For this week, I tried to find one simple form, because this processing for me it was newest and I didn't know how could it be. I choose one model on Thinghiverse about one ashtray with waveform.

I used Cut 3D software for to prepare the g-code file. In the Fab Lab Cascina, we have one small mill self-built that work with Linux CNC software. We have one tool of 4 mm, I have decided to use only one tool for the roughing and finishing toolpath. I set one high speed rate, because for this assignment I had to use the polyurethane foam for the mold.

Setting 3D milling.

Considering that I use only one tool, I exported the same toolpath for roughing and finishing. I used the G-code file, with *.ncc extension.

I cut one small piece of 5 mm polyurethane foam and I fixed it on the milling machine.

Cutting one piece of polyurethane foam.

Setting the milling machine.

After that, I set the machine and loaded the file for the work. In the video, you can see all processing.

Compositing and vacuum pumps

When the machine had finished, I used the wax for the surface. I gave the wax 5th times with one sponge, after 30 min of pause from each other.

Die milled and wax.

Smoothing die with wax.

In the same time, I prepared all layers for the vacuum.

Scheme of vacuum layers.

Preparing the vacuum layers.

Inserting the valve vacuum.

Before the vacuum, I gave the release with one brush and I awaited a couple of minutes for to make the vacuum.

Using the release with one brush.

Vacuum done.

As you can see, I made two important mistake!

The first one is that I cut the layers of vacuum more than the perimeter of square and then of the mastic! You can see in the video that I had many difficulties for to make the vacuum.

The second one mistake, I had to put the valve too close to the model.

In the last picture, you can see that the vacuum didn’t come well, maybe because the valve had one leak of air. I tried to close it with some mastic, but maybe it was not enough.

Finishing the model

After about 12 hours, I lifted the model. It was very difficult to remove it, because it was very strong! Forcing the movement, I broke one piece of the die.

The model without the vacuum layers.

Mold broken for the lifting the model.

For my opinion, this has happened because I didn’t sanded the foam, making it smooth, before to put the wax. But has been a bit porous, although I tried to rub the wax.

Anyway, I cut the excess pieces and I finished the piece, but it could not very well.

Upper surface of the model.

Bottom surface of the model.

I saw that the model not has the waves on the upper surface, but only bottom surface. This because the resin went at bottom and the piece of linen didn’t take the form. Maybe because the linen is too rigid and I used only one big piece. In my opinion it is would be better to make more small piece of linen, or even better to use another type of fabric, like the black fabric that I use on the upper surface.

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