标签: faceplate

Well, I have to admit that I have a great big Cheshire Cat-type grin plastered on my face at the moment, because the prototype for my Vetinari Clock project is now well underway.   Just to tease you, let's start with a small photo showing the current state of play, and then I'll walk you through the steps that have brought us to our present position. We'll finish with more photos and accompanying links to full-size renderings of the little beauty.     From the get-go, I knew that I was going to have a large "Hours" meter, two medium-sized "Minutes" and "Seconds" meters, and a small "Tick-Tock" metronome-like meter. One big aspect to all of this was deciding on the layout for the front panel. My graphic artist chum, Denis Crowder, suggested a symmetrical arrangement with the "Hours" meter on the top, the "Minutes" and "Seconds" meters side-by-side in the middle, and the "Tick-Tock" meter in the center at the bottom, with the switches mounted either side of the "Tick-Tock" meter. However, I decide that I preferred the asymmetrical presentation shown below ( click here to see the column containing the deliberations that led to this layout).     Another big consideration involved creating the new faceplates from the meters. As I described in this blog , graphics guru Denis created the artworks, master craftsman John Strupat machined and printed the faceplates, and analogue meter expert Jason Dueck refurbished the meters and inserted the new faceplates.     The first step with regard to creating the prototype was to mark the front panel out on a piece of 1/4" thick MDF (medium-density fibreboard).     Now, I could have cut this front panel out myself with my trusty jigsaw, but I knew that the end result would not be as tasty as I wanted it to be. Also, there's no point in knowing a master carpenter if you don’t use him, so I asked my chum Bob to take a crack at it. Since Bob has a workshop full of tools -- not to mention decades of expertise -- it didn’t take him long to whip something into shape.     In the fullness of time, the real clock will be fully enclosed in a cabinet. For the purposes of this prototype, however, we've left everything open to make it easier for me to wire everything up and perform my experiments. The only part of the surrounding cabinet represented here is the small panel on the top, which will be used to hold the vacuum tube. In fact, this provides a brilliant illustration of the value of creating a prototype. I had originally thought of making the clock 8" deep (from front to back). But as soon as I saw this top panel in the context of this prototype, I realized that 8" would be too much. I'm now thinking 6" deep, which means the vacuum tube will be 1" closer to the front in the full-up version. One problem with MDF is that it soaks paint up like a sponge, so the next task was to prepare the prototype with a combined sealer and primer.     Originally, I'd considered creating a base upon which the clock would sit. My first thoughts revolved around a hand-carved piece with curved legs, but this wouldn’t have complemented the clock's Art Deco-esque style. Bob suggested creating legs using small, unobtrusive, inverted and truncated 4-sided pyramid shapes. I was starting to lean in this direction when we hit on the idea of not having any legs visible, but instead simply raising the base 3/8" in the air so the clock appears to be floating above the table. This explains the two strips of wood shown in the previous image. In the image below, we see these strips glued and clamped to the base of the cabinet.     Since it wasn't possible to clamp the middles of the strips -- at least, not with the tools available to me in my garage -- my solution was to place the assembly on two books that I'm currently reading (biographies of Mick Jagger and Bernard Shaw, if you must know) and weigh everything down with a brick. When I come to think about it, it's amazing how often bricks make an appearance when I'm constructing my hobby projects.     I also applied sealer/primer to the base of the prototype, using masking tape to protect the bottoms of the two wooden strips, thereby leaving them clear for felt to be attached later.     As you may recall, the front panel of the final clock is going to feature an amazing wood veneer with an aluminum look-and-feel. Meanwhile, the surrounding cabinet will be 0.5" thick and made of ebony (or, more likely, ebonized pear wood because that's much cheaper, or possibly even regular wood with an ebony veneer).   Of course we're not going to waste the aluminum look-and-feel veneer on a humble prototype, so I simply painted the inside area of the front panel with a blue-tinged-gray latex paint.     Observe the circle painted in the middle of the top panel. The vacuum tube is to be mounted in the center of this circle. Since I have a spare non-functioning 4.5" meter in my collection (similar to the "Hours" meter on the front panel), I've decided to mount its bezel on the top panel with the vacuum tube in the middle. You'll see what I mean in a moment. I then painted the 1/2" boarders around the front panel with black gloss paint to represent the surrounding cabinet (you can just see these boarders in the photo below). In the final clock, the ebony-looking cabinet will be solid wood that protrudes 1/4" in front of the aluminum-colored front panel.     Also, I painted the bottom black. Why bother painting the bottom of a prototype when no one is going to look? Well, I could waffle on about preventing reflections so as to increase the illusion of floating and suchlike, but the real reason is that I'm well acquainted with my little foibles -- if I left it as is, I would know it wasn't painted, and this knowledge would constantly niggle away at me.   When the paint was dry, I attached two strips of felt to the base and then added the meters and the vacuum tube. Below are a few images to show you how everything is looking thus far.           Now you can see how the clock appears to float above the surface of the table. This effect is a little more noticeable with the real thing, but it's also subtle enough that you don’t perceive it immediately. It's only after someone has been looking at the clock for a few seconds -- making high-pitched squeals of delight about the meters (and that's just the men) -- that they realize the clock doesn’t appear to be resting on anything and they excitedly exclaim "Just a moment, what's happening here?"   Also, you can now see what I mean about having the spare meter bezel mounted on the top of the cabinet framing the vacuum tube. Under the tube (which isn’t permanently attached to the prototype) is a circular slot into which I'll be inserting a 16-element NeoPixel Ring from Adafruit. In fact, this is one of the things I'll be doing this coming weekend -- in my next Vetinari Clock column I'll be showing a video of what this looks like when the vacuum tube is illuminated from below.   When I first painted the gray on the front panel, I was rather pleased with the sharpness of my edges. Sad to relate, however, when I painted the black borders with the gloss oil paint, things got a little wobblier. I've been fighting with myself over this. On the one hand I desperately want to re-paint everything; on the other hand, I know I could spend years trying to make things perfect. The bottom line is that, at the end of the day, this is only the prototype, so I've decided to grit my teeth, love what I've got, and move on with my life.   One last point (at least, for today), is related to the five switches. Did you spot the fact that the switch movements are orientated horizontally instead of vertically? Do you know, I never thought to check the switches when I created my original layout? Curse me for a fool! It was only when I was mounting the switches on the prototype that I realized they were too large to be presented vertically. "Well, take me outside and spank me now," I thought to myself (or words to that effect). Fortunately, I'm growing to like this orientation, which is lucky, because I'm short of other options (LOL).   So, what do you think? How do you like this little beauty so far?  

In the recent months, I've been working with Max Maxfield on the analog meter problems and design challenges pertaining to his Inamorata Prognostication Engine , Ultra-Macho Prognostication Engine , and Vetinari Clock projects.   As you may have read in his columns, Max and I have been in almost constant daily communication, by either email or phone. During our conversations, we have had a blast talking about various aspects of these meters, such as the fact that some meter movements deflect 100 degrees, while others deflect only 90 degrees. This point took Max by surprise after he incorrectly had his graphics guru Denis create the Vetinari Clock's "Hours" faceplate assuming a 100-degree movement when the meter was designed to operate over a 90-degree swing. Fortunately, we managed to make the meter's movement match the faceplate.   As part of this, I've been telling Max about some of the meters we make and repair here at Instrument Meter Specialties (IMS). Take the small Triplett .5E edgewise meter that goes in an older aircraft. These meters read "GOOD" in a green area in the middle, with red areas on either side. They would cost hundreds of dollars when the aircraft were created, but they now sell for thousands. The thing is that the planes were certified with these meters, which are FAA approved, so no substitutions are allowed.   Another job I was telling Max about involved an upgrade on some meters that go in a nuclear power plant. These meters were stockpiled when the plant was commissioned. As they started to reach their end of life, replacements were brought online, but they were failing their 0.6% calibration tolerance, and we had to work our magic on them. (I'll describe how we achieved the required accuracy in my next column.)   We do a lot of work on the older Hickok tube tester meters. We've also experienced an analog meter resurgence in the recording industry. In fact, we make several different meters for old audio compressors from companies/products such as Fairchild, Gates Sta-Level, and Federal TV. Being a custom meter shop with the ability to make complicated artworks means we can satisfy just about any meter-related requirement, so long as the parts are available.   Based on his projects, the topic Max and I have spent the most time discussing by far has been the creation of artworks (faceplates) for the meters. A lot of work goes into analog meter movements and artworks. This tends to be why new meters can cost a lot of money. The parts can be as small as those in Swiss watches, and it takes skilled hands to make a really good meter movement. This is why we always have our trusty microscope at the ready. Even meters with a "linear scale" only have movements rated to be within 1-2% of the full scale input at any given point of the scale. The trick to this "linearity" is accurately placing the coil within the magnetic field and making sure that nothing affects the spring constant, like friction caused by two spring turns rubbing against each other or deformations such as creases in the spring. That said, as important as the meter's quality is to accuracy, equally important -- especially for high accuracy -- is the meter's artwork.   The highest-accuracy analog meters actually have the divisions on their artworks printed to address nonlinearities in the meter movement's, um... movement across the dial (faceplate). This is interesting, because it allows lower-quality meter movements to compete with higher-quality ones, especially if the nonlinearity is somewhat repeatable during production. That said, making nonlinear artworks is challenging. It can require a great deal of time, knowledge of interpolation that few have, and/or the use of custom software. All of this greatly complicates the creation of meter artworks, and this was especially true earlier in the history of analog meters.   The process of printing of analog meter artworks has undergone several changes over the last century. Originally, everyone was using the same methods -- offset printing press and hand-drawn. Hand-operated offset presses were typically used for printing more than a single dial, while hand-drawn dials were created for prototypes and single-piece custom orders. The offset presses used were a bit different from letter presses, as they were meant to print on to metal and not paper.   The Grauel model R-1 printing press as used by many meter shops and manufacturers. The ratchet mechanism made a distinctive hollow clanking sound like a sad bell.   Aside from that, the process was similar. There are five main components on an offset press: the ink disk, ink rollers, vacuum table for the positive plate, rolling printing pad, and printing table where the dial blank goes. The ink was taken from the inking disk to the positive plate by the ink rollers. Next, the rolling printing pad took the ink off the positive plate and rolled it on to the dial plate. Single-color artworks were typically the norm, because cost was prohibitive for more colors. Requesting another color meant a great deal of headache for the meter manufacturer, since each added color required a separate artwork.   Before printing could begin, a hand-drawn artwork would be created using India ink on a substrate that allowed the easy and accurate removal of the dried ink. Fonts could be penned using a KE Leroy set or large Letraset sheets.   I have never actually seen one of these Leroy sets in operation, but it was fun having my grandfather show me how they worked.   All this work would be done at about 4X scale to increase accuracy. The artworks were then sent out to be photo-reduced to actual size, and a matching film transparency would be created. From that point, the transparencies would be used to burn an offset press plate.   Here's an example of a zinc offset press plate and the corresponding faceplate. I have actually seen these used.   The transparencies were retained in case a new plate was ever needed. This occurred quite often after the material used to form the plates changed from zinc to a plastic, which suffered from warping and cracking.   A zinc offset press plate and its plastic equivalent. As you can see, the plastic positive plates did not fare well over time.   Once the plates were received back in house, the actual printing could begin. During the printing of each artwork, faceplates were often scrapped due to alignment issues. Remember that each color required its own artwork. Due to problems with alignment, a three-color artwork might require 20-30 attempts to obtain five "good enough" faceplates. Observe the photograph of the Hickok faceplate below, and note how the red line is not quite in the right place.   Known for their vacuum tube testers, most Hickok artworks had at least two colors. It is impressive how many of them were actually better than this one.   The tolerances for alignment were very tight -- within about 0.015" for single-color artworks and 0.005" from the first layer for each additional color. Making things more difficult, the faceplate's screw/mounting holes were the registration marks, and they were only about one inch apart. Much of the success came down to the skill of the individual press operator to align the registration marks of each plate in relation to the dial. This is not as easy as it sounds, and there was a long tradition of rude phrases moving ballads during operation. As they do to this day, customers would call in the hope of expediting their orders. This pressure didn't help the printers who were waiting for the ink to dry in their industrial ovens. Each printing would take a day to dry before the next could be performed.   Not surprisingly, there was an extra cost added for each color on the faceplate. Additionally, for each color there would be an increase to the cost of each finished meter due to the difficult task of aligning the artworks with one another. Back in the 1960s to 1980s, for example, artworks would have started at $75 for one color with $25 for each additional color. Converting 1960s dollars to today's value, that comes to about $600 and $200, respectively. Jewell Instruments currently charges $150 for a one-color custom scale. Each additional color costs $75. It would seem the company still uses offset printing, but it probably works with computer-generated transparencies these days. Compare that to $0 to $75 for artworks generated here at Instrument Meter Specialties using a direct-to-dial process and our own PHP script. (Again, I'll describe this in more detail in my next column.) Back then, however, these services were seen as a loss leader. The goal of the manufacturer was to minimize loss and hopefully generate a big order.   Perhaps those big orders were more of a common thing back in the heyday of analog panel meters. I found the following picture of an Apollo control room at NASA with more than 100 analog panel meters in view.   I counted more than 100 analog meters that I could identify in this picture (which is presented here with the permission of Shaun O'Boyle), but there may be quite a few more.   Installations involving such quantities ensured that any loss associated with creating the faceplates was recovered in the cost of each meter. That said, low-quantity custom orders required an entirely different printing method. Faceplate blanks with division markings would be stocked, and numbers would added by hand using Letraset dry transfer characters.   I have used Letraset pages before. I was trained to use a pencil and to push hard, so I could see where I had rubbed and perhaps take advantage of the graphite as a lubricant. I remember using these sheets with mixed success.   Even though these faceplates were created by hand, new artworks were still charged at $75 for single colors. This covered the time required for a certain skilled someone to sit down and -- using dry transfer sheets -- carefully place each character on the faceplate with the proper spacing. Many times, this was good enough for customers who wanted multiple colors, especially since colored regions could be added on to the division set with a permanent marker or using some other DIY method. Prior to the 1960s and rub-on lettering, a KE Leroy pen set could be used to ink a custom dial (an image of this was shown earlier). This was more difficult than the rub-on lettering, and it was abandoned after rub-on letters became available.   From about 1995 to 2005, the meter industry experimented with, and tried implementing, various printing techniques. Many still retained the offset press method, if only for current artworks. One popular method was lovingly referred to as "using paper dials." This meant that the faceplate image was printed on a waterproof surface that would absorb the ink, and then this "paper" would be adhered to the blank dial. This technique employed mid-level and high-range consumer inkjet printers for color matching purposes. This became more popular in the late 1990s with the availability of inkjet bumper-sticker sheets. Even though this approach saved much time over the offset press method, it was still a fairly time-consuming process. Laser etching was attempted in the late 1990s, but the low number of custom built machines, the high cost of those machines, and the lack of duo-toned or multi-toned substrate that would work in different brands of meters meant that adoption was low.   Eventually, the "Holy Grail" of faceplate printing was found in small format, inkjet, flatbed presses. But this still leaves the task of creating the artwork in the first place. In my next column, I will describe an innovative technique we developed here at Instrument Meter Specialties that made Max say, "Wow, I am very impressed." Until then, I welcome any comments and questions.   Jason Dueck Product Designer Instrument Meter Specialties

I've been meaning to bring everyone up to date as to the current state of play with regard to my various hobby projects, but so much is going on that I never seem to find the time.   For example, I spent a large part of this past weekend working on my BADASS Display . Even though the front panel and the surrounding cabinet are made out of regular plywood, this really is starting to look like a piece of old furniture.     The main display panel at the top and the small control panel at the bottom look like brass (they are actually made out of 3/16" thick hardboard), and I flatter myself that the acorn nuts holding these panels onto the cabinet add a certain something to the proceedings. The next step will be to add the matrix of 256 brass washers and Fresnel lenses, followed by the tri-colored LEDs and controller (any guesses what I'll be doing next weekend?).   I'll be talking about the BADASS Display more in a future column. For the moment, however, I want to focus on the antique analogue meters I'm using for my Vetinari Clock and Prognostication Engine projects. Let's start with the Vetinari Clock. I opted for the cabinet layout shown below.     The front panel of the clock is going to feature a really tasty aluminum-colored, wood-grained veneer, while the surrounding cabinet is going to be ebony. The whole thing is going have an Art Deco-esque look-and feel, so I asked my graphics guru chum Denis Crowder if he could help me out with the designs for the meter faces, and he responded with the following:           As we can see, Denis came up with a stylized "MAX" logo that I will be using on all of my meters from this point on. Also, I particularly like the understated touch of red on the "Hours" meter.   Meanwhile, I was finding it a tad difficult to remove the old faceplates from some of the meters to the extent that I became worried about damaging them. Thus, based on some engineering drawings I created, master craftsman John Strupat in Canada created a set of new faceplates out of thin aluminum sheet.   Once I received the graphics from Denis, I emailed them to John, and he "printed" them onto the new faceplates. The reason I say "printed" in quotes is that I'm not too sure of the exact process used, and John is keeping this under his hat. All I know is that it starts with a powder coat and the result looks like white (very lightly cream-colored) enamel. In fact, the end result looks astounding -- I was performing my happiest of happy dances when these little beauties arrived in my office, let me tell you.   The next step was to send my Vetinari Clock meters and these new faceplates to my chum Jason Dueck at Instrument Meter Specialties (IMS) . Jason and team stripped the meters down and refurbished them. As part of this, they added in the new faceplates from John, plus they did a lot of other stuff that I will discuss in a future column. The image below shows these meters just after they had arrived back from IMS.     A few days ago I took these meters, along with my plans for the Vetinari Clock's cabinet, down to show my master carpenter friend, Bob. I was hoping to enlist Bob's aid in making the cabinet, but I know this is going to take a substantial amount of work, so I must admit to being somewhat trepidacious as to the cost. You can only imagine my surprise when Bob told me that he loved this project so much that he wants one also, so if I furnish the meters and the electronics, he will build two cabinets -- one for me and one for him. Well, I didn't see that coming, but it sounds like a great plan to me.   Prognostication engines As you may recall, when last we discussed my Pedagogical and Phantasmagorical Inamorata Prognostication Engine in this column , I'd just created a test jig for the little beauty. Here we see my test jig just after I'd performed a trial installation of the switches, potentiometers, and meters.     Remember that this Inamorata Engine is intended to predict whether the radiance of my wife's smile will fall upon me each day. (Also remember that, should she ever learn this machine's true purpose, I won’t need a Prognostication Engine to predict her mood-of-the-moment, so let's keep it our little secret.)   Just to remind ourselves, the large meter in the upper right-hand corner will reflect the full range of female emotion, from Extremely Disgruntled to Fully Gruntled. Underneath this we have the Fickleness Factor meter, which will reflect the chaotic nature of the multi-universe. Next we have the Suspicion of Wrongdoing meter, whose underlying algorithm has been the undoing of many a poor soul. When we come to the lower panel, the meter on the left will indicate the number of days until the next full moon (which has the potential for trying times), while the meter on the right will indicate the number of years, months, and days to the next blue moon (with the possibility of good fortune).   As you will observe in the image above, at this stage the meters had their original faceplates. Now, as we discussed in this column , for the past six weeks or so I've been working with Jason at Instrument Meter Specialties (IMS) to come up with the designs for the new faceplates.   Jason has developed some very interesting graticule (reticule) generating software, which he will be describing in a future article. Suffice it to say for the purposes of this column that Jason used his software to generate the faceplates shown below (observe that we used the stylized "MAX" logo created by Denis for the Vetinari Clock meters).             Initially, I was worried that the tan background was a tad too dark, but Jason assured me that this would be much lighter in the real world, and he was right, as we shall see. But first let us take a moment to remind ourselves that the Inamorata Prognostication Engine, which will eventually be housed in a wooden radio cabinet circa 1929, is to be complemented by a Phrankly Phenomenal Ultra-Macho Prognostication Engine, which we last discussed in this column .   The Ultra-Macho Prognostication Engine is to be presented in a box that sits on top of its Inamorata counterpart. In the image below, we see this box in the progress of being created.     In the fullness of time, there will be a brass panel inlayed in the front of this box. Mounted on this panel will be my largest and most bodacious meter reflecting units of Magnificence Magnitude (there will also be a number of other items, but we'll leave those for a future column). The following shows an early rendition of this faceplate before it was transposed onto a circular template.     As for the Vetinari Clock, I sent all of my Prognostication Engine meters to Jason for them to be checked out and refurbished by the IMS team. As part of this, Jason removed the existing faceplates, printed our new designs on the backside of the faceplates using a super-duper UV printer, and then reassembled everything and gave them a final once-over before returning them to yours truly. The results are as shown below.       As we see, the tan background color on these meters is very subtle -- just sufficient to give them an old-time appearance. Also note that any brass nuts and bolts shown in the above images are the ones I was originally working with as place-holders. IMS also supplied me with a complete set of age-appropriate nuts and bolts in black.   So, that's where things stand at the moment. I know these projects have been a long time in the making, but -- as I hope you will agree -- they are all starting to come to fruition. In future blogs we'll start assembling everything and honing the code to drive the various engines. Meanwhile, as always, I welcome any questions and comments.

My degree is in Control Engineering -- a core of math with "surrounding subjects" of electronics, mechanics, and hydraulics and fluidics. The only official programming I did as part of this course was in FORTRAN. Once I was out of university, I picked up various assembly languages and programming languages (e.g., BASIC, Pascal, C, and smatterings of other languages) along the way.   Now let's turn our attention to the Full Moon meter, whose purpose is to indicate the number of days to the next full moon -- an event with the potential for doom and despondency. There are lots of different ways in which we could have implemented this. Originally, I'd considered a fairly typical presentation showing (from left to right) the New Moon, the First Quarter, the Full Moon, the Last Quarter, and the New Moon again.     In this case, the reticle would have been divided into approximately 30 days (more on this in a moment). Another idea was offered by EETimes community member csquared0. As csquared0 said: "I personally like analogue meters to display continuous events continuously, and not go to one end and snap back." I wasn't quite sure what this meant, at first, but now I understand it to look something like the image below.     In this case, we have the new moon graphic on the left, the full moon graphic on the right, and the reticle would be divided into approximately 15 days (again, more on this in a moment). So we start with the new moon; day-by-day the needle gradually approaches the full moon, at which time it returns day-by-day to the new moon again. Also, several community members offered suggestions as to how we could indicate which way the needle was going, including the use of different-colored LEDs.   The solution I actually decided to employ, however, is as shown below. In this case, the time of the new moon occurs 3/4 of the way to the meter's FSD (full scale deflection). Furthermore, the reticle is divided into 32 days, with 24 days preceding the time of the full moon and 8 days trailing it.   Not to scale; the actual faceplate is only approximately 2" in diameter.   An earlier rendition of this solution prompted EETimes community member zeeglen to share: "But I have to ask -- since the moon's synodic orbit appears to us earthlings as about 29.5 days, why does the meter scale have 32 days?"   Ah, that's a great question. Well, this reflects the significant amount of thought that goes into this type of stuff. As zeeglen noted, the moon's synodic period is about 29.5 days, so let's round this up to 30. I want the reticle to be divided into four equal "chunks" reflecting the four quarter phases, but that would give 7.5 days per chunk, so I rounded up again to 32 days, thereby giving me four chunks of 8 days each.   As an aside, an additional point I'd like to highlight while we're here is the textural treatment of "MAX" that we're using as a logo on all my meter faceplates. I think that this little beauty, which was created by my graphics guru chum Denis Crowder , who now hangs his hat in Hawaii, really complements the "meter" theme.   As we noted earlier, most of my meters follow a progression from green (start or best case) to yellow to orange to red (end or worst case), which means dividing their scales into four color bands. In the case of the full moon meter, however, we can think of this more as a circular progression along the lines of green (farthest from the time of the full moon) to yellow to orange to red (the period around the full moon) to orange to yellow and back to green again.   If we say there are 6 red days (3 before and 3 after the full moon), and if we then make the 5 days before and the 5 days after the red days into orange days, this nicely fills the right-hand half of the display. Similarly, we can have 6 green days corresponding to the 6 red days on the other side of the display, with 5 yellow days before and 5 yellow days after. The end result is -- at least to me -- satisfyingly balanced.   The fact that the scale contains 32 days is of no consequence whatsoever. Visualize the pointer as being in the red zone during a full moon. Following the full moon, the pointer will move to the right day-by-day until we reach +8D (the meter's full scale deflection), where 'D' stands for "Days." At this point, the needle will swing back to the left of the display, but it doesn't have to return all the way to the origin (zero or -24D). Instead, it will only swing back to point to whatever number of days remain until the next full moon.   But why did I opt to have the full moon at the 3/4 point on the reticle instead of the 1/2 way point or the FSD point? Well, this reflects another important facet of the design process, which is that you can’t think of things in isolation; instead, you really have to consider how everything is going to play together...   The Full Moon meter is located at the left-hand side of the Inamorata Prognostication Engine's lower brass panel. The corresponding Blue Moon meter, which is located on the right-hand side of this panel, reflects the number of days until the next blue moon -- an event that is generally considered to be a time of positive energies and possibilities.   As another aside, I'm going by the traditional definition of a blue moon, which occurs when four full moons occur in the same season. Usually there are three full moons in a season, each of which has its own name as follows:   Full Wolf Moon (January) Full Snow Moon (February) Full Worm Moon (March) Full Pink Moon (April) Full Flower Moon (May) Full Strawberry Moon (June) Full Buck Moon (July) Full Sturgeon Moon (August) Full Corn Moon (September) Full Hunter's Moon (October) Full Beaver Moon (November) Full Cold Moon (December)   In the rare case where four full moons occur in a season, the third is referred to as a "blue moon." So, just how rare is this event? Well, a blue moon occurs about once every 2.7 years. We won't go into this too much here; suffice it to say that -- as I know to my cost -- coming up with an algorithm to determine the date of the next occurrence of a blue moon is a task sufficient to make one's eyes water!   But we digress... if a blue moon occurs approximately once every 2.7 years, then how are we to use an analogue meter to display the number of days until the next occurrence? Once again, I'm sure there are numerous ways in which this can be achieved, but the solution I opted for is as illustrated below.   Not to scale; the actual faceplate is only approximately 2" in diameter.   In this case, we don’t use a variation of the green, yellow, orange, and red color schemes characteristic of the other meters. There's no such thing as "bad" and "good" here, we're just closer to, or farther from, the next blue moon, so we reflect this in the reticle using different shades of blue.   So here's the way this meter works. Let's assume that we start as far away as possible from the next blue moon around the -2.7Y point, where 'Y' stands for "Years." As the days and weeks and months go by, the needle will gradually move toward the -2Y sub-tick and then toward the -1Y sub-tick (these sub-ticks are shown as lines on the reticle -- they don’t have their own annotations).   On the day after the needle has reached the -1Y sub-tick, it will move directly over to the -12M point, where 'M' stands for "Months." This means that the needle will never actually spend any time in the -1Y segment, but this segment is still necessary to make sense of the -2Y and -3Y segments.   The needle now proceeds to work its way down through the months. In the final month, when there are only six days to go, the needle will move over to the -6D point, at which point it will commence to count down the number of days to the blue moon. I'm assuming that there is the possibility of some residual good fortune in the few days following the blue moon -- this meter shows up to +6D. (By some strange quirk of fate, I've always considered six to be my lucky number.)   Originally, I'd planned on dividing the right-hand half of this meter into 30 days, but this looked somewhat crowded as compared to the other meters. Personally, I'm rather pleased with the solution I opted for as discussed above.   The main point to focus on here is that the Blue Moon meter spans a large amount of time, with the interesting action occurring 3/4 of the way to the meter's FSD. This was the basis for setting the time of the full moon to 3/4 of the way to FSD on the Full Moon meter. I think the final result is a rather pleasing symmetry as shown below.     So there we have it. There were a variety of other considerations, such as whether to use the '+' symbol with the annotations following a full or blue moon (I eventually made an executive decision that we would use this symbol), but I think we've covered all of the main elements.   Going through this process, I've come to the conclusion that this sort of design is part art, part science. I think (well, hope) that you are going to be really impressed when you see the graphics for all of the meters in the Inamorata Prognostication and Ultra-Macho Prognostication Engines gathered together in a future column. Until that happy time, as always, I welcome any questions and comments.

As part of my ongoing Pedagogical and Phantasmagorical Inamorata Prognostication Engine project (try saying that 10 times quickly), I'm working with Jason Dueck from Instrument Meter Specialties to create a suite of new faceplates for my antique analogue meters.   I showed an early version of one of these meters in my recent column . This meter reflects the number of days until the next full moon.     Yes, I know this meter spans 32 days. Yes, I also know that it would be more common for the full moon to be presented in the center of the dial. The reasoning behind these (and other) decisions will be made clear in a future article. For the moment, I want to focus on the fact that --in this incarnation -- the negative values on the left-hand portion of the dial ("-24D," "-16D," and "-8D") are adorned with negative signs, while the positive "8D" value to the right is presented without an accompanying "+" symbol.   Now, I can understand that if all of the values on a meter are positive, there is no need to include "+" symbols everywhere, but what about a meter that is being used to display a mixture of negative and positive values?   Well, it turns out that, in the past, if you had a center-zero meter that displayed some quantity ranging from say -10 to 0 to +10, for example, then it was very common to omit the '+' symbols on the positive 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 values.   In many cases, in fact, meter manufacturers also omitted the '-' symbols on the negative values, so the faceplate would read 10 9 8 7 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 10. This was done on the basis that it was generally understood that negative values would be presented on the left, while positive values would be presented on the right.   To my eye, this form of display has a somewhat stark and overly minimalist quality about it. Personally, I prefer to festoon '-' and '+' symbols all over the place like confetti so as to ensure there is no ambiguity whatsoever as to what is being displayed. Apart from anything else, it seems to me that a pert little '+' symbol nicely counterbalances its '-' cousin. So, why did the designers of yesteryear omit '+' symbols (and sometimes their '-' counterparts) from their analogue meter faceplate creations? Well, Jason explained it thusly: Many of these techniques actually came from letter conservation. Way-back-when, most of the meter shops used rub-on lettering. Using only using minus symbols -- or only one minus and one plus -- meant saving time and characters on your transfer sheets.   Hmm, this does make sense. If one is applying individual characters by hand, I can understand the desire to use as few characters as possible, not the least that fewer characters equates to fewer cock-ups.   These days, of course, we are used to having access to high-speed, high-resolution printers coupled with software programs that aid in laying everything out "just so." The days of meter manufacturers using rub-on lettering have long gone, and we are no longer constrained by their limitations, so why do some manufacturers continue to omit '+' symbols? Is it just a matter of taste, or is it a case of "We've always done it this way?"   In turn, this led me to ponder whether there are other instances of the way in which we design things today being bound by constraints of yesteryear that are no longer of any consequence. Can you think of any such cases?