Marie Sester

Little Box : Tray

mariesester — Mon, 02 Jul 2012 03:42:38 +0000

The tray is an important element to the box. It needs to be elevated and flush with the top of the box and also allow the actuators to pass through, lifting the lid. To bring the tray up making it flush with the box we cut clear, square acrylic rod to the height of the box less the material thickness of the Corian. We placed the risers in each corner as supports and the tray rests neatly on them and flush with the exterior box.

We needed to make holes for the actuators to emerge through when lifting the lid. This was a nerve wracking part of the process, as we only had one chance to make the holes. Because there was a small tolerance around the border of the lid and because the actuators were elevated slightly above the height to allow the tray to sit flush, we could not use any pattern for making these holes. Our measurements and precaution served us well, though, and our holes were perfect.

We used a 3/8″ drill bit which was slightly wider than the diameter of the rod. Drilling through Corian is relatively easy, but you must drill from the top-side downward because there are small chips on the back side of the drilled hole.

Little box was commisioned by Harvestworks with funds from the New York State Council on the Arts supported by Governor Andrew Cuomo and the New York State Legislature.

Little Box : Sound

mariesester — Sun, 01 Jul 2012 03:27:29 +0000

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We attached speakers to the underside of the box for the sound to emanate from. Merche Blasco is creating the sound for the piece. Two speakers that are small enough to fit under the box have been attached and connected to an Arduino Wave Shield. After testing speakers inside the box, we knew that we needed to keep the speakers outside of the box. The inner tray severely dampened the noise making it nearly impossible to hear any range of sound. While this is good to soften the noise of the actuators, it will not work for sound intended to be heard.

We found very small speakers which we bolted to the bottom with rubber washers so they would not vibrate against the base of the box. The wires run through a hole and directly into the microcontroller.

The effect of having the speakers beneath the box feels like the sound is coming from off in the distance.

Sound by Merche Blasco.

Little Box : Sensing

mariesester — Thu, 28 Jun 2012 06:28:21 +0000

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We are using four of the Maxbotic EZ-1 Sonar sensors, which turned out to not be so “easy” when using more than one sensor. The sensors send out a sonar which bounces off an object allowing a distance calculation to be returned. There is a good tutorial for getting started with the sensor on Adafruit, but we needed a bit more functionality.

We wired the sensors as shown below communicating between the sensors with RX/TX. The pdf instructions of the image below can be found here.

The hurdle we had to overcome with the sensors is because of the sonar. When the sensors are pointed in the same direction, they create noise and interference if they are triggered at the same time because one sensor picks up the sonar from another. We solved this issue by daisy chaining the sensors together and triggering them at different times. This way, each sensor would get an accurate reading without interfering with the signal from the other sensors.

We embedded the sensors into the legs to make them as discrete as possible. The sensor does not see the box or the table since they are close to the edge. We drilled holes through the bottom of the box and ran the wires up inside so they would be hidden from view.

We’ve painted the sensors so that they blend in further, using a combination of metallic silver and black enamel.

Little Box : Metal Legs

mariesester — Wed, 27 Jun 2012 02:11:27 +0000

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To make the sensor looks as intentional as possible we discussed placing the sensors underneath the box, rather than drilling a hole into the box. To place the sensors underneath the box we needed to create legs which would elevate the box up high enough for our sensors to fit. We purchased the square tube shown below and cut slivers down to size for our legs.

We attached the legs to the base of the box with Plastic Weld 2-part epoxy. It’s not a pretty epoxy, but it’s extremely secure. We drilled holes in the two front legs and embedded the sensors within the tube. The back legs do not have holes in them because they do not house sensors.

Here the legs are shown with the sensors embedded, which will be described more in later posts.

EMOTION

mariesester — Sun, 24 Jun 2012 20:42:51 +0000

Little Box : LED Wiring

mariesester — Sun, 24 Jun 2012 05:38:30 +0000

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We are working with the LED Strip lights which come 60/meter and were purchased from Adafruit. These LEDs are Non-Addressable but can be cut every 3 LEDs. We purchase 15 meters and used them throughout the box.

Although the LEDs can be cut every 3, the provided soldering pads are very sensitive and can be ruined with too much heat, during de-soldering, or if cut improperly. We were aware of this before we soldered, so we wanted to create a system which would minimize the stress on the solder point. We came up with the solution to use header pins and pcb board. This way we could solder up all the pins for the lights, make the LEDs removable, and also make them secure. This minimized the amount of time the head was touching the LED strip, which ensured that we weren’t burning the connection.

The process for soldering is outlined below:

1) Cut, stip and bend the wires to length. You’ll need a wire for each color and for the +12V power input

2) Place the header pins through the PCB board and solder the connections accordingly. We noticed in our strip that Adafruit had the call outs for the colors switched, so the Green was the Blue and vice versa. Be sure to check your strand.

We selected headers which have an approximately 90 degree bend to them so as not to create shadows. We glued our PCB board to a plate so that it could be removable in our system and also laser cut risers to elevate the lights off the base of the box. This will also provide space for us to hide the electronics underneath the riser without interfering with the lighting.

3) Lay down your LED strips cut to length. In our case we needed 5 sets of 3, or 15 LEDs per strand. Solder between the headers and the pads provided on the strip. Be careful not to apply too much heat too or you could damage the 3 LEDs closest to the solder point.

Little Box : Actuator Housing

mariesester — Sun, 17 Jun 2012 05:55:35 +0000

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To house the actuators within the box we knew we needed to create a cage that would secure the actuators in place without vibration and also allow the actuators to be removable in case, for some reason, they broke. We came up with a “cage” that would be partly secured to the back of the box with a housing around the actuators themselves.

We first created housing for the actuators themselves. Here you can see we left room in the housing for the motor to remain open, which helped with overheating issues, but also allowed the wires to be free. We created holes for a bolt to slide through and secure the actuator to the housing.

These pieces slip into a cage that was glued into the back of the box. The cages were elevated to get the actuators flush with the bottom of the tray. We dropped them down 1/16 of an inch below the bottom so that we weren’t resting the weight of the tray on the actuator housing.

They are secured in place with a nut and bolt and have wood to help dampen any noise from vibration.

The drawing for laser cutting all these pieces is below. We used 1/4″ clear acrylic to so as to minimize the shadows created by the housing.

Little Box : Hinge

mariesester — Sat, 16 Jun 2012 06:23:05 +0000

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We purchased a stainless steel hinge from McMaster-Carr and installed it on the box after receiving the corrected tray. We chose not to get the hinge with premade holes as we will decide where the holes and bolts should be when we position the hinge.

The hinge can be cut with a miter box and a saw. We made it the entire length of the box to ensure that we had as much surface area to work with for attaching the hinge to both the lid and the base of the box. Holes and bolts will be added later to create a mechanical connection

We drilled 2 holes through the top and bottom of the hinge and adhered them mechanically with bolts and nuts. The bols on the bottom are hidden by the tray.

Little Box : Corian Box Received

mariesester — Thu, 31 May 2012 05:13:17 +0000

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We received the box back from Corian today.

Although the exterior looked beautiful, we immediately realized that the inner tray was made entirely out of the non-illumination series. We specified the bottom of the inner tray to made out of the illumination series. We also noticed a large tolerance around the outer edge of the tray.

If left as is, this would mean that the components inside would be visible and that light would seep out. We had to talk with the Corian team to return the tray and have it remade.

Little Box : Linear Actuator Test

mariesester — Fri, 04 May 2012 05:01:49 +0000

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After exploring many different methods for lifting the box lid, we decided that using linear actuators will be the best way to move forward. We avoided this option earlier because the actuators are more expensive than gears and motors, but they will be more quiet and better integrated into the system.

We’ve chosen a miniature linear actuator by Firgelli. We need the L-12i series which has an internal controller. The specs for the actuator are: 100mm stroke | 6V power input | 100 gear ratio also known as “6,100,100,i.” The link to download the data sheet is here.

Below is a video of our first tests with the actuators. This is using them just as an on/off switch and not incorporating the feedback control.