Is A Chair Cushion Possible With colorFabb LW-PLA?

Upon seeing an announcement about colorFabb’s LW-PLA, my first thought was cushions. The filament was on back order at the time and I waited a few months for it to arrive. I waited again before I tried printing with the filament as I learned a direct drive extruder was best. Finally, in February I was able to begin printing. I wanted to assess its squish factor after foaming and followed the advice of a couple of people who had experimented with it, namely, RichRap3d and Stefan of CNC Kitchen. I tried a few different methods, but learned that there was not much of a squish factor. I was disappointed. The photo below shows some tests.

LW-PLA filament test
LW-PLA filament tests
LW-PLA filament test 2
.2 mm space test

The test in which I placed .2 mm spaces between layers was the most anguishing. How could it not squish? It seemed the filament was just too strong. Then I started to wonder how strong it was. Was it strong enough to support hundreds of pounds? Could it support hundreds of pounds in a spiral shape, similar to thick wire in an inner spring mattress ? Maybe I could still make cushions, just not how I originally intended.

LW-PLA filament test - spiral
Spiral test

I created a model consisting of spirals between two flat layers of a small cube. To my amazement it squished! Not only squished, it returned to its original position. This happened many times. The next test was to determine if the same thing happened when I stood on the spirals. This brought me to my other goal for PLA foam – shoe soles. I wanted to return to my quest of making my own slipper and shoes. This was to be the next challenge.

Spring cushion test
3d model of spring cushion test

I designed a sole with holes around the edges to make it easier for hand sewing. I printed one sole with spirals and a corresponding sole without spirals as I did not want to use supports to print a top flat layer. I sewed the slipper together, mostly following McCall’s slipper pattern M6449. The video below shows the test.

As you can hear in the video, the slippers are rather noisy. I attributed the noise to the top free layer rubbing against the spirals. The small test square did not make a sound when squished. Another test was in order. I needed to print the two layers as one piece. The video below shows me stepping on a 3d print consisting of spirals, attached top layer, and two walls.

Sound test 1

My thoughts were that the print’s sound was mostly due to the walls on the side. I placed them in the model to facilitate formation of the top layer and to connect them to another panel. It was contributing to the sound, therefore, I removed them before recording the next video.

Sound test 2

The print still made a sound when deflated, but I think it can be muffled a bit by covering it with cotton batting and fabric. Printing with water soluble supports may reduce the sound as well, due to removal of the loose material generated from lack of supports. The shoes I made were very comfortable except for the heel area. I did have two layers of cotton batting; however, that is something I will add to any shoe I make, regardless of the sole material. When I sat on the print for cushion testing, it was comfortable, but more height was needed. I will conduct more tests sometime in the future.

Author: Sandra James

Blogger, Designer, and Astrologer

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