Skew grind Angle - newbie Here!

[Tom Norton]

I bought a 1" skew chisel from someone In another forum. It is 5/16" thick. My understanding is the ground surface length should be 1 1/2 times the thickness. When I laid this out the angle comes to about 25 degrees. Does this sound correct?
Thanks!

[Dennis Ford]

It does not sound right to me. I suggest that each side should be ground at 18 - 20 deg, resulting in a 36 - 40 deg edge.

[Tom Norton]

I should clarify that the 25 degree angle is on one side only. So it would be 50 degrees combined.

[John Keeton]

Tom, you may want to review this thread - https://www.sawmillcreek.org/showthread.php?257223-Question-About-The-Combined-Bevel-Angle-Of-Skews

[Dave Carey]

Also there are several videos on youtube showing presentations by Stuart Batty to woodturning clubs that feature grinding angles. He favors a 40 degree angle on gouges so for a skew that's 20 degrees on each side (give or take.) Videos are worth watching for other info as well.

[David L Morse]

I bought a 1" skew chisel from someone In another forum. It is 5/16" thick. My understanding is the ground surface length should be 1 1/2 times the thickness. When I laid this out the angle comes to about 25 degrees. Does this sound correct?
Thanks!

No, your math is wrong. The calculated angle per that guideline is 19.5° each side or 39° total.

[Lawrence Schultz]

Brian Havens does a good job explaining the affect of different grind angles on a skew.

http://www.youtube.com/watch?v=yhuEVVSkDtE

[Perry Hilbert Jr]

Correct angle seems to be a many varied and complicated thing. Some videos I have watched very the angle depending on the wood. then there is the angle across the shew as well. Stuart Batty and Alan Lacer are the two I would heed. Lacer gave a demonstration to the Dallas woodturners, available on youtube, that is over an hour and only covers some of the skew uses. there are a few good German youtube videos as well and one or two have really good diagrams of skew angles and methods.

[Thomas Wilson80]

Hmm...seems somewhat more complex than I imagined. I'm new to woodturning and have done mostly bowls but would like to learn how to use a skew (just for small stuff for now). What are the recommendations for an all-purpose skew (thickness, angle, grind angle, etc) and would you recommend starting with a cheaper tool or starting with a Thompson?

[John K Jordan]

Hmm...seems somewhat more complex than I imagined. I'm new to woodturning and have done mostly bowls but would like to learn how to use a skew (just for small stuff for now). What are the recommendations for an all-purpose skew (thickness, angle, grind angle, etc) and would you recommend starting with a cheaper tool or starting with a Thompson?

Thomas,

It can be complex, but simple too - the skew is the most basic tool, the straight edge much simpler than the compound curves on a spindle or bowl gouge.

If you have mostly turned bowls, I strongly encourage your interest in learning the skew and spindle turning. I am a firm believer in what is echoed by some of the best all-around wood turners I know of: spindle turning will teach you the fine tool control that will let you turn anything, including bowls. I've heard this in person from some (Frank Penta, Jimmy Clewes, Richard Raffan) and in books by Keith Rowley, Mike Darlow, and others. This doesn't work the same in reverse. Some of the best bowl turners I know can't use a skew and some can barely turn a spindle.

When I started turning everyone told me to keep away from the evil skew. I heard lots of comments about using them as scrapers and for opening paint cans. (Most of this was from bowl turners.) But when I read the books I found out the experts were using skews so I thought if they could do it so could I. I taught myself from several books, primarily Raffan's "Turning wood" and Darlow's "Fundamentals of Woodturning."

For small things, a smaller skew is fine. I have skews from 1/4" to 1-1/4". My favorite skews for smaller work (for example, thin spindles) are 1/2". For details such as small beads and small v-grooves I usually reach for a 1/4" round skew but it's not too good for shaping tapers and things unless they are very small. For larger diameters and for roughing I often use a 1" or 1-1/4". A 3/4" is a good compromise. The larger the skew, generally the thicker is better. A smaller skew is easier to sharpen than a larger one.

Some of the basic cut with a skew are planing, peeling, beads, shallow coves, v-grooves, and facing. Planing is done on side grain to make a smooth cylinder or taper. Peeling will very quickly reduce the diameter at one place, similar to using a parting tool correctly. Beads are often done with the "short point", the obtuse angled point furthest from the end (can be tricky!) The larger the skew, the more difficult it is to make coves. V-grooves and facing are about the same, cutting across end grain, usually done with the sharp point on the end (the long point). Facing is simply on the end, often making a flat face, slightly coned, or rounded. I find planing and cutting v-groove cuts the most useful - done right the wood surface can be almost glossy smooth needing little or no sanding. Planing and v-grooves are what I teach first.

As for angles, there is the skew angle (the angle across the end looking from the flat side) and the included angle (looking down the sharpened edge from the edge of the tool).

The skew angle is somewhat a matter of preference - it changes how you hold the tool on the rest. I haven't measured my angles so at the moment I can't say what I use, maybe 60-65-degrees (where 90-deg is strait across) I could measure some tomorrow afternoon. Some people prefer a curved edge - for example Richard Raffan grinds skews that are almost 90-deg at the tip (the long point) and curve to a sharper angle at the other side. This is a good compromise since it lets you do peeling cuts near the long point and have a more reasonable angle for planing cuts the further you get from the long point. (Curving the edge has certain other advantages too.) One thing, the smaller the skew angle (the "pointer" the end), the longer the grind on the cutting edge which can make a large skew more difficult to grind.

The grind angleThere are several good reasons to use different grind angles, sometimes called the included angle since you include the angles on both side of the centerline between the two bevels. (If you set the tool rest at 20 degrees each half will be 20-deg so the included angle will be 40-deg.) It turns out that 40-deg is a pretty good angle for most skew use.

There are several good reasons to use different grind angles. Some of mine are somewhat smaller angles and some are larger. One advantage to a smaller (sharper) angle is it will cut better; a disadvantage is it can be "grabbier" if you get careless. A larger angle does not cut as well or as cleanly but it is more forgiving. I sometimes give a larger angle skew to a beginner. Another lesser disadvantage of a smaller angle is on certain woods it can pull out long fibers on planing cuts. I also prefer a smaller included angle when cutting deep v-grooves.

A cheaper tool is nice to start with since you can grind a lot of it away experimenting with angles. In fact, two cheap skews might be helpful so you can quickly compare one to the other. The better quality steel in the Thompson and other good tools is better in the long run since it will hold the edge longer. Also, I like the way Doug rounds one edge of the steel which makes it slide easier on the rest. If the steel has sharp corners they can dig into the rest - in this case use a stone or diamond hones and put at least some radius on the edges.

A skew is easy to sharpen and probably better to sharpen without a jig, just a platform. Set the platform angle for the desired bevel and hold the tool flat on the platform so the cutting edge is exactly horizontal. Move the edge smoothy across the grinding wheel on one side until you have a cleanly ground bevel, then turn it over and grind the other side. It is best to make each bevel the same length so the cutting edge will be in the center of the tool instead of to one side. You can look at the bevels from the edge of the tool and see if they look about the same. I like to use a 600 grit CBN wheel.

Learning the skew can be the tricky thing but it can also be extremely easy. I learned from books but a teacher would be better. I have been successful with a method I always use to teach beginners. In fact, the skew is the very first tool I put in the hands of someone who has never touched a lathe. After just a few minutes the beginner is making planing cuts on a cylinder and then a taper. The method I use to teach:
- I always start with a blank already rounded to a smooth cylinder. Roughing a square blank can be noisy, shaky, and terrifying to a beginner.
- Start with the lathe off
- Show how to stand and hold the skew, supported against the body.
- Make sure the tool rest is at the best height for the person. (I've had some short girls learning lately!)
- Make sure the tool is in contact with the rest, the edge 45-deg to axis of the spindle, and the heel of the bevel in contact with the wood.
- While I rotate the lathe slowly by hand, they adjust the tool so the edge starts cutting.
- Explain that the cut should be on the lower half of the edge to keep the point away from the wood. (I mark the top 1/2 with a red sharpie)
- Continue to turn the lathe by hand and let them play with the position to get a good cut.
- Explain how to change where the wood is cutting on the edge. (twist the tool slightly)
- Explain how to make a deeper or shallower cut (basically raise or lower the handle)
- Show how to move the tool down the work to plane - for right-handed people we start cutting on the right and move towards the left.
- Show how to move the tool with the body instead of the arms.
- I continue to turn the lathe slowly by hand while they practice making cuts. They very quickly get the "feel" of the skew without the fear.
- As the surface gets "lumpy" (it will at first!) I turn the lathe on and make it into a smooth cylinder again
- Finally, I turn the lathe on the lowest speed (a good variable speed lathe is great here) and let them practice peeling cuts.
- Turn the speed up and practice a few more seconds. Repeat.
In just a few minutes of practice even a brand new student is comfortably making planing cuts with the skew at high speed. Maybe 10-15 minutes, 30 minutes max for an uncoordinated klutz. I have never had a student fail to learn to use the skew in the first lesson. I have also never had one get a catch with this method.

As for the rest of the first spindle lesson, we next go to the spindle gouge and make coves and beads, to the roughing gouge to round a square blank and to for general shaping, then work on v-grooves with the skew. (V-grooves are harder than planing.)

I posted this in another thread recently, but here is an example. This girl came for one spindle lesson and one face turning (bowl) lesson. Then over two years later with no other lathe access she wanted to make a "magic" wand for a Christmas present. (Yikes - a challenging project!) With a bit of review and practice and then a lesson on special techniques needed for thin spindles she turned this on her THIRD experience at the lathe. I was impressed. After completing it she said for her the easiest of the four tools (skew, spindle gouge, roughing gouge, parting tool) was the skew! :)

375882

This is from yellow poplar.

Oops, I got a little carried away and don't have time right now to see if all this makes sense and is relatively free from typos. Maybe it will help some.

Best to find an experience turner for a lesson or two. Or hop in the car for a road trip and come visit - we can have an afternoon of spindle-turning and sharpening lessons and you can try out various skews and grinds! The cost is some good company and a maybe a good story or two. :)

JKJ

[Tom Norton]

JKJ thanks for sharing such a comprehensive reply!! I am going to print bthis out and take it out to my shop!

[roger wiegand]

I suggest trying different angles to find out what works well for you. Because a skew is not held in a fixed position you get to determine the angle of attack between the blade and the wood by how you hold it, so the "correct" angle for the grind will be the one you find most comfortable to use, and it will differ from turner to turner and situation to situation, as described in the great summary above. If it too obtuse you'll have to hold the handle in a funny position to present the edge, if it is too acute you might find the edge to be fragile and grabby. I have several skews, sharpened at different angles. I've never measured them so I can't tell you what the angles are.

I sharpen my most used skew with a slight hollow grind, and a slight radius, per Richard Raffan. I hone the edge with a slipstone while turning so I don't have to keep going back to the grinder to keep a sharp edge. It just takes a few swipes every few minuted to maintain a very sharp edge.

[Thomas Wilson80]

Thanks so much John. Great info and very understandable. Now I just need to get a skew and find the time to practice.
I would love to swing by your shop, but it's a little far from Chicago (though I do have family Greeneville, TN so maybe some day....).
Tom

[Roy Petersen]

I heard lots of comments about using them as scrapers and for opening paint cans.
I laughed out loud on that one. :)

I taught myself from several books, primarily Raffan's "Turning wood"
Same here, and spent a long time making interesting spiral grooves on pieces while I learned. I eventually got the the point where I was able to get a finish on a curve that need little to no sanding, and would use that to make beads of all sizes (several different skews). Well worth learning.

[Thomas Wilson80]

I hone the edge with a slipstone while turning so I don't have to keep going back to the grinder to keep a sharp edge. It just takes a few swipes every few minuted to maintain a very sharp edge.

Thanks for the reply. What type/grit of slipstone do you use?
Tom

[roger wiegand]

It's one of these: https://www.sharpeningsupplies.com/Norton-India-Round-Edge-Slip-Stone-P180.aspx in medium or fine grit--the markings on it are long gone.

Probably not ideal, it is just a stone that I've had around the shop since who knows when that is a convenient pocket size. I'm sure there are better choices!

[John K Jordan]

It's one of these: https://www.sharpeningsupplies.com/Norton-India-Round-Edge-Slip-Stone-P180.aspx in medium or fine grit--the markings on it are long gone.
Probably not ideal, it is just a stone that I've had around the shop since who knows when that is a convenient pocket size. I'm sure there are better choices!

I used the Eze-Lap diamond paddle-shaped hones (the blue, extra fine) for refreshing turning tools. I like the control I get by putting my forefinger above the active honing area which lets me feel for the contact with both the edge and the heel of the bevel. I use these so often I bought a lifetime supply directly from the manufacturer at a significant discount.

375892

I knock off any burr on the inside of the flute of gouges using a tapered round diamond hone: https://www.amazon.com/DMT-DCSFH-Diamond-Small-Handle/dp/B00004WFT1
I also rub polishing compound on the rougher side of a piece of resawn MDF and strop the cutting edges of skew chisels for a polished edge.

After several honings the flat on the hollow-ground edge gets wider and changes the geometry of the tools a bit so I go back to the bench grinder.

JKJ

[roger wiegand]

That's a good idea-- I even already have a set of them!

[Reed Gray]

This is a go to video for me and the skew. First half is with the skew and catches, well, how to cut as well, second half is with bowls and gouges. Richard's skew does not appear to be a 20/20 grind, but more blunt, maybe 25/25 or even 30/30, not sure. None of my skews are in the 20/20 category, and I am pretty sure most of them came with a 30/30 grind. Also not mentioned here is the convex grind that Eli Avesera uses. I found it easier to cut shallow curves when compared to a concave/standard grind skew, but not as good for long straight cuts. I may have to regrind another skew for the 20/20 grind...

https://www.youtube.com/watch?v=jOvF5f1phhY

robo hippy

[robert baccus]

Skews make me nervous yeah.

[Tony Allwright]

.....

After several honings the flat on the hollow-ground edge gets wider and changes the geometry of the tools a bit so I go back to the bench grinder.

JKJ

I've only been turning for about 12 months and am not a skilled operator with the skew but I do use one regularly. I have found that I have been getting a smoother planing cut since I started sharpening the skew on the side of the CBN wheel to give a flat rather than a hollow ground edge. That's a 1200 grit wheel on a tormek. I had been getting little vibrations, particularly on wood with irregular or interlocked grain, that was resulting in little spiral ridges on the surface. Dont know which deveolped first, the vibration or the uneven surface.
My observation may be complete rubbish and the improve results could simply coincide with improving skill levels be I would be interested in comments of others.

Tony

[John K Jordan]

I've only been turning for about 12 months and am not a skilled operator with the skew but I do use one regularly. I have found that I have been getting a smoother planing cut since I started sharpening the skew on the side of the CBN wheel to give a flat rather than a hollow ground edge. That's a 1200 grit wheel on a tormek. I had been getting little vibrations, particularly on wood with irregular or interlocked grain, that was resulting in little spiral ridges on the surface. Dont know which deveolped first, the vibration or the uneven surface.
My observation may be complete rubbish and the improve results could simply coincide with improving skill levels be I would be interested in comments of others.
Tony

That's a very interesting observation! Gives me things to think about and experiments to do.

I hate those spiral ridges but fortunately they are pretty rare. Once the wavy ridges start they are hard to get rid of since the bevel of the skew rides on the waves. I'll have to try sharpening one that way. I also have a 1200 grit wheel on a Tormek with grit on the side. It seems like sharpening a wide skew or one with a curved edge would be harder to do that way.

I have always used a hollow ground bevel. It does make it easier to hone the skew by hand - you can press a flat hone between the sharp edge and the heel of the bevel to control the honing. If the heel of the bevel is riding on irregularities and amplifying the wave on the next pass it would make sense that the flat bevel might work better. Perhaps softening/rounding the heel of the bevel would help, the same as we do with spindle and bowl gouges - I might try that too.

For the hollow-ground bevels I don't have any magic fix but I try different things until I find what works. Sometimes the fix does seem like voodoo. I think the waves can come from grain issues, flexing in the spindle, resonance, tool flexing, tool control, edge not quite sharp enough, or maybe an evil spirit. Or maybe two or three things at once, or something I haven't thought of. I had the same problem with a thin spindle and got a clean cut with turning the speed wide open, planing slower, and switching skews - I don't know which one of these did the trick, if it was one.

If flexing, it might be controllable by better support (I use the left hand steady rest method), otherwise by planing at a different speed (perhaps much faster?) or by consciously pressing the skew more firmly into the tool rest while making the cut (and make sure the overhang is not too great). Sometimes a different size skew works better - thicker, smaller (smaller bevel), wider. A different speed can change the resonance.

Since riding the bevel on the spirals just make it worse sometimes I'll make a cleanup cut with a method not usually recommended: with the very point of the short point of the skew. This will roll up fibers and may not leave a smooth surface but it can also take out the spirals and make the next cut better.

Another thing I try when I run into a particular spindle that seems out to get me - a different skew with a larger or smaller included angle. Another thing that may help is varying the angle of the edge with the work, normally at about 45-deg, try making it larger or smaller. (Making it closer to perpendicular to the axis cuts poorly but can help with things like grain tearout on certain brittle woods.)

If the piece permits I might also try planing the other direction and/or making the pass much slower.

I've had others tell me about problems with these spiral waves. Maybe someone else has a suggestion. (I must consult with my favorite skew expert when I see him next week.)

Anyone else using flat bevels, perhaps from sharpening on a belt sander?

JKJ

[Smitty Searles]

Here's a thought

If a skew is sharpened with either a hollow or convex grind you're going to have variable angles along the bevel. Add any small vibration of the work piece and it would be very feasible for any operator to have difficulty maintaining the exact angle / point of contact on the bevel. That could cause spiral ridges perhaps??? With additional passes over the ridges, the act of maintaining the same angle / point of contact would be magnified. A full flat grind would eliminate part of the problem by giving the user a consistent angle no matter what part of the bevel is touching the work.

I sharpen with a belt grinder / sander because that is what I have from my knife making escapades along with a plethora of belts ranging from 36 grit ceramic all the way to leather impregnated with Tripoli compound. Whenever I resharpen a tool I start with a full flat grind. My process has been 60 grit ceramic belt if reshaping is needed, otherwise 240 grit, 400 grit, and 600 grit ceramic belts followed by leather belt honing. Touch ups and additional honing are done flat on the platen for gouges and skews get touched up on the slack portions of the belt. This means the skews end up developing a secondary convex bevel as they get used. If/when the secondary bevel grows more to more than about 1/8" I'll hit them with the 60 grit on the platen and take them back to flat again.

Being new to the hobby, I've been very curious about the majority of people that turn sharpening on wheels rather than a belt grinder. I assumed it was because the cost for a bench grinder and wheels was less than a belt grinder and belts, is there something I'm missing?

I've noticed the spiral like crazy when using a roughing gouge and drawing it away from the cutting edge. (i.e. gouge open to the left while drawing it to the right along the work)

[John K Jordan]

...
I sharpen with a belt grinder / sander because that is what I have from my knife making escapades ... Whenever I resharpen a tool I start with a full flat grind....Touch ups and additional honing are done flat on the platen for gouges and skews get touched up on the slack portions of the belt ... the skews end up developing a secondary convex bevel as they get used. If/when the secondary bevel grows more to more than about 1/8" I'll ... take them back to flat again....

I've noticed the spiral like crazy when using a roughing gouge and drawing it away from the cutting edge. (i.e. gouge open to the left while drawing it to the right along the work)

A convex grind is not often attempted. Some people round the bevel almost completely to allow a continuous cut even on the transition at the bottom of a bowl, but even then there is a "nearly flat" bevel although it is pretty narrow - maybe 1/16" wide or less. For example, Chris Ramsey teaches this grind for turning cowboy hats - it doesn't get much more challenging than that! This is a poor cell phone photo of Chris's gouge - I highlighted the bevel in red since it's hard to see. If I remember correctly this is a 3/8" bowl gouge. (He sharpens free-hand with no jig.)

376246

Mike Darlow, in his book Fundamentals of Woodturning, describes using a belt grinder for sharpening. Where he comes from they call it a "linisher". I tried to buy one once and it was too expensive so I think cost is part of the issue for woodturners. Another issue is as mentioned, the ability to easily hone an convex grind multiple times before resharpening. Sorby markets their ProEdge belt sander to woodturners but it is pretty pricey, even before buying the accessories and spare belts. I'm sure some that read this forum have one.

I also have a belt machine made for sharpening knives and it puts an incredible edge on them. It uses two "sanding" belts, one ceramic one very fine, and a buffing belt. The belt is only 1" wide. It is made for knives so I would have to devise some kind of tool rest for lathe tools.

For me the grinders and the Tormek work very well. Don't misunderstand, as I mentioned, the spiral issue is pretty rare and it may be somewhat related to experience. To test different grinds I was imagining it might even be difficult to recreate for testing without picking the right wood.

I'm trying to imagine a sharp skew with a secondary convex bevel added to a flat bevel. Seems like that would significantly change the geometry of the cut which might make interesting issues at high speed with hard woods. I don't know anyone who sharpens that way for turning. Exactly what happens to the cut and the tool control (for planing, peeling, facing cuts, pommels, and deep v-grooves) when the smooth convex secondary bevel reaches 1/8"?

You should not get a significant spiral with a roughing gouge if moved with the spindle turning at high speed, best either angled into the cut or 90-deg to the axis. The wavy spiral with the skew is a different issue. If you move the roughing gouge rapidly, backwards, forwards or straight, you do get rough spirals but they are gone on the next pass or the first pass with the skew or spindle gouge. BTW, I turn most spindles with the speed wide open on my lathes, over 3000 rpm. Also, I tend to use the skew for roughing the square into a cylinder and save the roughing gouges for curves (and for students). A 1-3/8" skew with a 40-deg included angle is perfect for roughing.

JKJ

[Kyle Iwamoto]

You guys forgot to mention another use for a skew... A weeder....
JKJ you have a great amount if info as many have already said. I'll toss in my $0.02. I don't think there is a "right" angle for a skew. It really depends on what you are doing. I have several skews, you can get them cheap from the bidding site. Some may have dirt on it from being used as a weeder..... I have several different skew angles and grind angles. Some are really long, i use that for cleaning off the nub on the jam chuck. Some are blunt. Use that for beads. I also encourage the use of a skew, and not be afraid of it. I'm no expert, but I practice using it. Its a good tool, and you should use it. The angles? If they seem good for you, then I think it's a good angle.They are easy to reshape and sharpen......

[John K Jordan]

Thanks so much John. Great info and very understandable. Now I just need to get a skew and find the time to practice.
I would love to swing by your shop, but it's a little far from Chicago (though I do have family Greeneville, TN so maybe some day....).
Tom

Greenville is right on the way! Not trying to twist your arm, but all shop visitors go home with some wood and if desired, a free skew and skew lesson. :) And you can take a llama for a walk, get stung by a bee, drive the tractor, help on the sawmill, grab some peacock feathers, shovel some manure...

JKJ

[Thomas Wilson80]

Greenville is right on the way! Not trying to twist your arm, but all shop visitors go home with some wood and if desired, a free skew and skew lesson. :) And you can take a llama for a walk, get stung by a bee, drive the tractor, help on the sawmill, grab some peacock feathers, shovel some manure...

JKJ

That would be incredible John - I'm sure you could teach me a lot. Not sure if we'll get down your way in the near future but now I have less reasons to avoid the in-laws!
Tom

[Reed Gray]

I have thought that part of the spiral effect on spindles, or the bounce you get on bowls is from too much/hard bevel rubbing. I changed how I do that after seeing Ashley Harwood turn some of her finials for her sea urchin ornaments. She wasn't using her finger on the back side for a steady rest....

robo hippy

[John K Jordan]

I have thought that part of the spiral effect on spindles, or the bounce you get on bowls is from too much/hard bevel rubbing. I changed how I do that after seeing Ashley Harwood turn some of her finials for her sea urchin ornaments. She wasn't using her finger on the back side for a steady rest....

robo hippy

In one of his books Raffan mentions how to avoid too much pressure - he said if the supporting hand gets warm or hot, lighten up, you are using too much pressure on the skew.

I use the left-hand-steady-rest method to control vibration even on squares that are not yet turned round - not nearly the problem it might seem but it does take a light touch!

JKJ