How sharp is sharp enough for a hand plane?

[Jules Dominguez]

I sharpen plane irons, using water stones and sharpening guides (an old Veritas or Eclipse, depending on the iron), until I have a mirror finish on the micro-bevel (normally 30 degrees). I hone the back of the iron flat down on the waterstones, again to a mirror finish. I don't know the grit of the waterstones I use, because I've had them for many years, but they're very fine. My planes are 20-some-year-old Records, plus a new Veritas LA block plane. I can get a wispy thin shaving and a slick smooth finish on side or face grain, with my planes set right, and I'm working to develop proficiency on end grain. I'm in the process of trying to get away from sandpaper as much as possible.

I predominantly work with cherry. I'm not interested, at least at this time, in the problems of planing any of the exotic curly-grained woods.

I consider it easy for anyone to reach the level of plane iron sharpness I described, given decent waterstones and guides, but I keep seeing references to the need for super-sharpness on plane irons, as if there are further steps that would make the planing easier and the finish better. Would it help me to go to a higher degree of sharpness, and if so, how would it help and how do you do it?

[Steve Wargo]

I hone everything on a 12000 grit water stone. You can see yourself in both the cutting edge and backs of all chisels and irons. SOme may think this is a bit too much, but it's nice to take a nice thin shaving on a table leg and have all of the inlay and stringing work show up in the shaving. If the iron is a sharp as possible, then you'll not have to worry about tearout as much, wich means less scraping. Carving tools are even sharper.

[Roy Wall]

Tage Frid uses up to a 15000 Shapton stone - I believe..............So, as Steve W. has stated --- hone with finer stones. Norton and Shapton are popular waterstones and boast quick cutting-- and less "hollowing" because they are somewhat harder than the older style waterstones......

[Tim Sproul]

IME, sharpness matters in 2 different situations.

1. softer woods. The softer the wood, the sharper the cutter needs to be. Get a piece of hemlock fir from a big box - often the KD 2x4 is hemlock fir as denoted by the HF on the certification stamp. Plane that and see how sharp your iron(s) is. If not sharp, you'll catch wood fibers on the cutting edge rather than cut them and you'll not plane the wood....just burnish it with the torn fibers caught on the cutting edge.

2. figured/difficult woods. sharpness combined with a light cut make for less or no tear-out.

[Tom Jones III]

If you are getting good results out of your tools now, why would you need to go sharper?

[Maurice Ungaro]

If you are getting good results out of your tools now, why would you need to go sharper?
Bingo. If results are excellent, keep doing what you're doing.

[Derek Cohen]

How sharp is sharp enough for a handplane? I think that it is helpful to include chisels in the equation.

A distinction could also be made between "sharp" and "smooth". It is possible to have a sharp edge that is not necessarily smooth (e.g. when you do not remove the scratches from coarser grits), and this will cut satisfactorally on some surfaces but not on others. For example, a chisel sharpened to 1200 waterstone and then stropped with Veritas green hone will cut dovetails pretty well. A scrub plane blade sharpened the same way will also cut well. In these situations there is no need for smoothness. However, you would not want to do this for a smoother since the resulting surface will end up serrated.

Sharp and smooth could also be used interchangeably. A smooth edge occurs when you hone progressively through a range of grits, each one removing the scratches from before. Smooth could be seen to be the (relative) absence of serrations, and the smoother you get, the sharper the edge. But, as I pointed out above, sharper does not necessarily mean smoother. So on one level the question might be rephrased, "how smooth is smooth enough?

Sharpness is defined as two surfaces meeting at a line of zero width (to quote Leonard Lee). But the angle at which they meet is also going to determine the effect they have on the timber surface. One blade with a 25 degree bevel against another with a 30 degree bevel are going to cut differently. I have blades ground and honed at 50 degrees (for bevel up smoothers), and these do not "feel" as sharp as the low angle bevels even though they may be honed to the same grade. Such blades would be chosen for particular timbers. The point being that "sharpness" is a relative term that must also take into account cutting angle.

I very much doubt that Tage Frid used a 15000 grit waterstone. In his video on dovetailing he freehanded a chisel on a 220 grit belt sander and then honed on a wheel. It seems to me that he understood when edge smoothness was needed and when it was not. According to Steve Knight, honing beyond 8000 grit brings minimal returns. I accept that it can be "sharper" but I question where this is necessary for the average woodworker - not just because of the timber that is being worked on, but also because many metals do not have the grain structure to benefit from it. Perhaps a metalurgist here can comment on this.

The bottom line is "horses for courses". Use what is needed to do the job.

Regards from Perth

Derek

[Jules Dominguez]

Tom, that's really my question. I'm not doing anything extraordinary to sharpen my plane irons, and I thought they were sharp enough, but I had gotten the perception from various posts and references that you need to attain almost a mystical level of sharpness in order to get the most out of a hand plane.

[Chris Barton]

How sharp? My rule of thumb is that I should be able to shave arm hairs (not armpit hairs or facial hairs :-) with ease. Past that I think we get into hair splitting! There plenty of little tests, i.e. cutting thin paper on edge with no drag etc... But, how sharp, sharp enough to do the job easily, safely and precisely...

[Steven Wilson]

Degree of sharpness depends on what your doing. I usually take plane irons and chisels up to an 8000 grit Shapton. For a couple of chisels I use for paring cuts and if I'm planing a bunch of end grain (like a butcher block) then I'll spend the time and go up to 15000.

[Roy Wall]

Tom, that's really my question. I'm not doing anything extraordinary to sharpen my plane irons, and I thought they were sharp enough, but I had gotten the perception from various posts and references that you need to attain almost a mystical level of sharpness in order to get the most out of a hand plane.

Jules, This is a very good observation.............and perhaps an "internet aura" that makes us believe there is a "sharper level, better tool, etc..."

I think your sharpening must be very good - you have good results - so stick with it. Maybe treat yourself to a finer grit stone for Christmas and see how it works.....??? Or try a York Pitch Frog/plane - see if you get more of a "glow" to the wood....??? It's great that you enjoy planes so much - I do too!!

[Tom Jones III]

If you are getting tearout or chatter that is not attributable to any other setup issues, then sharpen more. If it takes an inordinate amount of force to use the tool, then sharpen more. There is a balance between working on your tools and working with your tools.

Why not rehone after every 50 strokes? Or maybe every 10 strokes? Why not re-hone after every stroke?

Steve Martin had a great standup routine years and years ago that reminds me of the ever smoother stones. He was talking about the record player he had. He thought it was pretty good, but then he got 2 speakers and he had stereo! Well then he heard someone with 4 speakers and a better needle. He kept upgrading and pretty soon he had a googliophonic system with a moon rock needle.

[Jules Dominguez]

Thanks for the comments, all. I knew I could count on you for some good sense answers and advice.

[Jerry Palmer]

One more word of advice, don't check the sharpness of chisel, especially narrow ones, by shaving your arm hair unless you like neat, painless lacerations that bleed real well on your arms.:confused:

My rule is that if it will shave the endgrain of a soft wood, it will generally do what I want it to do. I go to a 4000 grit waterstone, then finish removing the burr from the back on a polishing wheel with compound.

[Jules Dominguez]

Sounds like good advice, especially for someone with a tremor.