View single post by Salada
 Posted: Wed Dec 20th, 2017 03:24 am
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Joined: Mon Nov 4th, 2013
Posts: 1193
My thanks to Warren, Si & especially Helmut for the NMRA & RP-25 links. I had no idea the darling NMRA put so much info into the public domain. None of the Brit 'Societies' publish anything so detailed - you have to pay your £$Yen to join first.

I see what Si meant, it seems the NMRA think coning is either unimportant OR useful, depending on which page you read.

I was rather puzzled by the NMRA "Wheel CODE" column (what code ?) until I noticed that the "wheel code" is simply the wheel thickness in Imperial. (good 'ole Yankee boys, still sticking to proper 0.001 " dimensions rather than this EuroNapoleon junk).

But, I don't understand why wheel (or tyre) width is so related to all the other spec figures. ????.

I took the NMRA at their word but upped the cone taper from 3 to 5 deg, close to prototype practice (depending on which country, some national systems vary a bit + - ).

I've more or less followed the RP-25 110 spec except I've upped flange depth to .0325 from .030 (for a reason). I greatly increased the root radius between tyre & flange to .025 " due to tooling difficulties ( my initial setting was .003 " but it didn't 'feel' right).
I've also reduced the flange thickness from .030 " to .0215 " ('cos it looks like a proper flange now). Hopefully that won't be a problem in splitting switch toes ?!.

All I have to do now is reduce the Tri-orrible wheels to a reasonable width (RP-25 again I suppose ?).

Photos to follow, forgot to upload before typing.

Regards,     Michael


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