Trimming commercial turnouts to fit them into a specific track plan is a standard practice.
One thing about your original question has me curious. I presume you are referring to trimming the divergent side of the turnout to length. Normally the part beyond the frog of a standard-number turnout is straight - the only curvature is in the closure rail between the point and the frog. Trimming that straight extension presents no problem. If, on the other hand, you are working with full-curve sectional track (EZ-track, snap track or whatever it might be called,) butting two turnouts to form a crossover between double track will create a really bad S-curve. The result on coupler side thrust, locomotive tracking and such is not conducive to good operation.
For that matter, #4 turnouts on a crossover between tracks at minimum center-to-center spacing will create a fairly severe S-curve for long rolling stock with body-mounted couplers. It is usually recommended to go up to #5 or #6 for crossovers.
Another item of historical fact. The NMRA standards were set to approximate the AAR standards of the mid-20th century. Many prototype roads have gone to wider track spacing on new and rebuilt construction. UP is now using a standard that scales out to about 1 9/16 inches in N scale, or close to 3 inches in HO.
Chuck (who builds all his specialwork from raw rail, some of it on 9mm gauge track)
OK, that was the question I had. I know all kinds of things are altered in MRR'ing, but it seemed a bit drastic to have to cut a turnout to make it fit. In other words, the design of the plan must be bad.
One thing about your original question has me curious. I presume you are referring to trimming the divergent side of the turnout to length. Normally the part beyond the frog of a standard-number turnout is straight - the only curvature is in the closure rail between the point and the frog.
Of course you are correct. I mis-used the term "curves", mostly because I'm still juggling the appropriate jargon!! I was referring to the divergent rails (curves away from the main line).
Trimming that straight extension presents no problem. If, on the other hand, you are working with full-curve sectional track (EZ-track, snap track or whatever it might be called,) butting two turnouts to form a crossover between double track will create a really bad S-curve.
OK, I know that S-curves are bad from what I've read in the magazines and online. However, what you described is what I was trying to do. The plan called for three parallel tracks through a yard/industrial area. The two "butted" turnouts enabled a switcher to move back and forth between the lines. The S-curve is present in the plan itself. Actually, I see lots of S-curves in plans that are published in the magazines (not to mention in prototypical service).
OK, so I want to lengthen the divergent between the #4 turnouts or I have to go with a #5/#6 pair of turnouts. Either way I have to increase the distance between track centres. I was hoping to keep the track compact, but as I've stated before elsewhere, functionality is to take precedence in this, my first MRR project. It was the reason I looked to the NMRA standard in the first place; to avoid problems.
Interesting. That "modern" spacing does scale out wider than the 1 3/16" standard I was referencing. I was basically modelling an old yard that is just down the street from me. The tracks look pretty close. I'll have to wander down with a tape measure one of these days.
Thanks for the input Chuck. I guess it's back to the drawing board. Luckily I haven't bought all the material I'm going to need so no wastage yet! Glad I decided to sketch it out first!!
Rob
Rob: chopping has always been part of model railroading -- it's the way they're made.
There used to be a track brand called Tru-Scale, which made track on wood roadbed with milled ties. Their turnouts came set to make parallel tracks. For other formations, you had to saw off the roadbed and mount the rails on roadbed that went where you wanted. Crossovers required cutting everything down to size -- or buying their pre-made ones.
To close up the crossovers, you might just cut the rail opposite the frg, leving the frog sixe full length.
--David