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Guy Marsden
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David Bruckenstein
"Lux" Clock

March 2021




Lux clock
This is the seventh collaborative clock project that Dave and I have completed, and this one completely got away from us.  We started working together on this one in November and over the course of nearly 300 emails finally arrived at the design that we both liked.  During the design process of each clock we constantly reference the "KISS principle" (Keep It Simple Stupid) - in this case, somehow we lost sight of that basic design principle but it all turned out okay in the end.
Lux early concept rendering  Lux concept rendering 
The initial concept was a small wood mantelpiece style clock with a backlit hand of glowing dots that would show on a screen of translucent white plastic.  Brass dots would show the hour hand positions.  This was a simple and elegant design, but Dave went off on a tangent and became focused on the idea of a swinging back lit pendulum.  In order to get a pendulum that swung once per second, we needed a certain length to accomplish that, and of course it needed to be a backlit circle or line that would move back and forth behind the screen.
Luc clock concept asa a tall column  Lux clock concept with legs 
The pendulum concept drove the height of the clock to being quite tall, and we also experimented with a smaller pendulum above the clock face.  But finally we decided we liked the idea of a simple clock with legs in a design that would evoke a James Krenov cabinet style while also being reminiscent of a grandfather clock.  Once I saw the final rendering (above far right) that Dave did I told him that my best friend and neighbor John Rogers would be the perfect person to do the woodworking since this was a bit outside the scope of my skills as a woodworker. 
 Final case with legs made by John Rogers Lux case with ebony posts Dave's rendering of the final clock design
 John used his skills and experience as a woodworker to create a design with good proportions that evokes the Krenov style in which the cabinet appears to float above the legs.  Shown above is the completed case, and rendered the clock face and dots that I added later.  The rendering on the right was created after John had provided Dave with a detailed sketch of the overall proportions and colors.
Clock parts in John's workshop   John Rogers with clock case in progress
It took John a little over a week to make the case from cherry and legs from ebonized ash.  John is a consummate woodworker and used traditional dovetails and frame and panel construction.  His meticulous craftsmanship shows at every step and in every detail.  The clock case is made from cherry wood, while the legs are ebonized ash.
Cutting ebony plugs  Installing ebony dots   
The responsibility fell to me to install the ebony dots that define the clock hand positions.  Four of the dots were larger at the 12, 3, 6, and 9 positions.  It made me quite anxious to drill into John's beautiful cabinetry and my hands were literally sweating the entire time I was working on this but it came out okay in the end.  The tapered plugs had to be precision fit so the top surface was smooth and flush with the clock face.
Ebony dot installed  Ebony plug/dots installed 
The dots were actually an idea suggested by my ex-wife Rebekah Younger and really complete the clock face while making it easier to read the time.
Stepper motor and custom shaft  Clock mechanism assembled 
 A stepper motor drives the disc.  Stepper motors are extremely precise and can resolve 3200 steps per revolution.   I machined the shaft adapter on my metal lathe to which the clock disc will attach.
Test clock hand designs MIlling the clock hand slot
The clock hand is made from a disc of thin aluminum with a slot cut in it to allow light to come through from behind.  Originally, Dave and I had pictured the hand being a series of circles ending in a short thin line, and explored several options.  But we eventually decided to simplify it down to a basic single line.  I milled the slot on my mini milling machine. 
Clock "hand" and LED back light Inside the clock
The internal clock mechanism is relatively complex.  Shown above are the clock "hand" disc and the LED back light that I constructed from 8 - 1 Watt warm white LEDs.  The whole mechanism was constructed in layers starting with the screen, rotating clock face with hand slot, a layer of translucent acrylic diffusion, the LED lights, and then the motor on the back.  the structural supports all have slots to allow the mechanism to be centered perfectly in the cabinet clock face. 
Lux clock electronics Wire attached to leg
Shown above is the final electronics control system.  The two green buttons let you set the hour and minute position in five minute increments.  The two yellow buttons allow you to set the brightness in 20 discrete steps.  The whole clock operates from a small 12 V DC wall adapter and the black wire runs down the back of one of the rear legs where it is secured with small black clips so that it is not unsightly.

At the beginning of this project I had it in mind to embed cuckoo clock like features.  For instance every hour the backlight would change brightness by going dim a number of times relevant to the hour.  So for instance, at 6 PM the clock hand would dim six times.  We also considered a feature where you would wave your hand in front of the clock and the hand would swing around and stop to show the minutes position rather than the our position before reverting back to the current time.  The code for all of this became so onerous that it became too much for me and I was no longer enjoying the process.  Dave graciously suggested that we step back and make just a simple clock.  The only embedded "feature" is that at the 12 o'clock hour, the clock hand goes through a  complete rotation to  recalibrate.  There is a small sensor that detects when the hand is exactly at the 12 o'clock position in the clock and it swings around until it finds that spot and stops.  So this is something to look forward to every noon and midnight as the hand sweeps around once.
Lux clock inside Lux clock back
John had designed the case so that the back simply attaches magnetically making it very easy to remove.  I drilled two holes that allow for ventilation and also they make easy handles for removing the back.
Lux lecs crated Lux clock case crated
Since Dave lives in North Carolina, and I am in Maine, I had to build some very substantial crates in order to ship everything down to him via UPS.  Fortunately they survived intact and Lux now resides in Dave's dining room.
Lux in Dave's dining room Lux in Dave's dining room
The clock is 79 inches high, and in my workshop it felt quite imposing, but I am pleased to see that with Dave's taller ceiling it blends in very nicely.  Dave and I are both very pleased with this clock as is my friend John.

Visit Dave's web site:
DAB's Clocks

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