Topics

Stub turnouts


John Stutz
 

Bruce

In principal, you can take a rod off of your locking spring and use it to throw a lever at the base of your mast. rotating it from 45 degrees to 135 degrees relative to the rod.  Which is just the opposite of what a prototype rotary switch machine does.  However for a 90 degree rotation you need a lever length of about 1/sqrt(2) or 0.7 times the throw of the rails, which is a bit short and almost certainly difficult to adjust. 

Alternately build up the mast's base to make a friction drum of diameter about 1.4 times the throw of rails.  Then run a length of polyester thread (to avoid stretching) from the thrown end of your locking spring, a few time around the drum, to a very light tension spring.  You may need to adjust the drum diameter, but this diameter should rotate the mast 90 degrees, and the friction drive makes it easy to adjust the target angle. 

If the tension affects operation of your locking spring, run the thread in a rectangular loop around polished pins to the opposite side of the locking spring's thrown end, and put the tension spring in the middle of this loop.  This balances the tension spring load on the locking spring, all but the mast and pin friction.  Which also allows use of a moderately high tension spring.  A pair of pulleys could be substituted for the pins, if friction proves to be a problem, but I do not expect it to be.

John Stutz

On May 3, 2020 at 7:32 AM Bruce <in2trains@...> wrote:

....I have designed and printed a non-functional low level switch machine.  A fair looking model IMHO.  It has a hole that goes all the way from top to bottom for a wire the target will be glued to.


My "hope" is to connect the wire to the throwbar such that when your finger throws the turnout the target will rotate 90 degrees indicating the turnout's position.  I haven't nailed down the connection between the throwbar and the target wire.

QUESTION TO LARRY (or anyone): How do you make the connection to rotate the target?


With cinders in your eyes,
Bruce Bowie
419-602-3584
in2trains@...


Bruce
 

John,

Thank you for your response.  I have some thinking to do!  If/when I come up with my final, and successful, effort I will post tot he group.

With cinders in your eyes,
Bruce
419-602-3584 cell


Bruce
 

Attached is a TinderCad screenshot of the keeper box.

This is glued under the ties with the two top tabs sticking up on the outside of the rails with the split between the turnout and the moving section centered on the tab.

If I have a durability issue, I will print these with Polymax filament as it is a "tough" filament that will bend a little before breaking.  The roll I bought way back when is a medium gray.  They also have black, which might hide better.  

With cinders in your eyes,
Bruce
419-602-3584 cell


LARRY KLOSE
 

The Tam Valley 3 way board allows adjustment of the throw from the servo. Indeed, they do buzz when adjusted too firmly against the stops. On a three way stub, the center adjustment is done the same way but of course, there’s no stops.

I have no experience with using a servo for a two way stub or point turnout.

Larry Klose


LARRY KLOSE
 

Re switch stand connection, I haven’t got there yet. I’m holding the stands until I get most of my scenery and buildings installed. It’s too easy to “clear the deck“ while working with my big hands nearby.

Larry Klose


LARRY KLOSE
 

Re the keeper box, a similar fixture is molded into the head block of the PBL stub turnout. I used spikes as limiters on the Railway Engineering 3 way.

Larry Klose


Mick Moignard
 

Personally, I'd toss the Shino points, for two reasons:

1.        The frog gaps are enormous, sized for HO standard gauge wheels.  Our narrower tires drop down the frog gap and make the vehicles visibly lurch, plus the occasional derailment
2.        Shino rail metal tarnishes faster than Peco or ME, and you need to clean it sooner.

That all said, working switchstands off the tiebar isn't difficult:  I've added a piece of wire to the tiebar with a loop in the other end which lies between the headblocks.  Scratchtbuilt brass switchstands copied from Harry Brunk's MR article from about 20 years ago with the vertical rod bent in a z-shape as it leaves the lower brace. Assemble s/stand to headblock tie with superglue such that the end of the dropper is in the loop of the wire from the tiebar and the target where it needs to be for the blade position. Leave to set and operate.

Mick
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