hollow or flat grind your skew?

[Bob Glenn]

Early on, I used a flat ground shew chisel with out too many problems. When I got my Tormek, I hollow ground the skew chisel and found it had a tendency to catch more often. It seemed like it was harder to ride the bevel with the hollow grind. Your thoughts. Thanks Bob

[JohnC Lucas]

I played with all grinds. It's more about practice than how the tool is ground. My preference is a hollow ground that is honed so the ends are basically flat ground for a mm or so. Here is a video that might help that I did several years ago.
https://www.youtube.com/watch?v=YFlZyGKYro4&t=57s

[Dick Mahany]

I have reground mine with an Alan Lacer style profile and a hollow ground grind and really like using a skew chisel now. I consider myself a novice skew user, however I'm using it more and more and realizing the benefits it offers.

[John K Jordan]

Early on, I used a flat ground shew chisel with out too many problems. When I got my Tormek, I hollow ground the skew chisel and found it had a tendency to catch more often. It seemed like it was harder to ride the bevel with the hollow grind. Your thoughts. Thanks Bob

I agree with John L, that the use depends primarily on practice with a specific grind. I've also tried several different grinds and after a bit of practice they all worked.

A hollow grind will effectively create a smaller included angle at the cutting edge for a given measured angle, smaller for an 8" wheel than a 10" wheel. Since the larger included angle is a bit more stable than a smaller angle, perhaps your skew would be more like your previous flat grind if you simply increased the bevel angle a bit.

I usually grind skews with an 8" CBN wheel with 600 grit, occasionally with a 1200 grit CBN on a Tormek. I don't see any difference between those two and a flat grind. BTW, after enough practice you should never get a catch, except perhaps when you poke the point directly into the wood in a moment of inattention.

JKJ

[roger wiegand]

Hollow because it's much easier to hone without creating a secondary bevel.

[Alex Zeller]

Do you have a stone or diamond wheel for your Tormek? I have the Grizzly clone and I'm thinking of getting a diamond wheel for it. With the diamond wheels you can grind on the side of the wheel to get a flat grind vs the hollow grind on the face of the wheel. I haven't broken down and bought a diamond wheel yet (thinking that the 600 grit fine wheel should be about right) so I can't offer advice on how well it works. I know some people talk about getting 2 (or even all 3) grits but I really have no desire to be swapping wheels other than the rare time I was reshaping a tool.

[John K Jordan]

Do you have a stone or diamond wheel for your Tormek? ...I know some people talk about getting 2 (or even all 3) grits but I really have no desire to be swapping wheels other than the rare time I was reshaping a tool.

The CBN wheels I have for the Tormek have a few inches of grit down each side for grinding flats. I also have a 600 grit wheel but prefer the 1200 grit for my spindle gouges. I do keep three coarser grits on bench grinders, 80 grit for reshaping and up to 600 grit for some tools including scrapers. I prefer to get an additional grinder instead of changing wheels. Regardless of the grit, I think the Tormek turns too slow for shaping tools, especially heavy scrapers and large skews. Although the bench grinders use 8" wheels and the Tormek 10", the hollow grind curvatures are close enough that sharpening on the 10" after shaping on the 8" doesn't take long,

The point Roger makes about honing tools is a good one. Holding the hone so it's supported between the heal and edge makes it simple to hone the edge perfectly several times between sharpenings on the grinder, difficult to do with a flat bevel. I like the little Eze-lap diamond paddle hones for this, blue.

[Reed Gray]

I may have to get another grinder.... The only diamond wheels I know of for the Tormek was supposed to be out in June, but haven't seen it here yet. Glenn Lucas has a couple of them, 600 grit and up. I generally find a 600 grit wheel grind (CBN) works fine after honing, but I am not a skew master. I do prefer a slight arc in the skew. The main cut I do with them is a peeling cut where a totally straight edge would not be practical.

robo hippy

[David M Peters]

I used the medium grit (600) Tormek wheel for a week at a Glenn Lucas class and really liked it. Nice sharp edge with minimal fuss. His setup used the water bath along with some Hone Right.

[Alex Zeller]

I'm not sure if the diamond wheels are out yet. I knew they were suppose to be out last month and when I did a search for the fine wheel Advanced Machinery comes up with free shipping and allows you to put them in the cart. It didn't say that they weren't in stock yet. I just assumed they were. I didn't mean to hijack this discussion.

[Thom Sturgill]

There is a third grind, where the side are slightly curved outward (reverse of hollow grind). Several top knotch skew users recommend this grind. I personally use a Lacer grind on my larger skews and that shape on narrower ones.

[Perry Hilbert Jr]

Reverse of a hollow grind....? Do you use a round nose grinder for that? How do you get the benter hollow ground and the edges otherwise.

[Bob Bergstrom]

Which ever grind is used, the determining factor is developing the skill to use the minimal amount of bevel, with just enough pressure on it to make the cut. It is quite a balancing act to minimize bevel contact, lightest pressure on the wood and movement along the wood. Practicing on soft wood or wet wood should help in getting the correct parameters in cutting properly.

[JohnC Lucas]

The convex grind is what started my skew testing. People were saying I couldn't use the skew until I tried Eli Avisera's convex grind. So I ground one that way and played. I found it easier for some cuts, harder for others. Sharpening is interesting because it's hard to create the same acute edge every time. However as long as you get it close it works pretty darn well but I just didn't see any real advantage other that it might actually be easier to sharpen. However it's awfully quick to use a concave grind and then a quick hone creates those micro bevels that work so well on the skew. After my initial sharpening I strop the skew with my Tormec leather wheel. I can do that quite a few times before needing to sharpen again and I have a very sharp skew to boot.

[John K Jordan]

I do prefer a slight arc in the skew. The main cut I do with them is a peeling cut where a totally straight edge would not be practical.


I don't see how a flat grind would be impractical for peeling cuts - did you try it both ways? I saved this photo from Darlow showing a peeling cut and that shows that only an extremely tiny section of the bevel is actually in contact with the wood.

390320
(Photo from Fundamentals of Woodturning, Mike Darlow)

I think he has another photo with an even closer view; I'll try to find it when I get to the shop.

Or by "slight arc" do you mean a curved edge, not a hollow ground bevel?

JKJ

[Alex Zeller]

I don't know about a skew but a convex grind on a knife is usually for use where extra strength is needed, like for chopping. For a skew I would think it's advantage of a convex grind would be, as long as the angle of the tip is the same, that the hollow grind might flex more if pushed hard (do you push a skew hard?). I'm by no means an expert, actually I'm trying to learn, so if I'm wrong please let me know. At least one site that talked about skew sharpening that I read had you do a hollow grind and then use a flat stone to make it more of a flat grind with the middle part of the grind still being concave. I would think a convex grind would be more difficult to do.

[Reed Gray]

Well for the convex grind, I ground an old one that way after watching Eli Avisera use it. After playing with it for a while, I found it more difficult to get a long straight cut, like on a rolling pin, but easier for doing curves, especially cove type surfaces, they work better, kind of like grinding off the heel on your bowl gouges for inside bowl cuts.

I have been playing with peeling cuts a lot lately, and blame Eric Loffstrom for it. Watched him get a 220 grit surface on a piece of hard maple using just the peeling cut. So, I notice no difference in 'practicality' with concave. convex, or flat grinds. Heck, I even use my Big Ugly tools. Only real difference I notice in finish surface is that harder woods yield cleaner peeling cut surfaces than softer woods, and a more acute angle leaves a cleaner surface. Most of my skew type peelers are at 30 degrees, with one at 25, and my scrapers at 70. There is a noticeable difference with the 25 degree angle...

Now, out to the shop to make more drawer pulls for the new house and shop... 200 or so...

robo hippy