them. He prefers his flawed double-dimensioned standard with each dimension fully toleranced independently of the others. DOGA, NMRA, and many others do the same thing, and it is equally flawed, but it is entirely up to them.

 

Apart from 4-SF, the only other standards with the proper inter-related max-min dimensions are EM and P4.

 

Martin.

 

Hello Martin,

 

It's clear you have not done your sums correctly.

 

Any standard that is not correctly toleranced will result in a certain amount of rough running or derailments. All the toleranced dimensions in the AMRA ,P4, MOROP NEM and NMRA standards conform to the proper interrelated maximum minimum dimensions. It is the older UK standards and DOGA that do not add up correctly. Using the H0 AMRA fine tolerance standard as an example using the recommended values for any flange way 1.0mm to 1.05mm, if the track gauge is 16.25mm to 16.30mm any combination results in a check gauge equal or larger than 15.2mm. Considering the AMRA wheel maximum check gauge 15.2mm,  that is one interrelationship that adds up and  is correct. The second relationship I have explained more than four times in this thread but to be complete I will state it a different way. Any combination of the AMRA recommended values above results in a check span of 14.3mm or less. That is the second necessary interrelationship that adds up and is correct considering the minimum wheel back to back is 14.4mm. Considering Peco uses the same track check gauge most RTR 00 wheels will comply with the AMRA standards check gauge. They are the absolute critical relationships. The minimum wheel width for the AMRA standard is more flexible compared to the other standards, but if you are on the limit the wheel drop is about a scale inch for a flangeway on the recommended maximum. However if you use a wheel set to the 00-SF minimum back to back of 14.3mm it can be to tight to make it when you consider practical tolerances.

 

Cheers,

Terry Flynn.

[martin_wynne]

Hello Martin,

 

It's clear you have not done your sums correctly.

 

I have done my sums correctly. But I may not be doing the same ones as you.

 

Martin.

[martin_wynne]

p.s. Terry,

 

I will try to spell it out again for you. The 4-SF standard says that the check span should not exceed 14.2mm. So clearly if you build it to 14.3mm check span as you suggest, the track would not be compliant to the 4-SF standard. And a lot of RTR models would have problems running on it.

 

What this means is that for K-crossings if you increase the track gauge from the specified minimum, you must also increase the flangeway gap to match. You can't do one and not the other. If fact when building K-crossings the flangeway gauge shims are not used, all the rails are set using the check gauge from the opposite rail.

 

Here's this bit of video again, showing that. When you use the check gauges correctly, as the track gauge increases the check span actually reduces, not increases:

 

 http://screencast.com/t/U1nGHmU1

 

(It may take a few seconds to start.)

 

I have explained that K-crossings require careful construction. Ideally builders will have a digital caliper (inexpensive nowadays) and will be able to check the track gauge and check span dimensions as they work.

 

regards,

 

Martin.

[Pacific231G]

Great stuff. ,know just to flesh it out to include doga fine and 00-SF/4 SF

 

 

 

It seems I was wrong and you can attach a spreadsheet so do feel free to add to this.

 

16.5 mm gauge track and wheel standards compared.xlsx

 

Interesting that RP25, presumably because it's only a recommendation and not mandatory, is only given in imperial units. I simply converted it to 2 places of decimals. The "practice" in colum  D refers to Martin's comments about commercial wheels made for "BRMSB- OO" having a flange width of 0.75mm which puts them into line with the current standards. I don't know what flange depth they were usually supplied with but Martin might.  

 

I've only done this for the mainstream 16.5mm gauge standards plus DOGA intermediate. I might add OO-SF but I also want to measure some recent Peco code 75 points to establish what dimensions they're actually made to though I'm sure there are people here, quite possibly most people here, who are far handier with a digital calliper than me. 

[Pacific231G]

What about NMRA 'OO' which is to 19mm gauge or something?

 

Yes, it's 03.45 GMT (near enough for OO anyway).

Hi Richard

It is to 19mm gauge. A few British modellers (most notably Norman Mathews) also worked to 4mm/ft scale 19mm gauge as the "true gauge for the 4mm scale" in preference to 16.5mm up to the early 1950s but when, after some discussion, the BRMSB opted for 18mm for "OO fine scale" that became far more popular.

 

19mm gauge was quite popular for a while in N. America before WW2 and several manufacturers supported it but, apart from a tiny handful of modellers, has pretty well died out as a modelling scale (though the NMRA still publish standards for it).  That seems to have largely been because it lost some of the space saving advantages over 0 gauge of HO without enough compensating advantages in terms of extra detailing.      

[roythebus]

Can any of us honestly say we can consistently make track to .01mm?  Heat up to solder something and it expands, so the .01mm is out of true already. 

[martin_wynne]

Can any of us honestly say we can consistently make track to .01mm?  Heat up to solder something and it expands, so the .01mm is out of true already. 

 

Hi Roy,

 

No-one works to 0.01mm with model-making materials and tools -- that's less than half a thou!

 

The reason for the second decimal place in David's spreadsheet is to represent fractional millimetres. The actual dimensions are 16.1/2mm, 15.1/4mm, 1.1/4mm, etc. Or to represent imperial dimensions -- the 1.27mm flangeway in H0 is actually 50 thou.

 

regards,

 

Martin.

[Pacific231G]

Hi Roy,

 

No-one works to 0.01mm with model-making materials and tools -- that's less than half a thou!

 

The reason for the second decimal place in David's spreadsheet is to represent fractional millimetres. The actual dimensions are 16.1/2mm, 15.1/4mm, 1.1/4mm, etc. Or to represent imperial dimensions -- the 1.27mm flangeway in H0 is actually 50 thou.

 

regards,

 

Martin.

Indeed. in OO scale 0.01mm equates to 3/4 millimetre on the full size railway. I wonder what are the actual tolerances that NR are building track to?

 

MOROP's dimensions all seem to be to 1/20th mm (they include a couple 0.05s that aren't quarter or three quarters) but to get comparative dimensions from RP25 I simple converted them from imperial in the spread sheet to two decimal places.  but there are a couple of places where both RP25 and MOROP's dimensions are more precise than a quarter millimetre. MOROP's back to back is 14.5 +- 0.1 mm. Their wheel profile (NEM 311) has a range of flange depths from 0.6-1.2mm and some other contour dimensions are derived from that.

 

BTW since most RTR wheels seem to use one or other standard it's worth noting that there is a widely held misunderstanding that wheels to NEM standards are inherently coarser than RP25-110. Some manufacturers even offer a choice betweeen "RP25" and "NEM" wheels. The reality is that NEM311 covers a range of flange depths from 0.6-1.2 but manufacturers have been in the habit of using the coarse end of the standard. RP25-110 has a flange depth of 0.025 inches which is 0.64mm and if you use that flange depth with NEM311 you get the same wheel profile.  MOROP do say that the fine end of the standard requires "impeccably laid track "Les boudins de roues fins exigent une voie impeccablement posée"  but when they were called RP25-110 and were under American boxcars the same wheels seemed to run very smoothly on my very far from impeccable track.  

[Grovenor]

 

but when they were called RP25-110 and were under American boxcars the same wheels seemed to run very smoothly on my very far from impeccable track. 

The flange depth is very much less of an issue on short wheelbase bogies than on long wheelbase 4 wheel wagons with rigid suspensions which are intolerant of track twist.

Regards

[Pacific231G]

The flange depth is very much less of an issue on short wheelbase bogies than on long wheelbase 4 wheel wagons with rigid suspensions which are intolerant of track twist.

Regards

Good point and for that reason MOROP does justify shorter checkrails and wider flangeways (though there's actually considerable overlap in the standards)

Presumably the same would apply in OO so does that make the DOGA intermediate wheel, which seems to be the same as RP25-110, equally demanding of impeccable track or is MOROP just being over cautious? I know British wagons were tradtionally very short wheelbase but not always and not more recently; we did also have four wheel coaches.   

[Ravenser]

Good point and for that reason MOROP does justify shorter checkrails and wider flangeways (though there's actually considerable overlap in the standards)

Presumably the same would apply in OO so does that make the DOGA intermediate wheel, which seems to be the same as RP25-110, equally demanding of impeccable track or is MOROP just being over cautious? I know British wagons were tradtionally very short wheelbase but not always and not more recently and we did have four wheel coaches.   

 

For what it's worth my detailed Lima CCT has a rebuilt underframe using MJT etched W irons and is therefore compensated. However the Parkside PMV isn't and seems to be ok, though there's normally a little rock in the wheelsets of my kitbuilt stuff. . The Branchlines Pacer chassis incorporates compensation, The swivelling trucks on Hornby OAA/VDA/SAA and VIX wagons give compensation too (can't answer for the rather better Bachmann versions - don't own any.)

 

I think I would consider the possibility of compensation with anything having longer than 12' wheelbase. That doesn't mean it would definitely happen

 

 

 

 

Persona

[Pacific231G]

 

 

I think I would consider the possibility of compensation with anything having longer than 12' wheelbase. That doesn't mean it would definitely happen

 

 

 

 

Persona

I've just found an article in Loco-Revue that makes that point and basically grumbles about the manufacturers not using three point suspension and simply relying on deep flanges. I'll need to take the digital callipers to some of my more recent stock to see how deep they actually are

[nswgr1855]

Indeed. in OO scale 0.01mm equates to 3/4 millimetre on the full size railway. I wonder what are the actual tolerances that NR are building track to?

 

MOROP's dimensions all seem to be to 1/20th mm (they include a couple 0.05s that aren't quarter or three quarters) but to get comparative dimensions from RP25 I simple converted them from imperial in the spread sheet to two decimal places.  but there are a couple of places where both RP25 and MOROP's dimensions are more precise than a quarter millimetre. MOROP's back to back is 14.5 +- 0.1 mm. Their wheel profile (NEM 311) has a range of flange depths from 0.6-1.2mm and some other contour dimensions are derived from that.

 

BTW since most RTR wheels seem to use one or other standard it's worth noting that there is a widely held misunderstanding that wheels to NEM standards are inherently coarser than RP25-110. Some manufacturers even offer a choice betweeen "RP25" and "NEM" wheels. The reality is that NEM311 covers a range of flange depths from 0.6-1.2 but manufacturers have been in the habit of using the coarse end of the standard. RP25-110 has a flange depth of 0.025 inches which is 0.64mm and if you use that flange depth with NEM311 you get the same wheel profile.  MOROP do say that the fine end of the standard requires "impeccably laid track "Les boudins de roues fins exigent une voie impeccablement posée"  but when they were called RP25-110 and were under American boxcars the same wheels seemed to run very smoothly on my very far from impeccable track.  

Note NEM 310 changed in 2009, and is now closer to the NMRA standard but is still not 100% compatible. The problem with both the NMRA and MOROP H0 standards now is both are incompatible with H0/00 PECO code 100 and code 75 turnouts, both of which use a check gauge of 15.2mm. The difference in check gauge is small enough for most NEM 310 2009 wheels to bump through without derailment, however a NMRA wheel on the maximum NMRA wheel check gauge will often derail.

 

Cheers,

 

Terry Flynn.