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 Post subject: Parallel Crossing
PostPosted: Wed Feb 11, 2009 9:33 pm 
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Joined: Sat Aug 12, 2006 7:04 pm
Posts: 32
I have an idea to do a #6 turnout in one track of a double track main such that the diverging side of the turnout will cross the other main.
The question is what crossing angle would be needed to do this and is it available?


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 Post subject: Re: Parallel Crossing
PostPosted: Thu Feb 12, 2009 2:16 am 
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Joined: Sat Aug 13, 2005 10:48 am
Posts: 357
Location: East Texas - USA
It's a 1:6 crossing! Or a 9d 31' 38" angle. One can easily (I know - a relative term) hand lay such a crossing. Not likely you'll find a commercial representation.

With just a bit of eased curvature in the diverging route along with a slight widening of the parallel track center lines - you can probably get a 10 or slightly more degree crossing fitted in place. I'd actually build a curved crossing and shoot for something closer to a 12 degree approach. This gives a much safer guarding of the oblique frogs.

-ed-

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-ed mccamey-
COSLAR RR - http://www.coslar.us/
NMRA Standards and Conformance Department
PROTO & FINE Scale Coordinator
I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.


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 Post subject: Re: Parallel Crossing
PostPosted: Fri Feb 13, 2009 9:00 pm 
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Joined: Mon Aug 27, 2007 11:42 am
Posts: 17
??? hand laying a #6 crossing? why not using the double slip fixture? it's perfectly suitable, IMHO


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 Post subject: Re: Parallel Crossing
PostPosted: Sat Feb 14, 2009 11:24 am 
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Joined: Sat Aug 13, 2005 10:48 am
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Location: East Texas - USA
Each to his own. Buying a #6 double slip fixture to just build a #6 crossing is not my idea of efficiency. A crossing is not all that hard to fabricate (until you get down to less than 8 degrees (about a #7) - then you have to have moving center points).

-ed-

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-ed mccamey-
COSLAR RR - http://www.coslar.us/
NMRA Standards and Conformance Department
PROTO & FINE Scale Coordinator
I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.


Last edited by emccamey on Sat Feb 14, 2009 1:21 pm, edited 1 time in total.

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 Post subject: Re: Parallel Crossing
PostPosted: Sat Feb 14, 2009 1:13 pm 
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Joined: Mon Jul 02, 2007 10:39 am
Posts: 37
Location: Columbia, SC
Not up on all these smiley faces and stuff. [..] :) :(

Would I be correct in assuming that "IMHO" means "in my humble opinion"?

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Chuck Lobaugh
cfl9280@sc.rr.com
"oldsnowtop" ... A seller of switches on eBay


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 Post subject: Re: Parallel Crossing
PostPosted: Sat Feb 14, 2009 1:16 pm 
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Joined: Sat Aug 13, 2005 10:48 am
Posts: 357
Location: East Texas - USA
oldsnowtop1 wrote:
Not up on all these smiley faces and stuff. [..] :) :(

Would I be correct in assuming that "IMHO" means "in my humble opinion"?


Yep - that's what I've always assumed.

-ed-

_________________
-ed mccamey-
COSLAR RR - http://www.coslar.us/
NMRA Standards and Conformance Department
PROTO & FINE Scale Coordinator
I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.


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 Post subject: Re: Parallel Crossing
PostPosted: Sun Feb 15, 2009 5:59 pm 
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Joined: Mon Aug 27, 2007 11:42 am
Posts: 17
emccamey wrote:
Each to his own. Buying a #6 double slip fixture to just build a #6 crossing is not my idea of efficiency. A crossing is not all that hard to fabricate (until you get down to less than 8 degrees (about a #7) - then you have to have moving center points).

-ed-


O well, from that point of view even buying whatever fixture to build only one piece of track is far from efficiency, In My Humble Opinion (...); but since the double slip fixture is suitable for single slips and crossings too, I have been surprised by your statement, now far more clear, actually.

One more thing about moving points: in real world, or at least here in Europe, minimum frog angle is #9, but there is no evidence of moving center points: why do you consider them so compelling on model railways? A specification: I have already built a #8 double slip with moving center points and it's my pride so far, and until I will build something better...


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 Post subject: Re: Parallel Crossing
PostPosted: Sun Feb 15, 2009 11:29 pm 
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Joined: Mon Jul 02, 2007 10:39 am
Posts: 37
Location: Columbia, SC
It has to do with reliability.

I constructed a #8 Double Slip (Code 83) without the center movable points, but when I put it on the test bench the trains seemed to go thru fairly well in the forward direction, but in reverse it was a disaster.

Had numeous derailments because the trucks were able to pick the center frog.

It means four (4) more points to construct, but believe me you are better off with them.

Chuck L.

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Chuck Lobaugh
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"oldsnowtop" ... A seller of switches on eBay


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 Post subject: Re: Parallel Crossing
PostPosted: Mon Feb 16, 2009 12:46 am 
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Joined: Sat Aug 13, 2005 10:48 am
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Location: East Texas - USA
Model specifications and standards are much different than the prototype. Our wider flangeways and the check gauges have much more allowance for mis-direction in complex guarded trackwork. Crossings of number 7 and above (smaller angles) will REQUIRE moving points to avoid derailing routes at the oblique ('K') frogs. If you use tighter specifications of Fine Scale or Proto Scale - you can get by with a number 8 - but beyond that you'll still need moving points. Prototype reliability can handle up to a number 9 - but even then it's a very slow order crossing unless installed with moving points. Our space constrictions requires compression - and the miniaturization doesn't have all the physics of chassis equalization that the prototypes have. Mass weight and gravity doesn't scale - also speed for various momentum requirements is not scaled (thus no need for super elevation - it's just cosmetic and can create inverse string lining). Understanding the physics and geometry of the model requirements is important for reliability. Direct scaled from prototype practice imposes scaling of the specifications (like Proto:Scales) and is not "off the shelf" modeling.

There are 'tricks' that allow better reliability - but they demand a high skill of custom track with tight specifications AND even more skill at precision chassis equalization modifications - something not for the feint of heart.

-ed-

_________________
-ed mccamey-
COSLAR RR - http://www.coslar.us/
NMRA Standards and Conformance Department
PROTO & FINE Scale Coordinator
I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.


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 Post subject: Re: Parallel Crossing
PostPosted: Tue Feb 17, 2009 12:00 pm 
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Joined: Fri May 07, 2004 11:22 pm
Posts: 310
Location: Port Dover, Ontario
Hi Ed,

That was very well written and explains very eloquently the issues between prototype and modeling practice and why compromises must be made. Its all a trade off, if you want an exact duplicate of the prototype, be prepared for some challenges, but with a few compromises such as wider flanges and flange ways, we can get a workable solution that is reasonably good looking.

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Tim Warris
Fast Tracks
http://www.fast-tracks.net
service@fast-tracks.net


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