Correcting asymmetrical bevels on skew

[Jamie Straw]

Something that happens too often -- I work on sharpening a skew (standard 70-degree tilt, straight-edge; not oval or curved), and the bevels are off-center. Once they get that way, I'm not sure what is the most efficient and safest way (vis a vis possibly burning the edge) to re-center the cutting edge and the bevels. Advice appreciated.

 

[egsiegel]

Why does it really make a difference?
The wood doesn't know what angle the tool is gound at....if it is sharp, it will cut.

 

[Clifton C]

Jamie,
If you glance at the bevels, one will be shorter then the other, this would be the side to spend
a few more seconds on at the grinder. I wouldn’t spend to much time reshaping it all at once
unless it’s really off or you just want to…A few sharpenings will drift it back to where you want it.
The tool that gets a little “off” for me is the spindle roughing gouge, the bottom of the U sharpens
easier then the top corners. And when the top corners lead, the SRG gets a bit squirrelly,
so a quick glance tells me where to spend a few extra seconds.
The idea for me is to not let a tool get so far off that it needs a complete regrind, but to spend
an extra half second or two on a drifting edge every time I sharpen.
Of course a tool that takes a nose dive onto a concrete floor is another matter...
cc

 

[john lucas]

clifton nailed it. Just grind a little more on the shorter bevel each time you sharpen. It won't take long until they are the same. As the other poster mentioned it doesn't matter at all in actual usage. If you are using HSS tools don't worry about bluing the edge. It won't hurt them at all. It's better if you develop a light touch so that you don't blue them but you can't hurt HSS by overgrinding. If I have to grind a lot away I stop and quench the steel in water really often. If you wait until you get it really hot you could produce micro cracks in the steel. I can't say I've ever had that happen and I used to grind the steel really hot and quench all the time. Still the experts suggest keeping the steel as cool as you can.

 

[Jamie Straw]

Here's why...

Why does it really make a difference?
The wood doesn't know what angle the tool is gound at....if it is sharp, it will cut.

This asymmetry seems to go hand-in-hand with one side not cutting as well as the other. Not a scientific study with a big sample size, but I thought it was worth checking on.

 

[Jamie Straw]

Help is appreciated!

Jamie,
If you glance at the bevels, one will be shorter then the other, this would be the side to spend
a few more seconds on at the grinder. [break] The idea for me is to not let a tool get so far off that it needs a complete regrind, but to spend
an extra half second or two on a drifting edge every time I sharpen.
Of course a tool that takes a nose dive onto a concrete floor is another matter...
cc

Thanks, Clifton, I was working on a 3/4" skew and ended up adjusting it using the side of the grinding wheel (with due caution and delicacy). Will work at keeping it closer to centered using your advice. I'm also focusing on the length of the bevels, instead of obsessing about angles. Seems to get the results with less mental grinding. Re: the "nose dive" -- that's one reason I have rubber mats around the lathe and grinding station. I have a similar problem with spindle gouges and bowl gouges. Am realizing the reason I'm having so much trouble with the skews is that I hardly used them the first time around with turning, so not much practice. Putting on the Big Girl Britches this time and learning how to use this versatile tool.

 

[Jamie Straw]

Thanks for the confirmation, John. Onward!

 

[Dean Center]

This asymmetry seems to go hand-in-hand with one side not cutting as well as the other. Not a scientific study with a big sample size, but I thought it was worth checking on.

I suspect all of us have our 'better' side or direction for using the skew, as well as our easier side for sharpening it. While a very short or very long bevel on a skew will alter how it behaves, it's possible you're actually noticing which is your better side. Start using the skew in a shear cut, stop cutting without moving the tool and notice what the angle of the edge is, relative to the lathe axis. (45 degrees is most desirable for this cut) If cutting to your left side the angle of the edge is 30 degrees and cutting to the right it's 60 degrees, you may have found the answer to your difference in cutting. BTW, I found Alan Lacer's DVD on using the skew extremely helpful.

 

[Jamie Straw]

Working at ambidexterity

I suspect all of us have our 'better' side or direction for using the skew, as well as our easier side for sharpening it. While a very short or very long bevel on a skew will alter how it behaves, it's possible you're actually noticing which is your better side. Start using the skew in a shear cut, stop cutting without moving the tool and notice what the angle of the edge is, relative to the lathe axis. (45 degrees is most desirable for this cut) If cutting to your left side the angle of the edge is 30 degrees and cutting to the right it's 60 degrees, you may have found the answer to your difference in cutting. BTW, I found Alan Lacer's DVD on using the skew extremely helpful.

Yep, it's hard work getting to be ambidextrous, which is necessary for turning and sharpening. I'm sure the lack thereof contributes to the differences in cutting. Things are getting better though!

 

[robo hippy]

As far as being able to work from both sides, it is like Yogi Berra said, "It is 90% mental, and 10% in your head." To me, the big 3 things you need to learn for any turning, no matter what tool you are using, are 1) sharpen, 2) presenting the tool to the wood, and 3) moving with the tool. The moving with the tool part is really basic Tai Chi. If you have your hands and arms close to your body, and move the tool by moving your body, then your body is doing all of the 'fine' work, and the arms just hold the tools. Can't remember her name, but one of the Board members calls it 'Dancing with the lathe'. The exact same skills you use when free hand sharpening. Feet about shoulder width apart, move side to side, and rotate from the hips, not the shoulders and arms. Practice without the tool into the wood or on the grinding wheel...

robo hippy

 

[Bill Boehme]

...... Can't remember her name, but one of the Board members calls it 'Dancing with the lathe'.....

I have a really old Del Stubbs DVD from Fine Woodworking magazine and he used the expression "dancing with the lathe" when describing the basics of tool control.
https://www.youtube.com/watch?v=kbijBCos62E