Tuesday, March 6, 2007

Turning Tips Unplugged pt.2


This is a picture of Blacksmith Marc Maiorana in my class at the Penland School in North Carolina. Marc is a fantastic blacksmith. He and I found so much common ground that we've created a blacksmith/greenwoodworking/toolmaking class that we'll be teaching at Penland this summer.
A few more tips to improve you're turning while the lathe is unplugged. Of course I have to talk about sharpening! Imagine if I laid out 10 boards, each 10 feet long and I handed you a razor sharp carving gouge. Then I asked you to carve singe line down the length of each board. Would the gouge be razor sharp at the end? Now think of the piece spinning in the lathe. How quickly would you travel the same 100 feet?
For a turning tool to be controllable, it is vital that it's edge not only be sharp but geometrically correct. By riding on the bevel at all times, turning becomes stable and fluid. The problem comes when the tool dulls and rounds ever so slightly. Then in order to engage the cutting edge, one lifts off of the safety of the bevel and CATCH! The problem is compounded by the fact that a dull tool cannot take a light cut, so by the time you do get the cutting edge to engage, the size of the cut is overwhelming and you lose control. Which brings me to the next topic,
Quit bullying the tool! It is more common to think that we should squeeze the tool to death rather than go sharpen it. The problem is that as we tense up we lose our ability to respond with any sensitivity. It is also exhausting! I show my students, that just two fingers at the back of the handle can control the cut. Hold the tool like a bird, just firm enough so it can't fly away. Remember, the tool rest is a fulcrum and the reason we have those long lathe tools is to benefit from the leverage it gives us. Anyone who has tried turning with the tool rest too far away can attest to that!
A last thought for the day is to recognize the importance of our body's role in turning. Turning is a dance, you can't stand in one place. It's vital that you keep your knees bent and practice moving your body in a way that will allow the tool to do it's job. I take a tip from the Japanese here, always move towards stability. Our tendency is to start cutting what is right in front of us as we stand balanced and then as the cut proceeds away from us, we reach away, falling out of balance. If you place yourself in the position that you will be at the end of a cut, and then shift your body to where the cut begins, you will be moving towards balance and a more fluid cut. I like to keep my elbows in and the back of the handle touching my body whenever possible, benefitting from the stability of my whole mass. Get used to moving more than you expect.

5 comments:

Greg said...

Some turners go back to work right from the grinder. They don't stone their tools because, as you point out, turning dulls tools very quickly, and the finer (& sharper)edges of a honed tool dull even more quickly. Or so the patter goes (I read it in more than one book on turning!).

Being self taught & hard headed, I sharpen my turning tools the same way I do everything else- going from coarse to fine stones, and grinding only when I'm spending an inordinate amount of time with the stones (inordinate being a relative concept, since the guys who wrote the books I mentioned think any stoning is a waste of time). I have tried using tools right off the grinder, and it's not that bad. Even though the super-sharpness of a honed tool goes away quickly, I still don't want to grind every time my tools dull because it seems like I'm using the tool up to quickly.

Peter, can you comment on how you sharpen your turning tools and give us a rough idea how often you do it? (Maybe impossible to do, because one sharpens when it feels like you need to sharpen, not something rote like: every 4th leg, etc...)

Lefky said...

I was taught to buff a turning tool (specifically spindle and roughing gouges) after grinding. Is the honing you suggest an alternative or in addition to buffing?

On another note I want to tell you how much I enjoy your blog. It is the first site I go to every day. I really enjoy your attention to detail, subtlety and the wide ranging subject matter. It is very hard to find the kind of detailed and in-depth information that can make a good chair into a great chair. Thanks for being so generous with your time and information.

Jeff

Peter Galbert said...

Jeff,
Buffing turning tools after grinding can be a substitute or in addition to honing. Sometimes I will hone will coarse grits and then finish it off on the buffer. The reason that I don't recommend the buffer initially is that it is so easy for those new to using a buffer to round the edge over and undo all that grinding! I'll be talking soon about tools that benefit from this slight rounding. I hope this answers your question.

Lefky said...

Pete,

I believe I have been rounding over the ground edge on the buffer. I will switch to honing instead, which is easier to control. Thanks for the advice.

Jeff

Peter Galbert said...

Jeff,
On gouges I like to use the little diamond paddles (cheap and usedful) and a diamond cone for the interior, although sandpaper and a dowel will work fine,