Dave Hinz — My Story

Sometimes there is a “gear guy” lurking inside an ordinary engineer. Risking the embarrassment of a poor result on an unexpected “pop quiz” was the right decision for today’s guest blogger. Chuck Schultz

I was working at a hydraulic cylinder manufacturer, just a few years out of college. I was bored. There was little challenge to what I was doing, so I began to look for a more interesting career.

I landed an interview at a small gear motor manufacturing company. The interview went well and then I was asked if I would take a test on gearing. The engineering manager was adamant that the test was strictly voluntary and would not affect his decision. I told him that I knew almost nothing about gears, but I would take his test — while thinking that not taking the test would likely be a deal breaker.

What did I have to lose?

I knew about ratios and rotational direction, as they were obvious physics principles. He told me that I scored better than anyone ever had on his test and offered me a job. I eagerly accepted the job and began learning the details of gear design. Most of our work was spur and helical gearboxes and gear motors. We also did some worm gears and also had one double-enveloping gearset. The double-enveloping gear set was a patented design which was developed by the founders of the company.

We had been making it for many years, but suddenly began having serious quality issues. This gearset was for a defense application and we were suddenly unable to deliver the product. My boss assigned me (there was no one else) to figure out what was wrong. I looked at the original patents and questioned the people who had been making these parts. We made the worms in a conventional hobber. Essentially it was a worm cut with a shaper cutter where the cutter was mounted where the gear would be and the gear blank was mounted where the hob would have been. The gear was cut with a fly cutter which was offset from the centerline. Eventually I determined that, in the past, we always had the fly tools reground whenever we had the shaping cutter sharpened. It took about two weeks to determine why the geometry was not working and why we had a problem in the first place.

It turned out that they had bought new flycutters — out of sequence with the cutter sharpening — and had no idea as to why it did not work. I eventually figured out that there was a relationship between the shaper cutter and the flytools that had to be maintained to get a quality set. I sent the flytools out to be reground to match the current shaper cutter and then made a chart to match the flytool geometry to the status of the sharpened shaper cutter.

That was when I was hooked on gears.

I took a sabbatical from that job for a year but went back into gears when I re-entered the working world and stayed in gears for the rest of my career. The more that I learned about gears taught me that I knew less than I thought I did. I would probably still be involved in gearing if I were not living in Florida. There is very little gear manufacturing going on here.

Dave Hinz attended the University of Illinois, Urbana in the mid-70s, receiving his degree in General Engineering. The only thing we did with gearing involved ratios and mechanical advantage. I served in the Peace Corps for a short time after graduation, designing and building rural foot suspension bridges in Nepal. The USA was in a recession and jobs were a bit tough to find. I had several jobs before going to Bison Gear, where I began my gear design phase. We used an Apple 2E computer for our programs which were based on AGMA standards. We wrote the programs and saved them on cassette tapes. Our printer was an old teletype machine which was so loud that we closed the door as we left the room while it printed. I wrote the programs for worm gears, i.e. — strength, durability and efficiency, as I remember. And state of the art at that time. I worked at a number of different gear companies, and spent most of that time writing and drawing sketches, manually, i.e. — pre-CAD — for gear manufacturing processes. I was always drawn back to gears in some manner. I moved to Florida in early 2000s and took some education classes and obtained my certificate to teach high school math. I taught math for a few years and then got a call from a recruiter who asked if I was interested in a gear job in Georgia. I spent another four-and-a-half years there doing reverse engineering and manufacturing, and also noise testing of gears. I never felt that I knew everything there was to know about any type of gear, and I never met anyone who thought that they knew everything about gears, and I met some people who knew an immense amount about gears.


About Charles D. Schultz 555 Articles
Charles D. Schultz is President of Beyta Gear Service and one of Gear Technology's technical editors.

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