Wavy surface pattern after skew chissel?

[Tony Latham]

I'm using a (sharp) 1" oval skew on a 5" piece of maple and get a "wavy" or "rippled" surface. I think the problem diminished a bit after I turned the speed up to about 1000 RPM and maybe by slowing the lateral movement of the skew. But it's certainly still there.

Is this something that just has to be dealt with using another tool type and sanding or is it my skew technique? A search of "skew & surface" on this forum really didn't come up with the answer...

Thanks,

TL

 

[Steve Worcester]

It is from not rubbing the bevel through the entire cut. One you get one ripple, they just follow right down the line. You will need to back up and cut that ripple out and start again.

 

[George Foweraker]

Or rubbing the bevel too hard and making it bounce.
It also sounds like you are turning very slowly.
If what you are turning is small enough diametor to use a skew on it 1000 revs is to slow.
George.

 

[Tony Latham]

George: This is a piece that is about 4" in diameter. Going to be a rolling pin one of these days. Is that too big for my skew????

TL

 

[George Foweraker]

Hi Tony.
I find anything over 3" a bit risky for getting a catch.
If you can manage 4" well done.
I wonder if you are pressing too hard with the bevel.
Try and relax that might help.
Regards George

 

[MichaelMouse]

I don't like the angles you're forced into using on a skew chisel, so I use a straight chisel. Gives me a lot more options in how much or little skew I put into the cut. I find this reduces washboarding to a minimum. If you get a chance, try one. http://s35.photobucket.com/albums/d160/GoodOnesGone/?action=view&current=CylinderRough.flv

Now imagine where the handle of the skew would have to be to get the same angles of attack.

 

[George Foweraker]

The option with the skew is use it point or heel leading so i dont realy see your point is valid.
At the end of the day it what suits you best.
George

 

[john lucas]

Using the skew on pieces larger than 3" gets tricky. The skew is taking a larger bite and it tries to pull the skew into the work. I find that you have to take light cuts. If your skew is not really sharp you will push harder on the bevel to get the cut. This can make the skew bounce across the hard and soft grain. Sharpen the skew, take a light cut and vary the angle so the bevel is not following the same ripple. I tilt so the edge is either at a sharper of flatter angle than my first cuts.
For rolling pins I use a rough out gouge. I have the upper part of the U sharpened so it's fairly flat or straight. I rough out the cylinder and get it as close to the final shape as I an using the bottom of the U. Then I rotate the tool so that one of the wings is cutting like a skew on the straight portion of the U. Try to keep the cut on the lower 1/3 of this straight portion and you shouldn't have any trouble. This will give a cut almost as clean as the skew and is easier and safer to control.
I'll try to post a photo of this tomorrow.

 

[Bill Boehme]

I agree with what John Lucas said. My first reaction to the initial post by Tony was that he might be using the middle or upper portion of the cutting edge which is going to reduce the stability of the cutting edge. Whether using the toe or the heel of the skew, keep the cut close to the trailing edge until you get very good with the skew.

 

[George Foweraker]

Hi Bill you have got that wrong.Keep the cut in the leading half of the skew.
Until you are experianced allways keep the wood aproaching the skew at approx 45% and cut with the lower half of the tool as soon as you go above half way the tool will roll over.
Rubbing the bevel is more important with the skew than any other tool.

Regards George

 

[john lucas]

Tony If you can, buy a copy of Alan Lacer's video on the skew. It's excellent.

 

[Bill Boehme]

Hi Bill you have got that wrong.Keep the cut in the leading half of the skew.
Until you are experianced allways keep the wood aproaching the skew at approx 45% and cut with the lower half of the tool as soon as you go above half way the tool will roll over.
Rubbing the bevel is more important with the skew than any other tool.

Regards George

George, I think that you misinterpreted what I said. Reading your explanation, it is a different way of saying what I said as far as I can determine.

The point of confusion might be the interpretation of what is meant by trailing edge. I am using it with respect to the way that the wood is moving (towards you and inclined downwards) and not with respect to the direction that the tool is moving (either left or right). In other words, the trailing edge is the edge that is closest to the tool rest. I had not considered this alternate interpretation of "trailing edge".

 

[George Foweraker]

George, I think that you misinterpreted what I said. Reading your explanation, it is a different way of saying what I said as far as I can determine.

The point of confusion might be the interpretation of what is meant by trailing edge. I am using it with respect to the way that the wood is moving (towards you and inclined downwards) and not with respect to the direction that the tool is moving (either left or right). In other words, the trailing edge is the edge that is closest to the tool rest. I had not considered this alternate interpretation of "trailing edge".

Hi Bill
A missunderstanding.
I took it you meant the trailing edge as being the edge farthest away from the cut.
As long as it has got him thinking about it .
Regards George.

 

[Joe Greiner]

...
As long as it has got him thinking about it.
...

And the rest of us too.

 

[Tony Latham]

Gentlemen:

Thanks for the words on this. I'll probably order that video by Lancer on the skew.

Tony

 

[MichaelMouse]

Rubbing the bevel is more important with the skew than any other tool.

Rubbing the bevel is what burnishes and bounces, if you're thinking in the sense of rubbing perpendicular to the edge. If you're thinking of registering the bevel parallel to the edge as the cut is made, then true. That's why I like to use the straight chisel, I find it much easier to maintain a constant cutting angle, exclusive of the degree of skew, if I am merely pushing the tool forward rather than having to lean it against wood. A conventional skew either has the handle so far down (point up) that I'm pulling sideways with my clumsy hand, or forces me below centerline with the point down.

Small stuff allows good use of the skew at 11:00 or later, with the thumb of the "off" hand maintaining cutting angle, and fingers, when traveling L to R, stabilizing under the piece. R to L is begging for a stubbed finger.

 

[rsser]

Someone said something like 'rub the bevel but not so the wood feels it'?

AFAIK a skew cut does not give you a perfectly round cylinder and rubbing the bevel too hard gives you a vicious cycle (circle? :cool2: ).

 

[Malcolm Smith]

Interesting but using a skew is just about impossible to describe. Turners who didn't have the opportunity to learn from a highly skilled turner often give up when it comes to this particular tool. Fortunately, today there are very good instruction videos that one can watch.

Malcolm Smith.

 

[MichaelMouse]

AFAIK a skew cut does not give you a perfectly round cylinder and rubbing the bevel too hard gives you a vicious cycle (circle? :cool2: ).

Has to by the laws of nature. That's what turning any material is about. If the operator presses rather than lets the wood come to the tool, different matter. If he varies the distance between tool and axis at the same point along its length, he's not going to make things round.