Curved vs straight skew chisel

[Frank F]

I've often heard that there are advantages to a curved skew chisel over a straight skew chisel. But I've never heard what these advantages are or why.

So I'll ask. Why is a curved skew chisel more versatile, or is it. What cuts can you make with a curved skew that you can't make with a straight one and why?

Thanks,
Frank

 

[john lucas]

I'm one of the disbelievers. I've ground a round edge skew and tried it out. I could not see any advantage over the straight edge skew and in some instances I found it worse.
When cutting beads with the heel of the skew I find it harder to watch the edge because it's kind of tucked under.
I found it harder to sharpen when using the grinder. I grind a hollow grind on my skews and then sharpen them with diamond hones. I found the hollow grind harder to do accurately. I built a jig for my skews that fits on the Oneway flat tool rest which makes grinding the straight edge pretty much fool proof.
I know some people claim that a curved edge skew is less likely to catch. I don't see how. If you come off the bevel with either skew it catches.
Here is a photo of my grinding jig. This is the one for my oval skews. I have another one for my flat skews.

 

[Gary Slater]

Check out Alan Lacer

Frank, if you can get the first Alan Lacer DVD, "The Dark Side The Sweet Side", you can at least see the pro's thoughts and uses of the curved skew. It is a very good video and was enough to help me make the choice to go with the curved skew.

 

[Randy]

John
I believe he is talking about the cutting edge being curved not the profile on the skew. I have both but I believe the curved skew cuts planning cuts better than the straight edge but the straight edge does a better plunge cut with the long pont than the curved skew, IMHO.

 

[jffink]

Most cuts can be made with either type of edge profile on the skew — for example, planing, rolling beads, and peeling cuts can be made with either. The curved edge lets you do some "finer" and "more localized" scraping/peeling cuts since you can put a small portion of the convex edge in contact with the workpiece. I have several skews and find the curved edge skews less likely to catch/dig-in. A curved profile is my favorite.

I agree that the Alan Lacer video is good, but also suggest that you look at some of the Richard Raffan videos. Raffan too uses the curved profile. Several of Raffan's videos show a lot of skew work — I learned a lot by playing the skew shots over and over and by using the freeze frame and slow-motion mode on the video player. In the straight profile camp, I believe you will find Mike Darlow, so you might take a look at one of his books or videos too.

Happy holidays to all!

 

[Frank F]

Randy, you are correct. I was talking about a curved cutting edge.

I have Alan Lacer's first DVD and several Raffan's DVDs. Both Lacer and Raffan mention that the curve skew has advantages, but don't provide much detail on those advantages.

I suspect one advantage is that you cut with only one point of the edge at any instant. Does this give you control that you don't have with a straight skew? I don't know the answer to that.

I'd like to know what others think.

Frank

 

[Bill Boehme]

There is more than one kind of curved edge skew. The one that Alan Lacer likes is a rather extreme curve. I have one and although it has some useful features, I am not really a big fan of that type of skew. My idea on a good curved skew is the Sorby oval skew with a very slight curve which is the type that Nick Cook likes. I also like the straight skew and do not see a big difference between it and the type with a very gentle curve except that I think that I can do a slightly better planing cut with the gently curved edge.

 

[MichaelMouse]

If you have a curved edge, you can't use the tool as a flatening scraper. You can make better down and in roundover cuts, and depending on how you hold the tool, the retreating edge can make planing smoother than a standard skew. Neither of the latter is unique to the curved skew, so I don't bother. Been there, done that, ground back to straight.

I now use my large-radius gouges, which have both a rounded nose and a flute to make down and in and roundover moves. They're quite controllable, and don't skate backward if I overdown. For planing, it's tough to beat a straight chisel, and you can push control it easier than a skew with the handle in your lap. Makes dynamite beads, too.

 

[steelguy]

Alan Lacer's skew grind results in an edge that is partially (25-30%) straight and partially curved. From his sharpening guidelines:

"First let me describe the shape of the cutting edge. About one-fourth to one-third of the edge from the long point is a straight line-and 90 degrees to the long point edge. The balance of the edge is a curved shaped. Two other aspects of the edge are critical: try to maintain an angle of approximately 70 degrees from point to point, and grind the bevel length to approximately one-and-one half times the thickness of the steel." Complete details can be found at www.alanlacer.com

Jerry

 

[Russ Fairfield]

My opinion is that sharp is the only option that counts; and when you lose the bevel, you have lost control of the tool, regardless of its shape. Everything else is a personal preference.

Some people will find it easier to follow the bevel with the curved edge, while others will prefer the straight edge; and there will be those in both groups who prefer a concave, flat, or convex bevel. Then there are those who prefer a tool that is flat, round, or oval. There must be a few of us left over from an earlier time who learned to use a chisel with a single bevel.

I see the benefit of the straight section Alan uses below the long point as being there to make a flat peeling cut for a tenon at the ends of a spindle. I prefer to use a square chisel with a single bevel for making tenons, but that is a personal preference, not because it is better, but because I have always done it that way. .

 

[Bill Boehme]

For those who also do "flat" woodworking and know what a bench plane is (hint: it is not a power tool), there is a bit of an advantage in putting a very slight (as in barely perceptible) curve to the shape of the iron, especially if using the plane to flatten a very large wide surface such as a table top. While I don't recommend using a skew for planing flat surfaces, the curvature in my "curved" skew is not much greater than it is in my curved plane irons. As others have said, there is not much difference between the various ways to grind a skew and it is mostly a matter of personal choice. I find that I can touch up a skew using a diamond hone a bit quicker if it has a slight curve since it does not require honing the entire edge if only one part needs attention.

 

[john lucas]

Bill I'm not sure the analogy of the plane fits. A planes blade is curved to keep the outer edges from leaving a line. That's not a problems with a skew. I can sharpen just one section of my flat skew if I need. I sharpen all of it because I use all of it.
I also don't understand the concept that a curved edge will cut better when planing because it's angled back. You are using so little of the edge when planing that I don't believe the wood will see the minor difference between a curved edge and straight edge that is cutting at the same angle.
I have tried both as well as convex grind skews, flat grind, hollow grind, and different sharpening angles. I have some sharpened at 25 degree included angle all the way up to 90 degree, although I've kind of settled on 35 degrees for most of them now after lots of playing. I have skews from .015" (I'm not joking here) up to 3" and use all of them. I'm still playing and still learning so all this discussion is interesting. One of these days when I'm rich I may buy one of Alan's skews and test drive them side by side. I find the sharpening angle to be the most critical difference between skews and learning to work with them. Not the shape of the edge. At least that's what I think. I don't find the cutting action or the ease of use to be any different for most work using the flat or curved edge skew. I like the way the flat edge lets me work.

 

[Bill Boehme]

John, I really mentioned the plane to describe the amount of curve that I have on my skew and not as some sort of analogy about any similarity between the two tools. Sorry that I confused you.

However, I have seen a demonstration of using a bench plane as a turning tool.

I am impressed by your wealth of experience with the skew, but my preference is the is the Sorby oval skew. It is a good fit for my turning style, but don't feel the need to insist that others do it the way that I do.

 

[john lucas]

Bill Let me say first that I hope I wasn't coming across strong. I always respect what you have to say and read your posts thoroughly. It's very easy to missunderstand what people really mean on the web so if I got it wrong I apologize.
I have used the plane on turnings. I thought that was how it was done in the beginning. I tried several but would still get tear out. I find block planes work well. When I use them in my skew demo's I don't get tearout so I don't know for sure what I do today vs 10 years ago. Probably cutting with the grain and not forcing the cut.
I have been using an oval skew for 15 years and like it. I guess because I got used to it. I now use my Thompson skew about equal. What I usually do is use one until it gets dull and then use the other one. Then I'll stop and sharpen both.

 

[MichaelMouse]

I have used the plane on turnings. I thought that was how it was done in the beginning. I tried several but would still get tear out. I find block planes work well. When I use them in my skew demo's I don't get tearout so I don't know for sure what I do today vs 10 years ago. Probably cutting with the grain and not forcing the cut.
I have been using an oval skew for 15 years and like it. I guess because I got used to it. I now use my Thompson skew about equal. What I usually do is use one until it gets dull and then use the other one. Then I'll stop and sharpen both.

It goes back to cutting theory and the idea that a block plane has a low sharpness angle. I have used a standard jack on pillars, but it wasn't the same as a low angle-bevel up block plane. You skew the tool to the work to effectively lower the cutting angle, same as you do with flat planing.

As to the curve in the edge of a jack, scrub or skew, what it does is involve less edge contact for the same depth of cut. Smaller the radius, greater the depth/breadth ratio, just like a gouge.

I don't do it with skews or straight edges which are so easily honed, but I do change the planer and jointer knives at the same time because it's more worthwhile to set up the Makita for two sets than just one.

 

[Chipe]

If you have a curved edge, you can't use the tool as a flatening scraper. [snip]

I use my curved edge skews as a scraper all the time. Never had a problem.

 

[john lucas]

They do work great as scrapers but your missing their best benefit. They make great can opener when you need to pry a paint can open.

 

[Bill Boehme]

They do work great as scrapers but your missing their best benefit. They make great can opener when you need to pry a paint can open.

or scraping you-know-what off your boots.