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Fighting new skew chisel

A

Alex Ku

Joined
Nov 24, 2008
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Location
San Francisco,CA
Hi guys!

Just made a new skew chisel. It's 0.5" thick by 1.5" wide by 12" long.
No handle yet. Rectangular cross section(not oval) straight edge(not rounded like Alan Lacer's skews )
Skew angle is standard 20 degrees. Bevel angle is 32 degrees inclusive(I guess it's a little less than "standard").

Before heat treating I've sharped it and tried to "plane" 2" walnut spindle with my new chisel.
Oh man, this is not an easy tool to use! 😱
I've read some online articles and watched videos on how to properly use skew chisels. Should I mention that my skew chisel just keep digging in anyway? 🙂
Is there any specific video or a book you guys can recommend that might help me to master my skew chisel skills?

Thanks,
Alex

P.S. What handle length is normally used on heavy chisels like mine?
 
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Try one with no skew angle, otherwise known as a chisel, or in its 1/2 form, a beading tool. You provide the skew angle as you would any other tool, and the handle remains in a fairly straight line with the rest to give good control of the cut, rather than dropped low.

Planes just fine anywhere from about 9:30 to 11:30 on a piece, and beads can be cut with minimum risk. The upper is a beading tool, the lower a parting tool being used as the same. The cylinder was slicked with the beading tool after the original hack-down, though a 1" straight will rough with enough extra above the point of contact to be safe as well. These were Q&D for a beading demonstration.

http://i35.photobucket.com/albums/d160/GoodOnesGone/Shoulder-Peeling.jpg

The handle length depends on comfort and clearance. I use shorter handles because I cut with the tool handle very close to horizontal. With an overhang of 1/2 inch or less, I've got a ratio of 20:1 to work with. Makes minor presentation adjustments a snap. To make a 1/20" adjustment at the business end takes an inch at the butt of the handle.
 
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May I suggest finding a local club or nearby woodturner who can give you a hands-on lesson to ease the learning curve. woodturner.org lists all the clubs and all the members with contact info. Videos and books are great, but hands-on is much better.🙂
 
Learn to love your skew

Hi Alex,
There is a video out by Mike Darlow titled, "The Taming of the Skew." It contains a ton of information about the use of the skew. In fact, if you are like me, you may find that you can only view it one chapter at a time. One of the guidelines that has really stuck with me is to lead with the toe (the pointy end), keep the angle formed by the wood and the face of the bevel against the wood to less than 5 degrees, and use no more than the bottom third of the edge. You can read much of the same information in his book, "Fundamentals of Woodturning," on pages 32 - 41.

The biggest problem that I think those new to this tool encounter is that they create too large an angle(the clearance angle) between the spinning wood and the tool. The build up of the forces generated by the wood over the top bevel creates a force so great that you cannot react fast enough to withdraw the tool. Result: the famous spiral --- oops. Fear not! Probably everyone who has used the tool has been there. No mistakes -> no learning! Good luck and don't give up! If one of us can learn to use this tool, so can all of us.
 
A half-inch thick slab is just too thick for a skew unless you want to spend a lot of time sharpening. I have Alan Lacer's 3/8 inch thick skew and even that tool is too thick as far as I am concerned.

A skew is meant for delicate fine detail work so a big heavy chunk of steel just feels cumbersome to me. A skew is the one tool that needs to be sharper than razor sharp and a half-inch thick skew is going to get dull and need sharpening in exactly the same length of time as a quarter-inch thick skew. However, the one difference is that you will spend about three times longer sharpening the thick tool because of the extraordinarily long bevel. There is also another problem with the thick tool -- the long bevel will have considerable concavity if sharpened on the typical sized grinding wheel. While that might allow for easy touch-up with a diamond hone, it presents a potential problem when laying the heel of the bevel on a piece of wood and then raising the handle to bring the cutting edge in contact with the wood. Depending on the type of cut that you are making, it could easily result in a situation where you can't control the minimum amount of cut and, instead, will be plagued by dig-ins.

BTW, the included angle should be around 40 degrees. If you are using 32 degrees then the bevel length will be even more of a problem and the cutting edge will get dull sooner without any noticeable improvement in cutting performance while it is sharp.

It sounds like you might have left the edges square on the tool which is another problem. The heel edge should be completely rounded the way that Alan Lacer's skew is done and the toe edges need to be chamfered so that the tool doesn't create digs in the tool rest.
 
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I really don't see the advantage of such a massive skew except for planning large furniture parts. That is even 1/3 thicker than the Lacer skew. This skew with a heavy duty handle won't have the sensitivity for fine detail work that skews are best for.
Alan Lacer usually starts his demo with a micro size spinning top with his large skew. But for detail work, I don't think it is comfortable to use. The handle is too long and can't stand close to the work. The body is always in the way when swinging the handle.
The heel of the 1/2" thick hollow grind from the grinder may be in the way when gliding the bevel. If you lift the heel too much to get clearance, you may be off the bevel. We all know what will happen next.
IMO this one will be excellent to used as Negative Rake Scraper.
 
Yes, my skew chisel is massive.
But sharpening it is not a problem since my other hobby is knife making and I am a lucky 🙂 professional belt grinder owner(2 HP, variable speed). This grinder eats steel like butter and let you can grind/sharpen your tool on:

1. 14" wheel
2. Flat surface
3. Special attachment that will produce very slight concave(opposite of hollow) bevel on a tool. It's the best in my opinion. It makes cutting edge stronger, more lasting and little less likely to dig in.
(Can't help not to brag about my grinder 😀 )


Having said that sensitivity for sure is the problem with the chisel this massive. I'll take your advise on that and make my chisel out of 1/4" steel instead. I'll also regrind my 1/2" chisel into a scraper.

Thank you for all your advises,
it really helps to avoid a lot of beginners mistakes.
 
I have a 1/2" thick skew. It is 2 1/2" wide which leaves a sharp edge about 3 1/2" long. It's hard to use because it takes a very big cut and tries to self feed. You have to concentrate to use it. A longer bevel also makes it harder to cut narrow coves or concave recesses. I have one skew that is fairly thin and is sharpened to a steeper angle. This has a very short bevel and will let me turn a fairly short cove.
 
Don't know how you're approaching your work but would like to point out that your skew chisel cuts on its "sweet spot" which is situated between the two points. The points, while useful in some specialized orientations, are not typically used for planing.
 
Bill I think I learned that term from some other turner. The skew is taking such a wide bite that the wood tries to pull it deeper. With this wide of a cut it succeeds because the bevel is not really long and your dependant upon how firm your grip is on the lever end of the handle to keep it from doing that.
As long as your taking a small, 1/4 or so cut it works well. I still don't understand the mechanics behind this because I can take the size cut with my smaller skews and they don't seem to pull into the wood as bad.
 
john lucas said:
I still don't understand the mechanics behind this because I can take the size cut with my smaller skews and they don't seem to pull into the wood as bad.
Click to expand...

The mechanics behind the difference between a normal sized skew and one with a super wide bevel has a lot to do with the location of the heel of the bevel because it is used as a fulcrum point in controlling the skew. Another factor that is also very important if the tool has a concave bevel is that there is a limiting minimum angle of attack between the blade edge and the wood. This minimum angle necessarily becomes larger as the bevel length increases for a thick tool. This would probably be most significant for a planing type cut. Even using a tool with a flat bevel would be dicey because it would be marginally stable in controlling the angle between the wood and the edge. I have heard of some turners using a convex edge on their skews. While difficult to do this well without creating facets, it provides the most stable design from an engineering perspective.
 
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are you putting a concave grind on your skew or hollow grind if you are using a concave type grind that might be your problem because the concave will let your bevel rock or not set flat on to the work so if it rocks you can not control it, the bevel rubbing is the control point. the concave might be great for some things but not the skew. only my thoughts.
thanks
 
rjones said:
are you putting a concave grind on your skew or hollow grind if you are using a concave type grind that might be your problem because the concave will let your bevel rock or not set flat on to the work so if it rocks you can not control it, the bevel rubbing is the control point. the concave might be great for some things but not the skew. only my thoughts.
thanks
Click to expand...

I think that you have confused concave with convex -- almost everyone puts a bevel on their skew that is slightly concave, however, to keep this idea of concave vs. convex in perspective, if you are using a typical eight inch wheel and a skew that has a thickness of about a quarter inch then the amount of concavity is on the order of only a thousandth of an inch.

There is another widespread misconception about "riding the bevel" -- if the tool is laid down so that the bevel is flat against the wood, it can't cut anything -- in order to begin cutting, the heel of the bevel must be raised up off the wood so that the cutting edge begins to make contact. The part of the bevel that is "riding" on the cut is the very tiny part that has entered the cut and providing the support for the edge. This is a very small part of the bevel for most normal skews.
 
If I understood Alex right he is putting a concave grind opposite a hollow ground. I thought that he is putting a pot belley on his bevel and if he has that when he starts to try to pickup the micro bevel that you cut with on the cutting tools the pot belley gets in the way and starts the uncontroled cut. again just my thoughts.
 
boehme said:
There is another widespread misconception about "riding the bevel" -- if the tool is laid down so that the bevel is flat against the wood, it can't cut anything -- in order to begin cutting, the heel of the bevel must be raised up off the wood so that the cutting edge begins to make contact. The part of the bevel that is "riding" on the cut is the very tiny part that has entered the cut and providing the support for the edge. This is a very small part of the bevel for most normal skews.
Click to expand...

Once the cut is begun, the tool can be maintained in continuous contact from edge to heel of the bevel (perpendicular) and more or less parallel to the edge depending on the skew angle and depth of cut. Lots of metal on the wood, though not as much as is possible with a gouge, which can take a broader shaving without having to cut thicker.
 
rjones said:
If I understood Alex right he is putting a concave grind opposite a hollow ground. I thought that he is putting a pot belley on his bevel and if he has that when he starts to try to pickup the micro bevel that you cut with on the cutting tools the pot belley gets in the way and starts the uncontroled cut. again just my thoughts.
Click to expand...

A hollow grind and a concave grind are different words which mean the same thing. What you are referring to as a "pot belley" sounds like a convex grind (i.e., the sides of the bevel bow outwards ever so slightly). In general, it would be difficult to put a proper convex grind on an edge without the right sharpening tools since it should bow outwards by only a couple thousandths of an inch. I don't consider some of the obviously fat freehand bevels that I have seen to fit in the category of "proper". As far as the ability to control the skew is concerned, the convex bevel theoretically has less tendency to dig in. In actuality the difference is so insignificant that other factors such as he operator's skill will overshadow these microscopic differences in the bevel.

BTW, I don't bother putting a so-called "micro-bevel" on the skew because I consider it a waste of time. An incidental "micro bevel" (if one wants to use that terminology) will show up on my skew after the edge gets dull and I use a diamond hone to touch up the edge a few times before going back to the grinder. I forgo the jargon and just refer to it as touching up the edge -- maybe I should get with the trend to use buzzwords and say that I am applying a micro bevel to the cutting edge. 😀
 
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I believe it's Eli Avisari who promotes the convex grind. I may be wrong I got to his demo late. I have tried it. I find it hard to control on beads. I sharpen it on the belt sander which makes it very easy to get as much or as little convex shape as you want. I'll stick to my hollow grind. I tried a flat bevel. It works just as well as a hollow grind but is much harder to maintain. I prefer to hollow grind and then use the diamond hones to polish the edge. By rubbing both the toe and heel of the hollow grind I maintain the proper angle all the time and can touch it up all I want with the diamond hones.
 
In general convex(belly) grind produces stronger cutting edge. It is very similar to what some people call "micro bevel". Actually convex grind is the oldest and so more "traditional" than hollow grind. Practically everyone who does sharpening manually without a jig produces convex grind.
People on knife forums who have experimented with convex grind on knives report improved edge holding with no penalty for having belly (scientific term 🙂 ) Given that belly is very small.

I don't have much turning experience (two weeks to be precise.) but I doubt that small belly can cause "rocking". Keyword here is small. You should barely see it.

If I had any experienced turner in my area I would sharpen and hone a couple of his chisels on my grinder's convex attachment so he can try and let us know about his experience.

You can also produce convex grind on any belt grinder grinding against slack part of the belt but my experience is that for really good convex grind you need some support behind the belt(like on my grinder's convex attachment)

BTW I am using KMG grinder with this attachment:
http://beaumontmetalworks.com/rotaryplaten.html
 
I agree convex grinds have a place in Knives. Look at a Katana. The Samari knew how to use this edge. I used to accidentally get convex grinds on my flatwood chisels. They were sharp enough to shave with but I had trouble controlling the cut. I bought a jig and reground them perfectly flat. It was amazing how much more control I had when cutting dovetails.
I think the same is true with the skew. I can cut with a convex grind I just don't feel I have the fine control of a hollow grind skew.
 
Alex Ku said:
In general convex(belly) grind produces stronger cutting edge. It is very similar to what some people call "micro bevel".
Click to expand...

That had occurred to me that a micro bevel is just a variation on a convex bevel.

Alex Ku said:
Actually convex grind is the oldest and so more "traditional" than hollow grind. Practically everyone who does sharpening manually without a jig produces convex grind.
People on knife forums who have experimented with convex grind on knives report improved edge holding with no penalty for having belly (scientific term 🙂 ) Given that belly is very small.
Click to expand...

That would definitely be true. Even if you are grinding on a perfectly flat surface, the resulting bevel will always be slightly convex (it may be microscopic, but it will still be convex). My opinion is that woodturning is steeped in a lot of folklore and tool bevels rank high on that list.

Alex Ku said:
I don't have much turning experience (two weeks to be precise.) but I doubt that small belly can cause "rocking". Keyword here is small. You should barely see it.
Click to expand...

It would need to be some kind of extreme bevel to do that.

Alex Ku said:
You can also produce convex grind on any belt grinder grinding against slack part of the belt but my experience is that for really good convex grind you need some support behind the belt(like on my grinder's convex attachment)
Click to expand...

I like that fancy knife sharpening tool. Looks like the platen is either a flat belt or micro-v belt.
 
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