The Home Machinist

TechShop: a playground for machine-shop enthusiasts.


Buying your own machine tools is a daunting journey if you’re without experience. Even after you take the leap, operation of those tools the first time is, well, quite a step. In this series Ive tried to lift some of the fog, but there’s nothing as effective as getting your hands a bit oily. I visited TechShop in Menlo Park, California, and was treated to a tour of a toy shop for big kids.

Mills and lathes in this room, lasers and CNC sewing in another. There’s even storage for your project. Abe Downey (top photo) orients the author to the Tormach mill.

For most users, the attraction will be the lathes and mills that are available with an hours training. An instructor is standing nearby to help with the how-do-I questions. If you have something in mind thats more organically shaped, there is a computer-controlled Tormach milling machine, a plasma torch also under computer control, several laser-based tools, industrial sewing machines and something Id heard of but never seen: a 3-D printer.

The Dimension XPS 3D printer. If you can draw it, chances are the printer can make it. Yes, the printer.

Terry Sandin runs the Jet milling machine.

This last machine deposits a layer of liquid plastic representing the lowest slice of a CAD drawing; the platen moves down. The plastic hardens, the next slice is printed, the platen moves, repeat, until full thickness. Its not limited to solid parts, either. It will make a gear train that works, or a hollow, spherical item. After a demonstration of this I was half expecting to see Captain Picard ordering Tea, Earl Grey, hot. The parts it produces are as exotic as anything you can draw using CAD, but other than as a base for, say, a panel-top mount GPS, I would not trust the structural strength.

Rapid Results

Im sure you’re thinking that learning to operate these machines must take a lot of training. That fear was put to rest by attending a class in operating the computer-controlled Tormach PCNC 1100 milling machine. Five of us, ranging in experience from none to a long-ago high school shop class, stood as equals, listening as instructor Carter Stokum took us through the basics of safety unique to this machine, followed by loading a simple CAD drawing, installing the end mill, explaining the screen displays and then cutting a small demonstration piece. We were then each invited to use the supplied material to repeat the exercise. Total time from the start of class to a part in my pocket? Three hours, and I was the last to use the machine.

Left: The Jet mill is in the foreground. Right: The Jet lathe.

An eighth-inch ball endmill was to cut this in about a minute-after the drawing was done. But its a job nearly impossible on a conventional mill in less than a full day by an expert machinist.

Although workbenches abounded, and there was space to build the next electric car, there wasn’t enough room to build an airplane without someone having to use a wing as a workbench. While they don’t give classes in upholstery, using the CNC sewing machines to make some unique panels that you deliver to the upholstery shop would be a really novel way to use these tools and make your aircraft distinctive.

Even if there isn’t a TechShop ( in your neighborhood, a weeks time and travel might be both cost effective and fun for anyone whos thinking of buying a machine for home use. These kinds of shops offer a chance to have a clue about what you’re looking at when you’re considering a $12,000 CNC milling machine such as the Tormach, or a used lathe for under $500. Regardless, it was a pleasure even for a short while for this retired high school shop teacher and ex-Silicon Valley engineer.

Jarod McCormick mans the Tormach CNC milling machine.

TechShop visitor Victor Briggs tries out the milling machine.

The plasma cutter in action.

Editors note: If you have specific questions for author Bob Fritz, or if you have certain projects youd like us to cover, email us at [email protected] with Home Machinist in the subject line.

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Bob Fritz
KITPLANES readers will remember Bob Fritz (1947-2011) for his acclaimed Home Machinist series, but his accomplishments go well beyond that long-running feature. Following a stint in the U.S. Navy, Bob put his degree in mechanical engineering to use and was a tireless advocate for effective and consistent quality control. He brought that discipline to his work for KITPLANES. An avid diver and motorcyclist, Bob's love of flying was a surprise to no one.


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