Sunday, August 5, 2012

Share your toys

Sharing is Fun

So one of my other objectives with this project was to share my toys. Like I have said in previous posts, I'm not really out to win the race, I just want to have fun. If anybody else in race wants to use my tools to cut out their car I would be more than willing to help out. After all, it just means I get to have some more fun using my machines :)

So I wondered how many of the other men at church had access or the skills to use CAD software to design a car to be cut on my machine. There are perhaps one or two that could make their own model. But for anybody else it isn't really an option to learn how to use some of the free CAD software to generate a complex contoured car body shape in a short amount of time.  One option that is free and still pretty easy to use is Autodesks 123d CAD software.

However, it is pretty realistic to model a car out of clay and other sculpting materials. I figured that if someone wanted to sculpt a design is would be easy to make complex shapes using clay and then all that we would need to do is digitize the clay model and then we could cut it on the NC machine.

How to Make Clay Digital

So There are several ways to digitize a clay model these days. Most all of them use some method to create a point cloud from the surface of the part and then mesh that point cloud into a digital surface that is close to identical to the original. There are laser scanners, touch probes, X-Ray tomography, etc.. but there was one method that looked very easy and didn't cost any money. Autodesk 123d Catch.

123d Catch- Beautiful, but not very accurate

124d catch uses lots of digital photos of the object from different angles to create a textured mesh of the original object. Here are the results of my attempt. When you get to the site select the 3d button below the model. The model is beautiful because the texture is created from the photos, but the mesh is not very accurate. Also it bothers me that the calculations are done on the cloud. I would rather wait longer and do all of it on my computer. I'm sure that they do it in the could to gain ownership of the models.

Touch Probe it is

After discovering that 123d Catch would not provide the accuracy I wanted I looked into making a touch probe for my machine. I ended up making a touch probe with a piezo buzzer and an Arduino board. More details on that sensor will be in another post. Here are the results from that experiment:

And here is a picture of the resulting mesh next to the original model
Not Quite the faithful reproduction I was expecting, but it is a work in progress. Also, not all the part was sampled.

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