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Posted: 08:57:50 PM, 18/12/2014

Developing artworks for analogue meter

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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.

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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.

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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.

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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.)

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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.

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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.

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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.

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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.

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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. (Click here for a larger image.)
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.
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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.

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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 K&E Leroy set or large Letraset sheets.

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I have never actually seen one of these Leroy sets in operation, but it was fun having my grandfather show me how they worked. (Click herefor a larger image.)
I have never actually seen one of these Leroy sets in operation, but it was fun having my grandfather show me how they worked.
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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.

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Here's an example of a zinc offset press plate and the corresponding faceplate. I have actually seen these used. (Click here for a larger image.)
Here's an example of a zinc offset press plate and the corresponding faceplate. I have actually seen these used.
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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.

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A zinc offset press plate and its plastic equivalent. As you can see, the plastic positive plates did not fare well over time. (Click here for a larger image.)
A zinc offset press plate and its plastic equivalent. As you can see, the plastic positive plates did not fare well over time.
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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.

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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. (Click here for a larger image.)
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.
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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.

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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.

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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.

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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. (Click here for a larger image.)
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.
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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.

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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. (Click here for a larger image.)
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.
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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 K&E 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.

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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.

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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.

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Jason Dueck

Product Designer

Instrument Meter Specialties

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