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 Post subject: Curved Crossing
PostPosted: Tue May 22, 2007 6:08 pm 
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Joined: Tue Oct 05, 2004 6:00 am
Posts: 2
Location: River Falls, Wisconsin
I am trying to build a curved crossing where one leg is HO on a curve of radius 36". The other leg is HOn3 on a curve of 42". Although I haven't determined the degree of the crossing exactly, it is going to be under 10 degrees - maybe closer to 7 degrees. Does anyone know if there is a minimum for the angle of a crossing below which it is going to be pretty tough or physically impossible to construct such a crossing? I am using a Fast Tracks #8 Point/Frog grinding jig and that is helping; however the frogs need to filed way beyond what the Point/Frog jig is giving me.

Art VanDeWater


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 Post subject:
PostPosted: Tue May 22, 2007 9:18 pm 
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Joined: Sat Aug 13, 2005 10:48 am
Posts: 365
Location: East Texas - USA
Art,

Just like the larger numbered double slips, any crossing area that falls below 10 degrees will require center points at the oblique frogs. It's just physically impossible to get reliable operations otherwise. Even the prototypes had to deal with narrow angle crossing the same way - and their flangeways are much narrower in relationship.

This will be a custom - fit to order construction. Take you time, do each step carefully and plan the crossing frogs using hinged moving points in the center. Since you are crossing a narrow gage over a standard gage, you 'll need to fashion your flangeways carefully. Tighten up the standard gage flangeways to exactly fix the span gage at maximum and equally split the remaining space. That should have the standard HO flangeways at about 0.040" - 0.042" provided you tighten your track gage to be dead tight at 0.649" - 0.651". These will be perfectly acceptable and very reliable for all normal RP-25 - even code 110 wheels. The HOn3 flangeways will be easily done to the 0.038" equally (just less than maximum) allowing less track gage constraints restriction - shoot for 0.418" for narrow track gage.

Take your time - it'll be an effort of joy and pride!

_________________
-ed mccamey-
COSLAR RR - http://www.coslar.us/
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I estimate I have about 5 pounds of coupler springs somewhere in the vicinity of my workbench.


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