Bowl Gouge Shape Question

[treedoctor]

As stated before, I am relatively new to turning, but have already become somewhat of a tool junkie. I have several bowl gouges so far. I have a Henry Taylor, Thompson, Henry Taylor Raffan grind, and a Glaser. All 1/2 in. Granted, I don't "need" all of these but had some gift certificates and wanted to try several. I showed a fellow turner the Thompson gouge and he said it wouldn't take the grind he uses. I didn't quite catch the reason why. If these gouges are sharpened on the same jig, the same diameter of round bar shouldn't they be about the same? I know the shape and depth of the flute will play into it as well. My questions are:
1. For a grind like the Ellsworth grind, is it just a matter of altering the angles on the jig. Or is there something unique about the shape of the flute or the bar for that matter? I'm guessing that the pros do this freehand and the jig maybe taboo to some.
2. Along the same lines, shouldn't I be able to make the Thompson gouge more swept back like one of the other gouges if I match the jig set up?
3. The Raffan gouge has a longer grind on the left and on the right is steeper. I haven't figured out how to maintain this.
Any help is appreciated.
Thanks

 

[Odie]

treedoctor......

I have several different manufacturer's offerings of deep fluted bowl gouges......and I can tell you for a fact that the shape of the flute does absolutely have an effect on your grind.

I recently purchased a Pinnacle (I think from Woodcraft).....a cheap bowl gouge that has a very narrow base to the flute. I was surprised to see it's shape become something very strange looking......but, it cuts. The Taylors, Sorbys, and a few I can't even remember at the moment look much different.....but, they cut, too!

Play around with your grinding techniques, and you'll find that just about any way you experiment with has uses on the lathe.

otis of cologne

 

[robo hippy]

Deep fluted gouges will take a swept back grind better than a shallow one. The Thompson gouges are a case of this. Dougs U shaped flute is rather shallow, almost like a spindle gouge. It won't take the swept back grind well. His V shaped gouge is more like a super flute, or deeper flute. It will take a swept back grind very nicely. I have a Glaser V gouge, and it is much more of a V than Dougs V. It doesn't take the swept back grind very well. I use the Ellsworth jig for grinding all of my bowl gouges. It only changes the angle on the Thompson gouges a tiny bit, making them slightly more pointy. If I rotate the gouge more to the side when I grind, I will get more of a swept back grind. So how much you swing the gouge determines how much of a sweep you will get.

I don't know if they have them any more, but a year or 2 ago, the AAW sent out a sharpening DVD to members. It was very informative. See if you can find it. Other than that, more pointy makes it harder to round through the transition on the inside of a bowl (45 degree nose) and is better for plates and shallow bowls. More blunt (60 plus degrees) is better for making the transition and going across the bottom of a regular bowl. More blunt (80 degrees) is better for making the transition of a deeper bowl, and cutting across the bottom. Just about any of them will work on the outside of a bowl because there isn't anything to get in the way.

robo hippy

 

[Bill Boehme]

It is worth pointing out that the jig you use does not determine the shape of the grind. That is determined by you and how much grinding you do on the nose and sides of the gouge. The only thing that a jig is good for is to hold the tool to the grinder at the proper angle -- that is a very important thing, but only half of the story.

 

[Jim Keenan]

Try this link. Mike Mahoney

http://youtube.com/watch?v=4m8-8MNhpvY

I use 4 different 1/2 in bowl gouges. One has a sweep about 1 to 1 1/4 in. This is used for some serious roughing. The next has a sweep of about 3/4 in. I use this for shaping and shear finish cuts. The next two have a slight sweep and none at all. I use these for finish cuts when I can rub the bevel. All bevels are sharpened at about 42 degrees. Both of the latter are of M2 steel and are a little sharper than the "super alloys" of the first two which seem to hold the edge longer but do not produce quite as fine a cut.

 

[Doug Thompson]

This is a very good question with many different answers.

If you gave 10 people the same type tool put them on the same grinder with the same jig setting you'll end up with 10 different grinds. Everone has there own idea what a grind should look like and it's a grind that you learned to use over time.

The grind that I put on the tools won't suit everyone, for most woodturners the grind will change over time from the example above. Here's what it is... a good solid grind that works. BTW - the jig setting was from a old original Glaser tool. IMO - the wings should be ground back farther but there are people who don't want the wings.

Flute shapes do vary from different manufactures but if you looked at them side by side you would notice they are pretty close to each other. That's because bowl gouges for example only work in a certain range, once your outside of the limits the gouge doesn't work anymore. To narrow a flute and it clogs, to wide then the angle of the cutting edge is lost so there are limits.


The Raffan gouge sounds odd almost like the flute isn't centered to the steel.

It's late, hope this helps a bit.

Come on guys/gals there's more to be answered.

 

[MichaelMouse]

My questions are:
1. For a grind like the Ellsworth grind, is it just a matter of altering the angles on the jig. Or is there something unique about the shape of the flute or the bar for that matter? I'm guessing that the pros do this freehand and the jig maybe taboo to some.
2. Along the same lines, shouldn't I be able to make the Thompson gouge more swept back like one of the other gouges if I match the jig set up?
3. The Raffan gouge has a longer grind on the left and on the right is steeper. I haven't figured out how to maintain this.
Any help is appreciated.
Thanks

1 If your jig is capable of getting the swing required, you should be able to do an Ellsworth. The principles of most grinding jigs are the same.

2 Shallower flutes, as mentioned, work well on their thick noses with a mild fingernail grind. Deeper want the wings back because they are relatively thicker than the bottom, making a full poke and follow cut difficult.

3 My 5/8 Sorby is ground longer on the left because I use it for pulling inside to rim when hogging. Just works better that way, because I get a longer shear. Not sure if the Raffan is by intent or accident.


After all that, who's the turner here, you, or the tool designer? Because some guy makes his cuts with a particular grind doesn't mean you have to, nor, depending on your lathe, height, arm length, and other factors, does it mean you can. Take what you have and use it, not with the mindset that you're going to cut like turner X, but yourself. That way you won't be afraid to modify and experiment to see what works for you.

Meantime use the tool as its own jig.

 

[waltben]

Some points I'd like to add:

1. A jig is an essential tool to help keep the same grind on several tools. This gives me consistency, especially since I have more than one of the same size. I've two 'studios' with two sets of gouges. I hate stopping to sharpen when working on a piece, so I've two of each size I prefer.
2. Each of the sets pairs are identical tools. Even though the two pairs of 1/2" bowl gouges are from different makers, the cross sections are very similar, so I have very close to the same grind on all. A jig can't make a similar grind on two different shaped bars of steel.
3. The grind you end up liking the most should be your grind, not someone else's. It may be very similar to one some famous turner has copywrited, but it will be slightly different. That's OK. Mine is a mild Irish grind, and all my bowl gouges have it. I can pick up any of them and get the same performance every time.

Many of us obsess on having exact angles, or lengths of wings, or whatever. The most important thing is to find the grind profile that works best for you and then duplicate it. After you develop further skills, you will probably want to evolve and modify that grind. I experimented with a very aggressive one for a while, but didn't see any real increase in utility for what I do. That doesn't mean you wouldn't.

 

[john lucas]

I'm not sure exactly what everyone is talking about but I don't have any trouble making a swept back grind on the Thompson tools. In fact the first thing I did was match the exact grind of my previous tools. The one thing that I find changes the most is the wall thickness of the swept back wings on the different grinds and different flutes. On some the cutting angle of the wings will be as sharp as 25 degrees and others more like 45 degrees. The nose angle on most of mine is about 65 degrees unless I choose to change it.
To bad we don't have video's to show these differences because it's impossible to do in words.

 

[Fog Tanner]

The Raffan grind has two different angles and two different profiles, one on each side of the gouge and blended in the nose. Right now there is no jig that will duplicate this and it is one of those things you have to learn to do by hand. I have one of the Henry Taylor gouges that had the Raffan grind on it, then Raffan regound it to get the correct "Raffan grind". The flute is centered, it just has two different grind for doing different things and making use of the tool instead of having two differnt tools and only using half of each. He does this on both his shallow and bowl gouges.

Like John, I had no problem putting a swept back grind on my Thompson tools. I have a Henry Taylor Super Flute 5/8" gouge, which I use a Ellsworth jig to sharpen. The "Ellsworth" grind from Henry Taylor isn't the same as what you get from the Ellsworth jig. When I got my Thompson 5/8" gouge, I used the same jig and got the same grind. The flute shape is close enough to the one used by Henry Taylor to give the same profile.

 

[justaccord]

I have a Glaser V gouge, and it is much more of a V than Dougs V.

This puzzles me, since I was under the impression that Doug's V was an exact copy of Glaser's V --58 degrees.

Doug?



Dave

 

[Brujo]

2 ways to get not quite the same thing. What gives?

Now I'm confused.

I have the AAW video from a few years, I just watched the you tube M. Mahoney video. They both say "here is how to do a fingernail grind" and go about it two different ways.

The Mahoney video shows setting an angle on the tool rest and rolling the tool from side to front bevel (kind of like they way they show to do a side ways grind in the AAW video). The AAW video shows a finger nail grind being achieved by going from the front bevel to the side by pushing the tool up the wheel and turning it on it's side, you don't even really need the tool rest to do this.

May be it is my lack of tool control (I do not use any jigs), but I get two completely different looking grinds from those two methods. The angle of my wings seem to want to be much steeper when I try to sharpen using the Mahoney way (not a bad thing), where as it seems to me to be much easier to have longer wings (also not a bad thing) using the AAW way.

Am I doing something wrong? They both cut fine but this is getting seriously confusing.

 

[john lucas]

What Mike is showing is a technique very similar to the Stewart Batty grind but different angles. Stewart Uses 40 degrees for the tool rest and 4o for the marks on the tool rest. At 45 degrees you get a little longer wing.
On the AAW video with John Jordan he establishes the length of the wing by first grinding with the flute flat on the wheel. He marks the length of the flute on the side with a marker and then grinds down to that. That establishes the length. Then he grinds the nose to the angle he wants, which I think was about 65 degrees but I would have to watch it again. next he places the wings flat on the grinder and grinds them until they are sharp or the flat area created in the first step is gone. Now you blend the flat areas into the nose.
When resharpening this grind it would resemble what Mike is doing but set it on the flat wing to start your grind, then move around to the nose. Go to the other side and do the same. With Mikes grind it is very similar but more rounded over all I think. Stewart's grind is totally round with all edges being sharpened to 40 degrees.
Someone tell me if I'm reading that wrong. I haven't seen Mike do this in person. Sometimes you have to look at their tools very closely to see the difference in flute shape and grind.

 

[Gordon Seto]

This puzzles me, since I was under the impression that Doug's V was an exact copy of Glaser's V --58 degrees.

Doug?



Dave

This is not Doug. I know for the fact that the original Jerry Glaser "V" is narrower than the Thompson "V".

Our Club has the bowl gouge clinic by Bill Grumbine yesterday. Our members brought their problem bowl gouges for tweaking. We had a discussion about that; we had the two side by side for comparison. The Glaser has tighter radius flute width. The similarity in both gouges is only in A-11 steel and same cryogenic heat treatment. The flute design is different.

Doug Thompson is a member of our Club. He is a cowboy hat turner. I knew he has experimented with different flute curvature and depth; because I have seen some of the prototypes. He said he found the combination of flute angle and depth, so they don't clog like the old V gouge.

Gordon

 

[Doug Thompson]

Fog, thanks for clearing that up... my brain isn't thinking about a different grind on the tool.

Dave, Jerry Glaser designs were outstanding and he changed the woodturning world.... but IMO - the V shape flute was a little tight and the small dip near the nose when grinding was tough to avoid. The flute shape I designed is opened up a bit and the dip near the nose doesn't happen. The V shape tool of any brand had a problem with clogging... these don't clog. This is the shape that worked the best after many, many tries.

 

[Odie]

I just watched the you tube M. Mahoney video.

Brujo......

I wonder if you wouldn't mind giving a link to that youtube video....?

I just tried to search for it, and came up empty handed.

thanks

otis of cologne

 

[Gordon Seto]

I wonder if you wouldn't mind giving a link to that youtube video....?

Here is the link:

View: https://www.youtube.com/watch?v=4m8-8MNhpvY


Gordon

 

[Odie]

Here is the link:
http://www.youtube.com/watch?v=4m8-8MNhpvY

Gordon

Thanx, Gordon......

otis of cologne

 

[treedoctor]

Thanks for all of the comments.
Like I said before, the reason for the question was a comment from a fellow turner who has years of experience compared to my 6 months. Still, I questioned the validity of the comment. BTW, I really like using the Thompson tools. Just order 2 more last week. Haven't had a chance to try them out, but I will soon.

 

[treedoctor]

..... To bad we don't have video's to show these differences because it's impossible to do in words.

so true. But for someone new, these
posts give me some new things to think about. Thanks for the input.

 

[Brujo]

I'm still confused about sharpening...I should modify this statement. I'm happy with the edge I get on my bowl gouge (most the time), but if there is room for improvement I'm all for it. The more I try to learn about sharpening the more confused I seem to get.

The AAW video shows how to sharpen a variety of tools. They give two ways to sharpen a bowl gauge. The sideways grind and a fingernail grind. I also have a book by Raffin that shows how to sharpen a bowl gouge in the fingernail style.

Both Raffin and the AAW show starting the tool on or near the tool rest and pushing it up to the top of the wheel to grind the side, so that you are moving the tool vertically on the wheel.

The Mahoney video (previously linked on this tread) show one moving the tool side to side on the tool rest, essentially only moving the tool horizontally on the wheel.

Both are called fingernail grinds. Both get a sharp edge with a different profile (at least when I try it).

Should I be able to get the same shape using either method?

If not, why are they both called fingernail grinds if they are different?

One more question. How does an Irish grind or an Ellsworth grind fit in to all of this?

I'm self taught and happy with the edges I get, but I have no idea what folks are talking about when they start talking about the different "grinds".

Can some one clear this up for me?

 

[Malcolm Smith]

The replies are interesting and, especially with all the references to the way different well known turners sharpen their tools, illustrate the fact that ultimately one has to do a great deal of experimentation to end up with a system that works for the individual turner. I use Glaser tools sharpening on a Tormek system. I'm now at a point where I can sharpen tools without changing the profile that works for me. To do this, some parts of the edge need a lot more grinding than other parts. Ruining the profile of the tip of the tool is especially easy to do. I don't know of any way to learn to do this without a great deal of time being spent at the grinder. I do use jigs. In fact I have a number of them set permanently for specific groups of tools. This saves a lot of time.

The wood one turns, I turn very dense tropical hardwoods, and the bowl profiles are a big factor. I don't often turn bowls with an open profile. If I did, It's possible that the profiles on my tools would be different.

A lot of time and experimentation is unavoidable.

Malcolm Smith.