O31 1/2 : Man, you gotta be kidding me!

@Mannyrock posted:

I just read with interest the TinMan3 website, and it certainly looks like they will have great stuff.  But dang, now I learn that there is something called O31 1/2 track.  Man, you gotta be kidding me.  (Shame on you guys for not telling me.  :-)  )

How do I know that there isn't some 031 1/2 track mixed up in the odd lots of Lionel and K-Line track I bought?   

Thanks for all info.

Mannyrock

 

It's just a "half-section" (half-length) of O31 curved tubular track. It would readily stand out from the full length curved track.

https://www.tandem-associates....onel/lioneltrack.htm

It is likely a half length curve of O, a standard offering.  It would take 16 halves to make a circle. (normally 8) . Each has 22.5° of arc vs standard 45°. 

You can make these by simply cutting a curve in half and adding a tie....and pins .. to the halfs that need them. (or soldering to another track to stop rail twist/roll at the joint)

Standard O min curve is 31".  I don't think that ad line means 0-31.5" dia. The ¼" extra  would barely be perceptible even with a measuring tape. I guess you could assemble such an exacting circle if you combed tons of track for the very longest variances and grouped them. It may be of use for using 0-27 and 0-31.5 together parallel, witbout trains clipping each other in curves. 

It would also be useful for transition curves built from successive radii..

"It is likely a half length curve of O, a standard offering.  It would take 16 halves to make a circle. (normally 8) . Each has 22.5° of arc vs standard 45°. "

Actually, they are more than 22.5 degrees.  So-called "half" sections are bigger than what you would get by cutting a standard section in half.  (Which would result in a piece of track with a tie sliced down the middle, or with two ties that wind up being closer together than any two ties on a full section.)  If you lay a half-section on top of a full section, the first and second ties will line up.  A little bit of rail will hang out the end.  That means that two half sections when placed end to end are slightly longer than one full section.  If you try to put 16 of them into a circle, your engineers and passengers will be disappointed.  

I don't have the exact dimensions handy for the curves, but here are the dimensions for straights that demonstrate the concept:

O-27  Straight:  Full = 8.75  Half = 4.8" (exact half would be 4.375")
O -31 Straight:  Full = 10"   Half = 5.5"  (exact half would be 5")

This was probably done for two reasons: Lining the ties up on a machine that installed them onto the rails, and those weird track arrangements that we need to install to get sidings the correct distance apart for pairs of operating accessories.  There's also something rattling around in the old brain about figure 8 layouts, and getting crossings to play nicely with switches, but I'll let the next guy tell you about that.

I agree with Arthur. 

I have always found the "factory" pieces of 1/2 straight and 1/2 curve to be longer than 50%.  

I'm assuming the OP was humor... right?

Jon

@Mannyrock posted:

I just read with interest the TinMan3 website,.. But dang, now I learn ...

Don't feel bad, there are some re-writes needed on their website due to glaring errors and confusing terminology.

There are also glaring errors in some of his processes, especially when grounding transformers. Sure, to the layman it seems like the right thing to do, but then look around, what other train transformers have a ground? See https://ogrforum.com/...y=148675927400293147

Even modern UL specifications for Toy Transformers  in section 16 of specification 697 state that the cord, plug and unit should NOT be grounded, at least 18 gauge in size, between 5 and 10 ft long and not detachable from the transformer. I can't directly quote the source because it is copyrighted, but you can purchase your own copy: https://standardscatalog.ul.co...aspx?productId=UL697