On Thu, 26 Feb 2009 10:20:01 +1300, Greg.Procter wrote:
No, 1:87.1 or 3.5mm/ft is what NMRA defines for H0. And these two are not
exactly the same, but so for all practical purposes.
Incidentally, I am building French prototype to NMRA standards.
But, European standards association MOROP defines in their NEM standards
H0 scale to be 1:87 ... The difference is futile.
In practice the most annoying is that MOROP did not accept the NMRA
wheelset dimensions in relation to switch points. NEM adheres to a back-to-
back distance for wheelsets of 14.3 mm, while NMRA defines a 'check gauge
G' from inside one flange to the outside of the other of 15.3 mm.
That cannot easily be measured by means of a caliper, so NMRA sells a Gage
for that. Although all dimensions of rail and switches, turnouts, are
virtually the same, the misunderstanding about the required wheelset
dimensions remain. Fortunately the RP25 is more widely used here too.
Some makes, like ROCO, only give problems with Shinohara code 70. Not with
handlaid code 70 or PECO code 83.
The check gage is indeed one of the sort of silly things to meaure as it is
more valid towards what track is to be measured by. It ends up being
directly the number that is needed to clear a point or other obstruction in
the trackwork so it is indeed a viable number to meet. If you have a thin
flange, and you do the back to back dimension, you can fail that critical
check gage value in reality but still meet the specs of the standard.
Thus with the NEMA standard, I'd have to pull the point back further from
the stock rail to insure that I don't pick at the points while the NMRA
standard tells me exactly where I can go with the spacing of the points as
the wheel will never get under that 15.3mm spec.
Maybe only a mm but the spacing between a point and the stock rail is
already way too large compared to the relationships of the prototype.
rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net
It's a design that's very difficult to alter dimensionally on proprietry
I've often shimmed the check rail(s) of proprietry turnouts to pull
wheelsets away from the frog nose, but that leaves narrow tyred wheels
in danger of dropping between frog and guard rails.
The wide spacing also causes wheel drop, particularly on European 4 wheel
I've concluded I eather build my own turnouts or accept the wheel drop.
You could always put a shim in the bottom of the vee crossing (frog) if you
run uniform wheels. i.e., all wheels to RP25 for example. This will stop
the wheels from dropping.
See the GER at: -
True, but my HO modelling started in 1959 which results in a wide variety
of wheel types in my collection.
I convert the worst operating and worst appearing wheels, but I never
I prefer spending my time building new models and I continue to buy those
new models that fit my modelling theme.
(it's a compromise)
I have a small, by North America standards, collection of rolling stock.
Something like 150 freight cars, around 20 vans (cabooses) and about 15
passenger cars. A few of these came with metal wheels, usually those
purchased in the past couple of years which, in my case would be the
passenger cars. However, almost all the freight cars and vans came with
plastic wheels. It took me about two years of buying a package or two or
three per month of 33" metal freight car wheels to convert the lot over to
all metal wheels.
Have you considered doing something similar to standardise your wheel sets?
I found it made a noticeable different by running all cars with the same
brand of wheels. My switches could be fine tuned to the one brand and my
locos could pull a couple more cars thanks to the freer running steel
See the GER at: -
I've started to purchase bulk packs of KD couplers and metal wheels. I
seem to run out of both fairly quickly, and the bulk packs are usually
cheaper per unit.
Availability not guaranteed. Products available in my location in the US
may not be available in other countries, or even the next hobby shop.
On Usenet, no one can hear you laugh. That's a good thing, though, as
some writers are incorrigible.
I got a thousand odd wheels and axles made in various sizes by a local
Problem #1 is that there are a variety of sizes and axle lengths.
The "standard" size wheel (1m diameter = 11.5mm scale)is loosely adhered
different manufacturers, so I found I needed three different diameters to
physically able to fit in the underframes. I needed three different axle
(24, 25, 26mm) and both spoked and disk. That's more than a dozen
(26mm axles aren't common so I just got a bag of loose axles)
Problem #2 is that I have to buy a large batch which requires money.
Problem #3 is I've currently run out and there are other calls on my cash
I long ago discarded all plastic wheels - same result as you have found.
I occassionally set up a production sequence and do a large batch of
Nowdays several European manufacturers have switched to NMRA profile, but
I have about 50 locos to do before I can fill the frog gaps.
So you're not actually into scale modelling - fair enough, it's your hobby!
Umm, the NMRA thought that extra .1 was worth mentioning!
Tell them your theory.
The distance between flange back and opposing flange face is the important
for wheelsets. Everything else, other than fl.depth and tread width stems
from that dimension.
It's very annoying that NEM did not go straight to NMRA compatibility, but
generally wish to maintain compatibility with their past products in that
customers may well
have layouts using turnouts that were designed for original wheelsets.
I upgrade older rolling stock wheels and operate them over a variety of
and self laid code 70-75 turnouts. I've used code 100 track and turnouts
in hidden staging areas.
When did _I_ become the NMRA?
(I was on the NMRA DCC working group for about 3 years, but not the scale
THEY considered the difference between the internationally accepted
1:87, the British 3.5mm:1' and 1:87.1 to be significant enough to set it
into their standards.
If they hadn't felt the distinction to be significant then they wouldn't
made the distinction.
Of course it's significant!
For a start it requires two extra key presses on the calculator to convert
from full size to scale size.
Now it's time for _you_ to stop avoiding the issue:
- why add two extra keystrokes and an extra .15% to an already existing
(and somewhat irrational) scale?
Those extra keystrokes increase the likelyhood of errors.
What intrinsic advantage is gained by that addition?
- US arrogance?
- a significant improvement in accuracy?
- something I've overlooked?
Yes. Let me reinforce that in hopes of drilling the idea into Greg's
horrendously thick skull: IT DOESN'T MATTER WHETHER YOU USE 1:87 or
1:87.1. NOBODY'S EVER GOING TO NOTICE THE DIFFERENCE!
So it *doesn't matter* that certain organizations, publications,
standards, etc., use one or the other. For all practical purposes,
they're completely interchangeable.
Got it? End of discussion.
Personally, I like Vista, but I probably won't use it. I like it
because it generates considerable business for me in consulting and
On Sat, 28 Feb 2009 18:23:30 +1300, David Nebenzahl
So long as you never do any modelling it doesn't matter if you use 1:240,
1:87 or 1:32, so I can see where you're coming from.
Your US standards setters have made the statement that the .1 does make a
difference, in that they added it over the existing international standard.
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