Grinding Gouging Blades

August 1, 2009

The other day I went into Mr. Weber’s shop where he taught me how to sharpen and grind gouging blades.

I’ve ground my own gouging blades for several years by hand. In some regards, it’s actually easier, but in other regards, you can’t get the blade quite as sharp. A while back I bought a graf machine off a kid from NEC who quit oboe, and the blade was all messed up so this was a good time to experiment with it.

Mr. Weber rarely touches gouging machines unless he has to. So for him to take three hours out of his day to teachc me how to check, grind, and experiment is unprecedented. In fact, I was more than humbled by his generous help to get the machine working, because it wasn’t a simple grind and check job. It turned out the machine was set up entirely wrong.

Using a Starrett diameter gauge, we determined that my guide is somewhere between .60 and .55 of an inch in diameter. Which is bad, because it should be closer to .45. But unless I want to change the guide, which means some sanding of the brass, rechecking, etc, I’m going to have to try to make due. Maybe eventually I will go back and change the size of the guide, but I don’t have the time nor the desire at the moment.

Next we checked the blade, which was around .43. Which is also bad, because it needs to be just slightly smaller than the size of the guide (which was .58 or so.) So we ground the blade down with his nifty machine which has a grindstone on a mini lathe, and then a clamp that can be rotated up, down, side to side, and closer and farther. The whole process of measuring/changing the angle is extremely complicated and it’s hard to describe items on an x, y and z axis, so I’ll skip it for now. But we started grinding the blade and realized the maker of the blade hadn’t tempered the metal correctly. So, he hung the blade on a coat hanger, pulled out the blowtorch and heated the blade until it was glowing red, and then dunked it in oil to temper (harden) the steel. Which helped a lot. Then we put it on the machine, to find out the previous owner had jimmied the blade up with a washer underneath it because the blade wasn’t the correct size and would hit the cane stop if you took out the washer. So he reground the blade even further.

Eventually, he got the blade to the right size, so now I have a really big radius’d blade in a really big radius gouging machine that I’m playing around with now. I may eventually go back and file it down a bit with Mr. Weber, but the whole process was so complicated, long, and tedius, I understand why he swears he’ll only set up one gouging machine a year!

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