Thursday, July 21, 2016


Preparing for the next operating session, I have been tackling a number of “little” tasks that were postponed for lack of time or higher priorities.  Such has been the fate of my caboose track in the Eugene Yard complex.  The caboose track is just off the RR-East switch lead, with switches close to the layout edge.  Therein lay the problem leading to delay.  These switches use Blue Point manual throw switch machines, just as many within the yard complex. 

The Blue Point throw arm is 7/8 inch below the underside of the subroadbed.  My standard throw rod mount through the fascia is 1-1/2 inch below the subroadbed to provide for an inset knob on the layout face.  This leads to a very difficult mechanical function unless the throw rod can be attached to a lower point on the switch machine.  My prior attempts at mounting close-to-layout switch machines involved a switch machine throw bar bracket that lowered the mounting point.  These have not been completely successful.

Former offset throw rod bracket on Blue Point switch machine mounted near layout edge.  Brass bracket mounts to Blue Point throw bar at top.  Throw rod through the fascia attaches at bottom of bracket.

My former offset mounting bracket was a case of me getting too complicated—because I could.  Sometimes it is a curse to have well-developed modeling and small parts fabrication skills.  This was one of those times.

After thinking about this for a long time, the idea light bulb finally lit!  All I needed was an offset of the entire switch machine further below the subroadbed.  My Intro to Mechanical Engineering professor’s words are now ringing in my ears:  “The SIMPLEST solution usually is the BEST solution!”  Color my face red and my forehead properly smacked by hand palm.  All I needed to do was mount a spacer block for the switch machine, dropping the throw bar to my standard layout fascia throw rod mount location.

New Blue Point mount with the machine moved further from the subroadbed with a spacer block.

With this roadblock cleared, I could mount switch machines for the switches at either end of the caboose track.  The track switches have been on the layout for most of a year.  Now they are ready for service.  While I was at it, I mounted the switch machines for the Oregon Electric Interchange track, further along the switch lead.  That also prompted wiring said O.E. Interchange track and the switches.  Now I just need to add some waybills for transfers to and from the Oregon Electric (BN).

SP 2732 switches the caboose track.

Saturday, July 9, 2016


One issue that can develop with North Coast Engineering’s (NCE) engineer throttles with potentiometers (Cab04P and Cab06P) is that the potentiometer shank can develop a wobble.  The throttle knob is fairly large (a good thing!) so it is possible to put the wrong torque (not the potentiometer rotation—rather more of a side-to side forcing) on the shank.  Alas, one of my throttles developed this malady.  The solution is two-fold:  replace the damaged potentiometer and add support for the throttle knob.

The first step is to acquire a replacement potentiometer.  The NCE website lists replacement parts with this potentiometer listed: NCE Part 524-507 - !online-store/c1n1m/!/Replacement-potentiometer-for-Engineer-Cabs-Cab04-5-6-limit-2/p/40150682
This is a “free” replacement (limit 2), but that is good really only if you have other work going on at NCE.  Another alternative is to go to the “Parts and Pieces Depot” on the NCE webpage and then look at the DigiKey parts list.  Listed there is:
potentiometer for engineer cabs  - cab04 /06   Digikey 987-1276-ND
manufacturer part number  P090S-04F20BR10K
I used this option and ordered several potentiometers, as I can see that over time I may need to replace more potentiometers.  The parts are fairly cheap so order a small batch!

With the replacement potentiometer in hand, I then opened up the throttle.  With this, I could de-solder the bad potentiometer and replace it.

 Throttle opened up for access to the potentiometer, sticking up from the printed circuit board.

Upon reassembly, the second task could be addressed—adding support for the throttle knob.  I cut a couple of thick felt circles wider than the knob.  I punched a hole in the center using a simple punch made from sharpened brass tubing.  The felt disks were then fit over the potentiometer shank, followed by NCE’s rubber disk that fits inside the knob.  The knob was attached with an Allen wrench.  A quick check showed the throttle was ready for service!

 Reassembled throttle awaiting felt disks for knob support.

 Knob attached, batteries installed, and throttle checked.  Good to go!