#### code 72 wheels?

Tim O'Connor

Just note that NWSL makes P:87 .064 wheels, and also makes what they
call P:HO .064 wheels, that have a narrower back-back distance so they
can run on NMRA standard HO scale track. I think the .072 wheels were
discontinued and replaced by the P:HO wheels.

Tim O'Connor

According to my imperfect math, 3mm = 1'-0" scale (assuming I interpret this correctly)is 1:101.6, or just a bit smaller than the new scale I'm about to launch one of these days, D (for Dennis) scale, which would have a proportion of 1:100. :)

A scale width wheel at 1:101.6 would be .052 wide, so Code 72, 64, and 54 wheels would all be too wide. It appears that 3mm scale has specified overly coarse track standards, just like all the other "small" scales.

If you are committed to adapting HO scale wheels, it would appear that your choices these days would be Code 88 or Code 64 (P:87 wheels). The Code 64 wheels should work if you fill the flangeways to match the .014" flange depth. Of course, that's going to cause a problem with Code 72 wheels with their .020" deep flanges, but that's why railroad wheels are designed to NOT be flange bearing, which forces the wheel to be more than twice the width of the max. flangeway, plus the width of the frog point, which is exactly the same reason the NMRA won't adopt the Code 99 wheel as the standard for HO.

Dennis

soolinehistory <destorzek@...>

--- In STMFC@..., "Benjamin Scanlon"
the reason i am interested in them is because they sound like they are quite close to the 3mm (UK) finescale standards that i want to use and perhaps less likely to have problems in 3mm flangeways than code 64 wheels.

and similarly the extra width may result in less problems in mounting them properly which i have heard is a problem with code 64- i've been advised to buy a wheel press or jig to mount code 64 wheels, which sounds a bit extreme.

ben
According to my imperfect math, 3mm = 1'-0" scale (assuming I interpret this correctly)is 1:101.6, or just a bit smaller than the new scale I'm about to launch one of these days, D (for Dennis) scale, which would have a proportion of 1:100. :)

A scale width wheel at 1:101.6 would be .052 wide, so Code 72, 64, and 54 wheels would all be too wide. It appears that 3mm scale has specified overly coarse track standards, just like all the other "small" scales.

If you are committed to adapting HO scale wheels, it would appear that your choices these days would be Code 88 or Code 64 (P:87 wheels). The Code 64 wheels should work if you fill the flangeways to match the .014" flange depth. Of course, that's going to cause a problem with Code 72 wheels with their .020" deep flanges, but that's why railroad wheels are designed to NOT be flange bearing, which forces the wheel to be more than twice the width of the max. flangeway, plus the width of the frog point, which is exactly the same reason the NMRA won't adopt the Code 99 wheel as the standard for HO.

Dennis

Benjamin Scanlon

--- In STMFC@..., Tim O'Connor <timboconnor@...> wrote:

I bought some 36" .072 wheels from NWSL many years ago and put them on
a superdetailed tank car model. They are completely compatible with RP-25
trackwork and the car ran reliably on a club layout for a number of years.
But nowadays I only buy Intermountain or Reboxx .088 wheels. But the .072
wheels do look good!

Tim O'Connor

the reason i am interested in them is because they sound like they are quite close to the 3mm (UK) finescale standards that i want to use and perhaps less likely to have problems in 3mm flangeways than code 64 wheels.

and similarly the extra width may result in less problems in mounting them properly which i have heard is a problem with code 64- i've been advised to buy a wheel press or jig to mount code 64 wheels, which sounds a bit extreme.

ben

Tim O'Connor

I bought some 36" .072 wheels from NWSL many years ago and put them on
a superdetailed tank car model. They are completely compatible with RP-25
trackwork and the car ran reliably on a club layout for a number of years.
But nowadays I only buy Intermountain or Reboxx .088 wheels. But the .072
wheels do look good!

Tim O'Connor

It's an obsolete size. When the NMRA did the original work on the RP-25 recommended practice, they defined a series of proportional sized wheel contours, each intended to work with the common coarse standards of the different scales. These are defined here:

http://www.nmra.org/standards/sandrp/pdf/RP-25%202009.07.pdf

Code 72 was used for a while by people who anted a finer than common wheel in HO scale, although that use was not sanctioned by the NMRA because the wheel is too narrow to ride across the frog flangeways. More recently, work on the P:87 standard has encouraged some manufacturers to make exact scale width wheels, which are .064" wide, and therefore would be a "Code 64" wheel. Because of this, I suspect the Code 72 wheel is just going to fade away.

Dennis

soolinehistory <destorzek@...>

--- In STMFC@..., "Benjamin Scanlon" <benjaminscanlon@...> wrote:

There are many mentions of code 72 wheels here but who makes them and what are the dimensions, wheel width, flange depth and width, that kind of thing ?

I can find only one code 72 HO size wheel on NWSL's site, and it's only 26" dia, so I doubt it is them.
It's an obsolete size. When the NMRA did the original work on the RP-25 recommended practice, they defined a series of proportional sized wheel contours, each intended to work with the common coarse standards of the different scales. These are defined here:

http://www.nmra.org/standards/sandrp/pdf/RP-25%202009.07.pdf

Code 72 was used for a while by people who anted a finer than common wheel in HO scale, although that use was not sanctioned by the NMRA because the wheel is too narrow to ride across the frog flangeways. More recently, work on the P:87 standard has encouraged some manufacturers to make exact scale width wheels, which are .064" wide, and therefore would be a "Code 64" wheel. Because of this, I suspect the Code 72 wheel is just going to fade away.

Dennis

Benjamin Scanlon

There are many mentions of code 72 wheels here but who makes them and what are the dimensions, wheel width, flange depth and width, that kind of thing ?

I can find only one code 72 HO size wheel on NWSL's site, and it's only 26" dia, so I doubt it is them.

Regards

Benjamin

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