Exercise 05 > 1:1 Prototyping

This exercise was based on creating a functional 3d printed part for our 1D CNC machine. The intention was to begin to imagine how the simple step movement in one axis could be transformed into any type of design machine.

 

SKETCHES

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Our initial idea came from our interest with the human body as input into the machine. Those are would act like human arms, they would have two main rotating joints; the shoulder and the wrists while we represented the elbow by a sliding joint.

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We wanted to maintain the idea of water-color, where water and pigment interact, therefore we looked into creating arms to our 1D CNC machine.

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Liz forgot the word for pulley at one point and had to draw it to ask.

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Furthermore, we started to think of the relationship between the machine and the page which led us to want to elevate the machine and add wheels at the bottom.

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The wheels would travel along sinusoidal tracks that we would want to CNC. We want the machine to move in the Y direction rather than having the page move (such as a vinyl cutter).

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MODELING PROTOTYPES

A link to a dropbox folder with all the STL files of the parts detailed in this section is here

The bed: this piece attaches to the top of the CNC machine and houses 4 ball joints.

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We found this ball and socket joint and altered it for our needs by making the base wider and adding a hole for a connection.

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This is an axonometric view of the ball and socket joint along with a single piece of the slide joint.

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3D PRINTED PARTS

First test of a part! The biggest functional problem was the friction between the sliding pieces. This is due to the way we printed them upright, with a layer height of 0.15.

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In order for the pieces to move with each other, we sanded the pieces and oiled the joints. This really didn’t help enough.

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One of the hands of the machine was holding and pen. In order to attach the pen to the arms, we removed it from its case and used a zip tie to attach it.

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We had a few messed up pieces that didn’t function. We also broke some trying to remove the supports from the hole.

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At the tip of the arms we added one pen and one brush.

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The pen was a test, we wanted to see if it would work while the brush was more thought of.

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The brush would pick up watercolor pigment from the side of the page and then drag it onto the paper. Because of the one direction of the machine we knew where to set up the watercolors (at the beginning of the revolution). The paper was taped onto cardboard and had yellow, blue and red watercolor pigment on the side.

 

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The bed failed to print properly so instead of using it we directly zip tied the arms to the cardboard CNC machine. This was not a great idea because the zip ties tore the cardboard a bit and the arms still did not stay attached quite properly.

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Finally we wired the arduino board to move faster than the initial script as well as having it travel over a larger distance.

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Watch this version of the machine here.

 

 

MODELING PROTOTYPES TAKE 2

A link to a dropbox folder with all the STL files of the parts detailed in this section is here

 

The biggest problem with our original arms stemmed from the orientation of the part during printing. We know that the smoothest side of a print is the bottom against the glass bed, so we altered our pieces to make this orientation possible.

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We split the stick pieces up into two different parts, and added notches to attach them. We also decided to add varying lengths of arm segments.

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The next important change we made was printing the pieces without any supports. This was definitely the correct move. We never needed them. Our blind faith in Cura mislead us. Sorry Cura. We really wanted to believe in you.

We also printed more of the same ball and socket joint pieces from the first attempt — also without supports this time.

 

 

3D PRINTED PARTS TAKE 2

Like we said, we printed the sticks flat and the bottoms were so much smoother. We just took a knife to them to cut them out of the brim smoothly.

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So many pieces and so many zip-ties! 3 mm was the perfect width notch for our tiny little zip ties (4 inch Commercial Electric from Home Depot).

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There are little two-pronged plastic parts in the middle of the sponge brushes, so we pulled off the wooden handles and zip-tied through the plastic.

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And the slide joints are so much smoother! Watch here.

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However, in actual practice, the joints don’t work great. They aren’t heavy enough to pull and change direction and/or length. We think this might be alleviated by adding weights to the tops of the brushes.

The slide joints also twist a little when they are fully extended. We think we can alleviate this by adding a stop in before it is completely extended, or by adding secondary notches to tie that would also serve as a stop before the member is extended.