Tools and Sharpening

[Paul Stroik]

Can someone explain to me the difference between Hollow Ground and Flat Grind and how each relates to different tools!? Which tools should be Hollow Ground and which should be flat. It was my understanding that turning tools, and plan knives should be hollow ground. Recently I read an article that suggested that flat grind was better. Need some education here.

[robert hainstock]

I personaly have always liked hollow ground, (term come from the curvature of the grinding wheel transferring to the blade edge.) Flat grind obviously has to come from ta flat grinding wheel,(side of wheel) or a stone The only place I can see any difference that might matter is on skews. The hollow ground edge can then be rehoned several times before regrinding. Most turners do not like to hone, but instead prefer to go back to the grinder. I hone with a buff of white diamond,(Pumice) on y high speed 6in machine. I turn the point down and ride the bevel briefly to remove the wire edge. I can go back several more times before regrind becomes needed. REMEMBER, grind point up, buff point down. :)
Bob

[Ken Fitzgerald]

Paul,

Most turners that I know use a grinder to sharpen their tools. Sharpening on outer edge of a round wheel leaves a hollow grind. I use an 8" wheels which should leave less of a hollow grind than a 6" wheels because the 8" has a larger diameter.

Some famous turners prefer a hollow grind.

There is a lot of theory involved concerning the difference between flat grind and hollow grind. There is also a lot of personal preference. I'm not sure I'm skilled enough to make the determination as to which is better. Sometimes.....theory and practicality clash..........

[Rod Sheridan]

Robert, I laughed about the grind point up, buff point down.

I have a LV belt grinder I use for sharpening and honing.

The grinder has a reversing switch to change belt direction.

Sure enough, one day with the leather belt on the machine, I had it going the wrong direction and of course the skew neatly sliced the belt off the grinder.

The belt flew up in the air and draped itself on my head and shoulder, wish I had a photo.

Now my grinder has a label that says "Hey Stupid, check Rotation".

Regards, Rod.