Tag Archives: CNC machine

Dimmer Not Dumber II: Servo-controlled light fader

Introducing the “Dimmer Not Dumber” II

A novel approach to fading line voltage lights!

This video shows me triggering the unit and then at the end, applying a reset signal. The unit is programmed to climb slowly to preset light levels upon repetitive triggering (10%, 20%, 30%, 40% and 100%). The reset signal applied at the end [44s] slowly fades down the light intensity to fully OFF.

A client wanted me to control the brightness of two sets of residential 110v pot lights. The only experience I have in controlling line-powered equipment is through using relays and opto-isolated solid state switches. However, these just provide simple ON/OFF control; and dimming lights is a whole different ball of wax! Plus, I did NOT want to mess with mains voltages!  There are devices on the market to do this but they are a) expensive, b) require electronics connected to the 110v load side and c) require real-time software to control (see discussion below). I wanted a simpler solution that used off-the-shelf residential electrical components, used simple electronics and gave me complete electrical isolation.

So, I came up with the “Dimmer Not Dumber” light fader design.

In this design, a servo motor is connected to the shaft of an unmodified residential light dimmer (Levitron, I believe) via a simple gear pair. This dimmer has a control shaft that rotates about 320 degrees to fade between full OFF to full ON. In addition, pushing the switch knob turns the whole unit ON and OFF.

As servo articulation is typically a maximum of 180 degrees, a 2:1 gear pair means that the full range of the servo translates into a complete rotation of the dimmer shaft. Control of the servo position therefore allows full control of the intensity of the light, so now all I have to do is connect the servo to a micro-controller and voila!  Full control of the light intensity and complete electrical isolation!

The Dimmer Not Dumber II version now includes an Arduino Nano, input conditioning for 5 – 24V triggers and a 5V buck converter. An 8-tooth gear attaches to the electrical fader’s control shaft and tightened with a small set screw, while the larger 16 tooth gear attaches to the servo using a plastic servo horn.  All electrical components are located within pockets in the base attachment plate while the upper plate holds the servo and has holes to access the pair of 3-pin servo connections and the 4-pin screw terminal block for external connections.

The body of the unit is made in two parts: a 12mm HDPE base attachment plate and a 6mm HDPE upper plate servo mount. The base and upper plates are attached using 3 3mm Allen-head bolts. The electrical fader mounts inside an electrical box as normal, and the Dimmer Not Dumber II unit bolts to the dimmer using the normal screw holes used for fascia plates.

Dimmer Not Dumber II: showing top face with the two servo pins and the external connection screw terminals.

Dimmer Not Dumber II: closeup of the two servo connector pins and the screw terminals for 9-12V, Ground, Trigger and Reset connections

“Dimmer Not Dumber” works like a charm, both in the light and the dark!

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CORONA TOUCH: Touch activated light display

Introducing the “CORONA TOUCH” interactive light display.

Based on ongoing developments for the elderly and/or people with cognitive challenges, CORONA TOUCH is a touch-activated light machine that creates a wide range of beautifully animated and soothing light patterns that emanate from its core.

Corona Touch

Corona Touch

Here are a few movies (care of Shirley Lee) of the CORONA TOUCH in operation

  1. CoronaTouch-v07
  2. CoronaTouch-v03
  3. CoronaTouch-v04
  4. CoronaTouch-v06
  5. CoronaTouch-v12
  6. CoronaTouch-v09
  7. CoronaTouch-v10
  8. CoronaTouch-v11

According to Wikipedia, “A corona (Latin, ‘crown’) is an aura of plasma that surrounds the sun and other stars… ” noting that “… the high temperature of the Sun’s corona gives it unusual spectral features”.  This is fitting for this little machine, as everyone who has played with CORONA TOUCH has been enthralled and attracted by its vivid colours and animated patterns.

Corona Touch

Corona Touch: the touch-activated light pattern machine

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Elemental Clock

Simply put, the Elemental Clock uses three fundamental shapes – the square, triangle and circle – to display the current time in hours, minutes and seconds.

Elemental Clock

Elemental Clock: measuring 50cm x 16cm, displaying hours (square), minutes (triangle) and seconds (circle)

The design breaks apart the displayed elements of the common clock face, and repackages the “hands” into separate, distinct, and yet connected, representations of the measurement of time.

Elemental Clock

Elemental Clock:  under the watchful eye of the seconds circle, minutes traverse the three sides of the triangle, while the hours advance as each facet of the triangle is illuminated.

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Sands Of Time

Introducing my latest work-in-progress: The Sands of Time

This is a project inspired by a piece of articulated artwork by Bruce Shapiro, called “Sisyphus Machine“, described as… “an elaborate kinetic drawing machine that uses magnets to drag rolling steel marbles through a thin layer of sand to create complicated mandala-like patterns”. I found the the patterns to be mesmerizing. I felt I could create something along the same lines to experiment with dynamically changing patterns, and – in keeping with my clock making and fascination with time- that would allow the ephemeral praxis of writing time in the sand….

UPDATE: 9 June 2016: My first sand pattern with “Sands of Time

The software traces a simple helical pattern that traverses the centre of the drawing surface so the final design shows two spirals… Neat huh!

Sands Of Time

Sands Of Time: my first sand drawing.. Here, the ball is making a pair of intersecting spirals.

A new top lip – made of 6 identical sections of alder that I shaped on my CNC machine – captures an acrylic drawing surface that is covered in a thin layer of finely ground sand. The magnetic coupling between the carriage’s magnets and the 12mm steel ball bearing is lower than expected so that the friction of the sand is sometimes too great and the ball loses connection. The gap that separates the magnet from the ball is slightly over 3/8″ – 1/4″ ply (as the top support) and 1/8″ acrylic – and this appears too great to ensure a really strong magnetic coupling. So, rather than redesigning the top to reduce this thickness, I shall try out a spherical rare-earth magnet, rather than the current steel ball bearing.

Here, a small thrust bearing is magnetically coupled to the carriage of the carousel, which is rotating underneath a temporary sheet of acrylic. In the completed design, a thin layer of fine sand will sit atop the acrylic and a ball bearing will be moved through it. Articulation of the carriage and carousel will allow for the tracing of “mandala-like” patterns.

In this clip, the carriage and carousel can be seen operating together under the control of separate stepper motors. The unique design (all mine!) places the carriage servo at the absolute centre of the carousel’s rotation. This geometry allows completely independent motion of the carriage and carousel. In other words, the carousel can rotate freely in any direction while the carriage can traverse the carousel’s diameter, and both can operate completely independently.

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CNC – Update 5: Jog Box

The USB CNC Controller has a 14 pin connector for connection to an external “Jog Controller”. This controller allows the user to move the spindle along each of its three axis, and control the speed at which the movements are made. While there were no instructions for this, a little trial and error established the connections and the necessary circuitry to perform axis movement.

Even though I’m waiting for the 14 pin connectors and big fat momentary switches (on order from China), I made a prototype. It consists of a sloped-top wooden enclosure with an engraved fascia (CNC’ed, of course). I have populated it with LEDs, small momentary switches (which I have previously found to fail intermittently !!) and the jog speed control. The Jog Box connects to the CNC USB Controller with a 14 conductor ribbon cable.

CNC-USB Jog Box-Final

CNC USB Controller Jog Box: Final version with large toggles

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CNC – Update 4: Limits & homing

I have been playing with the CNC machine and all too often I’ve accidentally hit both X and Y extreme limits of travel. I don’t know if there is any damage being done but felt I should do something about it.  The controller software has a panel in the setting menu for both positive and negative limit switches for all three axis so I needed to find the associated hardware connections. The company I bought the machine from claimed not to have hardware schematics for the CNC controller or the USB interface. However, I did receive an image of the CNC Driver Board board indicating where limit switches may connect (top left).

CNC Drive Board

CNC Drive Board

Through trial and error, I found that the model of my controller only provides one input per axis for a limit switch. This means that in the X and Y axes, a limit switch only works when the unit is traveling in a positive direction (i.e. towards the back and right edge). For the Z-axis, the limit switch only works when the spindle moving downwards.  In normal operation the limit switch input is open circuit. If and when the machine moves to a limit, the switch shorts the input to GND and this stops the movement immediately.

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CNC – Update 3: Cutting images in plastic

If only Matisse had his own CNC machine…

The CNC Controller software has the ability to import 2D images in .bmp, .jpg and .png formats. I chose one of my favourite Matisse’s black and white line drawings of a woman’s head and shoulders, called “La Pompadour” (see note below) and uploaded it into the software. The following screen shots show the sequence of windows and screens as the image was converted to a cutting pattern.

CNC image details

CNC image details

CNC image processing

CNC image cutting control

CNC image pattern trace

CNC image cutting pattern






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