When using a pair of Peco medium turnouts to build a crossover, how long a piece of straight track should be inserted between the diverging legs in order to get 1 1/4" center to center track spacing?
If I were at work, I'd have a go at drafting this up, to give a precise answer. I've looked up the Peco geometry for my own use in track planning, although I'm not using those specific turnouts. However, one way to go about it, assuming you have two said turnouts to play with, is to draw two parallel centerlines at the 1.25" spacing you desire, set one of the turnouts down on one line (perhaps tape it down), and then place the other on the other track. Slide it up and down the centerline until the diverging route rails appear to be aligned, as sighted by eye. Then, just measure the gap between them.
Eyeball it. Fer cripes sake, you're not doing brain surgery...
Lee
Route of the Alpha Jets www.wmrywesternlines.net
FulhamFCHad a look at it on the anyrail software i've got
Note that templates are not correct in all CAD programs. This can be particularly true in low-end or free versions (though it happens with more-expensive programs, too), and especially for N scale components. So giving an answer based on a CAD program is often not correct (such as in this case).
There can also be differences in different turnout lines from the same manufacturer, as in this case between PECO Code 80 and PECO Code 55, which use different frogs and are different sizes overall. We don't know which the Original Poster is using.
As Lee said (in essence), this is a case where it is often significantly better to draw the track centerlines on the layout surface and then lay out the turnouts to align properly.
Byron
Layout Design GalleryLayout Design Special Interest Group
You're suggesting a bazooka where a fly swatter will do. Cut a short piece of track, install it, see if it aligns the track spacing the way you want it. If it's too small, cut a slightly larger piece. Etc. A pair of rail nippers and a small file is all you need, oh, and a piece of scrap track you can cannibalize.