A Wood Carving Supply Providing Tools & Supplies To Carvers & Whittlers In Wood
Disclaimer: The preceding opinions are based on personal experience
and not scientific analysis in a controlled laboratory environment;
therefore, no claim to factual accuracy is expressed or intended.
Sharpening Questions and Answers
By Rick Ferry
with the assistance of Timmy
Timmy's comments are in blue text
Small wire edge on a # 5 Gouge
top edge leading the cut
square to the tool shank
top edge trailing
(These are examples of the end grind only,
no tool thickness is shown.)
This sketch shows the configuration of a properly ground V-tool
Okay Mr. Rick, may I ask, just what is “sharp”?
Sure Timmy, but please make it a simple Rick.
You may hear people mention “extremely sharp”, “razor sharp,” or even; “so sharp it makes the hair stand up on the back of your neck.” In truth, there is only one “sharp”, and varying degrees of dullness. When two planes or surfaces meet at an apex, it is sharp; as sharp as that particular angle will ever be.
A convex or rounded grind provides extra support to the edge and will withstand some harsh treatment on difficult materials.
The hollow grind most often seen on straight-razors does not work for carving knives, but is used to advantage on gouges by some carvers.
A single sided grind is designed to cut in one orientation (or one side only); it is most often seen on flat chisels and Japanese knives.
The double sided grind may be used from either side and still performs well; this is the grind used most often on woodcarving knives.
Could you explain edge geometry (single-bevel versus double-bevel, convex or rounded, hollow, and the application of a single sided grind.)?
Timmy, you do realize I don't give college credits?
The edge geometry of a tool tells a lot about its intended use. A single-bevel is the best grind for carving knives and most carving tools. Double-bevels are often seen on pocket knives and some carving knives that are designed for roughing.
My shop teacher is always talking about Rockwell readings; what is that?
Rockwell "C" testing is a method of determining the hardness of steel by testing it’s resistance to penetration by a diamond point under a 150kg load.
A typical carving tool has a reading of Rockwell C59 – 62. Hardness though, is just that; how hard the steel is. Toughness is the steel’s ability to hold an edge; this is more difficult to measure. Although many tool makers give Rockwell readings in their advertisements, hardness alone does not make a good carving tool.
Could you explain Lead angles on V-tools?
This is a little off the subject of sharpening Tim, but none-the-less important. There are basically three ways to grind a V-tool, with the top edge leading the cut, with the cutting edge square to the tool shank, and with the top edge trailing.
For most situations, grinding the edge square to the shank is best. When you are doing incised carving or shallow flowing V-cuts, the top edge should lead the cut. The “top edge trailing” grind is used to get the V-cut close to an edge or under an overhanging surface.
So Mr. Rick, how often should a tool be sharpened?
When you are unable to bring the edge back by stropping, sharpening is called for. If you are seeing white streaks in the cut or the tool requires considerable force to cut the wood. There is no set timetable between sharpening; it could be 6 months or 6 minutes. Even if a tool is unused for extended periods, it may become dull from exposure to changing humidity.
What is the “grind”?
"Grind" refers to the bevel or shape of the metal near the cutting surface.How a tool is ground has more effect on performance than the actual sharpness. Yes, sharpness is very important, but the tool must be ground properly or a sharp edge does little good.
What are common prices for professional sharpening?
The typical cost of professional sharpening is $3.00 to $5.00 per tool. Prices often depend upon which tool it is, and what needs to be done. Some services charge $3.00 for a knife, $5.00 for a V-tool or gouge, with additional charges of $7.50 or more if regrinding or reshaping is involved. The highest price I have seen is $19.00 for one tool.
When should I bring my tools over for you to sharpen?
Anytime except my nap time.
Or whenever a tool is not a pleasure to use and home sharpening does not improve its performance. V-parting tools should be professionally reground and sharpened at least once a year. It makes a huge difference in the tools performance.
Mr. Rick, does it matter if my tools are thick?
When we carve wood we are actually forcing a sharp wedge through the fibers of the wood. If the wedge is thick, it creates more resistance. If a tool is excessively thick, it makes carving difficult if not impossible.
What should I sharpen my tools on?
Any method which produces a good edge without heat or wasting of the tool is good. I prefer power sharpening simply for the speed and accuracy it provides. Arkansas, Ceramic and Diamond, or even Silicon carbide abrasive paper (wet-or-dry) all work very well.
Which strop compound should I use?
While all compounds work, some are more abrasive and polish an edge quicker, while the finer compounds will produce a better finish. I prefer white and red rouge for my leather and buffing wheels. Use whatever works for you.
Mr. Rick, are buffing wheels, good or bad?
Used correctly, they can restore an edge quickly; used incorrectly a few times and sharpening will be required. Just a little hands-on experience is required to use them properly.
What are micro-bevels?
Micro-bevels are used for making micro-chips. Ha, Ha, Ha! Hmmm...
Well Timmy, they are more a concept than anything else; they are so small as to be invisible to the unaided eye (at least to mine). I apply them to most tools I sharpen, to strengthen the cutting edge. Once the tool is sharpened and the wire edge has been removed, I dull the tool ever so slightly on the buffing wheel. This slight rounding will help maintain the cutting edge longer.
While rounding is not a true micro-bevel, it works well for me. When used, micro-bevels are always applied on the side opposite the primary bevel for carving tools.
Okay, now that I have a sharp tool, how do I keep it sharp?
Once you have a sharp edge, maintain it by stropping it every half hour or so while carving. A good practice is to strop a tool before using it each day. Tool rolls and tool boxes are helpful in protecting tools; but it is best to protect the individual tool edge from accidental damage. Plastic tubing, resin corks, surgical tubing, and carved blade covers all work. If tools are allowed to touch one another, they will inevitably become chipped, nicked, and dull.
If I can shave hair off my arm, is the tool sharp?
What hair? I meant if I had hair on my arms.
Yes the edge is sharp, but just because a tool can shave hair off a gnats bottom doesn't’ mean it will cut wood. The sharp edge must be formed on the proper grind or bevel or you won't be carving any wood.
Mr. Rick, I think I understand honing, but why do I have to strop?
Stropping gives you time to reflect on your carving; also it realigns the cutting edge and along with strop compound, micro-polishes the cutting surfaces. Here is a good example of what I mean.
What is a “slip”?
Son, I'm not going there, you should ask your mother that one.
I mean, what is a slip-stone?
Oh, why didn't you say that the first time? A slip-stone is a small stone used for removing burrs from the inside contour of tools. Most common is the hard Arkansas slip-stone, which comes in a variety of shapes.
Mr. Rick, can you explain why I have to sharpen?
Well Timmy, if you are dull, you will never get the girls. Har ! Har !
Perhaps we should go back to "Simple Rick"?
Eventually the edge of all carving tools need to be restored. Whether it is due to chips, nicks, or rounding; sharpening is required to renew the perfect intersection of the two cutting planes.
What is a “wire edge”?
When a tool is ground or honed, a small burr forms along the cutting edge; this indicates you have created an apex at the intersection of the cutting surfaces. Done correctly, this is as sharp as you can get that tool.
You said I could use compound, what does strop or polishing compound do?
Simply put, it polishes the cutting surface of the tool. Compounds are available in various grits similar to sandpaper. Some are more aggressive at removing metal; but most all strop compounds work well.
Mr. Rick, perhaps later you could explain what fruit has to do with sharpening; but for now, I would rather know what a "Strop" is.
A strop may be many things, rubber, wood, leather, cloth, etc…
By tradition, most strops used in woodcarving are leather attached to a piece of hardwood. It may be used alone or with a strop compound.
Do I need to “hone” my tools after I sharpen them?
No Timmy, you are comparing apples and oranges. A hone is the stone or surface you sharpen on.
Okay, I understand sharp, but what is “dull” Simple Rick?
Uhh, Timmy let's go back to using "Mr. Rick" if you don't mind. To answer your question, "Dull" is when the carving tool stops leaving a clean polished finish on the wood and stropping does not restore it.
So why do some knives feel sharper than others?
Several factors can improve a cutting edge or at least make it feel sharper. By reducing the angle of the bevel; we feel less resistance and the tool feels sharper. By polishing the cutting edge and bevel, we also reduce resistance. Blade shape, thickness, width, and profile may also greatly affect the resistance to cutting.
Proper application of a micro-bevel
strengthens and provides support
for the cutting edge.
Before stropping the edge is misaligned from removing chips.
This creates resistance and can weaken the edge.
After stropping the edge is realigned and polished
How can I tell if a professional service does professional work?
Timmy, this is a very good question; the answer is to send a single V-tool to be sharpened. When it returns it should cut better than any tool you own. If it doesn't, try another sharpening service.
Mr. Ferry, I want to learn about sharpening my carving tools.
Glad to hear that Timmy, everyone should learn to sharpen their carving tools; but please, don't call me Mr. Ferry. No need to stand on formality, call me Rick.
Anything else on your mind son? Yes, could you loan me $20 against future lawn mowing so I can take my girl friend to the movies?
Son, when I was your age, I could take my girl to the movie, get two large popcorns and sodas, go to the drugstore afterwards, buy two milkshakes, a couple peppermint sticks and still have change back from my dollar.
Sooo... that's a no?
Timmy, you are a bit young to be speculating in lawn futures anyhow. Perhaps you should run home and tell your mother she wants you.
Okay Mr. Ferry, I'll be back tomorrow and you can explain what apples and oranges have to do with sharpening.