Posts
How much effort does a panel of meters and switches deserve?
When we build a model railroad for operations, we’re not just building it for our own amusement, but also as an object to be shown and operated by others. If we’re going to invite folks over to spend several hours reproducing prototype roles, we’d like to make the layout welcoming and easy to operate. Some of us with nice inside spaces (not me) might make sure there’s a comfortable area for crew to hang out in with some comfy sofas and model railroad magazines scattered about. Others (like me) might focus on usability: are the controls for switches in obvious locations, and are the locations marked neatly and in a matching style on the fascia.
There’s also the less-obvious improvements. We might declutter the layout and hide storage with curtains below the layout, or make sure the fascia is neatly painted. All of this can make a big difference in our first impressions of a layout. I visited a home layout last year in Minnesota that was beautiful - well lit, clean, in a carpeted basement. Future kits were stashed away neatly on shelves as if in a hobby shop, layout markings followed good graphic design traditions, and general cleanliness would make crawling under the layout for repairs would be a pleasant experience. I described it later as “exactly as childhood me thought all those beautiful layouts in the magazines looked.” After touring a lot of layouts, I can safely say not all of them are that clean or welcoming.
Cleanliness also affects how others might operate the layout. One of the local modelers thought that folks might be rougher on his freight cars because he had a layout that lacked scenery and a pleasant space. “Folks will be extra-careful with Jack Burgess’s cars because of the beautiful fascia and carpeting, but then they’ll be less careful with my boxcars when they can see the 2x4s and the pink insulation.” I’m not sure that’s true, but I could imagine the level of care the layout owner applies to the space might affect the level of caution that operators apply.
Perils of the C-Clamped Panel
When I was cleaning the layout up for an operating session at the last PCR Layout Design and Operations meet, I got thinking about this. A few years back, I realized I needed a place for some layout controls and monitoring. The first was to find a place for the fast clock controller with its switches: I made a Plexiglas panel, cut a hole in the masonite fascia, and dropped the panel in. A couple years later, I realized it was helpful to know how much power was being drawn from the repurposed AC adapters I was using for layout lighting and switch machine power. That added a second panel for a bunch of digital meters to monitor power use. After a couple of problems with DCC power, I got some track meters to check voltage and amperage. The location on the fascia wasn’t big enough for the new meters, so I cut a scrap of masonite to hold the meters, and c-clamped the assembly in a convenient spot - good enough for the debugging I wanted to do.
When I started cleaning up the layout for the op session, I realized that the temporary meter panel stuck out. It was easy to bump, and looked slapdash. There also wasn’t room where the existing panels were located for a more permanent and professional site. Moving the existing electronics wasn’t easy. I’d attached every panel with machine screws into the masonite in random locations - moving panels around required cutting new openings in the masonite, drilling new holes, and covering any openings from the previous locations. Changing the existing panel locations wasn’t easy.
Now, the way I’d attached the different electrical panels isn’t a big deal; most visitors aren’t looking at the panels. However, the ad-hoc way I’d done it did look awkward to my eye, and detraced from the overall look of the layout. To make it look better - and to make me more proud of my work - it deserved a rethink. I wanted something that would be more amenable to change if I wanted to change what meters, lights, and switches I had, or change their locations. I wanted the different panels to be more uniform and similar so that the set of panels looked intentional and related. Because I sometimes needed to pull out the panels to access all the electrical terminal strips just behind, I needed an approach where panels could easily be removed and replaced.
A Sound Solution
One bit of inspiration came from electronic music. One of the big trends for folks interested in sound synthesis is a system called “Eurorack” where similarly sized small electronics modules can be placed into a case and connected as needed with patch cords. The idea of connecting individual oscillators, modulators, noise sources, filters, and effect processors dates from the dawn of computer music; Eurorack’s standards define how devices from different manufacturers connect electrically and mechanically.
Typical Euroarck setup. From Wikipedia article on Eurorack. Credit: Matthew G Daniel, wikipedia.org, Creative Commons "Attribution-ShareAlike license.
Mechanically, Eurorack relies on some mounting channels from professional electrical equipment. Individual module panels are fixed height (about 5.25 inches, or 3U in electrical rack units) with widths that are a multiple of 0.2 inches. Panels always mount with M3 screws into screw holes or sliding nuts in the mounting channels. (There’s also an electrical standard for supplying individual modules, and for the audio signals at patch points; those were irrelevant to me. The idea of a common 12 volt supply and common ribbon cable to connect power might be useful for model railroad accessories, though.) Multiple electrical manufacturers sell the mounting channels which the Eurorack folks repurpose and resell.
Eurorack mounting rail / channel
Eurorack seemed like a decent starting point for me. It allowed for neat panels that could be adjusted or rearranged as needed. Matching the Eurorack size constraints avoided needing to rethink appropriate sizes for individual panels, and gave me measurements for locations of mounting screw holes and tolerances for widths. This wasn’t the cheapest way I could get panels done - screws into masonite would have been fine - but this solution would look good, allow the panels to change over time, and showed visitors and operators that I cared about appearances.
The channels use aluminum strip and screws to set the precise spacing; I put this together and double-checked the height between the channels. Once this was done, I mounted the channels to wood blocks glued to the Masonite fascia.
Finally, I fabricated the different panels that mounted in the new panel frame. I’d previously used thin Plexiglas for panels. These panels were rigid and held switches meters firmly, and could easily be painted and marked. However, the plastic was hard to drill and mill because of its brittleness. I instead decided to use 1/16” aluminum on these panels. The aluminum worked well because it’s rigid and easy to decorate, Some local folks reminded me that some of the sign making franchises such as FastSigns can print designs on aluminum, but I decided to do everything from scratch. I did markings by printing designs on transparency material and then mounting these with Spray-mount to the aluminum.
I did hit some challenges moving to aluminum.
First, the tolerances expected for the Eurorack channels are tight, so I had to be precise when cutting and finishing panels to size and drilling holes in exactly the right places. Panels that were cut a bit too large wouldn’t fit between other mounted panels and needed to be filed down. Eurorack channels can use captive sliding nuts or continuous rods with even screw spacing - the continuous threaded strips I got seemed better because they couldn’t slide behind another panel. However, the threaded strips turned out to make tolerances even tighter because of the requirement that the holes in the panel exactly match the spacing of holes in the threaded strips. Some commercial Eurorack modules use rounded slots instead of screw holes to allow some play when attaching in such cases. The precision required meant I needed to be very careful making the panels and drilling holes for mounting screws. I’d started out assuming I could use a center punch and a drill, but realized that it was too easy for a hole to wander a bit too much. Instead, I had to drill the mounting holes with a milling machine, a center drill to start the hole, and a final drill to size. I still ended up having to file holes larger if the hole positions weren’t quite right.
A second problem was with the lettering approach. Using transparent plastic allowed me to set up lettering exactly as I needed. However, I couldn’t drill or cut the panels with the transparency material on, or it would get pulled off, get metal fragments stuck between plastic and aluminum, or get damaged. I needed to transfer holes for panel switches precisely to do the drilling, then needed to glue the transparency material down in the same spot for the lettering to correctly line up with switches.
My final problem was cutting the large openings for meters. Cutting in thick aluminum isn’t particularly easy. I initially tried milling the openings, but had a hard time holding the aluminum sheet securely on my Sherline mill. I tried a jeweler’s saw next; it worked fine for openings close to the edge of the panel, but couldn’t cut openings in the middle of a 6” wide panel. I finally fell back to using a nibbler tool which was slow and painful but eventually got the job done. I’m proud that I didn’t give myself blisters this time - the nibbler tool is particularly successful at that.
The panel for control and monitoring is done now; it’s got controls for the fast clock, accessory voltage and current, DCC fault lights, and DCC meters. I still need to add meters for the third booster on the layout - for now, I had a blanking plate over the space where this may be placed.
Making the layout look good is important - both for my pride of craftsmanship, for ease of getting around the layout, and for its effect on the folks visiting the layout. Functionally, I now see all the meters which help me spot and troubleshoot problems on the layout. Redoing these panels wasn’t strictly needed for the layout, but it looks much better, can handle future change, and represented a fun project for me.
