Traverser Automation Plan

controllerpartsI have acquired the necessary electronic components to implement my plan for automating the traverser. Working with stepper motors is a new thing for me so I wanted to start in on that sooner to qualify the technical risk aka figure out if it can be done. In the interests of speed, I decided to go with fast and effective for the prototype.

Initial major components are:

  • A NEMA23 stepper motor which the size typically used by small CNC machines. The traverser table will be rolling on drawer slides and hopefully this motor will have enough torque to move the table when loaded with cars and loco.
  • A Big Easy Driver board to control the motor. This motor can draw up to 2 amps so you can’t drive it directly from microcontroller PWM outputs like a small servo. This driver is one that has good Arduino support.
  • An Arduino Uno R3 microcontroller board. This is major overkill for this application in terms of processor power and functionality but the quickest to get something running. Final version will probably be an Arduino mini but that board doesn’t have on-board debugging support so I wanted to defer that until later.

I am going to use the Arduino development environment with its associated cornucopia of software and community support. I would not base a commercial product on Arduino but nobody is paying me for this so I am trying to focus on the model railroad goal and avoiding the temptation to start from scratch firmware-wise.


In preparation for cutting out roadbed and sub-roadbed, I have been creating the detailed track templates. General track planning software such as AnyRail which I use is good for general planning but does not produce templates for hand laying track.  For that, the go-to tool is Templot by Martin Wynne.

Templot is free to use although I bought it when it was a licensed product. It is a powerful specialized CAD program specifically for producing custom trackwork templates according to prototype practice.  If all of your turnouts are a standard, regular size then something like a FastTracks jig may be all you need. If, however, you need to produce more challenging track formations such as a yard ladder or a crossover on a curve, Templot can’t be beat.

That’s the good part. Not so good is that Templot, like other serious CAD programs, has a steep learning curve. It takes time to get up to speed which is an additional hurdle if you, like me, only need to produce templates every once in a great while. All of the terminology is based on UK prototype practice which also takes a bit of learning.

That being said, I have blown most of the dust off of my modest Templotting skills and am mostly done the tough bit of the Comstock Road plan.  Here is a screenshot of some of the work in progress.templottingwip

The lower right turnout is not a model railroad-esque right hand turnout with what should be the normal route going through the curved leg, it is a #6 left hand turnout diverging from a right hand transition curve.  And incidentally going straight into an asymmetric crossing. Once I had got back up to speed with the Templot interface and watch a couple of subject specific videos, the actual template creating didn’t take that long.

Still to do are:

  • spurs out from the crossing
  • assorted tweaking of ties such as those overlapping and/or too widely spaced around the crossing
  • check turnout motor locations against module boundaries.

Once everything is as good as I can make it, I will print out the whole thing full size on my home laser printer and there will then ensue a lot of trimming margins and taping sheets together. The whole thing then gets used as a template to cut out the Homasote roadbed and off we go.

Baseboard Frames Done

Tonight I finished gluing up the baseboard frames.  I decided to do a test setup just to make sure everything fit before the glue dried.  There was a bad moment where I was looking at two section ends both labelled 1 and top but had pins on the same side.  After a little bit of panicking and preparing to rip and end out I flipped the end section over so the pins and sockets aligned and…. it all fit.  Which leaves me pondering where I mislabelled an end or accidentally made things symmetrical enough to work upside down.  Almost certainly the former.  Still, I don’t like it when software bugs magically go away without explanation either.  Oh well.

Here, crammed into the aisle in the shop, is the current state of the layout.  Internal cross bracing will wait on getting the trackplan laid out full size so that turnout linkages can be avoided.  Next up is a big tidy/declutter/rearrangement so that the layout can go up against the wall to the left and a start on the backdrop ends and valance.