Tag Archives: mechanical

seXY – computer-controlled mechanism for a new clock

s e X Y

Computer-controlled mechanism for a new clock

seXY is a motorized mechanism that under computer control can move a carriage slide in two separate axes: up to 380mm (15″) in the X-axis (side to side) and 350mm (13.5″) in the Y-axis (front to back). A huge “design space” to play with! My intention is to mount a head to the slider equipped with a servo that engages either a pen or an eraser… More to come on that front!

In the following video, the left and right steppers are being controlled by the micro-controller which is just moving the slide to and fro the X and Y axis, and the four diagonals.

seXY: Stepper-driven X-Y mechanism

So, this weekend CNC project was largely inspired by an interesting product called AxiDraw,  that is described as “the personal writing and drawing machine that mixes the precision of robotics with the warmth of a hand-drawn note.”  I was primarily fascinated by the control belt arrangement that allowed the two steppers to be stationary. This avoids all the complications of creating wiring harnesses that have to flex with the machine movements.

It appeared from the video and other similar designs that the two steppers are fixed at either end of the x-axis and that axis movement is achieved by moving BOTH. This belt arrangement has an interesting effect. When both steppers turn in the same direction, the carriage slide moves along the x-axis. When the steppers move in opposite directions, the carriage slide moves along the y-axis. If either stepper is stopped, the carriage slide moves along a diagonal.

Neat, huh.

So I decided to design and build one.

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CYCLOPS: servo-controlled Mechanical Iris

It’s been a while since I’ve posted – I have been busy though – and even longer since I posted something not related to a clock!

So, behold… CYCLOPS – The Mechanical Iris!

The video above – taken from the front – shows the completed CYCLOPS Mechanical Iris opening and closing as the servo runs back and forth. The video below – shot from the back – shows the mechanical linkages between the outer gear ring and the “petals” of the iris, and how the assembly operates to open and close the iris.

 

The CYCLOPS Mechanical Iris is made up of a face plate and five pivoting “petals”, each linked to a large rotary gear ring. The petals are carefully shaped to allow them to open and close a central iris that is 200mm (8.6″) in diameter. A 5:1 gear connects the outer ring to a small metal-gear servo motor mounted to the face plate. As the videos show, as the servo rotates through 180 degrees, the petals move so that the iris fully opens and closes.

Mechanical Iris: with outer gear ring and linkages to each of the 5 petals

Mechanical Iris: showing 5 petals in open position

Mechanical Iris: showing 5 petals in closed position

Designed and built as a proof of concept, the CYCLOPS Mechanical Iris was made quickly to test geometries and mechanical operation. It was designed using SketchUp with CAM operations using SketchUCam, and cut on my CNC machine  The face plate is cut from 12mm baltic birch, while the petals, linkages, outer ring, servo mount and servo gear are cut from 6mm HDPE (High Density PolyEthylene).

The initial design was for a proof-of-concept mechanical door to a “locked” compartment. Upon receipt of a trigger signal, the iris was required to open to allow access to the compartment behind and whatever it contains. While the POC was very successful, a number of design changes will be made to improve performance and usability. In this design, I incorporated three different linkage points on each petal, each a different distance from the pivot point, to test different lengths and designs of linkage arms. Tests showed that only the outermost (furthest) connection point was necessary, so the others will be removed. A simple curved linkage allowed for some spring in the mechanism that helped to fully close the iris, and this design element shall remain. The teeth of the outer gear ring covered an arc of 90 degrees. This proved to be in excess of what was needed and a sweep of only 45 degrees will be used. Additionally, the face plate will be redesigned with a deeper pocket to accommodate the outer gear ring and servo gear. This will also allow for a simpler servo mount and gear ring restraint. Also, the new face plate will also have simpler attachment points to the hidden compartment to make it easier to install.

Neat huh?

Pop-UP Clock… now in colour!

The Pop-Up Clock described in a recent post “Pop-Up Clock and Flipper Clock – Magnetic Digit Elements” is a work-in-progress proof of concept as I develop a full 4-digit clock (complete with flashing colon).

So far, the design displays the time on this single digit display in a sequential manner: two digits for the hour, then a dash (“-“) followed by two digits for the minutes.

Wishing to increase the illumination of the display and the contrast of the segments between ON and OFF (or IN and OUT) states, I made some changes. I added a strip of addressable WS2812 LEDs around the periphery of the display and blacked-out the rear of each segment so that little light passes into the HDPE when it is extended (OUT).  When retracted (IN), light from the LEDs shines into the elements and illuminates them.  In the software I reversed the direction of the segments so that when it is ON, it is retracted (IN).  Here’s a video that shows the effect.

This test shows considerable light bleed from the LED strip, and this shall be rectified when there is a fully enclosed baffle between the front plate and servo mount plate… In addition, I shall also increase the contrast of the segments with a better light seal.

As with many of my clocks, the accurate time is obtained from an NTP request to the US National Institute of Science and Technology (NIST) atomic clock server, using an ESP8266 WeMost D1 Mini WiFi module.  WiFi channel access parameters, local time relative to GMT, daylight savings active, and duration between display updates (minutes) are entered on its web server and subsequently stored in EEPROM when the unit is powered on for the first time, or if it fails to connect to the local WiFi channel.

Oh yes, and just for Lise, the display its blue!

 

Pop-Up Clock and Flipper Clock – Magnetic Digit Elements

Season’s Greetings


It’s been a while since my last post, while I have been working on two new proof-of-concepts for some new clock displays. Both of these displays employ magnetic coupling – attraction and repulsion – to animate elements (segments / flippers) of a numeric display that will be incorporated into a clock.

The first is a single 7-segment digit for a new POP-UP CLOCK.

Pop-UP Clock: Single 7-segment Digit

And the second, for The FLIPPING TIME CLOCK -is a 3×3 flipper array for a digit that displays numbers 0-9 as “pips” on a domino.

Flipper Clock Digit: Showing 3×3 array of flippers used to display the numbers 0-9 like pips on a domino

Interested in reading how these elements work????

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LightWriter Cricket

Hard on the heels of the LightWriter Clock project, comes my latest creation – LightWriter Cricket. This little critter writes the time with light onto a phosphorescent screen, and like the LightWriter, the displayed time just fades away until it is rewritten at the next minute. And, mirroring the ephemeral perception of time, each specific moment quickly fades into the past.

Here, LightWriter Cricket is seen writing out the time 14:13. Notice how quickly the display fades away such that the hours are almost totally invisible by the time the minutes are written.

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LightWriter Clock: Resurrected?

The original idea for the LightWriter Clock was to play with the ephemeral nature of time – in that each specific measurement of its passing quickly fades into the past. In a very literal way, this clock writes out digits of the time onto a phosphorescent media which then slowly fade away.

Here’s the latest and long awaited update of the LightWriter Clock project, and yes, I did paint the body a lurid shade of lime! (Why, because I can! or at least had a can?)

The final design is covered with a sheet of clear acrylic, the bottom section of which is painted with several coats of a phosphorescent spray paint. Every 3 minutes, the LightWriter bursts into life articulating the two arms to write out, using a UV laser, the four digits of the time, in 24 hour format, onto the phosphorescent coating.

LightWriter Clock

LightWriter Clock

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ROUND ABOUT Clock

Continuing the theme of examining metaphors for the measurement of, and perception of, time, the ROUND ABOUT Clock makes concrete the response to “What time is it?” … which may be…  “it’s a round about eleven twenty five”.

Round About

Round About Clock: displaying 11:25 PM

A rotating face – the “round-about” – and a periphery of lights combine to replace the hands of a traditional analogue clock such that time is displayed both spatially and through continual movement. (I plan to design a new and larger top disc for the “round-about” to have the lights fully illuminate the numerals, but as a prototype, this is quite functional.)

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