Monday, April 14, 2008
Three Signs of Spring
Three sure signs of spring around here are coffee on the porch, buds on the trees and the return of Gerry Felix. Gerry is going to be tackling my new rodback armchair. I'll keep tabs on his progress.
Back to turning,
The parting tool is the much abused but essential workhorse of spindle turning. Imagine sizing all of the diameters with a gouge, no fun. But for all its usefulness, it gets little glory. The most common problem that I see with parting tools (besides being dull, but that's another post altogether!) is the technique used when sizing with them.
I guess that the instinct when handed a sharp pointy thing is to stab away with it until the job is done. Perhaps this will help, imaging the spinning workpiece as a grinding wheel, the last thing you'd want to do is jam the tip into it, right? The problem is that the unsupported tip will dull quickly, vibrate profusely and give poor feedback of the cut quality or speed. Sure, it feels like you have control because you can stab to different depths to get the diameter you want, but I find the price too high.
Here is a video showing my preferred technique for cutting with the parting tool. The one difference that the parting tool has from the other shearing tools that I'll cover later is that the bevel is actually riding on the area being cut. This is a bit like cutting a tree limb that you are standing on! The position of the tool has to compensate for the material that it is removing the entire way. This isn't so hard because the direction is pretty simple, forward. Later, I'll talk about tools that ride on the bevel and cut areas just to the side of the tool, but for now, this exception to the rule deserves some focus and practice.
It is well worth the time to practice this cut with two hands on the tool. Once one feels comfortable with the maneuver, the caliper can introduced. As with so much hand tool use, I try to focus on the wood being left, not the pretty shavings. I would rather feed the parting tool too far forward on the bevel, which disengages the tip and stops the cutting, than to descend into a scraping cut.