Devon, I used 3.5mm.
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Devon,
#4 frogs are just sitting for now. I only used 3 on the staging yard and donāt have room for anymore turnouts in staging unless I punch a hole in the garage door and build another extension out the frontā¦
Actually thatās not a bad idea!
So this is what I was able to come up with in CAD for printing. I havenāt looked to see if I can print the entire switch or If I will only be able to print the section that includes the frog and outer guard rails. Basically what I will do is print as much if it as will fit in one piece.
I am glad I decided to make it a stub switch. Not only was it was it easy to draw but will be much easier to ābuildā. Instead of point rails and getting that all right, I will just need to shift the mainline rails. The challenge to this or any switch will be the ability to operate it. This will for sure need some sort of remote actuator. And with it being a stub, I canāt wait until the first time I forget to set it and have to climb up there over all my junk to put it back on the rails.
I should add that I plan to add some cross pieces like Dan did that will hold it together for laying on the ties. Just havenāt gotten that far.
If you use plastic rail they will bend easier .
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Well done, Devon. I donāt see any reason that wonāt work. Will you have a way to tell which way the switch is thrown from the floor?
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I actually have spent a bit of time thinking about this. The nice thing about where this switch is going is it can have a full 3 feet of rail leading into it. So the unfixed moving sections of rails can be fairly long. So they should bend easy enough.
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Yes I will put a harp style stand on the throw with a nice big flag. I like the harp style anyway and for a stub its nice because it clearly indicates which way the switch is thrown since it does not rotate but moves in the same line as the point rails (though if I am not mistaken its opposite).
Good News, the entire switch as shown will fit in my printer. It will be a long print as its taking up most of the height to get it to fit but it is not vertical and has still enough angle that it should print just fine. And since it is not a detail part I can live with things like build lines should they occur. I think this will work out just fine.
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Looking forward to seeing what comes out of the printer.
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That depends on what kind of wheels you are using. Finescale wheels require the frog guard rails and check rails to be further apart. LGB wheels need a wide gap. Thereās no simple answer.
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Well honestly i donāt know what wheel I will be using. I am going to assume I will need some forgiveness in this area. The motor block I am using for both locos that will run on it are bachmann lil big haulers. I would say that would be the widest flange.
If my printed wheels for my cars donāt hold up then I will likely use the small bachmann wheels.
I have it set at 3.5mm does anyone see this as problematic?
If it were me, Iād try printing shorter sections flat against the build plate. Really quick printing that way, zero supports, no distortion, and super flat underside. It would take a few test runs tho to get the rail flange width corrected for the natural spread of the resin against the build plate. And Iād print with supports between rails, perhaps the topsides of ties even, to maintain everything while knifing off the build plate.
Just my 2 cents.
It wonāt fit on the plate flat unless I cut it down. I might have to play with it and see how much I can shorten it.
I could slice it in half I suppose
Thatās what Iād do.
But do it your way first and be your own judge.
Actually Cliff I am thinking I like your way. Would be easy to do. And would be a much faster cleaner print.
Even flat on the plate the curl wonāt bother me. First you wonāt see it on my ceiling and Ballast would cover it anyway. I think thatās the route to go
It probably doesnāt matter for this project, but a frog should not have any curved lines in it. The running rail should straighten just before entering the frog.
This old diagram I found on the web years ago might help at least with naming conventionsā¦
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Jon,
I couldnāt agree more. And in no way would I think to do this in a ānormalā situation. But this is a special case that breaks all the rules. Its a compromise between whatās proper and what needs to happen.
I used to not really understand why. But after enough reading about it awhile back I understand why itās problematic
At least itās a quick test. Maybe on a piece of track an inch or two long. With a bit of frog maybe.
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Hmmm Is it done yet ? 
As Jon posted the diagram, (I was just about to) Iāll refer to it.
Devon - Iām not even sure where your 3.5mm gap is located. There are 2 critical gaps. Between the wing rails and the frog, and between the stock rails and the check rails.
When a wheel set runs through from L to R, the back of the wheels is controlled by the check rail to prevent the wheel from heading the wrong way down the frog. If your back-to-back wheel measurement is finescale (1.575" or more) then your gaps need to be tight. If you are running wheels with thick flanges at less than 1.575" then the gaps should be wider.
In 60 years of making switches and frogs, I concluded the only āuniversalā way to do it that controls all kinds of wheels is to make the gap at the frog/wing rail wide and the gap at the stock/check rail much smaller. You want to hold all kinds of wheels against the stock rail.
The problem is that most wheels will drop into the gap at the crossing/point of the the frog before riding on the frog. Hence you need to build up support for the flange so it rides on the support and doesnāt drop too low. [What is supposed to happen is that the wheel smoothly transitions from the frog point to the wing rail or vice versa without ever being unsupported.]
There was a discussion recently about LGB frogs. Iāll see if I can find it.
Edit: here you go - 2 good threads to review:
https://www.mylargescale.com/threads/issues-with-other-manufacturers-on-lgb-turnouts.91945/
https://www.mylargescale.com/threads/switch-frog-groove-depth.27202/