“1. Engineering is done with numbers. Analysis without numbers is only an opinion.
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7. At the start of any design effort, the person who most wants to be team leader is least likely to be capable of it.
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33. Space is a completely unforgiving environment. If you screw up the engineering, somebody dies (and there's no partial credit because most of the analysis was right...)” -- Dave Akin, Akin's Laws of Spacecraft Design
Many home machinists with limited budgets have made a poor man’s DRO by mounting inexpensive digital calipers or scales on their mini-mills. They seem to work pretty well, but their displays are small and they tend to get mounted where they will be hard to read and their buttons hard to push.
Now there’s another affordable option. You can buy inexpensive scales with remote readouts and controls. The scales are available in different lengths and come with mounting hardware and a large easy-to-read display at the end of a 50-inch cord. I think if you shop around for the best price you’ll probably be able to add them to all three-axes of a mini-mill for about $125 or less.
I haven’t had a chance to play with one of these things yet and I’d like to know your opinion of them if you have. One concern I have is that they are still battery powered, although there’s probably a solution for that. They also only have a resolution of one-thousandths (.001). In most cases that’s probably enough, but I sometimes wish the DRO I made for my mini-lathe had a resolution of at least one-ten-thousandths (.0001).
Here are some places where you can buy them. (Thank you John W. and John Z. on the Mini-Mills group)
If you would like to see some cool projects made with a small CNC mill then take a look at David Morrow’s web site. It may inspire you to try CNC or give you some new ideas if you already have. You’ll find an eclectic collection of clocks, hot air engines and motorcycle and car accessories. His work shows how CAD and CNC can let you be more creative and quickly design and make things that just wouldn’t be practical with manually operated machines.
David made them on a Sherline mill that he converted to CNC. He doesn’t say much about the conversion, but he does provide details about some other modifications that can greatly increase the capabilities of a Sherline manual or CNC mill. They include an extra long and heavy base, an extended column and a flood coolant system.
If you’re interested in plans then check out Gary’s Clock 2003. You can download the DXF file for it and David’s very detailed construction and assembly manuals for it.
Entering into machining as a hobby can be a bit intimidating for the uninitiated, but Bernie Vinther had no fear.
The 65-year old former electrician took up the hobby 10 years ago after a medical condition forced him to retire at only 38. He enrolled at classes at a local community college, and began the slow process of learning to transfer his skills designing, building and fixing radios into machining.
His entry into the hobby sounds the same as countless others, but what makes his story remarkable is the medical condition that forced him to retire: Vinther is blind.
Now, Vinther has another battle. He and his guide dog were crossing a busy four-lane road in Kennewick, Wa., last month when a driver who was looking behind to change lanes struck them both. The dog was killed on impact, and Vinther was sent to the hospital. He suffered a cut on his eyebrow and cracked a few teeth (Tri-City Herald Article about the accident).
The dog had served as a guide for Vinther for nine years and without him Vinther is forced to use a white cane and a Braille compass.
During his time living in Kennewick Vinther has gained a bit of notoriety for his work in the machine shop and the lengths he went to in learning it. To complete a required course for blueprint reading he used a drawing kit that included Velcro and yarn and made three-dimensional images from clay.
He listens to the machinery to judge its relative speed and uses a special device designed by a non-profit eye institute to read out the more precise measurements. Vinther also labels all his cutting tools with Braille printouts and has a multi-page index of drill sizes in Braille that he spent hundreds of hours to create and organize.
It sounds difficult—and even Vinther concedes that it is—but he said becoming blind was “one of the best things that ever happened to me” because it helped him learn his true capabilities.
“Most of the challenges of being blind can certainly be very frustrating, but I’ve found a lot of satisfaction in striving to keep blindness from becoming an obstacle that keeps me from doing all the things I like to do,” he said in an article published in the American Foundation for the Blind. “I just won’t take “No” for an answer. Blindness has taught me not to sit in the corner and be passive.”
Vinther came into machining after retiring. In 1988 he bought an IBM 286 clone and took a booth at a local industrial products fair to try to find work designing and prototyping electronic devices. He found work with a machinist who was working on a gas bottle warning flasher, and after visiting the man’s shop Vinther asked if he could use one of his lathes for a simple project.
Soon Vinther started working more and more on the lathe and milling machines in exchange for doing some light work making duplicate parts. Vinther decided he should learn the skill more intently so he bought a lathe and enrolled in a two-year machinist program at his local community college.
After completing the program he tried to find work using his new skills, but had no luck.
“I got some calls to come in for various interviews, but when I walked through the door with a white cane and a guide dog, the interview was over before it could begin,” Vinther said in the American Federation for the Blind article. “A couple of times they acted insulted that I had the nerve to even come through the door. Being blind, I figured it would be harder to get a job, but not this hard.”
So now the work he creates is mostly for people he knows, but Vinther does some contract work too, including making stainless steel parts for LIGO, the Laser Interferometer Gravitational-wave Observatory at Hanford operated by the California Institute of Technology.
I know, you would probably rather make something more interesting than a laundry rack. But have you ever considered that someone you know might want one? That it might be someone you should show some gratitude to for all the time they let you spend in your workshop and all the money they let you spend on tooling? Have you considered that Mother’s Day is coming soon and someone might like a drying rack with some nice new jewelry hanging from it? Did you know the free plans will show you a way to fasten together tubing that might be useful for other projects?
This drying rack folds flat for hanging on a wall and was designed by the talented Ralph Patterson. Here’s how it came to be and some construction notes:
“This project was inspired by a Honey-Do directive that came from a mail order catalog. They offered a rack 60 inches tall by 18 inches wide that had a painted finish. Naturally, we were too cheap to spend $25 plus postage for something that simple. So, a trip to the metal store yielded three 12-foot lengths of aluminum extruded tube, plus a foot of 3/4-inch round bar. At $15 each for the tubes, economy was no longer a factor. The purchased bits and pieces made the total for materials something over $60. I should have used EMT conduit, but no one seems to offer any pre-made tips or caps for that size.
It would have been possible to turn some aluminum plugs to be a press fit into the tube-ends, to accept a bolt that would hold the corners of the rack parts together. But, being engineering-oriented, a two-part cup and wedge was designed instead. The wedge taper angle of 5 degrees would be self-locking and should hold tightly in the open end of a tube segment. So far, nothing has become loose in use.
After a few hours of effort, the tube insert parts were completed. Then an existing boring bar that holds a carbide insert was adapted to cut the radius needed in the cross-tube ends, so that the horizontal parts would fit snugly against the vertical parts. The boring bar was inserted in a collet in the mill spindle for cutting the scallops. The tubes, cut to length, were held in the milling vise horizontally and the cutter advanced from above. Several steps were needed to cut to full depth, since only a small part of the cutter extended past the side of the boring bar. Much care is needed to cut the opposite ends of the tube cutouts, since both ends must be kept exactly parallel.
The long tubes each needed 3 holes drilled along the length, and these must also be kept parallel. A length of steel angle was used to hold the tubing for mounting in the milling vise so that the holes could be place on the proper axis.
After the holes were complete, the assembly went together with no hitches, and is serving the wish very well.”
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I know, you would probably rather make something more interesting than a laundry rack. But have you ever considered that someone you know might want one? That it might be someone you should show some gratitude to for all the time they let you spend in your workshop and all the money they let you spend on tooling? Have you considered that Mother’s Day is coming soon and someone might like a drying rack with some nice new jewelry hanging from it? Did you know the free plans will show you a way to fasten together tubing that might be useful for other projects?
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