July 14, 2022
[starbox]Spending too much time on your computer? I’m guilty of that too, but I use the occasional educational content as an excuse. One of my favorite Facebook pages is “Thrust Me, I’m a mechanical engineer.” In recent days they posted a video on gear grinding and another on making “Organic Gears at Home.” I was puzzled about “organic gears” too, but couldn’t resist clicking on the link: (https://www.facebook.com/video.php?v=475345352607073&set=vb.173678916107053&type=3&theater.) When it comes to teaching newbies about gears I usually skip the entire involute curve, string unrolling from the base circle thing, as I find it makes people’s eyes glaze over. This organic gear explanation may become my go-to replacement lesson. It reminds me of a great lesson I learned from one of our Polish maintenance men. His father ran an underground car repair shop back home in the pre-Solidarity years. Parts were not available for most vehicles in their little farming town. But not to worry, the old man had a lathe, a welder, and a pile of scrap steel. Many times they would just weld up a broken tooth and file or die grind it to shape, sometimes without taking the gear out of the gearbox. Feel free to cringe; I sure did. But for more serious damage, when multiple teeth were gone, a suitable blank was cobbled up from stuff in the scrap pile. Then the broken part was tack welded to it. An apprentice then spent a morning at the drill press putting a hole thru to match each root. Followed by an afternoon on the band saw doing whatever flanks they could, tack welds were broken if needed and the other flanks sawed. A bit of filing and grinding and the gear was ready to go. What about splines, you ask? Turn the teeth off the damaged gear, tap the spline up into place, and weld. Heat treat? A torch and a bucket of oil are all you need. This is truly “organic” gear making! I wonder if someone can post a video of the process before the improving Polish economy renders the skillset obsolete.