I have been hearing a lot about 3-D printing and how it will revolutionize manufacturing in the United States. Millions are slated to be spent on an advanced manufacturing center here in Chicago just west of the Loop, and bold predictions are made for the number of jobs it will create.
The technology is certainly intriguing and the entry price point dropping below $5,000 makes it affordable even for (serious) hobbyists. A local company recently built a scale 1920s Miller race car to showcase the capabilities of the various different 3-D printing methods. A good friend builds large-scale models of famous race cars the old fashioned way — from steel, aluminum and fiberglass — so this Miller model really caught my eye.
My model builder thought it was very neat too, but commented that it was “a lot of computer time to make a toy. Probably as many hours as I have in one of my models.” Having observed his projects over the years, I think he has a point. 3-D printing seems to be a new tool that can be used in product development but it doesn’t “do” anything that can’t already be done by conventional means.
The biggest limitations that I see are strength and accuracy. Plastic gears and housings have their applications and 3-D printing may be a way to reduce tooling costs for molds. I can’t see the piece cost being low enough to supplant injection molding.
My other concern is accuracy. Unconventional means have been used to make gears; we have seen wire EDM (electro discharge milling) produce useable gears at one size (say, 3 inch pitch diameter and 6 diametral pitch) and junk at another size (1 inch diameter and 72 diametral pitch). Where will 3-D printing fall in the accuracy range?
Remember when the Segway was touted as the future of personal transportation? Other than a nice way to sightsee tourist areas, it hasn’t lived up to the hype. Before we spend millions of tax dollars and get the public’s hopes up on job creation, perhaps we need a reliable process capability study.
It is only April 2nd, but I can already predict that local TV cameras will have the post office staked out 13 days from now as thousands of people rush to get their income tax forms postmarked ahead of the deadline. I’m no fan of income taxes but have to admit that deadlines are a good thing. Not the fake deadlines we see on reality car repair or real estate remodeling shows, but the real, honest-to-goodness, get-it-done-by-Friday-or-the-ship/plane/rocket-leaves- without-it-and-you-lose-the-account, kind of deadline.
There are a lot of complications and distractions in most organizations that make “expediting” a frustrating occupation. It gets even more difficult in large organizations where there are multiple decision-makers who each have a different notion of what is most important. You can end up spending precious hours arguing what could have been put to more productive use.
That is part of the reason why I enjoy the occasional breakdown/rush/emergency project — especially one that comes down from upper management. And the higher up the chain-of-command, the better. As an apprentice I once got assigned to making sure Mr. Falk’s sail boat rudder got repaired. The battered bronze piece had an official shop routing with specific operators who were to work on it. I got a red coaster wagon, a map of the shop, and a letter authorizing me to interrupt any job on the floor except (for Department of Defense orders). It was a heady couple of days for a green kid; getting screamed at by foremen, laughed at by co-workers, and learning the best ways to get people to see things your way. Needless to say, Mr. Falk’s parts were done ahead of schedule.
Properly managed rush jobs can really pull a team together. Most of us never get the opportunity to take the final shot in the big game, but we can contribute the short-cut that helps make the customer happy. Rush jobs have a way of cutting through the red tape and processing cues in ways that bring satisfaction to the team members. Sometimes they are important lessons that change the way we do our routine business.
So when that phone rings and your salesperson has a big challenge he wants you to take, step up to the line and take your best shot. The thrill of victory lasts a long time.
While driving from Dallas Fort Worth Airport to a new client’s factory, I listened to a very troubling story on PRI’s Marketplace. It seems Silicon Valley is becoming a major market for cosmetic surgeons! This hub of innovation worships youth to the point where “coders” are considered washed up at 35; potential company founders over age 40 are dismissed on the grounds that “If they were going to hit it big, they would have done so by now.” In desperation, people are relying on plastic surgeons to disguise their age.
This attitude is worrisome on many levels. My adult children worked hard to find employment in computer-related fields. The thought of them being obsolete and unemployable in a few years will cost me and my wife plenty of sleep. On a broader basis, how can you build an industry that discards its most valuable assets the moment their skills need updating?
Imagine a gear industry where you got kicked to the curb the moment you finally understood what was going on? A few weeks ago I blogged about Professor Faydor Litvin’s 100th birthday. His work at the University of Illinois/Chicago began at the age of 65! And his is not an isolated case in our industry — most of our superstars continue to “produce” well past normal retirement ages.
One of my favorite things about our industry is the opportunity to learn new things — no matter how long you have been involved. My Texas trip involved meeting some great “young” guys just starting off in this business; the oldest of them would be three years away from Botox in Silicon Valley. Instead, he has the chance to master an exciting branch of mechanical engineering his college curriculum limited to about three classes.
A word of warning to those of you starting out on the gear trail: once you get in, you may be in it for the rest of your life. There are “secrets” that will only reveal themselves to you over time. Even when you think you have those mastered, new insights will come to you. It becomes a life sentence to some of us and we never apply for parole.
PS: We’re set to begin our 4th month on the Gear Technology website. The comment activity has been picking up but we want to remind you that your input is appreciated. Topic suggestions are always welcome.
Thinking back on my experiences on the Helical Gear Rating Committee, I am a bit shocked at what hasn’t happened. As AGMA 218 was being finalized in 1979 there was an extended discussion of where the committee should next put its efforts. The esteemed members were tired from years of negotiating on the landmark document but hardly short of ideas for improvement.
The committee is still hard at work and many of the topics being improved were on the list developed long ago. The standard remains the best place to go for design methodology and is truly useable by the individual engineer or design team without expensive investment in third party software.
Software is helpful in reducing design time and manpower requirements. But as one of our commentators recently pointed out, it is dangerous to put high tech software in the hands of inexperienced engineers. Unless you know what is going on inside that “black box” you can risk your entire project by not verifying the results by other familiar and trusted methods.
This has turned out to be the stumbling block to some of the things on that 1979 “Wish List.” We had every confidence back then that our rating methods would be forever transformed by Finite Element Analysis. FEA was viewed as an inevitable technology that would quickly obsolete our computer aided calculations and replace them with beautiful and easy to understand colored renderings.
Like you, I enjoy seeing those beautiful pictures in technical papers and magazines. I don’t fully trust them yet and don’t see any chance that they will supplant current calculation methods. For now I’ll class FEA of gears with the Jetson’s flying cars: possible for some people in some circumstances but not likely to solve rush hour traffic any time soon.
One of the most important aspects of a gear rating standard is the allowable stress charts. For spur and helical gears we want to calculate durability and strength ratings for a wide variety of materials and heat treatments, so the charts have gotten large and require many footnotes.
AGMA and other standards agencies work very diligently to keep commercialism out of technical matters. All proposed changes are scrutinized by a broadly based committee of engineers from AGMA members before being adopted as part of the standard. Completed standards are then submitted for membership comments and approval. The objective is to deliver a reliable methodology for making gears that will meet industry expectations for performance.
Unfortunately, the allowable stress values cannot be directly derived from the material properties you would test in a metallurgical laboratory. There is no formula for taking tensile, impact, or other physical test results and calculating an allowable contact or bending stress allowable.
The values shown in the charts were negotiated over the years based upon committee member input and their field experiences. The process has been compared to making sausage; you don’t always want to know what goes into the sausage but as long as it tastes good and no one gets sick we come back for more sausage.
This situation frustrates companies that would like to use new materials, but protects the general public from untested products. All AGMA standards include language that permits the use of alternate methods and procedures — provided the design is properly tested. The “standard” methods represent the consensus of the best engineers in the trade and hundreds of years of collected experience.
On the Helical Gear Rating Committee we jokingly refer to the area beyond what the standards endorse as a “Land of Dragons.” Brave engineers can go there if needed. We enjoy hearing the tales of the survivors of those journeys and use them to redefine the borderline to Dragonland when the standards are revised. If you are one of those survivors your input is welcome at the AGMA committee near you.
By now readers of this Blog are aware of my interest in gear trade history. The more I learn about how we got to this point in our understanding of gears, the more I want to know. Part of what I miss about going into the office every day is the opportunity to talk about gears with others; hence the motivation for writing this Blog.
A long-term project is to assemble a timeline on gear rating methods. As it turns out, I was “in the room” when the most recent “big change” was made in the general helical and spur gear standard. Had I been more aware of what was going on, I should have taken better notes and gotten more explanation from the experts on the committee. Sadly, many of those leaders are no longer available for interviews.
So I’m reaching out to our readers for help in developing this timeline. If you have old rating standards, domestic or foreign, that you can share, I’d love to have a copy. If you have correspondence or stories about gear rating, those would also be helpful.
Eventually I hope to publish the timeline along with the calculated rating of some reference gear sets or gearboxes at different points along the way. Any help will be greatly appreciated and publicly acknowledged.
Recently I learned that it took over 20 years for the gear industry to agree on its first “standard” tooth form — and that was after spending 25 years experimenting with alternative forms. We have been using a reprinted magazine article for the rating of splines for almost sixty years. Despite the high interest in epicyclic drives for wind turbines, we still don’t have an AGMA rating method for the bending strength of internal helical gear teeth.
One was first proposed in 1953!
We are making progress on the internal helical gear bending strength; look for it to be included in the next version of the basic gear rating standard, perhaps as early as 2015. A committee was formed to develop a spline rating standard several years ago, but progress has been slow. With the amount of splines used in machinery and vehicles, this topic should be getting more attention. Perhaps the method reprinted in Machinery’s Handbook is all our designers need.
Standards development is a collaborative effort and reaching consensus takes time. Gone are the days when a single gear company could take on a major “science project” and share the test results with the rest of the industry. We need to identify topics that deserve study and find ways to get the testing done.
We sincerely appreciate the increased activity in the comments section and hope to make this blog more of a two-way street. Let’s use this forum to develop a things-to-do-list for the next generation.
PS: Anyone have drawings of the finger gears used in the famous Hulet self-unloaders? I want to reference them in my upcoming Fall Technical Meeting paper and would prefer to show an actual drawing rather than a sketch based upon my memory of making spare parts back in 1981.
PPS: A completed word search is attached; hope you enjoyed hunting for those (50) gear terms.
When you work as an engineer for smaller companies you get to wear a lot of hats. Whether it was an emergency structural repair — snow causing a roof collapse right over a parked crane — or the owner’s latest idea for an invention — don’t ask — the company “engineer” is expected to have an answer. Once you get over the fear of total and complete failure, these unexpected challenges can be educational and fulfilling.
Our profession has not always been as specialized as it is today, so it was accepted that management expected this versatility. A steamship foundering mid-ocean couldn’t wait for an expert to helicopter in to fix a ballast pump or patch a hull leak.
In the same January 1912 issue of Industrial Engineeringthat published Percy C. Day’s article on herringbone gears, we find a paper by Sterling H. Bunnell on “Expense Burden: Its Incidence and Distribution.” Yes, in 1912 engineers were expected to be informed and involved in financial decisions as well as technical ones. To quote Mr. Bunnell:
“The engineer must now master the problems of financial operation, the principles of estimating correctly and providing for fixed charges, as well as operating expense, and all the other details of accounting required for the continued successful operation of the enterprise.”
Not exactly the cruise most of us signed up for! But keep in mind that the professional engineering exams place equal value on the “engineering economy” questions as they do on the stress analysis ones. More companies fail due to unsustainable overhead rates than due to product failures. Today’s complex world economy makes controlling production and development costs as important as being on the cutting edge of design.
Another point Mr. Bunnell makes is that not everything that can be done should be done. Management and your co-workers need your honest appraisal of whether a policy, practice, or investment is in the best interest of the company. Would Commander Montgomery Scott ever tell Captain James T. Kirk that something “wasn’t his job?” Certainly not, if the fate of his beloved Enterprise was at stake.
After all, while he wasn’t a miracle worker, he was an engineer. And that was usually enough.
Writing this Fall Technical Meeting paper has me digging through old files for references I am certain are in there some where. Of course I am finding many things I had forgotten about and this is not helping me get things done in a timely manner.
Amongst the treasures unearthed was a box of 3.5 inch floppy disks and a few of the earlier 5.25 inch versions as well. Some of my younger readers may not have ever seen or used floppy disks but there was a time when they were the cutting edge of computer technology. For engineers of a certain age, our first “network” was the “sneaker network,” as in lace up your shoes and run this disk over to NC programming or accounting.
Anyway, I have several boxes of 3.5 inch floppy disks I can’t bring myself to discard. The programs that used them are around somewhere and, who knows, if the zombie apocalypse really happens I may be the only guy left who can still boot up a 2-D CAD program. My secret weapon? A portable floppy disk drive!
And just to prove it still works I provide today’s special diversion: a Gear Technology word search. These came in very handy back in the day while waiting for the sneaker network to respond. We’ll publish the solution in a later posting.
An old proverb posits that “The beginning of wisdom is calling things by their proper name.” In my previous posting I brought up the need to identify the meaning of the acronyms when you cite them. Our trade has many names for the same “thing,” and where you first learned something may affect what you call it.
AGMA has a nomenclature committee which develops definitions, symbols, and terms for use in the standards. They also coordinate with ISO to insure that our standards can be understood around the world. It is a testimony to the fine work these people do that we have a thriving international discussion of gear technology without more disagreement over what certain symbols “mean.”
It hasn’t always been this way. I have a 1972 copy of H.E. Merritt’s Gear Engineering that is tricky to use because of the different Greek letters used for key angles. I have to constantly convert formulas and keep a “cheat sheet” in the book to remind me.
I mention this topic in conjunction with earlier exhortations on teaching and mentoring. Make sure your pupils learn the common understanding of gear terms and can recognize non-standard usage when they see it. No matter what your “local dialect” is, they need to be able to converse with people outside your firm without having a translator present.
When AGMA first introduced software to rate gears according to ISO 6336, they held training sessions around the country. I was able to attend the class in Chicago and was embarrassed for some of my classmates. They knew “gears” in their local dialect but were unable to accurately fill in the input forms because of nomenclature differences.
This isn’t a new situation and it isn’t easy to resolve. AGMA and ISO are doing their part to make the standards consistent. No one is going to go back and revise all those cherished reference books. You can do your part by making sure our “newbies” learn to call things by their proper name.