How do you know when it's sharp enough?

[Victor Robinson]

What is your benchmark for sharp enough? On chisels and plane irons, I've always used the arm hair or thumbnail tests. Of course, the true measure is how well the tool does what you want it to, but with varying woods (dry vs. green, hard vs. soft) and my newb-ness, I don't know if I've gotten the tool as sharp as it could be.

How do you quickly gauge if your tool is sharp enough?

[Roger Chandler]

Experience! Once you get a grind that really peels the shavings, you will know what it is........then when your gouge no longer gives you the cut you desire, you know it is not sharp enough!

[John Keeton]

Victor, I assume you are referring to the initial act of sharpening - not the question of when does one feel the edge to have become dull. If that is true, then the answer is really simple, a pass of a properly ground (contoured) gouge across a stone/wheel will give one the best edge that stone/wheel can give. To compare, an edge passed across a 100 grit AO wheel does not compare, IMO, to an edge passed across a 180 grit CBN wheel. So, I think the answer lies in which abrasive does one choose to use.

Keep in mind that the 'arm hair' test is of little use in determining gouge sharpness, as an edge that acute will degrade nearly as quickly as it is presented to a spinning piece of wood.

I am confident that when I lightly pass my gouge across my CBN wheel (a matter of 2-3 seconds), it is as sharp as that wheel will get that particular metal, ground to that particular profile. I don't see a need to 'test' it or otherwise gauge it.

[Greg Just]

I was taught that its sharp when you can't see the edge, meaning there is no reflection of light on the edge.

[Ian James Webster]

I tend to stop when the grinding stone hits the handle!!!:D

[Victor Robinson]

Victor, I assume you are referring to the initial act of sharpening - not the question of when does one feel the edge to have become dull. If that is true, then the answer is really simple, a pass of a properly ground (contoured) gouge across a stone/wheel will give one the best edge that stone/wheel can give. To compare, an edge passed across a 100 grit AO wheel does not compare, IMO, to an edge passed across a 180 grit CBN wheel. So, I think the answer lies in which abrasive does one choose to use.

Keep in mind that the 'arm hair' test is of little use in determining gouge sharpness, as an edge that acute will degrade nearly as quickly as it is presented to a spinning piece of wood.

I am confident that when I lightly pass my gouge across my CBN wheel (a matter of 2-3 seconds), it is as sharp as that wheel will get that particular metal, ground to that particular profile. I don't see a need to 'test' it or otherwise gauge it.

Fair enough, thanks John. I guess I compare it to sharpening a plane iron on a waterstone. There are a number of ways one can get a suboptimal hone, e.g. if the waterstone is dished or the honing jig is slightly off. When I hadn't yet learned the little things that could go wrong honing my plane irons, I'd finish off with my last stone/strop but maybe it wouldn't quite shave arm hair. That let me know it wasn't as sharp as I knew I could get it with that particular stone, and that I had to go back and check my jig or the stone itself.

I wonder how to tell if I've messed up the grinding on a turning tool in subtle ways, which I will surely do. I'm sure with experience I'll have the confidence that a pass over the wheel has got it as good as possible, but for now I feel like I need checks!

[Fred Belknap]

When roughing out a bowl I usually just touch up lightly as I feel it needs. When I'm doing final cuts on a bowl I stop at the honing wheel and slick it up a bit. I doubt if it would cut arm hair, but it brings the gossamer type shavings flying.

[John Keeton]

Victor, if you use a Wolverine and Vari-grind jig, assuming the circumference of the wheel remains constant (as with a CBN wheel) all the variables are eliminated. The tool is inserted in the Vari-grind exactly 2" each time. The Vari-grind jig never changes once set. The arm of the Wolverine is marked such that it is the same for any given tool (in my case, I use the same setting for every tool except my bottom feeder gouge.)

Each time you sharpen, the tool will mate to the wheel at the same angle as the last time it was sharpened, and you take off a wisp of metal that leaves an edge as honed as that particular grit is capable of doing.

With my flatwork tools, I use a scary sharp board, taking the edge to 2000 grit, and then honing with compound to a mirror surface. The steel is a different steel than the HSS or CPM of a turning gouge, so the quality of edge will never be as good. The 'mileage' of the edge against the wood (handplane vs. lathe gouge) is significantly different.

When you take a swipe with a handplane, you want that even, ultra thin, read a newspaper through it, shaving that leaves a surface that shuns sandpaper. When you make a cut with a turning gouge, you want a nice, smooth surface, but without doubt, one that is ultimately going to be sanded. Hopefully, over time, you will gain sufficient tool control to be able to begin sanding at a higher grit, but it is unlikely you will ever achieve such a polished surface as that left by your handplane. Striving for that surface is probably not really worth the effort, IMO.

I believe the efforts should be toward tool control. I return to the wheel often, as I do like a sharp edge, but I also am confident that the edge I get each time is identical and as sharp as I can get it with the system I have. Probably not 'as sharp as it could be', in your words, but easily sufficient to achieve my purpose.

[Jon Lanier]

If you look at it straight on and you see lots of shiny spots, it's dull. Lots of sparkles and it's on its way to dull. When you look straight at the edge, you basically shouldn't be able to see the edge.

Or... you just try licking the edge, you cut your tongue, it's still sharp. ;-)

[Victor Robinson]

Or... you just try licking the edge, you cut your tongue, it's still sharp. ;-)

See now this is what I'm talkin' about! :D

[terry mccammon]

If you are talking plane irons, knives and things of that nature, sharpen and hone and then take a block of carving wood like basswood and make a cut with the grain, looking for irregularities, in the cut surface. Once you have honed your blade so that the with the grain cut is smooth, then cut across the grain, the cut should be smooth and as slick as with the grain. There will be a sheen to the cut. If not, then you are not sharp enough. For turning tools, this is silly as the abrasive (I presume silica) in the wood will dull that type of edge in a moment.

Having said all that, I have an 8" muslin loose buff charged with the white compound that I run my turning tools over between visits to the grinder. But I am cheap and do not yet have a CBN wheel, so I do not get the best result from my grinder. When I have a CBN wheel, I suspect I will stop with the honing of turning tools.

[Bob Bergstrom]

I sharpen on CBN wheels. If I can barely touch the wood and still pick up the cut, it's sharp. If I touch the tool to wood and it doesn't pick up the cut I'm back to the wheel. Since using CBN wheels I have less tolerance of any dullness. My tools now can cut fluff.

[robert baccus]

Sharp is a direction and not a noun I think. I usually sharpen with a 120 blue wheel for most turning and go to a diamond 1200 grit 6" disc for critical cuts and crazy grain ect. I have a 1200 & 180 grit mounted back to back on a 6" HF longnose buffer--maybe 50$ in the whole thing. Someday maybe a CBN if I find I need it. PS A really sharp edge often will not feel like sharp because of no "saw" edge from a grinder but the curls will tell.

[Lloyd Butler]

Vic,

As mentioned, turning tools do not need all the attention of a carving chisel.

When sharpening on a wheel, you will know you are grinding right to the cutting edge if you can see tiny sparks dance across the edge.

With a grinding jig for a gouge, you start with the tool positioned so that the existing bevel is parallel to the wheel surf, and then lightly touch the tool to the wheel, moving the entire bevel surface over the wheel. If you are just touching up the edge, then that is generally a 5-10 seconds trip. A good habit initially for beginners is to use a marker on the bevel before sharpening to see if they are getting the entire bevel on the wheel. If you are, then watch for the sparks and you are done. If the bevel is not right on, then the marker area gives you an idea of where to adjust the tool to try again. The really fine wheels may not produce a spark at the edge, but all the 60-120 grits I have used on various grinders all seem to. Reshaping the tool will take longer, but you generally do not do that more than once or twice in the tools life. If you are changing the bevel angle all the time, it is a good hint to get gouges and grind them to the other bevel angles.

Some people will then hone the flute to remove any fine burr that formed during sharpening. If the gouge is headed for roughing out a piece, the this may not be necessary as the roughness of the material will get rid of the tiny burr in a hurry and it will not affect your cut. If you are going back for that light final cut, then you may want to remove the burr to have a fine edge to cut on.

If your tool is cutting and you see more dust than shaving, you should be heading to the grinder. Experience seems to be the best help here as the tool can be sharp, but could be sharper for the cut you want to make and it is good to know that.

Lloyd

[Michael Stafford]

For me, sharp enough is when I can easily begin cutting and removing tiny shavings by just raising the tool handle until the cutting edge engages the wood. If it requires pressure to begin cutting then the tool requires sharpening. If the tool is gliding along on the heel of the bevel and the handle is raised to allow the edge to come into contact with the wood cutting should immediately commence if the tool is sharp.

[Dan Hintz]

I tend to stop when the grinding stone hits the handle!!!:D

I stop when it hits my knuckle... tough to see through all of that blood and tears.

[Thom Sturgill]

This is a discussion that always fascinates me. At the same time that people will tell you to go straight from the grinder to the wood, and seem to like the saw edge and grinder burr and that a truly sharp edge is not worth the time, they will tell you that they hone their skews and get a surface that shuns sanding.

I remember a test (IIRC done by a SMC member in the Neander group) where he tested how long the plane blade stayed sharp based on how sharp it started, and using an objective measurement, force needed to cut a string I believe. The curve was not linear, the less sharp it was the quicker it reached the next lower measure. I feel the same is true here, the sharper you start the longer you keep a usable edge. this does not mean that the time to get a scary sharp edge pays, but a few strokes with a hand held hone or buffing wheel? Probably, but start with the best wheel you can, say a 180 grit CBN and even that may not be needed, except of course on that skew...

[Brian Kent]

Or... you just try licking the edge, you cut your tongue, it's still sharp. ;-)

You're a sick man, Jon. But that's funny.:D

Questions:

First, John, I appreciate your naming the fact that 2-3 seconds touch-up does it. I did that last night instead of 15-20 seconds, and it was just as effective. You just save me a lot of steel.

Second, I know what my tools look like off of my blue and white grinding wheels, and I was wondering if someone could post a close-up of a gouge right after using a higher grit CBN.

Third, Thom and others (some recent sharpening videos) have recommended a couple of swipes with fine sandpaper to get the burr out of the inside surface of the groove of a gouge. How many have tried that?

And fourth, do you all use the same standard for your skews? I read from one of the creekers that you sharpen a skew to a mirror finish. Is that typical?

[Prashun Patel]

For the bowl gouge, I am in the straight-from-grinder-to-wood camp. I have a CBN 180 with a Varigrind jig, though. It's so darn fast and leaves an extremely good surface. The need to sand is more a function of my technique than the edge of the tool. I just don't (yet) see the benefit to honing here. The edge of a good gouge lasts very long by virtue of the quality of steel that's used. However, when you hit an inclusion or bark, all bets are off, and the edge deteriorates on (probably) every kind of edge.

For skews and scrapers, perhaps there's a benefit; but for a bowl gouge, I just can't see the performance improving much.

[Mike Cruz]

I have to admit, I was expecting a pic...with blood.

Answer for me is I use the same method for sharpening each time. When I've gone through my routine, it is then sharp enough. When I am cutting, noticing that I have to use force, or the cuts aren't smooth, or they aren't clean, that's when I know I have to resharpen.

[Victor Robinson]

This whole CBN thing keeps coming up. This is not good. I'd appreciate if you guys could refrain from mentioning expensive things in any thread I am participating in...or browsing. Thanks.

[Mike Cruz]

Oh, I forgot to mention... I DID just get a CBN wheel...:D

[Victor Robinson]

Oh, I forgot to mention... I DID just get a CBN wheel...:D

Didn't see that one coming... :rolleyes:

[Jamie Donaldson]

If you and the gouge and the wood are having a fight to cut, then its time to sharpen. I've always liked John Jordan's saying that the final few cuts should be made with a freshly sharpened gouge, because even though the gouge may still be sharp, its not as sharp as it could be. In my shop, anything that reduces sanding is legal!

[Roger Chandler]

If you and the gouge and the wood are having a fight to cut, then its time to sharpen. I've always liked John Jordan's saying that the final few cuts should be made with a freshly sharpened gouge, because even though the gouge may still be sharp, its not as sharp as it could be. In my shop, anything that reduces sanding is legal!


AMEN! :D I agree!

[Roger Chandler]

Oh, I forgot to mention... I DID just get a CBN wheel...:D

Woo hooo, Mike! I really like my CBN wheel!

[Victor Robinson]

Woo hooo, Mike! I really like my CBN wheel!

As far as I can tell, you're one of the biggest perpetrators of CBN fandom around here, Roger! I'm going to refer my wife to you...and Mr. Keeton.

[Jon Lanier]

Where does one purchase a CBN wheel?

[Ryan Mooney]

So I took a closer look at a gouge after a few cuts (~dozen) with and without a light honing (sorry I lack any photography equipment that can get a useful looking picture). It appears that the edge on the honed gouge didn't chip as badly for ~close to the same amount of cuts. My tentative theory is that the burr was either catching or breaking and taking the edge with it. I'm curious if this is more due to the steel quality (this is a psi benjamins best so not the highest priced tools, I started there because why waste the steel when I keep re-figuring out my grinding anyway - still figuring out my grind..), an anomaly (I only did a couple of tests and my grinding skills are still.. variable) or if its an actual effect for other folks as well.

I also wonder how much the skew being sharper / giving a cleaner cut is partially because it "forces" you to have a good approach (at least for me a gouge is more forgiving, the skew lets me know right fast when I'm skewing it up). I have found that I can get near skew quality cuts even with a roughing gouge when I sharpened it well (both angle and sharpness) AND hit the approach correctly so it was taking a similar skimming cut. I have only achieved that with a bowl gouge a couple of times (mostly by accident, but an accident that seems worth repeating) but I'm pretty convinced that that is a skill problem and not a tool problem. Short version: A lot of the cut quality looks to be some combination of the grind angle and approach (assuming equally sharp tools) and working on that has ~generally gotten me further than worrying about absolute sharpness so far (lack of tool handling skill apparently being the limiting factor to date).

Oh yeah and please stop teasing about the CBN wheels. Don't need to spend more money.. don't need to spend more money. You people are a bad influence.

[Victor Robinson]

Where does one purchase a CBN wheel?

A large multinational corporation that manufactures them in Asia and doesn't give a rat's you know what about customer service.

If only that were true, maybe it would be easier to resist. D-way is the name of the turner-owned business that sells them. By all accounts, nobody has even the slightest negative thing to say, aside from the expense.

[Mike Cruz]

Yup, D-Way tools.