A lifelong dream has been to have the ability to design a robot using a CAD program and then easily produce a prototype or finished product from that design right on my desktop. After a few months of tweaking my Reprap Mendel 3D printer, that dream has finally come true. I’ve always been interested in designing, modifying and refining robotic grippers. Last week I used Solidworks to create and test a new design that would lower the complexity and number of parts. The great thing about Solidworks is the motion study capability. It lets you simulate the movement or your assembly before creating a physical object. This tool saves a lot of time when figuring out if the assembly is functioning as desired. When the simulated design was working properly, I exported the parts as sterolithography files (.STL). Another program named Skeinforge was used to create g-code that the control software uses to direct the 3D printers movements. The grippers were printed using a strong biodegradable plastic called PLA. I really like the white plastic because it reminds me of the Star Wars storm trooper body armor suits.
In my last blog I detailed the conversion of a manual rotary axis into a CNC rotary axis. I finally got some time to mount the rotary axis on the mill, configure the stepper in Mach3 and run it through some tests. The parameter for the g-code command to position the rotary axis is a positive or negative number ranging from 0 to 360 degrees. Positive numbers rotate clockwise and negative numbers rotate counter clockwise.
I started by creating a 3 dimensional object using Solidworks and designed a projectile that will eventually be milled in metal for a coil gun project that I’m working on. I decided to do the cut in wood since this was the first project using the rotary axis and I wasn’t sure how it would work out.
At July 12th’s KwartzLab Tuesday Open Night there was a Balancing Robot made by Phil and Nick, two UW mechatronics students, for their 4th year project. It’s designed to eventually allow telepresence, but the fact that it stands on its own is awesome!
A friend was selling some 200 ounce/inch, 3.5 Amp stepper motors for a great price so I thought it was time to upgrade the taig cnc milling machine. With the old steppers installed, the machine was accurate but slow. Since the old controller couldn’t handle 3.5 amps I decided to upgrade that too. I found a 5 axis controller on ebay for a great price. This controller uses the Toshiba TB6560 stepper driver that can handle up to 36 VDC at 3.5 Amps. I wanted a board with at least 4 axis’ so that I could add a rotary axis to the mill but more about that in another post. I went to the local electronics supplier (Sayal elelctronics) and Parm set me up with a Hammond electronics 24 VAC, 10 Amp transformer (a local manufaturer). I picked up a bridge rectifier, large capacitor, switch, fuse, computer power cord socket and indicator light to complete the power supply. The entire conroller and power suppy were mounted in a computer case.
The CNC router machine has been busy cutting more CNC art experiments. The larger face above is 3-1/2 inches wide and the smaller faces are 1-1/2 inches wide.
I wanted to see how small I could make the faces and still be recognizable.
The faces were all done with a staight .045 inch cutting bit.
I’m jumping ahead with a blog posting about the router mounting bracket. But, since I only have a few minutes tonight, here’s the mount fabricated out of aluminum with a hacksaw, grinder and a small drill press.
I have completed the X-axis and most of the z-axis of my my CNC machine and will be posting about that soon. The router I decided to use is the RotoZip RZ2000. The mount will allow me to attach the rotozip to the z-axis.
During one of my robotics adventures this week I was given what appears to be the controller for a robot arm named Excalibur. It was manufactured by a Canadian company known as Robotics Systems International. According to the serial number tag, the company was located at 9865 W. Saanich, Sidney, B.C. Canada. Each degree of freedom on the device actuates a potentiometer that is connected to a controller board with a parallel port output.
The CNC machine is considered by many to be the Holy Grail of the maker. This sacred object figures into the literature of maker technology, most often identified with the guru and said to possess miraculous powers. There comes a time in every makers life when he quests for such a thing. But if he is to prove himself worthy he must build it himself. Building such a device will challenge the builder to call upon all of his previous experience culled from the toil of midnight engineering and creative problem solving.
Okay, maybe that’s a little dramatic but this project is exciting because it involves many of my main interests: automated control systems, electronics, mechanics, software, design and building. To paraphrase our friend Darin White and fellow maker commenting on his own cnc machine, “When you see it running for the first time it’s like magic!”
A couple of months ago I decided that it was time to build a CNC router to cut light aluminum, acrylic, and wood. I was designing a new robot that will include some more intricate parts than usual. The thought of using a CNC router in place of the band saw and drill press crossed my mind and a new project was begun.
Now it’s time to create some magic. The following blog posts will update the progress in my search for the Holy Grail.
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