are 0-42 fast track curves possible?

Here's close to GarGraves O42 using FasTrack O31/O48.

Here is us using FasTrack O36/O48. Neither one really fits a 4x8 sheet unless you're okay with being right on the edge.

You can't make O42, but you can combine O48 and O36 to get a similar footprint.  I use this on my Christmas layout.

1 - full O48 to 1 - 1/2 O48 to 2 - full O36 to 1 - 1/2 O48 to 1 full O48.  Makes 180 degrees.

To do what you want, you will probably want to intermix the O48 and O36 so that there is not 2 O36 curves connected to each other but it is absolutely doable.

Tony

Here's what Tony's will look like:

DoubleDAZ posted:

Here's what Tony's will look like:

You beat me too it!  lol

Tony_V posted:

You beat me too it!  lol

I still had SCARM open.

I'd give Tony's curve a try.  The 048 track into and out of the curve would act as easements, and your passenger cars may actually be quite happy on the 036 portion in between.

Paul.

Thanks so much. I knew there had to be a way to get there but curve geometry is not my strong point. This forum as always proves to be a great resource.

Just a note - the arrangements above (nor any arrangement except matching or exceeding the recommended minimum) will not guarantee O42 rated equipment will navigate successfully. Your mileage may vary depending upon your exact equipment and track configuration.

Good point. From what I gathered from his first post, he runs them on O36 curves now, so they should work a little better on the new configuration. He didn't say what kinds of problems, it any, he was having with them though, so who knows?

bmoran4 posted:

Just a note - the arrangements above (nor any arrangement except matching or exceeding the recommended minimum) will not guarantee O42 rated equipment will navigate successfully. Your mileage may vary depending upon your exact equipment and track configuration.

Again,  beaten  to it.  

I always recommend testing the piece of equipment on the minimum track diameter you plan to use.  In your case, you need to be sure the trucks of your passenger cars do not bind on O36.  I would test that before I laid out money on O48 curves for any of the configurations in this post.  I've run MTH O42 minimum passenger cars on O36 without issues.  The overhang is terrible, but it works.  Part of the spec includes clearance for switch machines, etc.  On my Christmas layout, the only turnout I have is on a straight section and passenger cars would never use it.

For testing, I would do the following:

1) Build an oval loop with just O36 curves and see if there is any binding (there should be almost no difference in effort to push a car between the straight and the curve).  

2) If that doesn't go as planned, try the arrangement you want to use on your layout.  As Paul pointed out, the O42 cars may be happy on a short section of O36 even if 180 degrees of O36 doesn't work.  You are probably thinking, "how do I do that without buying the O48 sections".  Well in my case my LTS accommodates me.  If that is not an option for you, let us know what passenger cars you plan to use in the O36 curves and someone may have your answer.

Tony 

Fastrack O-42, using O-48 7.5degree & 15degree, and O-36 12.5degree.

Yes, it is a lot of sections, and not inexpensive based on the cost of all of these pieces, but it IS a very close match.

I've actually had done this with 027. 1curve,1straight,1curve,1straight etc.... Actually worked even pulling long consist's.

I am in the final planning stages for my 48" x 120" Lionel Fastrack Layout. Since 048 will not fit in this space, is it possible to use the below track configuration without  any forseable problems?  I looked at the previous suggestions but this seemed to work in the AnyRail program. However, I want to ask the experts.

The blue rectangle is 2.5" in from the sides. The yellow square is 4.5" and the pale yellow squares are 3.25". AFAIK, general clearance standards are:

2.5" from the wall and at least that from the sides, but a mishap could result in an engine on the floor.
3.5" center-to-center in yards where trains move slower.
4.5" on mainlines.
Even more on curves depending on the overhang of the engines and rolling stock you plan to run.

Engines overhang on the outside of curves and rolling stock (such as long passenger cars) on the inside. Where they meet determines the minimum clearance needed. If you go tighter, you need to avoid the trains passing each other on the curves.

As you can see in the photo, you're configuration will result in only 3.25" of clearance on the straights. Obviously, that pushes the standard even for yard tracks. While you can get 4.5" clearance at the apex of the curve, the entry/exit points are where trains will collide. The sample engine and car show the overhang problem, though I don't know how close to scale they are and I don't know the scale length of the car.

Your curve arrangement gets you close to 42" (42.62") BUT you're also building in a horizontal offset of 1.45". A better choice would be to go 036, 048, 048, 048, 036. That gives you 44.49" with a 0" horizontal offset.

Keep in mind that FasTrack dimensions are based upon center rail to center rail.

Gilly, not sure why a "horizontal offset" is a bad thing.   If some of the O48 curvature is toward the ends of 180-degree turn, then they also act as an easement into the tighter O-36 curves - always a good thing.

As I see it, Cliff's problem is not really getting the outer loop to fit the 48" space, it's having clearance for the O36 inner loop to fit inside it and still be able to run trains.

NEILB711, I understand your goal is an outer loop to go around O36, you might be happier with a slightly larger diameter than O42.  O42 to O36 is only 6 inches difference, or 3 inches center line between tracks- too close to be comfortable.

O44 is just a bit wider, and will fit on a 4x8, and gives 8 inches in clearance.   This example (the bottom diagram is O44.   I have another solution (somewhere in my files) that is O44.5, giving 8.5, or 4.25 track center offsets, and not many sections of track.   Both have a nice O48 easement leading into the tighter O36 curves:

I'd be VERY careful with 4.5" clearance on the curves.  While small stuff will make it, anything even reasonably large is going to have a problem.  The mention of cars with a 42" minimum suggests at least 18" passenger cars.  Combine that with any locomotive that has an overhang on the curves and you'll likely to have contact.

John, I have run trains on the O44 illustration above, with the scale Lionchief Plus SD60M on the outside, and passenger cars on both the inside and outside, which make it OK, but tight.   Lionel train set passenger cars from their FT train sets anyway, of course nowhere near scale.

I've discovered the hard way that even smaller articulated stuff and longer cars seem to get together a lot on curves.

Here is my O44.5 concept:

As you can see, 4.25" is the minimum center line separation, but up to 4.4" at the widest.

Here is a pic I took some time ago, with the scale SD60M LC+ on the outside, and the LC+ Berkshire on the inside (bottom pic).   Its tight, but no contact, or close calls with these two.

I will repeat my experiments and post, once I get my revised layout up.   I don't run (or have) really long cars, my longest loco is the SD60M, and longest cars are (I think) my passenger car fleet from Lionel FT train sets (I was collecting those at one point).

Thanks for research, comments and suggestions. I appreciate it. I am going to run post war trains for the most part. The space I am planning really restricts me to 4' x 10' arrangement. I might be able to stretch the 4' to 50".

Cliff, here are additional pics taken today of my O44.5 loop with O36:

The outside O44.5 loop has my scale SD60M LC+ loco.   The inside is my next longest loco, a C44-8 MTH loco.   At the tightest contact point.  You can clearly see there is no contact! But it is tight -  OK for LC+ and traditional equipment, test if you want to try anything else.  -Ken

You might also notice that although the track and roadbed is within the 4x8 footprint, the SD60M overhangs beyond the limits of the track base.   Smaller equipment will not stick out beyond the roadbed.

Great discussion.

Attached are pdf drawings (in CAD) showing a hypothetical O-42 FT curve compared to the O-36 and other alternatives. Please note that the distances shown are from outside of track to the outside of track - NOT centerline (in order to determine if FT will fit within NeilB711 criteria - 4' wide layout). I personally like the O-60/O-36 easement curves - I use them on my layout.

It's a shame Lionel didn't produce the O-48 FT in 45-, 22.5 or 11.25 degree curves (like the O-31, O-36, O-60, O-72, O-84 and O-96 are available). Would have been much easier to design easement curves using O-48 FT (I always thought them as odd track).

As far as Cliff24G wanting an inside curve, suggest using O-31 FT, but it will still have overhang issues noted above.

Ken, great examples that show why yours is about the only configuration that will work given the space dimensions of 4'x10'. IMHO, increasing the width to 50" doesn't do anything for operations. In fact, going from 8' to 10' may not add enough to justify the 10' length and only increases the costs by moving away from a standard sheet of plywood.

I was able to accommodate an O-36/O-31 easement oval within the O-60/O-36 easement oval WITH switching - and able to fit on a 4'x8' sheet. Used a 1-3/8" filler piece at the apex of the O-60-/O-36 curve.

DoubleDAZ posted:

Ken, great examples that show why yours is about the only configuration that will work given the space dimensions of 4'x10'. IMHO, increasing the width to 50" doesn't do anything for operations. In fact, going from 8' to 10' may not add enough to justify the 10' length and only increases the costs by moving away from a standard sheet of plywood.

If you take one straight track out of each side of the inner loop, you will have gobs of clearance in the curves. There is nothing that requires both tracks to be right next to each other for the full length of the loop.

RoyBoy posted:

DoubleDAZ posted:

Ken, great examples that show why yours is about the only configuration that will work given the space dimensions of 4'x10'. IMHO, increasing the width to 50" doesn't do anything for operations. In fact, going from 8' to 10' may not add enough to justify the 10' length and only increases the costs by moving away from a standard sheet of plywood.

If you take one straight track out of each side of the inner loop, you will have gobs of clearance in the curves. There is nothing that requires both tracks to be right next to each other for the full length of the loop.

Royboy, check the diagrams, and you can see that the center of the 180-degree curve is already pulled-back to create a larger spacing at the midpoint.   The tightest point is at the entry and exit to the curves, at top and bottom.   Pulling-in the inside track won't add very much clearance.   But it would ease clearances a tiny bit as outside locos transition from the curve to the straight.  With your suggestion, the RR builder would need to accept that he won't have parallel double-track any longer, and the inside track would be shorter-around than the outside track.   However, a small amount of inside-route pull-in will capture most of the transition clearance that can be obtained this way, about 1/4".  But is this even necessary?

I think the actual construction pics demonstrate that the center spacing is now sufficient, for most people and most equipment requiring O36 or less, including the large scale SD60M LC+.   I wonder what rolling stock could be longer than the SD60M and still navigate O36 curves (any existing?)?   So there really is no need to add additional separation between the curves.   But of course, a person can do what they want regardless of the engineering analysis, its their RR.  -Ken

DoubleDAZ posted:

Ken, great examples that show why yours is about the only configuration that will work given the space dimensions of 4'x10'. IMHO, increasing the width to 50" doesn't do anything for operations. In fact, going from 8' to 10' may not add enough to justify the 10' length and only increases the costs by moving away from a standard sheet of plywood.

I agree with Dave, that adding 2" to make 50" width does not add much to operating clearances, as clearances are already sufficient.   Adding an additional 2" strip along one side adds a construction complexity.   

The design already has easements on the outside route.   I suppose that one could try to stretch the width of both the inside and outside routes with easements on the O36 and wider easements on the outside, for what that is worth.

Instead, I would frame the 4x8 or 4x10 with 1x4"s or 1x3"s, adding about 3/4" around the outside, which would give a bit of clearance for engine overhang on the outside of the outer track - we don't want to overlook that clearance issue.   BTW, Lowes shows that they offer 4x10 sheets of plywood, but I suppose not every store carries them, you might need to special order a sheet.   So a 4x10 track plan would be on a 49.5" by 121.5" layout base.

Here is the Greenville & Western track plan (to appear in a future OGR issue), with the outside framing adding outside clearances.   The track plan is 4x9, but could of course be expanded to 4x10.  The layout base with outside framing adds 1.5 inches to length and width.   -Ken

In addition to the O48 easements on the outside route, there are now 1/2 O72 sections giving easements to the inside O36 route as well.

Ken, that's a great design for the space. I was going to add the "indents" to the O36 oval, but didn't want to spend the time without knowing what Neil was looking for beyond the O42 question. Thanks for the tip on the 4x10, I didn't know anyone had 4x10 sheets.

Wow, wow!!!. Ken, Patrick and Dave et al. Thank you very much for your insight, wisdom and guidance. I can move forward with my layout with confidence. I love this forum!! Thank you all once again. It is trully appreciated.

Folks, here is video of the O44.5 curves with O36 inside.   (under  construction mess).     You can get a good visual of the adequate spacing between center rails (4.25").   I am running my scale SD60M on the outside, along with the LC+ Berkshire, and on the inside an MTH Railking SD70 (not scale). -Ken

I think the track spacing looks pretty sharp, like real parallel track.

Ken, Thanks for the video and I have even more confidence.

Cliff

Love the look, but I'm afraid with 4.25" spacing my VL-BB would clean off the other track every time!   No problem on the straight stretches, it's making the curves that's tricky.

Ken-Oscale posted:

Cliff, here are additional pics taken today of my O44.5 loop with O36:

The outside O44.5 loop has my scale SD60M LC+ loco.   The inside is my next longest loco, a C44-8 MTH loco.   At the tightest contact point.  You can clearly see there is no contact! But it is tight -  OK for LC+ and traditional equipment, test if you want to try anything else.  -Ken

You might also notice that although the track and roadbed is within the 4x8 footprint, the SD60M overhangs beyond the limits of the track base.   Smaller equipment will not stick out beyond the roadbed.

This is fine with short wheel based locomotives like these.  But if you get a Lionmaster or Rail King Big Boy or Cab Forward on the inside loop they will take out anything that passes on the outside loop.  You almost need 5.25 inches between center rails for the Cab Forward to pass on the inside.

gunrunnerjohn posted:

Love the look, but I'm afraid with 4.25" spacing my VL-BB would clean off the other track every time!   No problem on the straight stretches, it's making the curves that's tricky.

I'm all about running on tighter curves then speced, but I'm pretty sure the VL-BB would have other issues on O36 before it got a chance to clean off the outside curve.

Well, even O72 curves spaced at 4.25" would have the same problem with the VL-BB.   I know that because curves at 5" didn't work, and the freight coming the other way suffered.