Curve Turnout from scratch

[crisco1]

Hi,

     Is there anyone out there has made a large radius curve turnout from scratch?

Specifically, 40" radius on the outer curve,and 37.5 " radius on the inner curve.

                                                                                              Thanks,

                                                                                                Chris

 

                                                                                               

 

 

[doctorwayne]

I can't say what the radii might have been, but the second scratchbuilt turnout that I made was built in-place on the layout to fit a specific situation.   I'm only guessing, but I'd estimate it to be the equivalent of perhaps a #12.  I worked from an article in Model Railroader, but I don't recall the author or the particular article...this would have been in the late '70s or early '80s.  

The turnout featured a moveable frog (points and frog were continuous pieces of rail) and I powered it with a Fulgurex motor-driven switch machine.
That was on a previous layout in another house.  I was going to tear out the layout when we sold the house, and save that turnout for use on a new layout, but the buyer asked if I could leave the layout (it was operational, but mostly just track and cork on cut-out 3/4" plywood roadbed), so I did.
I always figured that I could build another if I needed one, but never did.

The turnout was in what would have become a very difficult area to access once scenery was in place, but it worked flawlessly.

The first scratchbuilt turnout for me was built, using what was probably code 70 rail, directly on a piece of plywood, spiking the rails directly to the wood, with no ties at all.  Manually operated, it was just a test to determine if I could do it.

If you need the turnout that you describe, build it...it certainly wasn't as difficult as I had initially imagined it to be.

Wayne

[carl425]

crisco1

Specifically, 40" radius on the outer curve,and 37.5 " radius on the inner curve.

Assuming HO, at those dimensions this turnout will be about 4' long.  You're probably going to want a bigger difference betwen the radius of the two curves.

[selector]

I built such a turnout using the FastTracks method for a place on my second layout, the one whose images appear here mostly when I post them.  I used it in my loft layout that never got completed because we moved two summers ago.  I just finished placing it, slightly repaired, on my newest build two days ago.

As suggested by Carl above, the dimensions you are interested in will make this necessarily a substantial length, perhaps not quite the 4' he mentions, but it will be close to 24", as mine is.  It's outer curve radius is about 36" and the inner was (now modified outward) about 30".

What you might be most impacted by is the length of the (dead?) frog.  Mine is about 3", quite a chunk for a tiny switcher to negotiate, but negotiate it they did, and reliably. If you already know you will be adversely affected by such a long dead frog, then you know what you gotta do...isolate it anyway, but wire it and switch it for reversing of phase/polarity.

[RR_Mel]

Building your own turnouts isn’t a hard task, early on I built all of my turnouts at the ripe old age of 14 using the old steel rails at 5¢ per rail in the early 1950s. Today I’d use NS rails and a thin piece of brass sheet metal for the frog bottom plate.  I’d go with a Tortoise or similar switch machine to switch the frog/point rails polarity.

 

If you’re good at soldering absolutely no problems making your own turnouts.  

 

Layout it out and do it to it. 

 

Mel

 

Modeling the early to mid 1950s SP in HO scale since 1951

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[carl425]

selector

perhaps not quite the 4' he mentions

I didn't just pull this number out of the air.  I actually drew it with XTrackCAD.  The distance from the tip of the points to the frog is almost 4'.  I added a couple inches past the frog and before the points like you see in a commercial turnout.

BTW, a quick sketch agrees with your 24" length for a 36/30.

[7j43k]

Carl,

What's the frog number?

Except for the points and the frog, building this switch is easy. 

Ah, but:  the points and the frog.

I suspect the points are going to have to be pretty long.  Which might mean there'll have to be TWO throw bars.  I don't see why that's a big problem, but I might if I were to try building it.

I suspect the frog will be so long that it will be VERY attractive to build one with closure rails that are moveable near the frog.  This will deal with the very long gap.  Tru-scale made a similar one, once, except that the entire point/closure rail assembly turned on a center pivot.  I doubt this would work on a very long switch. But moving about 6" of closure rail over to the frog would be pretty easy--separate throw bar and switch machine.

 

Ed

[carl425]

7j43k

What's the frog number?

Assuming you measure a curved turnout the same way you measure a standard turnout, I get 17.35 for the frog number.

I agree that this would be a seriously good looking turnout.

BTW, I measured wrong last time.  From 3" in front of the points to the spot where there is a gap between the full ties on each track is only 3 feet (straight line measurement).

[7j43k]

17.35 frog?  Not as bad as I thought.

I am hoping/planning on building some #20's.  The prototype has a "non-mobile" frog area.  And it DOES have two throwbars (at the usual location and at the mid-length of the points).

Ed