Skew(y) thoughts

[randyrls]

There was some mentions of skew tool usage in a recent post and I thought it deserved it's own thread; so here goes.

If you look at any skew in a store notice the bevels of the skew are flat. This is important! The grind on a skew can make or break your use of it! I got a skew for my pen turning and I liked how it worked until the first time I put it on the grinder. It became so grabby I didn't use it for a long time. Then I saw an article that explained skew bevel controls the use of the skew.

Concave(hollow grind): sharpest edge; best surface finish; most difficult to control; prone to catches
Flat(flat grind): medium surface finish; not as grabby; easier to control and guide
Convex(belly grind): dull edge, easiest to control

My solution (and it took me a while) was to make a jig that attached to my 12" disk sander. A wheel intended for metal work restored my skew and its utility. I now use a CBN wheel with a side surface that gives me a flat grind.

HAPPY DAY!

War Story: Some years ago I was convinced my skew was cursed by the devil. I tried everything and could not get it under control. I ground on the skew until in disgust I threw it in my old tools. Some time later the local Woodcraft had a demo of the (new then) Sorby Pro Edge. They asked anyone to bring in their tools for sharpening. I remembered that old skew and took it in. The person doing the sharpening looked at it and said, "Oh My!"

 

[sorcerertd]

Concave(hollow grind): sharpest edge; best surface finish; most difficult to control; prone to catches
Flat(flat grind): medium surface finish; not as grabby; easier to control and guide
Convex(belly grind): dull edge, easiest to control

This is interesting. I can't imagine using a convex grind, or even how to create one. Maybe a lot, lot, lot of stropping?

I had never given it much thought but, based on this, it seems safe to say that a larger stone = shallower hollow = more control. I wonder what the difference is between an 8" and 10" wheel? Just thinking out loud really. In practical use, I don't suppose there would be too much noticeable difference. I use a 10" tormek clone, but have a worksharp that was given to me. Now I may need to consider trying it for a flat grind. Lately, I've been lazy and just using carbide, but I do prefer the final results better with a very sharp skew as opposed to the carbide, which is essentially a scraper.

 

[InkyMike]

I found this interesting as well. I just picked up a 1/2" rounded skew and I also just got a Tormek. In the Tormek documentation they talk about the slight hollow the wheel can create and how minimal it is in practice. (They also make a jig to grind on the outside of a wheel for a completely flat grind) the documentation does not discuss the hollow depth of an 8" wheel vs a 10" wheel.

I've been experimenting and I've found the grind I get (30 degrees, rounded) using my Tormek works great and isn't grabby at all. I've only been using acrylics and I've had really good luck with light sheering cuts - skew flat on the rest. Not so much with planing cuts. But I think this is a function of my technique and I haven't seen a lot of folks use planing cuts in acrylic. I'm sure it's possible. I normally use carbide.

 

[howsitwork]

I grind using an 8" wheel but I then HONE a on a diamond stone until I can see a nice flat with no grinding marks for about 1/8" back from the edge. This also makes sure the edge is burr free and truly sharp.

I then touch up using diamond hone during use to keep my edge. Use a Tormek to get a nice curve on my larger skews as this makes them much easier to control but still hone. Face it you wouldn't use a plane blade with nicks in it would you ? A skew is a fine finishing tool for a planing cut

 

[InkyMike]

I grind using an 8" wheel but I then HONE a on a diamond stone until I can see a nice flat with no grinding marks for about 1/8" back from the edge. This also makes sure the edge is burr free and truly sharp.

I then touch up using diamond hone during use to keep my edge. Use a Tormek to get a nice curve on my larger skews as this makes them much easier to control but still hone. Face it you wouldn't use a plane blade with nicks in it would you ? A skew is a fine finishing tool for a planing cut

I've got my rounded skew so that it can shave hair - I've yet to master a planing cut on acrylic, though. But it works great for light sheering cuts.

 

[randyrls]

This is interesting. I can't imagine using a convex grind, or even how to create one. Maybe a lot, lot, lot of stropping?

Todd; I've seen it done and done it myself. You have to hand grind the skew. Put a platform on the grinder. Rest your hand on the platform. Touch the grinding wheel at the point where the bevel meets the shaft of the tool. Then withdraw the tool downward and back until it reaches the cutting edge. Do this a few times with the grinding wheel stationary as practice. Use very gentle pressure on the wheel.

My skew usage is the "twist on, twist off" style and I use a shearing cut.

 

[duncsuss]

I've got my rounded skew so that it can shave hair - I've yet to master a planing cut on acrylic, though. But it works great for light sheering cuts.

Mike, can I ask you to explain your terminology? I've never heard of a "sheering cut" with a skew.

The two cuts I know of are:

1. the planing cut - which has the skew tilted so one corner is on the tool rest and you glide that fulcrum along the toolrest (and simultaneously the bevel along the workpiece) to produce a beautiful clean cut. The action is similar to a hand plane.

2. the peeling cut - set the skew flat on the toolrest, arrange the cutting edge so it's parallel to the lathe axis and lift the handle to peel away material very quickly. The action is similar to a parting tool.

 

[InkyMike]

Mike, can I ask you to explain your terminology? I've never heard of a "sheering cut" with a skew.

The two cuts I know of are:

1. the planing cut - which has the skew tilted so one corner is on the tool rest and you glide that fulcrum along the toolrest (and simultaneously the bevel along the workpiece) to produce a beautiful clean cut. The action is similar to a hand plane.

2. the peeling cut - set the skew flat on the toolrest, arrange the cutting edge so it's parallel to the lathe axis and lift the handle to peel away material very quickly. The action is similar to a parting tool.

Hey Duncan

Admittedly my terminology might not be correct - when I said sheering cut I meant a peeling cut. This is what I've been successful with when using acrylic. I've practiced some planing cuts, but I've had good luck with them despite a razor sharp round nose skew.

 

[jttheclockman]

Hey Duncan

Admittedly my terminology might not be correct - when I said sheering cut I meant a peeling cut. This is what I've been successful with when using acrylic. I've practiced some planing cuts, but I've had good luck with them despite a razor sharp round nose skew.

The skew. I have said this many times here that I believe this is the best turning tool in the tool bag. But of course it can not do all jobs as well as other tools designed for specific cuts. But for what we do it is the tool to learn. Ther terminology and the cut procedure should be learned from either watching videos and there are a ton of them or watching a pro first hand and up close in person. I sort of did both. Learning to sahrpen the skew is probably the easiest tool to sharpen but again there are different methods and different grinds. Do not get pocessed with this but learn one way and stay with it. Hollow grinds as opposed to flat grinds will get pros and cons to both but again for what we do either works well. If you take the skew into other facets of turning you will need to see feel and know the difference because they do play a roll. Cuts, peeling cut is basically a scraping cut and your carbide tools are probably used the most with this action. Not many people get carbide up on edge and use a planning cut but again if you learn that you will be surprised the cleaner cut you can get. Yes you can plane cut with carbide also. Planning cut or shearing cut as it is called is the same thing. As I said there are a ton of videos for all turning tools and practices. Here is a video that is close to pen turning and it shows the cuts I use. https://www.bing.com/videos/search?...014A8390368E1487C80B014A8390368E148&FORM=VIRE

As far a sharpening goes I use the platform to keep my tools sharp so I have a hollow grind from the 8" wheel. Again forget the size of the wheels and types of wheels used. 8" grinder is what most use. Using the flat size of a wheel is not recommended for ceramic stone wheels. That gets done many times with those CBN or diamond wheels. Again for what we do if you want to spend the huge $$ on those go for it. They are no better in my opinion that your white or blue wheels. Honing can help in the sharpness as well as quick dressing when turning our small blanks. Use a good quality diamond stone.


The finish you can get with a skew is better than sandpaper when don right and you learn to control the tool. Practice and you will never look back. Happy turning.

 

[jttheclockman]

Another thought I had that I think is important is speed. It does not get talked about enough in many videos when there is tools and machines meeting each other I think. Speed counts in all aspects of woodworking. Speed we feed the work piece through the saw blade. Speed we feed the router around a work piece and also the speed we turn at. Not only the speed of the lathe spinning our work piece but also matching the speed at which you feed your tool into the cuts. Too slow and you get divots for the cutter staying in one place too long. and the opposite when you push the tool too fast and you create skips or hills over the surface. It is a fine dance of matching speed of machine to speed of tool feed. Your brain should be able to compensate for such speeds. It is like using a block plane and pushing it across the wood. You want to keep the ribbon of wood to continue to grow so you match the speed of the cutting edge to the speed you push the plane. Now the sharpness of the planer blade will play a part as well as the sharpness of your turning tools will play a part in your speed of advancing them across that spinning work piece. Have to love woodworking. Hand eye coordination and the combination with the use of our hands and brain and playing with sharp objects.

 

[howsitwork]

Agree with JT on everything , wheel type is not critical, sharp tool is !

Surprised Hank hasn't commented as yet ?

For a planing cut try leading with the tip of the skew rather than the heel . It feels difficult at first as your tool handle is close to the wood but it works . NB DO NOT try it for the first time on a piece you value , it's challenging ! DAMHIKT.

I have managed planing cuts on plastic but do resort to flat scraping for that minute last feather cut on occasion