40/40 Grind versus Fingernail grind

[Jerry Streeter]

After watching an IRD several years ago I ground my gouges to a fingernail profile using a Wolverine jig mimicking the demonstrator. Since then I observed that other IRD Demonstrators use a 40/40 grind for bowls and at a recent club event a member suggested that I try using a 40/40 grind instead a fingernail grind to eliminate some tool chatter marks I had in the end grain of a bowl. Another member showed me how to regrind a gouge with a fingernail grind into a 40/40 grind. Once home I took and old gouge and changed its profile to a 40/40, then tried it on a piece of scrap. As a fairly inexperienced turner with no experience using a 40/40 grind I did like how it cut but not sure I could tell enough improvement to either change some of my current gouges over to a 40/40 on buy a new gouge. Am I missing something?

My question is, is there a significant different between the two grinds and if so what is it?

 

[Doug Freeman]

IMO the best place to start is with some Stuart Batty videos. There are are 2 or 3 on utube where he goes through his theory of the advantage of the 40/40.

Might help if you posted a pic of your “fingernail” grind and measure the bevel angle. Fingernail gets used to describe a lot of variations.

The real advantage of the 40/40 is removing large amount of material and leaving a nice surface. I use it a lot for roughing, for bowl ID’s as deep as feasible, hf Exteriors, and other places where I can reach with a 40 deg bevel.

The advantage vs a more swept wing grind is having the wing there to peel the wood away. It all about angle of attack.

It does not work for me for finish cutting all of a bowl OD, just due to my preference of processing. There are several threads on the forum where people go through some approaches to be able to use it for the whole bowl OD.

Each bg grind has its pros and cons. I use 3 different grinds to take advantage of the pros of each.

 

[robo hippy]

There are so many 'grinds' that are called 'fingernail' that I never know what some one means by it.... I quit using the swept back grinds years ago. This came after learning the 40/40 grind, which I had no trouble learning how to do. Basically, it is exactly what you do when turning, ABC, anchor the tool on the platform, rub the bevel and cut. I now use 2 basic gouges for bowls. One is the 40/40 for the outside of the bowl, and the inside of the bowl down to the transition area. Then I switch to a BOB gouge, of which I have several variations. All are ground to 70 degree bevels. All have a ) shape for the nose. These get me through the transition and across the bottom of the bowl. The swept back grinds do provide a long edge for shear scraping, but I prefer a couple of different scrapers with burnished burrs.

robo hippy

 

[hockenbery]

depends on what your current grind is and how well you did creating the 40/40

if the front bevel on your current grind is 50-40 degrees you won’t see much difference. If the front bevel on your current grind is 60 degrees you will see a difference.

It is my opinion that newer turners should stick with one grind and get competent with it.
You haven’t seen a big difference - consider sticking with the grind you have for a few months and then try the 40/40 again.

 

[Kirk Amidon]

It sounds like this gouge has been converted to 40-40. I'd recommend a second gouge to grind to a fingernail type ground and play with both. Switching back and forth simply grinds away the gouge. Agree on sticking with one and learning it, but also find that I like both, for different scenarios and when learning it is often challenging as one has no body of experience to compare against, so having gouges with both profiles (in this case) can be helpful to figure out what works or does not work.

I'd also suggest working with people at the club to navigate these waters too. One of the biggest benefits I've found at the club is the ability to borrow and test drive many different turning tools.

 

[john lucas]

I use a 40 degree swept back tool. In other words I use my wolverine jig and set it so i get a 40 degree nose. I still have the swept back wings because i like and use them. 40 degrees gives a cleaner cut than 50 or 60 but of course it limits the shape of the bowl. I do have a gouge that i hand grind to Stuart's 40/40. I don't see any difference in function between the 2 other than it's easier to shear scrape with the longer wings.

 

[Bill Blasic]

You know what all these pros have that espouse their grinds and tools - 30+ years experience that most of us don't have (although I'm a ways past 20 years ). I've had a good many of the best pros in my shop teaching my club members and I've seen them take a students crappy grind and make a perfect cut and then take the student to the grinder and show them how to sharpen their grind or whatever. What to me is more important is how you approach the cut with what ever grind you are using as any sharp tool will cut wood cleanly in most cases. Learn where your grind cuts the best and you're good to go. There is no special grind that makes you a better woodturner!

 

[hockenbery]

There is no special grind that makes you a better woodturner!

this is true. Newer turners should focus on learning to used the grind they were taught
after the newer turner gets consistently good curves and surfaces they are in the intermediate skill realm.
time to experiment
there are grinds that let you do different cuts which yield better results.

 

[John Erickson]

this is true. Newer turners should focus on learning to used the grind they were taught
after the newer turner gets consistently good curves and surfaces they are in the intermediate skill realm.
time to experiment
there are grinds that let you do different cuts which yield better results.

Totally agree. I'm trying out an Ellsworth grind now, after using a Thompson V-gouge with a "fingernail" grind for years. There are many options, and you can get a good result with all of them by learning technique. One thing I'm loving with the Ellsworth grind is that I can get a good clean surface on the inside, all the way through the cut. With the Thompson gouge I had to switch to a bottom bowl gouge to get a good clean transition on the inside. Whatever grind you use, I would advise focusing on why it's the way it is, and how to maximize it's utility.

 

[Roger Wiegand]

Some beginners do create grinds that only an incredibly competent turner could possibly use (I made a few myself over the years), so it is worthwhile to make sure you are starting with a "standard" shape of whatever grind you choose.
I now use both a 40/40 and Ellsworth-style grind gouge that seem to complement each other nicely. The 40/40 can move a lot of wood in a hurry, leaving a nice surface in the places it can access. The Ellsworth is nice for shear scraping and getting around the inside bottom of bowls. I also have a dedicated BOB gouge that I haven't yet leaned to use properly; I usually make a mess with it so I'm in need of a hands on session with someone who knows how to use it.

 

[Doug Freeman]

Out of all the turning tools the BG has the most variations. With 3 base flute designs, add some mfr variation of flutes, add shaft size, then the various grinds, its mind boggling for the uninitiated. I could come up with a number but I dont know what factor to use for grind variation, as there are so many. It is by far the most cussed and discussed tool we use. @Jerry Streeter dont feel bad or totally exasperated if you cant seem to nail down what friggin BG to use!

Personally, as I gained knowledge of all these variations, I made BG’s a project to gain as much knowledge about them and experience using them as I could. Been a good 5-6 years, and I’ve not finished yet! I keep finding a new grind twist here and there, and I havent bought a U flute yet. To me its part of the fun/interest/challenge of turning, an attempt to answer one simple question, why? Why all this variation?

 

[Dean Center]

Totally agree. I'm trying out an Ellsworth grind now, after using a Thompson V-gouge with a "fingernail" grind for years. There are many options, and you can get a good result with all of them by learning technique. One thing I'm loving with the Ellsworth grind is that I can get a good clean surface on the inside, all the way through the cut. With the Thompson gouge I had to switch to a bottom bowl gouge to get a good clean transition on the inside. Whatever grind you use, I would advise focusing on why it's the way it is, and how to maximize it's utility.

IME, the flute on the Thompson bowl gouge makes a good Ellsworth grind impossible. (Unless you get the Jamieson edition from Lyle.) For a good Ellsworth, you need a 'parabolic' flute shape, found on almost all the English brands of gouge.

 

[robo hippy]

I think the biggest difference with gouge roughing cuts with the 40/40 and the swept back grinds is that with the 40/40 you can take off a thicker and narrower shaving, and with the swept back grinds, you can take off a wider but thinner shaving. The difference between platform or freehand sharpening and jig sharpening is that the wings on jig sharpened gouges is more acute than those that are freehand sharpened. Not really sure what type of difference that makes....

robo hippy

 

[Dean Center]

Some beginners do create grinds that only an incredibly competent turner could possibly use (I made a few myself over the years), so it is worthwhile to make sure you are starting with a "standard" shape of whatever grind you choose.
I now use both a 40/40 and Ellsworth-style grind gouge that seem to complement each other nicely. The 40/40 can move a lot of wood in a hurry, leaving a nice surface in the places it can access. The Ellsworth is nice for shear scraping and getting around the inside bottom of bowls. I also have a dedicated BOB gouge that I haven't yet leaned to use properly; I usually make a mess with it so I'm in need of a hands on session with someone who knows how to use it.

Roger, I, too, was initially frustrated by the BOB. I got much better results when I ground off the heel to a not quite 'micro' bevel, but certainly a smaller one. It's also important to realize that we start using the darn thing in the toughest spot on the inside, where we're asking it to start a cut directly into end grain. A tough ask for any gouge. Also, as I'm sure you know, making thinner cuts is a big help.

 

[John Erickson]

IME, the flute on the Thompson bowl gouge makes a good Ellsworth grind impossible. (Unless you get the Jamieson edition from Lyle.) For a good Ellsworth, you need a 'parabolic' flute shape, found on almost all the English brands of gouge.

That’s right. That’s what I found out, haha. I’m using the Ellsworth grind on a different gouge—the Crown 1/2”.

 

[Gordon Patnude]

Can you please expand the abbreviation "IRD" for me?? It is not one I've seen before. Also "IME", which I saw in several of the replies to the first in this posting.

For that matter, if you use ANY abbreviation, please expand after the first use, for me and any other relative newbies.

It will be much appreciated!!

 

[Brian Gustin]

Can you please expand the abbreviation "IRD" for me?? It is not one I've seen before. Also "IME", which I saw in several of the replies to the first in this posting.

For that matter, if you use ANY abbreviation, please expand after the first use, for me and any other relative newbies.

It will be much appreciated!!

IRD = Inter-active Remote Demonstration (Live Real-Time Video streams) IME = In My Experience (AFAIK.. which BTW means As Far As I Know, while BTW = By The Way) I believe there is an acronym database online somewhere (Google "Internet Acronyms" perhaps)

 

[Jerry Streeter]

I got busy in the shop with flat work this past week and haven’t had time to check the forum the past few days so thanks for all the input and suggestions. To go back to some of the earlier questions, my finger mail grind is a swept back grind with nose at 40 deg, and it is correct that I had a gouge ground in the finger nail style on a wolverine jig that I converted to an ugly (meaning poor) free hand 40/40 grind. I did like the way it cut but need to work on it more (both the grind and tool skill.).

So thanks again for all the comments