Proto 120

Proto 120

Postby taiwest » Wed Sep 22, 2010 4:14 pm

Hello. I am a new member and this is my first post.

I am interested in modeling proto 120. I know there are no official standards, but am curious if anybody is modeling this? I searched the archive and saw where some were using proto:87 wheelsets etc. Anyhow, on the Scalefour Society website, I found some standards calculated for proto 120 that came close to what I have calculated for myself.

My current project is building Kozo Hirokas' Pennsylvania A3 Switcher 0-4-0 to my proto 120 specs with a small switching layout using Templot to generate my pointwork. I have a small machine shop, casting facilities and photo etching setup. Anyhow, I would be interested in corresponding with anyone doing something similar as I am curious about running reliability with these wheel and track specs.
mm in
1 Track Gauge min. 12.00 0.472
2 Gauge Widening 0.14 0.006
3 Check Gauge min. 11.57 0.456
4 Crossing Flangeway max.0.43 0.017
5 min. 0.41 0.016
6 Between Checks max.11.13 0.438
7 Effective Flange max.0.25 0.010
8 min. 0.22 0.009
9 Wheel Back to Back max.11.31 0.445
10 min. 11.26 0.443
11 Tyre Width max.1.27 0.050
12 min. 1.18 0.046

-
TW
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Re: Proto 120

Postby ConducTTor » Wed Sep 22, 2010 4:54 pm

Welcome aboard! I think "scaro" is the person closest to a Proto120 modeler that we have on the board.

I would say we all want the closest to proto but many of us are ok with what's available. The biggest limiting factor is the rail available (Tillig) although Kuehn will soon be introducing rail with a more realistic profile. "TT filigran" (sp?) in Germany offers prototypical rail.

I am very interested in the progress of your model.
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Re: Proto 120

Postby taiwest » Wed Sep 22, 2010 5:14 pm

ConducTTor,

I am hand laying code 55 rail, which I believe is about 115 lbs per yard scale weight. I am still trying to figure out a way to model tie plates that is not too work intensive.

At this point, I am still converting dimensions for the tender, but will start manufacturing the tender trucks this weekend as well as small hand laid diorama base with a single turnout.
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Re: Proto 120

Postby ConducTTor » Wed Sep 22, 2010 5:23 pm

taiwest wrote:ConducTTor,
I am still trying to figure out a way to model tie plates that is not too work intensive.


Cast or etch 'em and crank out as many as you need?
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Re: Proto 120

Postby ctxmf74 » Wed Sep 22, 2010 5:59 pm

taiwest wrote:I am interested in modeling proto 120.
I am curious about running reliability with these wheel and track specs.


Welcome, I've never tried P120 but I have tried HO P87 and found it works fine. I know there is an N fine scale group so they might be able to tell you more about running tight tolerances on smaller models....dave
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Re: Proto 120

Postby scaro » Wed Sep 22, 2010 6:18 pm

ConducTTor wrote:Welcome aboard! I think "scaro" is the person closest to a Proto120 modeler that we have on the board.

I would say we all want the closest to proto but many of us are ok with what's available. The biggest limiting factor is the rail available (Tillig) although Kuehn will soon be introducing rail with a more realistic profile. "TT filigran" (sp?) in Germany offers prototypical rail.

I am very interested in the progress of your model.


i do not think there is anything inherently more difficult about doing P120 than P87 and as marquette has already pointed out, 24" and 26" HO NWSL wheels scale to 33" and 36" wheels respectively in TT. the 'standard' TT axle is 18.5mm long and NWSL don't do it but say it's possible - but if you prefer, the australian equivalent, steam era models, do HOn3/HOn3.5 axles to this length, 2mm diameter. they are quite cheap and well known for their quality. modmueller does 1.5mm dia axles to that length.

trucks are a bit limited, you have the gold coast ASF ride control and precision scale do a nice HOn3 archbar that would make a very fine archbar. alex's barber truck's probably a bit out of era. in truth, it's the trucks and wagon detail area where it's a bit limited. if you can etch you may be able to solve that problem. i believe P87 wheels will work with the 3mm society's finescale standards so you may check and see if your standards are similar.

i'm a bit hamstrung at the moment as i'm unemployed so a bulk order of NWSL wheels isn't on the horizon for me anytime soon.

as an aside, one australian TTn3.5 guy is looking at using the 2mm finescale standards for his track which should result in very fine track appearance.

ben
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Re: Proto 120

Postby Marquette » Wed Sep 22, 2010 11:15 pm

I'll have to do some digging for it, but some years back I calculated specs for Proto:120 as well, and found it perfectly feasible.

ConducTTor: what track is available is irrelevant: for P120 (as for P87) you'd have to lay your own track, because the proto wheel profile would derail the instant it hit the coarse tolerances of the NEM-standard switches (or even RP25 switches). Rail down to Code 40 is readily available; a friend has even worked at doing some Code 25 as a theoretical experiment in 1:160.

Tie plates: well, if you want super fine, etching would probably be the way to go. The above-mentioned friend represents them in N scale by painting them IIRC.

Trucks: don't forget Peresvet's arch bar trucks, and Peresvet also has two other trucks - one that can be kitbashed into a Vulcan truck, another that can be modified to represent a Dalman truck.

Having once been very keen on the idea of P:120, I'm very interested in seeing what you come up with, taiwest!

I'm not sure I'm still into it, though; I think I may end up contenting myself with RP25 and code 55 track. In part, because I can't afford the special runs of wheels that I'd need, 33", 36", loco wheels, etc. But we'll see!
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Re: Proto 120

Postby taiwest » Thu Sep 23, 2010 4:45 am

Thank you everyone for your replies. Any information you can provide is helpful. I will post some picts as soon as I make some progress on my tender.

Marquette, I would be interested to see what you came up with for P120 if you can find it.

Thank you,
Tai
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Re: Proto 120

Postby taiwest » Tue Sep 28, 2010 10:00 am

P120 Standards.png


I am machining some wheels to these standards. I am using 1.27 mm for the freight wheels and 1.42 mm for the drivers.

TW
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Re: Proto 120

Postby ConducTTor » Tue Sep 28, 2010 10:38 am

taiwest wrote:
P120 Standards.png


I am machining some wheels to these standards. I am using 1.27 mm for the freight wheels and 1.42 mm for the drivers.

TW




Hmmmm, very interesting.......

Are you using existing wheels and turning them down or starting from scratch? What size axle will they be able to fit? And oh yeah, will one of each pair be insulated?
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