I been turning for a long time now and believe that I know how to sharpen, hone and use a skew chisel -- at least for a straightforward parallel cut along a simple cylinder. I've done it a thousand times. But recently on a hard maple cylinder about 2 1/2 inches in diameter and four inches long with the grain running parallel to the lathe bed, I keep getting really bad catches. I even tried switching skews, resharpening and honing them. What happens, with everything running perfectly true, at speed about 1800 RPM, is that I begin to get tinny little ticking sounds followed by the catch. It happens cutting in either direction. I am definitely not cutting any differently from what I have always done, at least as far as I can tell; but this is driving me crazy! If I do a peeling cut, everything is fine, just fine, clean as a whistle with not vibration -- but not when rubbing the bevel parallel to the axis with the tool rest a bit high. Has anyone had a similar experience?
I have had that happen on curly maple and birdseye maple but not usually on straight grain stuff. I think what happens is it chips out. I don't get a catch it just bounces the skew. When I get wood like that I use a spindle gouge to turn it. The rounded edge somehow solves the problem of those little chips outs.
Could be bad grain, but I'd say you are using too firm of a grip. Lighten the grip and make sure the bevel is riding. Maybe rotate up the handle a little more so you are closer to 45 degrees to the wood.
Dick brings up a couple of points. Cirst off is to make sure its sharp. Notna little sharp like straight off a 100 grit wheel but really sharp like honed to 1200 grit with a diamond hone.
Second is what i call angle of attack. Typically im cutting with the the edge at about 45 degrees. Move the handle one way or the other to present the edge to the wood at either a more acute angle or a more blunt. I find that a more blunt angle often works better but occasionally a lighter cut with a mkre acute angle works.
Of course usually when i have problems with the skew indo both. A freshly sharpened edge even using a srtop followed by light uts at varying angles.
That's exactly what happens. There's no problem whatever with a gouge; and what you say is what happens: the skew bounces. It feel like a catch to me because chunks of wood fly out, and I get a scare at 1800 rpm! There's no scroll catch; it's chunks of tear-out. I get that scroll type of catch when I turn a bead wrong.
Actually, it's more like the opposite happens: i.e. only when I tighten the grip and press really firmly down that I can control it. (Sort of.) But I hate it, and don't want to do it this way. I have to get to the bottom of this problem and not resort to just forcing it through.
You are either off the bevel, your bevel isn't dead flat, or you are feeding it too quickly. Shut off the lathe, hold the skew with one hand, turn the lathe by hand. Move the skew around till you are rolling a curl off it. Make note what is going on. Turn on the lathe and duplicate your previous position.
Only a possibility by it may be feed rate given a very hard wood. I had a similar problem turning 16" wands for a friend of my daughter, the walnut and cherry went well but the ash was completely different.
Stuart Batty explains some of the problems here even though it is with a roughing gouge. You can see the small spirals and chip out.
...only when I tighten the grip and press really firmly down that I can control it. (Sort of.)
Eliot, I've seen various problems with some woods, but not repeated catches. Are the catches long point dig-ins or those that make a spiral down the cylinder?
When I run into something that gives me problems I make sure the gouge is pressed down firmly onto the tool rest with my left hand, but keep a light touch with the controlling hand. However, most of the time I have a light touch in both hands, often just a thumb on the shaft at the toolrest for steadying.
Another thing I do when I have trouble with any particular skew - try one with a different grind. I have a number so this is easy. For example, one with a small included angle, say 25-deg, cuts better but can be more difficult to control than one with a larger angle, say closer to 40-deg. I find that the 40-deg skews are easier for a beginner to control, also. A skew slightly rounded across the edge also behaves a bit differently.
Also, some wood just doesn't agree with the skew. I have some osage orange that chips badly when I use the type of planing cuts that work perfectly on almost every other type of wood.
When you first hear the clicking sounds, do you stop and inspect the wood?
I don't know if this would help, but I usually run spindles that size at a faster speed. Sharp, honed edge of course. Are you using a relatively small skew? A large skew with greater mass usually feels better to me on a diameter that large. (I mostly turn thin spindles.)
Do you have another skew user close by? They might take a look, try your skew and their own, help pin down the problem. I've got some students coming this afternoon, but maybe tonight I can chuck up a piece of hard maple that size and try some of my skews.
I got it right by more careful sharpening, including power honing using an MDF disk charged with that grey stainless steel stuff. Apparently, the piece of hard maple I was working on needed an especially sharp skew. I've been getting away with a slightly less sharp tool because most of the wood that I turn is softer.
John, thank you for your thoughtful response -- and to all who have written in. As I have said in my last post, I solved the problem by resharpening several of my skews and power honed them on MDF charged with that grey stainless steel polishing stuff. I don't usually have this problem , and that's why I posted here. The repeated catches were not the spiral kind. I was getting sudden " shocks" that resulted in nasty little chip-outs. This kind of thing can spoil your confidence; and I am more careful now about sharpening.
Great, glad you got it solved! I've heard an MDF wheel was great for that but I've never made one. I do use the leather honing wheel on the Tormek on all tools, especially skews and spindle gounges, usually followed by stropping on leather charged with a bit of polishing compound. After using the skew or gouge a bit I hone with an EZE-Lap diamond hone, extra fine (the blue-handled one) and strop again. This gives me a razor sharp edge again.
