Weight Loss Coach Construction

Main page Overview Outer shells Inside components Software Assembled 'Bots

Robot Construction

Outside of the robot: shells in detail

As I said on the previous page, the process of building the shells has been a big learning process for me.

This page is an illustrated step-by-step guide if you're interested in following along. If not, just go back to the previous page to continue the tour.

The basic process is described on the last page: design molds of molds in software, print those on a 3-D printer, turn those into molds, pour silicone, pour plastic. The first step is printing on the ZCorp printer. This is me setting up the printer for a new print:

Once the printer is ready, I import the piece into the software that controls it. This program breaks the part into slices that are each 0.005" tall. Each of these layers is printed in order to build up the piece.

Now we're closer to being ready to print, but this printer is quite finicky and takes a lot of care and an extreme amount of cleaning. Each of the print heads has to be individually cleaned before a print.

The whole print head also must be carefully cleaned.

And the self-cleaning area of the printer has to be scrubbed. Overall it takes about 20 to 50 minutes to set up a new print depending on how much has to be done that time.

When the pieces come out of the printer, they are not very structurally sound. Here is an assortment of pieces that were part of the neck molds in the front and a quarter of a head mold in the back left. For an idea of the time required, any one of these pieces took 7 to 9 hours to print.

In order to strengthen a piece, I infuse it with cyanoacrylate (superglue). As I mentioned, this stuff is not something you want to come into contact with, hence the respirator, goggles, and gloves. There's also a ventilator running for the entire room.

This is a part 24 hours after being glued. It doesn't look much different, but it's much stronger. It's also quite rough, so it has to be sanded down before being used as a mold.

These neck pieces took about 90 minutes to sand before getting a good fit between them. You'll see these further down the page being used to make a silicone mold.

Each piece of the head mold that will show in the end was sanded with 3 grits of sandpaper, starting with a rough and moving up to a quite fine one.

It doesn't look much different at the end, but this piece felt like a piece of sandpaper to start. Now it's quite smooth.

Here's 3/4 of the head pieced together. Note the keys that I added into each part to help in registering them with one another at this stage. It helps to make sure that the fit between pieces is correct.

Here are the pieces that will make the front of the face mold pieced together. They aren't ready to go yet, as the seems need to be filled and sanded first.

These pieces for the neck collar mold are sanded and fit nicely. Before using them for the mold, I wax them and let the wax soak in for a few hours. Just before using, I'll spray them with a mold release. Together, these will help to ensure that I'll be able to pull the final silicone part out of the mold.

Now I'm piecing them back together and hold them with rubber bands. Some of the molds have to be held more tightly, but this set is designed to lock together, so a rubber band is sufficient. I'll just leave it on the table with the injection hole and air vent holes facing up while preparing the silicone.

This is part A of a two-part V-1065 mold-making silicone. The mix is pretty simple, 10 parts of part A to 1 part of part B by weight.

Part B is going in now that I have part A measured. B is much thinner and bright blue.

The silicone takes a lot of stirring. By the time I finish any one mold, my hand and wrist usually hurt. You have to make sure that all of both parts are thoroughly mixed together in the cup or bucket.

The last step before using the silicone is to remove all of the air bubbles. This is a small vacuum chamber that I use in the shop. It takes about 3-4 minutes to get the air out of a typical batch.