January 10, 2015 Modifying an Atlas Turnout

This post is about a modification to an Atlas Snap Switch turnout for improved performance.

In my original layout design and construction all of my viewable turnouts were Atlas code 83 purchased in the late 1980s.   I have changed my preference to Peco turnouts recently mainly because I'm really impressed with the Peco spring lock points.

It's a very simple idea and keeps the moving rail points firmly closed.  The only downside to a Peco turnout is that their under the layout switch motor requires a 2¼" hole under the points.  However I also like the Peco switch motor better than the rest of the available switch motors, low current and high power.

The picture above shows the Peco locking spring, the picture below is a Peco PL-10 switch machine.

All of my Atlas turnouts use under the layout switch motors, the Atlas ATL65 has a 1" throw arm and is marginal at best.  Operating the throw arm at 1" it must be exactly centered under the turnout or it will not be reliable.  The picture below is an Atlas ATL65 below the layout switch machine.

I saw a post on one of the model railroad forums where a fellow added a spring to his Atlas turnouts and I decided to give it a shot.

First I cut away a 1/32" recess a ½" long from the fixed tie next to the moving throw arm.  This will give the spring room to move freely.  

I duplicated the Peco spring using .015" piano wire.  I bent a ¼" leg then the ¼" V with a second ¼" leg.  

I drilled a #74 hole in the moving tie slightly offset from the throw arm hole, placement of this hole isn't too critical.  The hole in the fixed tie is critical!  Move the throw arm fully in both directions making a slight scratch in the recessed cut area of the fixed tie to mark where hole in the moving throw arm ends up.  Those marks are extremely critical.  Next drill a #74 hole in the center of the fixed tie exactly centered between the two marks.  That will be the center balance point for the spring pressing the points against the outside rails. 

Next insert the spring and check for smooth operation.  To keep the spring in the holes glue a strip of styrene across the recessed area making sure the spring moves easily.  Flush cut the spring legs after the glue has dried.

This modification makes the Atlas Snap Switch a real snap switch.  I always thought it was funny that a Peco turnout snapped and a Atlas Snap Switch didn't.

Next cut off the center mounting tabs and bend over the side tabs.  I used Super Glue to attach the Peco Switch Motor to the bottom of the Atlas turnout.

I used a short pigtail with a three pin connector on the Peco switch motor because the terminals are solder type.

The real Atlas Snap Switch with the Peco PL-10 Switch Motor is ready to go.

The above picture shows the modified Atlas turnout in place.  The 25 year old original turnout turned brittle and needed replacing.

Using a short pigtail with a connector simplifies testing and installation with the switch motor mounted directly to the turnout.  The Atlas switch motors are connected with screw terminals, the Peco motors have solder terminals.