I'm not sure if this is the correct term for what I'm about to describe but here goes. I envisioned two O54 reversing loops on my upper level passenger service and in fact it fit on my RRTrack plan but, you guessed it, not when I actually went to lay the track. I've read somewhere that you can mix different radii, in this case O42 and O54. Is it start and end with the smaller radius, O42, O54, O54, O54, O54, O42 or start with the smaller radius and alternate them O42, O54, O42, O54, O42?

Thanks in advance for your help.

Mike

PS: I've posted this question elsewhere so to those I've offended, I apologize in advance.

Hi, ideally, you want to transition into the curve with your broadest radi and work up to the sharpest radi at the center of the curve. Once at the center you want to again have the curve broaden as you lead into a straight away. I hope this makes sense. Perhaps someone can explain it better. Bill B.

I have a couple of these:
Straight run into 1 piece of 072 into 1 piece of 031 into 1 piece of 072 then back to straight. Works well and reduces derailments at speed. Although the 031 in the center is a bit of a shock!
I also tried 1/2 031 into 2 pieces of 072 and back to 1/2 031. This made the engine look jerky as it entered and exited the curve.

Does the O-72 curve above make a 90 degree turn in the three pieces listed? Also, what can run through that curve? i.e. stuff needing O-31 only or stuff up to O-54, etc?

Thanks guys, I'm going to play around with it a little to see what works and looks best.

Mike

quote:

Originally posted by bazonkers:
Does the O-72 curve above make a 90 degree turn in the three pieces listed? Also, what can run through that curve? i.e. stuff needing O-31 only or stuff up to O-54, etc?

Yes the two 072's and and the one 031 make a 90 degree.
I can run all the large Lionel Hudson's thru it including the scale modelfrom 1991.I don't have anything bigger so I can't tell you. Looks like it would allow bigger stuff.
Went to this after a GG1 went to the floor.

There's your problem. O42s are a 30-degree turn, while O54 and O72 are a 22.5-degree turn.

So you can mix radii, but not when O42 is involved. At least not without cutting pieces.

I do it on my layout:
O-72 to O-54 to 1/2 O-54 to O-72 for a 90° curve.
Curves are O-72=22.5°, O-54= 30°, O-42=30°, O-31=45° half curves half the degrees.
For the max in sectional track gradual curve you can go O72, 1/2 O-54, 1/2 O-42, 1/2 O-54, O-72 for a 90° curve. Fill in as you need for the radii desired and the space available. I'm looking at putting in O-82 lead in/out on my mainline curves.

Can you run an engine that requires O-72 through the transition curves you listed?

I use gargraves flex track, and transition all radii, its easier than you think.

quote:

Curves are O-72=22.5°, O-54= 30°, O-42=30°, O-31=45°

Incorrect information above in red (assuming Lionel tubular).

O-54 curved sections are 22.5° (also their half-curve).

The example "max in sectional track gradual curve you can go O72, 1/2 O-54, 1/2 O-42, 1/2 O-54, O-72 for a 90° curve." would only turn you 82.5 degrees.

Also, note that there has been no HALF O-42 curve in recent times -- you have to cut the full curve to get 15°. If someone knows a part# for "half O42 curve" from earlier eras, please post it.

quote:

it fit on my RRTrack plan but, ... not when I actually went to lay the track.

I find this troubling, and wish that you would explain the discrepancy.

As it stands, the implication is that RRTrack has errors in its track geometry. All who use it, (not to mention the developers of the softwar) depend on its accuracy.

If there is something wrong, please tell us (so we can work-around) and the RRTrack company (so they can fix it and provide an update).

Rail Reading;
The error is assuming I use Lionel Tubular.
I use MTH RealTrax, for which the numbers are correct. I should have stated that in my original post.
Also, RRTrack can be very loose in its connections if you played with the joining error value. You must read the instructions and understand the result effect.

Realtrax also makes a 42 half. One full 42 and 1 half gets you to 45 degrees.

I find myself mixing on curves a lot. I think it looks so much better than just one size curve. As long as the math works out and you can run what you want.