Whole new vistas of worry

That's not what I asked.

Which RP25 profile? Are RP25 "standard" wheels narrower than they were

That's not what I asked either.

When I was in OO, RP25 wheels were wider than were coming into use from Airfix, Mainline and later Hornby.

I don't think they have changed the standards because Hornby are still doing the models I bought from Airfix and Mainline.

Are the RP25 wheels still wider?

I'm not talking P87.

Just the wheel standards on ready to run stock.

Saying they are RP25 tells me nothing.

I have already explained that when I was into OO, RP25 wheels were wider than the wheels used by Airfix and Mainline, having a narrower back-to-back and shallower flanges.

Have things changed?

Thanks gemtlemen, some very useful pointer there. The Hattons trip is his idea, he lives near Northwich so it's no so far to go. I did suggest 53A but he's impatient and want to look round the shop. He's trying to run before he can even stand up, and he has no conception of scale or how that fits his available room, but I don't want him to get cheesed off and abandon the project.

I think it's the sound he likes on the DCC stuff (had a demo of some German stuff in Waltons of Altrincham a while back, -very- impressive, - very very - expensive).

I hope to keep him under control, get enough for a loop round the room with a branch and some sidings/ loops. That'll take a while to get done and in the mean time he will be getting a feel for space and scale.

Thanks again, copious notes made!

Regards

Mike

But with OO being a very slightly larger scale than HO, the wheels should seem even better! :)

Christopher A. Lee wrote: [...]

I gave you NMRA references. Didn't you read them?

wolf k.

True, but regardless of scale, any wheel profile standards depend on track standards and vice versa. Gauge is less fussy, but turnout and crossing dimensions are critical. I've used Peco's "universal" turnouts in the past, and found that their check rails, spaced to accommodate Hornby et al, allowed NMRA wheels to go down the wrong side of the frog ("crossing vee"). I cured this by gluing a thin (ca. 0.005") strip of plastic onto the check rail. The wheels still bumped through the frog, though, so I gave up on Peco. I haven't tried their newer track made for the N. American market.

BTW, NMRA is revising the "Standard" scale turnout and wheel specs. Some of the dimensions could interfere when extreme plus meets extreme minus tolerance. In practice, this almost never happens, since mfrs aim for the middle of the range.

Cheers, wolf k.

Of course.

They seem to have tightened up track standards recently.

But just saying RP25 still doesn't tell you enough because it doesn't specify how fine or coarse the wheels are, just the profile and relative proportions.

It doesn't tell you how wide the tread is, or the back to back.

It specifies a minimum tread width. But I've already mentioned a OO RTR GWR small prairie tank whose flanges were shallower but the treads were much wider than Airfix or Mainline.

It seems to me that wide treads or deeper flanges both help keep the models on the sort of track we lay.

Also the prototype US and UK wheel profiles seem to be different around the flange, with the UK one having a narrower, more pointed shape that angles toward the outside of the wheel when compared with the American one.

This affects the check gauge.

There is a diagram showing the UK prototype profile and the Gauge O Guild profile which British ready to run O-gauge uses at

Compare this with the NMRA profile at

These days I model 7mm scale. And the RP25 wheels on American ready to run O-gauge are coarser than on British RTR, with narrower back to back and wider treads.

I've had to do the same thing with Hornby points. With both Hornby and Peco I've also glued strips in the bottom of the frog to stop the wheels from dropping into the gap. I paint them Humbrol Coal Black.

???? The page you claim to have read gives the dimensions of the wheels. These are standard guage wheels, not fine sacle. So I don't understand your comment. These wheels are not of course prototypical, but they aren't meant to be (that's what fine scale standards are for). BTW, it's called "RP25" because 0.025" is the minimum flange depth specified under the the old S-4 (now S-4.2).

IOW, you're usinsg "fine" and "coarse" in a sense I don't understand.

RTR is not for fine scale modeller. IOW, there is no RP25 for fine scale wheels.

I don't know what your agenda is, but it seems to me that underlying your comments is some regret that fine scale wheels aren't fitted to RTR models. Well, I don't share your regret. I want commercial RTR to run well on the layouts built by most people, including those who aren't too careful about eliminating dipsy-doodles from their track work. RP25 meets that requirement.

IMO, RP25 is just fine. It tracks well down to code 55 track (and even code 40, if you glue the rail instead of spiking it). It looks good from the usual viewing distances (which in OO/HO scale out to around 100 yards and often more). It looks good from the usual more or less side-on viewing angles. Granted, an end-on, low angle view will show the wheels to be too wide, but 99% of the time you don't look at them from that angle. RP25 wheels work well with turnouts built to the tight end of the NMRA tolerance range. I've built such turnouts with code 70 rail, and they look good, and work well. Some long wheel-base locos touch the open point rail as they pass it, but that's another issue.

cheers, wolf k.

I didn't say fine scale.

I said it does not specify how fine or coarse the wheels are.

Once again, I have seen RP25 wheels that were coarser than Airfix and Mainline apart from the flange depth.

please pick one:

Main Entry: coarse Pronunciation: 'ko?rs\ Function: adjective Inflected Form(s): coars·er; coars·est Etymology: Middle English cors, perhaps from course, noun Date: 14th century

- coarse·ly adverb

- coarse·ness noun synonyms coarse, vulgar, gross, obscene, ribald mean offensive to good taste or morals. coarse implies roughness, rudeness, or crudeness of spirit, behavior, or language . vulgar often implies boorishness or ill-breeding . gross implies extreme coarseness and insensitiveness . obscene applies to anything strongly repulsive to the sense of decency and propriety especially in sexual matters . ribald applies to what is amusingly or picturesquely vulgar or irreverent or mildly indecent .

I have no idea of what you mean by "fine" and "coarse."

If you mean "wider", yeah, sure. So what's your point?

cheers, wolf k.

In OO is code 75 rail finer than code 100?

Duh. That just saying RP25 doesn't tell you enough.

It's closer to scale, so in that sense it's finer. Is that what you mean? Is it finescale or proto-scale? I don't know - I'm not up on UK rail profiles. It's 5.7" high rail in OO, which I suppose is close to the maximum height rail in the UK. Is it?

It tells me enough: "RP25" is a well defined wheel profile. It's defined for every wheel thickness available. (The table lists a number of commercially available wheels, actually.) It's explicitly _not_ fine scale, which means in RTR contexts it applies to standard gauge wheels. In HO that's a code 110 wheel (I typed "code 100" earlier, sorry.)

RP25 wheels are explicitly not finescale. If I wanted finescale wheels, I might get, say, code 88 wheels for On30 (1:48 scale, 30" gauge). Eg, a

So I don't get your point. RP25 is clear to me. if it isn't clear to you, well, I can't fix that.

cheers, wolf k.

It is neither. Finer just means closer to scale, coarser further from. It's comparative, that's all. Something beig better or worse than something else does not mean best or worst,

Lionel is finer than Hhornby tinplate but it does not mean it is finescale.

No, it isn't. Because it does not specify the width. Many other standards do.

I never said standard or narrow gauge. I was talking about the width of the wheel.

You keep arguing against something I never said.

Utterly irrelevant to what I have been saying.

What part of "it doesn't explain how wide a wheel is" is too difficult to understand?

Christopher A. Lee wrote: [...]

What part of TIRE WIDTH N' is too difficult to understand?

cheers, wolf k.

A MINIMUM BUT NOT A MAXIMUM.

Other standards specify an actualwidth or a fairly close maximum and minimum.

Have you heard the expression "steam roller wheels?

You can still have steam roller wheels and say they are RP25.

Like the imprted Korean brass small prairie and pannier tanks I mentioned.

Which had wheels WIDER than contemporary Airfix and Mainline models although the flanges were finer.

Well, I don't share your regret. I want commercial RTR to run

Precisely, and thats all most of us want :-)

Speaking of Mainline, was at their home town today - Coalville - visiting the Museum at Snibston. There was a very nice looking OO LMS 2F in a cabinet, presume kit built, but no mention of the manufacturer. See K's used to do one - could it be theres (in other words could a nice looking 2F be K's). Am beginning to like their models, got a Johnson 0-4-0 tank with chassis complete but body not started. Bit of a pig to get motor in but may well be a fine example.

Cheers, Simon

Back in the old days, with the wind up tinplate 0-4-0 engines and tinplate stock we could make track using unbrella ribs, not exactly finescale, but the trains didn't fall off on the corners.

Seem to remember a warning not to over wind if the temperature in the railway room dropped below zero.

Lot of fun was had though.

Sigh.

What ever happened to the Triang 'Big Big Train' idea, as I remember it seemed like a rather good option at the time.

Mike

It died. Pity. We still have the set I bought for my son w-a-a-y back, plus assorted additional bits and pieces picked up at yard sales (boot sales tpo you ;-) ). The grandchildren used to set up elaborate layouts from the den into the living room and back.

cheers, wolf k.