sharpening woes

[Derek Voigt]

I was working on hollowing a walnut blank yesterday and it was really giving me a hard time. I have done some bowl turning, so I'm not new to it, but I certainly wouldn't say I'm proficient at it. I eventually noticed that when I was sharping my bowl gouge that the edge wasn't coming out flat. There was a little bump in the middle of the edge.

I'm assuming the bump was the root cause of the issue, but I have no idea how it got there or how to get rid of it. I only notice it on right edge and not so much on the left edge.

I have a vari-grind jig and a raptor set up jig. I made sure that the wheel was ground flat across and not on an angle.

What is causing this and how can I correct it? I probably ground up 1/2" of my gouge yesterday trying to smooth it out.

Thanks,
Derek

[Bob Hamilton]

Hi:
Jigs control the angle of the tool, not the movement of the "sweep" as you are grinding it. The shape of the tool is controlled by the operator. If there is a bump then you need to grind a little more where the bump is. A bump indicates that you have removed less metal at that point than you did everywhere else, so you need to concentrate just on that point for a few seconds to bring it back in line.

Take care
Bob

[Joe Kaufman]

I will add to what Bob said. I don't know where you are in the age/eyesight and light requirement spectrum, but be sure you can actually see the grinding taking place. I have found that trying to repeat a motion w/o really seeing the grinding process will waste a lot of steel, especially when you change from a "U" to "V" profile gouge.

[Michael Mills]

What they said.... via video.


https://www.youtube.com/watch?v=M9G16ylEZHQ

[Joe Kaufman]

Michael, well done. Made me realize a disadvantage with CBN wheels besides the initial cost. The dark dull gray surface of my CBN wheel absorbs a lot of light and the lack of sparks over the edge indicating the edge of a ground surface.
(Being 70+ with eyesight issues doesn't help.)

[Reed Gray]

Some turners prefer a straight line from top of flute to the nose. Some prefer an arc. I usually have a slight arc. Main thing to avoid is having the wing sticking out past the nose bevel. John Lucas' video is pretty good. If the gouge still cuts, then use it till dull, then spend the little extra time on the bump. Sharpening is just touching up the edge, grinding is for reshaping.

robo hippy