Around the Shop

16 02 2010

Today Stuart received a donated two arm SCARA robot and controller:

SRX-340: High speed assembly robot.

The controller is: DRX double arm robot controller.

The equipment is in great shape. The controller turns on, but it seems to be hitting an error with some missing external dependency. Interesting how difficult it is to unlock the value represented by this machine.

We can’t find any documentation on google. If you know details, let us know.

First Coil

11 12 2008

coil1I ended up using ruby-serial to control embedded code in the Arduino. The problem with the wrong number of steps per revolution was from packet loss, by slowing down my ruby program the error went away. I need to get some more test wire to wind a full torus now!

Coil Winder

5 12 2008

Here are the pieces for the coil winder, partially assembled.coil_winder11


you can see the grain of the rapid prototype: 

Already I can tell the bobbin is not well supported axially. I doubt it will be able to keep tension with 12 gauge wire. But we can test thinner wire on this iteration. 

Putting it together:


As expected, the axel needed reinforcement:



Doing some quick checks. The stepper motors are supposed to take exactly 400 steps to complete a revolution. However, when I program the bobbin to take 400 steps forward then 400 steps backward, it appears to come just short of a full revolution! WTF! It looks like it’s closer to 415 steps per revolution. But I can’t trust that number to be accurate over many revolutions.

I’m learning RAD, a gem for controlling the arduino from ruby. Very cool.


21 10 2008

First off, I’m all about open source software. Free, unencumbered, agile, fast.

For CAD I’m using BRL-CAD which is based on constructive solid geometry

For glue code I’ll use Ruby or Python. I know ruby I don’t know python.

SAGE for a mathematics package.

I havn’t looked closely at this yet, but here is a list of robots software packages

My laptop is a mac, I use linux on the server side, and will likely use EC2 for cloud computing.

Fabrication Technology

21 10 2008

This is my favorite part.

Lets start with Direct Metal Deposition. This video breaks it down:


This approach can create fully melted seamless structural elements out of stainless or tool steel. Incredible! I see using this for the structural elements such as the walls of the core.


For delicate welding there is electron beam welding. EMC used this to weld the toruses without damaging the the coils inside.


For an additive process with a fine structure we have  Electron Beam Melting. Here is a cool pic from Arcam’s brocure:

Electron Beam Melting

Electron Beam Melting

However this approach requires 1) a level work surface 2) high vacuum 3) covering the work surface with metal powder. Arcam’s current size limit is 200mm X 200mm X 350mm, so too small for the core. However the technology could possibly be adapted for a larger format. I image EBM could be used to fabricate superconductors in-situ (wild speculation, more later).

Finally, we have old fashioned robotic milling, as featured recently in Apple’s making of the macbook video:

Robotic milling and polishing allow you to achieve high tolerances and high finish even while using an additive process like Direct Metal Deposition.

What is so exciting about these fabrication technologies is that taken together they allow for a direct to metal workflow. A CAD file goes in one side and a finished product comes out the other (with hours of WTF in-between).

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