We have a CNC Swiss that we use to turn very small precise parts. When a part has several different diameters I notice that when one diameter is on the nominal dimension, often the others are off nominal by several tenths. Is this due to different tool pressure at the different depth of cuts? Is there a solution?

Tiny Turner

Dear Tiny,

I doubt the issue is from tool pressure. It is more likely that your turning tool center height is off. Old timers will tell you that tool center height is very important in very small turning. I’ll attempt to explain why that is so.

In the following example take a look at how being off center can affect the diameter being turned. First let’s assume that if your tool was brought to X0, the tip would be dead on the centerline of the bar.

Line “a” is how far your tool is off center. Line “b” is your programmed X-axis dimension.  Line “c” is the actual distance to the cutting edge of the tool or ½ the actual turned diameter dimension on your work.

Imagine making Line “b” longer and longer (turning progressively larger diameters) and you’ll see that Angle “A” flattens out, which in turn will make Line “c” shorter relative to Line “b.” In other words the error becomes less the larger the diameter you turn is. So when turning very small diameters it is critical to be on center.

The Pythagorean Theorem tells us that a ²+b ²=c ².  Using that information, let’s assume that your tool is 0.003” off center, and you are turning a 0.030” diameter (side a=0.003”, side “b”=0.015”). Side c therefore is equal to 0.0153” because c=√ (.003 ²+.015 ²), so your turned diameter will be 0.0306” or will be 0.0006” off of nominal size.

Now assume you are using the same tool to turn a 0.125” diameter. Running the same math we find that the turned diameter (rounded) will be 0.1251” or will be 0.0001” off of nominal size.

Since the 0.030” diameter was 0.0006” off of nominal we have a differential of 0.0005” between the two dimensions. It follows that when you offset one dimension to nominal size, the other dimension will be 0.0005” off of nominal. All of which makes it difficult to dial in the workpiece without editing the program (bad), or using two separate offsets (nearly as bad).

You can also add a macro variable to the programmed dimension. But when you think about it, all that does is provide a convenient way for the operator to edit the programmed dimension. It’s better to fix the root cause of the problem by getting the tool on center.

You can use this information to calculate how far your tool is off center and correct it with an offset assuming you have Y-axis capability. Small capacity Tsugami Swiss lathes have a feature built into the control to calculate tool height using this principle. But you can see it works best at very small diameters where Angle A and the resulting error is greater.

There can also be mechanical reasons for disparity between turned diameters. If your tool is on center check for backlash, flex in the machine/tool holder, and of course the fit of the material to the guide bushing.

Question: When you watch the Super Bowl, are you more interested in the game or the commercials?

Machining of iPhone Body

I’m what people would call an “Apple guy.” I only buy mac computers, own Apple stock, and my iPhone and I are inseparable. The fourth generation iPhone was introduced yesterday, and I have to say, I covet it.

In addition to its products being superior in technology and quality, Apple takes pride in its products’ aesthetics, striving to portray them as glamour symbols. Apple’s designers shape their products with the care and sexiness of an Italian car designer. Fittingly, in his key note speech Monday, Apple CEO Steve Jobs even characterized the iPhone as the BMW or Mercedes of phones and its rivals as common sedans. Apple’s marketing team is quite deliberate in its choice of words to describe the company’s products. They say they strive to “produce technology as art form.”

In Apple’s description and video of the new iPhone it boasts that the body of the phone is “CNC machined,” which the company also boasted a few years ago when its aluminum MacBooks debuted.

One of the most successful, coolest companies of our time has just glorified the importance of precision machining. Who knows, maybe the next time I explain to average person what Today’s Machining World is about, I won’t get such a perplexed look.

Question: Do you care that Apple has drawn attention the importance of precision machining?

(Skip to the 5:00 minute mark to watch the CNC machining process)

Brian says he spends about $50,000 a year maintaining his Web site and spreading the word about his company’s capabilities on Yahoo, Google, ThomasNet.com and McCraes. He pays for Google ad words, but just to promote the company within a 100-mile radius of Orange County.

His niche is combining fabricating, welding and machining, a combination we don’t see that often as firms reach for specialization. He says he tracks 5-8 calls per week directly from his Web prominence, which he says enables him to land one new customer per month on average.

He lauds the work his Web designer has done for him—a firm that split off from ThomasNet—Creative Works.

Photo from BusinessWeek

For the May issue of Today’s Machining World, I interviewed Carl Hoffman, author of the new book, the Lunatic Express. The book chronicles Hoffman’s travels throughout Asia, Africa, South America and the U.S., during which he attempted to use the modes of transportation commonly used by natives, notorious for discomfort, tardiness and poor safety.

One thing Hoffman described to me is how the concept of time in Third World countries differs from that in the First World. In countries like India, the Congo and Columbia, people generally have a different expectation of what it means for things to start “on time.” People never know whether a train or bus is coming in one hour or three. Waiting for things for long periods of time, and arriving to destinations late is just an accepted way of life.

It’s mind boggling to me how anything gets done at all in places with such a low priority on punctuality. How can businesses operate if it’s unknown if workers will show up?

One would think the people of these countries would be happier if things functioned the way they do in the U.S.? It’s always so frustrating to me, knowing that precious time has slipped away that could have been used for things I care about. After all, time is a limited commodity. Once you lose it, it’s gone forever.

Yet many people I know from these places where things move so sloooooowly say they often feel more relaxed and centered when they return home to Slowville. And more and more it seems like us First Worlders in our civilized, efficient habitat are stressed out and paying top dollar for shrinks to help us chill out. We pay money to go to yoga classes and lie on the couch watching reality shows to slow ourselves down.

Is total efficiency sometimes unhealthy?

Jeepney Stop in Manila, Philippines

Alan Bentsen needs a Davenport for his living room. The piece he’s searching for has four legs and weighs around 3000 pounds—without cushions.

During the day, Alan is a toolmaker at Harva Company in Schoharie, New York, where they run CNC mills on military jobs, but at night and on weekends he restores old machinery because he loves the mechanisms and the feel of the weathered stuff.

Alan’s dream is to find a 70-year-old leg-type Davenport screw machine and totally restore it to running perfection. When finished he’s going to place it on a hardwood floor in front of a bay window in his home, which is a replica of an old train station

Alan is 36 years old. After attending Hudson Valley College to train as an engineer he left to work for Craftech in Hudson, N.Y., where they trained him to run their one and only Davenport screw machine, bought new in 1998. For Alan it was a love affair between man and machine. He adored that little five spindle, serial number 13485, and ran it for two years making plastic fasteners. Then Craftech lost the job. “They left the job set up on the machine for seven years and never ran it,” he said. It sits in storage.

Alan dreams of a “parlor piece” like nobody’s ever seen before—an operable ancient screw machine from the Rochester factory. He wants to be able to demonstrate the .4 second indexing speed to his friend over drinks and run off a few parts for the screw machine naïve.

I love Alan’s passion for old iron. As a side job he once helped make replicas of baggage wagons with a buddy. If you have a leg-type Davenport with a good casting decomposing in a corner, contact Alan Bentsen at pocketchrissy@yahoo.com or give me a shout and I’ll pass it on to him.

(Couldn't find a leg-type Davenport yet)

March 6, Olaf Tessarzyk, Managing Partner/President of ZPS America, test flew a Uh1-H Huey 563 helicopter he helped build as part of the Indiana Air Search and Rescue organization (IASAR).

IASAR is a non-profit organization which restores old helicopters, which will then be used for 3^rd tier search and rescue duty and air shows. Every Tuesday evening for the last five years Olaf and 36 other members of IASAR, many of them Vietnam veterans, gathered at a hanger at Indianapolis metro airport to restore the helicopter. Everyone took on different job, such as maintenance of the radio, working on the turbine, etc. Olaf got the sweet gig of being the test pilot because he was the only certified test pilot in group—he got his certification serving in the German military.

Olaf beamed as he talked about how honored he felt to be part of the eclectic group of volunteers who shared his passion for helicopters and working hard together for a good cause.

This specific helicopter has had an interesting life, one that kind of reminded me of the life of a good ole used machine tool. From 1968-1972 it had been flown in Vietnam. After that it was used for military training and finally it had been used for search and rescue. Olaf and the IASAR team either rebuilt or replaced all of the helicopter’s parts including putting in a brand new engine. Many times they would have to acquire parts by trading spare parts with other people building their own helicopters.

IASAR is entirely funded by donations, membership fees of $85 per year and corporate sponsors. ZPS America sponsored 10 memberships. Members get one helicopter ride every year, which a great deal considering that often a helicopter joyride will cost $400 or $500 a pop.

Go to www.iasar.org for a video of the first flight.

The First Flight of the 563

From left, screws made of polylactic acid, hydroxylapatite, and medical stainless steel. (Credit: Fraunhofer IFAM)

By Noah Graff

Great news for people with broken legs, but perhaps terrible news for the guys manufacturing titanium and stainless steel bone screws on CNC Swiss.

According to an article this week on CNET.com, “This month, researchers at the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research (IFAM) in Bremen, Germany, are unveiling a new type of screw that not only biodegrades within two years but actually encourages bone growth into the implant itself so as not to leave gaping holes where the screws used to be. (This has been one goal of fracture putty as well.)”

This could mean no more need to remove screws after bones have healed fractures nor having to leave inorganic foreign metal objects in our bodies. The precious medical manufacturing sector would be turned upside down.

IFAM researchers developed a moldable composite made of polylactic acid and hydroxylapatite, a ceramic that Philipp Imgrund of IFAM’s biomaterial technology department says is the main constituent of bone material.

Because the screws are made by injection molding, post processes such as milling won’t be necessary.

Could be a good time to get into the molding business.

Source: CNET News

The Machinist's APPrentice 2010

Jim Rowe, one of Today’s Machining World’s past “Shop Doc” columnists, recently invented two iPhone Apps to deal with everyday math problems confronting machinists, programmers and engineers. Presently at the iPhone APP store the “Machinist APPrentice 2010” is available for $2.99. It gives you 4 sections to choose from: Milling, Turning, References and Math / Conversions. “The Journeymen,” soon to be released sells for $9.99, and has a much more expanded platform with a variety of Chip Thinning Factors being calculated for Radial Width of Cut, Ballnose Depth of Cut, Torodial Depth of Cut and 45 Degree Lead Angles. Rowe has no formal computer programming training, just the knowledge from decades of CNC programming. Get more info on his products at his Web site: www.smartcalculations.com. Also as a side project Rowe is designing an iPhone app for www.todaysmachiningworld.com. We’ll keep you posted when it’s out.

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The PMPA management update conference is February 26 to March 1 in Scottsdale. For health and economic reasons I’ve missed the last several, but with Alan Beaulieu of the Institute for Trend Research on the docket, I’ve got to go. Three years ago his brother and associate at Trend predicted the economy’s turns with uncanny accuracy. I wish I had planned accordingly, I’d be a lot richer. This guy is really good at predicting and he does not waffle.

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Got a call from Wendy Rogers of AMSCO last week. Wendy is crusty as ever even in his mid eighties. He was interested in buying Acme cams if we would sell them cheap enough. Yesterday, I picked up the phone and Bill Currier was on the line. Bill had an eight hole turret for a Brown & Sharpe to offer. Incidentally, he’s still playing golf at 91. Old screw machine guys never die, they just _________. You fill it in on the  comments.

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Okuma recently ran a contest offering a prize of the free use of one of their machine tools for year to the company that created the most compelling video or essay expressing why they need the machine.

The entries poured in and the Okuma team gathered a lot of leads. But I think the long-term benefits may be that people in the company got a better sense of the job shop customer base, and Okuma took on the image of a company that listens to the members of its community. For probably less than half of what it would cost them to exhibit at a trade show they changed the perception of the company to a significant segment of their clientele.

Question of the day: Do you hope the new health care bill passes?

I admit to lapsing into that mindset, but after reading a provocative article in Inc. Magazine by Bernard Avishai I am becoming a believer in a new golden age of car technology.

Avishai used to sell car parts in college in the 1960s and is now a part-time professor at Hebrew University Jerusalem. He is convinced the electric car (plug-in) is coming soon in a big way and will present fabulous opportunities for entrepreneurs, including people who make stuff.

The core of the new electric vehicles will be the battery. The first generation batteries may come from LG in Korea but the much maligned Obama stimulus package is tossing a ton of taxpayer money at jump starting American competitors.

The cynics mock the $40,000 Chevrolet Volt coming in 2010, but what if it’s the prototype for an important new class of vehicles?

GM does not have Delphi anymore, but may have something much more valuable for the next decade of car making—OnStar.

According to the Inc. piece, OnStar gives GM the first mover position in car connectivity. We will see the connectivity of all of the car’s systems—charging data, mechanical components, GPS—as well as responding to collisions and malfunctions. If OnStar becomes the defacto standard for car connectivity it becomes the Windows of the new smart electric vehicles.

I think I have been so focused on the question of whether we are going to have a 10 or 12 million car year in America that I have missed the forest for the trees. The next several years will probably transform this gigantic business. With major change will come huge opportunities for entrepreneurs who are not wedded to making gas guzzlers.

Question: Are you looking to do more or less automotive work in the next several years?

The preference for American-built machinery strikes me as quite rational. For CNC Swiss there is no American alternative. The Mazak buy can be justified by the Japanese firm’s manufacturing presence in Florence, Kentucky.

Military spending for equipment and ammunition is a significant boost for the well-pounded machining world. Add to that the Obama paranoia in shooting and hunting circles and we have the interesting ammo-medical nexus propping up the precision machining world.

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A commentary on the recent auction of longtime fixture in the screw machine world—Marshall Manufacturing of Florida and Tennessee.

Marshall’s Biggest client, Sun Hydraulics, told the owners of the company that they wanted the company to run their work on the latest and best Swiss CNC lathes.

Marshall had been hurting in recent years and the owners were beaten up. They felt they were running the components competitively as they were and chose not to invest over a million bucks in Citizens or Stars.

Sun was true to their word and moved the work to a shop in Chicago that was willing to make the investment to acquire the work. Marshall chose to auction off their machinery after the Sun work went away.

Question: Should the U.S. government give strong preference to buying American made machinery? Do you consider Mazak an American firm?

U.S. Army Rock Island Arsenal