Thursday, February 25, 2010


I'm rather pleased with the way the chess pieces have come out!

The Mastercam/G&M code files for each of the pieces have been finished and tested. I'll have students testing out my lab procedure and finishing up the rest of the aluminum set next week, then I'll probably teach one of my assistants to make them and have him cut the brass set. They are cut from 0.875" round rod stock in either 6061 Aluminum or C360 Brass.

They take more hand finishing than I'd like, since the aluminum likes to chatter around 3.5" from the chuck, but a couple fine grits of sandpaper and some fine and very fine scotch cleaning pads put a nice shine on them.

Friday, February 19, 2010

Fits and Starts

Nothing spectacular to video today, but plenty of uneven progress on various projects over the last week or so. Charlotte continues to interest folks, having taken up a place of honor atop my small drawer cabinet. The rook is done and the knight is close to completion. Aluminum and brass rod stock has arrived for the full set. A lab to introduce diode functionality was written and done by the electric circuits class. And so on!

One noteable happening: last night was the inaugural meeting of the MSU Robotics Group where students are getting together to research and fabricate robotics related projects. For starters, they're going to be making a stationary arm that sets up dominos in patterns for domino toppling. The plan is to fabricate the mechanics and control it with an Arduino. The design options are being weighed and suddenly (as with so many things) a relatively simple concept turns out to require a surprising (for the students) amount of complexity. I'm happy with what has been accomplished already and looking forward to going over the designs with them, next.

Wednesday, February 10, 2010

Charlotte v1.1 Pics and Vids

Charlotte v1.1 is ready for her turn on the catwalk. She's just too hot with her matching legwear and new gear. . .

Other than the newly matching legs, the other change from v1.0 to v1.1 is the addition of the gear in the middle, demonstrating something that wasn't clear in the original. Although I'm using 4 motors to provide torque, the 4 legs on each side form one mechanism. The entire vehicle can be driven with 2 input gears.

Although she loves rug when walking in straight lines, turning is a whole different story. During the first turn below, you can even see one of the little cap washers fly off and roll away. Turning on rug just wasn't something she was happy to do.

Monday, February 8, 2010

En Passant

I'm working on a series of tutorial seminars to introduce students and faculty to the various major machining tools, starting with the 2-axis CNC lathe. For good reason, the classic lathe tutorial involves turning chess pieces, so I've succumbed to doing a set, starting with the pawn.

It's hard to beat the ubiquitous Staunton design, but that doesn't mean I can't try! I'm shooting for a design that's intended to be somewhat more abstract, with a decidedly industrial flair.

New Legs for Charlotte

Spent some of the morning cutting some new legs for Charlotte to remedy the lockups she was experiencing and to get rid of the ABS.
Tried some UHMW PE (Ultra High Molecule Weight Polyethelene) and decided I still like the HDPE (High Density Polyethelene) better, which is nice, since it's cheaper. Here's the latest Charlotte:
When I was assembling the new legs, I realized that the large three-holed bar is easy to get on backwards. The longer dimension needs to be closer to the gear. I had one set of the original legs incorrect.
With the new legs and the arm directions all correct, Charlotte now clacks along even more purposefully than she did before!

Saturday, February 6, 2010

Klann LEGO Spider v1.0

My Klann Lego Spider is a LEGO compatible prototype of the Klann linkage. The build files and details are posted on Thingiverse. At my wife's prompting, I'm christening the spider, "Charlotte Mk.i" since calling her "the spider thing" seems to be getting old.

The legs for the vehicle were milled from 3/8" plastic sheet stock. All the rest of the components are from LEGO Mindstorms, which we use to introduce freshman engineering students to robotic concepts.

Take a look at my interview with Priya Ganapati, of, on the GadgetLab blog: Robotic Spider Melds Legos and 3-D Printing.

Weller, a machinist and technician at the McCoy School of Engineering at Midwestern State University, combined milled plastic pieces with the basic Lego Mindstorms set to create a robotic spider that can crawl and turn.

“I wanted to open students’ minds to go beyond ‘let’s put the parts together and program the robot,’” he says. “This project is more than sticking the wheels on a Lego set.”

The folks over at Hack a Day featured the spider at Lego Spider bot, pointing out the design's relative simplicity and efficiency in incorporating legs into a robot chassis, when compared to other possible designs.

In the "near" future, I'm hoping to create LEGO compatible examples of Theo Jansen's strandbeest linkage as well. After building the Klann linkage, I’ve tentatively concluded that the strandbeest would be a much better cargo hauler, whereas Klann legs make a better light scouting vehicle.

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