The Four Geometries Compared
Single Bevel vs. Hollow Honing
Single Bevel vs. Hollow Grinding Followed by Freehand Flat Honing
Single Bevel vs. Double Bevel
Hollow Grinding Followed by Freehand Flat Honing vs. Double Bevel
Ranking the Geometries and Myth Busting
Choosing a Geometry and a Sharpening Plan
Conclusions about Sharpening
Other People's Conclusions
|Waterstones||David Finck||Steve Knight||Amie Ontario Fraser|
|Frank Klausz||Harrelson Stanley||David Charlesworth|
|Ian Kirby||Leonard Lee||Jim Kingshott|
|Scary Sharp||Mike Dunbar||Brent Beach|
|Oil Stones||James Krenov||Garrett Hack|
This page tries to solve the following common problem.
I have a dull plane blade in my bevel down plane which has a 45 degree bed angle. I want a 30 degree included angle and I am going to keep the back of the blade flat. How should I shape and sharpen the bevel on my dull blade?
This has turned into a interesting but long, detailed and I hope will evolve into the most careful and complete investigation and survey of ways to answer the above question. You may want to jump down to my conclusions and other peoples conclusions. Otherwise...
For the stated problem, all I can do is control the shape of the bevel and the abrasives and method I use to shape and sharpen the blade. This page assumes you are going to sharpen the blade you have and not modify your plane. The differences between bevel geometries in real world application is likely small compared to other factors like an improperly tuned plane where the blade is not bedded well or not held securely to dampen vibrations.
The cutting edge is supported by both the blade metal behind the cutting edge (edge support) and where the blade contacts the plane bed (blade support). I don't know which means of support is more important but can still make an investigation and some conclusions. Below I've investigated how four different practical sharpening geometries affect the edge and blade support in bevel down planes. The four geometries investigated are: single bevel, hollow honing, hollow grinding followed by flat honing, and double bevel. All four geometries below have the same 30 degree included angle and 15 degree clearance angle after the final honing and the blade is ready to use. This way the parts of the plane and blade that contact the wood are the same shapes in all four cases. I was asked if this is an apples to apples comparison. I am confident that it is.
I wanted to find a honing method that was capable of putting the finest quality cutting edge on the blade. If your wood does not have demanding grain and is not prone to tear out then perhaps you do not need the finest quality edge. Many of the honing methods described in the discussion below create cutting edges that are good enough for many situations. Also any of the honing methods executed well will probably produce a better edge than a better honing method executed poorly.
In his book The Complete Guide to Sharpening, Leonard Lee defines as sharp tool as one "that has a keen edge that will hold its shape in repeated use for a given material and technique while producing a good surface finish on the wood."
Grinding refers to fast and rough shaping of the bevel with course abrasives. Honing refers to the final polishing of the cutting edge with fine abrasives. This is a particularly important distinction between hollow honing and hollow grinding in the investigation. The word bevel is used loosely here and I mean the part of the blade that you shape and sharpen. The bevel could be flat or curved or a combination.
Metal bevel down bench planes have blade thicknesses from 0.080 to 0.125 inches. Krenov style wooden planes have 3/16 inch thick blades with cap irons sold by Hock Tools and David Finck. Steve Knight sells wooden planes with 1/4" thick blades without cap irons.
The diagrams are for 45 degree bed angle, 30 degree included angle, 15 degree clearance angle and 1/8 inch thick blade. The curved hollows in the diagrams would be produced by 6 inch grinding/honing wheels. I wanted scale diagrams and had to use thin lines so you might have to squint.
By single bevel I mean a flat single bevel. This is thought to be the ideal geometry and serves as a reference for this study. Contact height is calculated for when the cutting edge is flush with the sole (ie. zero depth of cut). The contact height is a measure of how well the plane can support the blade. If the force at the cutting edge is causing the blade to rotate or bend around the contact point then a lower contact height will reduce the torque and therefore reduce the bending. Contact height is also a measure of how well the blade can support the edge because a lower contact height means more blade metal behind the cutting edge.
Hollow honing means that the final stage of sharpening is finished on the curved surface of a wheel. The blade is held against the wheel to produce an 30 degree included angle. The diagram shows that hollow honing gives a more supportive geometry than a single bevel when the included angles are the same.
Table: Hollow Honing Contact Height. The 1/8", 3/16" and 1/4" columns are analyses for those blade thicknesses.
|infinite (same geometry as single bevel)||0.0915||0.1373||0.1830|
Figure: The single bevel is shown in black and the hollow honed bevel in red.
What I mean by hollow grinding followed by freehand flat honing is the sharpening procedure described in James Krenov's The Fine Art of Cabinetmaking and David Finck's Making and Mastering Wood Hand Planes. There is also mention of this method on page 14 of Jim Kingshott's Sharpening: The complete guide. A hollow is ground using a wheel grinder to create the basic shape. Then the blade is honed by setting the heel and toe of the hollow on the bench stone. The heel contact acts as a built in guide for honing a constant angle.
When creating the hollow grind, the blade will be held against the wheel at a different angle then for hollow honing method. For hollow grinding followed by flat honing, after grinding, when you rest the heel and toe of the blade on a table top then the length of the blade will make a 30 degree angle with the table. This is planning ahead so that after the flat areas are honed, the resulting included angle will be 30 degrees. With rehonings the included angle ideally remains 30 degrees. (You could argue the included angle increases with re honing because the thin toe will wear down in use and hone faster than the fat heal. But freehand honing is a skill and it depends where you apply the most pressure so I cannot analyze this. I am forced to assume that the user is skilled and maintains the same included angle or even uses a honing guide to insure he does.)
For the calculations and drawings the honed flats at the heel and toe are only 1/64 inch long. With rehoning the edge support increases: the flats grow, the support angle increases and the hollow shrinks. Contact height is the same for the single bevel and hollow grinding followed by flat honing.
The support angle measures the angle at which the hollow cuts away from the flat honed at the toe. This is for comparing one aspect of edge support against the double bevel method below. The greater the support angle then the more metal remains behind the cutting edge and the less likely the bevel/tip of the blade will flex.
Note that the larger wheel diameter you use the more hollow grinding followed by flat honing becomes like a flat single bevel. But using a large wheel takes away the advantage of quick rehoning of the edge when using the hollow grinding followed by flat honing because now much metal has to be removed.
|inifinite (same geometry
as single bevel)
Figure: The single bevel is shown in black and the hollow ground, freehand flat honed bevel in red. At the heel and toe you can see that the two methods overlap and are flat.
A double bevel can also be called a step bevel where the steps are the primary and secondary bevels.
In the figure the microbevel on the double bevel method is 1/64 inch long. The various primary bevels are 25, 26, 27, 28 and 29 degrees from top to bottom. With rehoning only the microbevel, edge support increases as the microbevel grows and blade support increases as the contact height is reduced.
|Primary Bevel (support angle)
|30 (same geometry as single bevel)
(same contact height as single bevel
or hollow grinding followed by
Figure: The single bevel is shown in black and the double bevel in red.
Closest to the cutting edge, the support angle with the double bevel can be better, the same or worse than for hollow grinding followed by flat honing. This depends on the primary bevel angle and wheel diameter. However, not much further from the edge there is more metal for the hollow grind method. The hollow grind followed by freehand flat honing contacts the bed closer to the sole. See the table for single vs. double bevel to compare contact heights.
Figure: The hollow ground, freehand flat honed bevel is shown in black and the double bevel in red.
1 = best
(support angle & bevel shape)
|Hollow Grind followed by freehand flat honing||3?||2|
When comparing the two methods that require work on the entire bevel to sharpen, single bevel and hollow honing, for a given included angle, the hollow honed shape is superiour. It has a lower contact height on the bed and will be more ridged. But in practice, with available equipment we can make a higher quality cutting edge with the single bevel (discussed more below).
Now compare the two methods that require work on less metal when resharpening: double bevel and hollow grinding followed by flat honing. They have the same geometry at the tip. They can both have the same support angle because you can choose the primary bevel angle or the grinding wheel diameter. But the hollow ground/flat honed method leaves more metal behind the blade and has a lower contact height. So the hollow shape wins this comparison too.
In both comparisons the hollow shapes are more supportive! This is contrary to popular myth that hollow shapes are less supportive.
It is also interesting to note that if only one of contact height or support angle matters then the ranking of the methods does not change.
The two question marks in the table indicate that in practice it depends on how you employ each geometry (for one, you may have a limited number of wheel diameters). If the support angles are different for the two methods then I need to do some calculus to see what the trade offs are and to look at the stiffness of the bevel supporting the edge. But the difference in contact heights and the possible resulting changes in flex along the length of the blade are tied to this same analysis. Only real world experiments could account for all factors. This lack of knowledge is reflected in my conclusions. If one method cannot accomplish a task then you can always use a single bevel and avoid the problem all together.
Available equipment affects the geometry you choose.
The hollow honing method gives the best edge and blade support. However the available wheels do not produce the finest quality cutting edge. Even the Tormek with 6000 grit on the leather buffing wheel did not produce the best edge in Fine Woodworking issue #157 which compared nine honing methods. Stropping on leather is discussed more below. Also the 10" wheel on a Tormek produces a geometry very close to a single bevel so the geometry advantage is minimized. A smaller wheel would be better. So for the time being, with available equipment, hollow honing is out. (N.B. You can't be sneaky and follow this method with flat honing. This would make a bigger included angle. If you want to follow by freehand flat honing then you must grind the hollow at a different angle. And if you are going to do that you don't need to use a Tormek. A regular grinder is good enough since it is not producing the final cutting edge.)
As an alternative or final step after the Tormek, maybe you could spin a maple wheel covered in diamond paste and produce the finest edge and support available. I don't know how safe it is to spin a home made wheel but it might be fine slowly so you don't spray the diamond paste all over the place. Alternately you could not spin the maple wheel and just hone by hand on the curved surface. This would be too tricky I think.
You could use a belt sander that has big wheels (approximately 5 to 8 inch diameter) and hone the hollow on the wheel part. Steve Knight says this is how knife makers grind hollows. The wheel diameter will never shrink with use like a regular grinding wheel and wouldn't need truing. In Lee's The Complete Guide to Sharpening on page 45 he shows a different set up for hollow grinding knives that might be useful to plane blades. This set up uses a curved piece between the belt and flat platen to create a curved grinding surface. But as for honing a hollow bevel, I don't think belts are available in fine enough abrasives to use this as a finishing step when you require the finest quality cutting edge. Perhaps follow this with the maple wheel idea. Leather belts are available for some one inch belt sanders.
How far can we take this hollow honing idea to get maximum support? For a 1/8" thick blade, a 1.56" diameter wheel would make the heel of the curved bevel parallel to the plane sole with a contact height of only 0.038". For 3/16" blade the numbers are 2.34" diameter and 0.052" contact height. For a 1/4" blade 3.06" and 0.059". But on a belt sander with even smaller wheels you could produce an even better geometry I haven't described above or seen anywhere else where the blade's toe is riding on the wheel and the heal is riding on the flat part of the belt. Smaller wheels could drop the contact height even more. At the extreme, the contact height could be dropped almost all the way to the sole (within thousandths of an inch if you had wheels that small) where the majority of the bevel is flat and parallel to the sole. Again this could be followed by an equally sized small maple wheel and you wouldn't have to worry about honing the flat part of the bevel. I can dream up many different ways to do this but I will only investigate this if all other plans (single bevel, back bevels, sanding the wood, buying a better plane and blade, etc) fail to accomplish my objective. Woodworkers have been doing alright for a long time.
That is enough about hollow honing...
The single bevel geometry is the second best for edge and blade support. Also the finest quality edges are possible so with available equipment it is the best we can do in a practical sense. A single bevel is slower to sharpen by hand because the entire bevel must be honed. An electric platter sharpener like Lee Valley's Veritas Mk. II Power Sharpening System could speed this method. However, Lee Valley only sells abrasive discs up to 1200x. With such a course abrasive I would either cut out finer abrasives to use on the machine or follow sharpening by honing a micro bevel with another method (paper/glass or water stones). But the latter option means changing honing guides or freehand honing. The Makita 9820-2 Blade Sharpener is another platter sharpener that is used by Steve Knight with a 120x Zirconia PSA disc for freehand grinding.
Using a platter sharpener free hand could potentially cause problems. The abrasive moves under the plane blade faster near the outside edge of the platter. So if even pressure is put across the bevel then the blade will wear faster near the outside of the platter. This will make a crooked cutting edge. Uneven pressure and experience could avoid this. A blade holder like the one included with the Veritas Mk II should avoid this problem as the blade must stay aligned with the jig.
But you could ask why use such an expensive sharpening machine if it isn't creating the final edge? You could use a belt sander (or bench grinder) to grind the primary bevel. But the common wisdom is you cannot use a belt sander to hone the final edge because the belt rises off the support surface as it moves past the cutting edge. This rounds the bevel near the tip ("it dubs the tip"). Perhaps common wisdom is correct but maybe the results are satisfactory or there could be ways around the problem. For example, if your belt sander only rounds the edge a little bit then you could think of this like a double bevel where the rounded portion is the microbevel. Also, fine enough abrasive belts may not be available to finish with a belt sander.
When using electric equipment make sure you do not overheat the metal and destroy the temper created when heat treating the blade to make it hard. The metal will turn blue if you do overheat the blade and the blue must be ground away. The blue metal is soft and will not hold an edge well. To avoid this you can grind slowly and/or you can cool the blade periodically in water. Wet grinders will constantly cool the tool.
You can grind the primary bevel by hand on course abrasives like 40x or 60x abrasive paper on glass, use a 220 grit waterstone or extra course diamond stone. There are also antique, hand powered wheel grinders that can be used with modern bench grinder wheels. You could build a hand powered belt sander. You could make a foot treadle for either of these hand powered tools.
After grinding the bevel by some method the final honing on a flat surface can be done by any of the usual abrasives. Diamond paste on maple produced the finest wood surface results in the Fine Woodworking #157 article "Sharp and Sharper". Diamond paste was recommended as a finishing method after any of the other methods for demanding woods and grains prone to tear out. Second place was the 8000x Norton waterstone for regular use. Then came a group including other 8000x waterstones and the green buffing compound on leather. The final group included Arkansas oil stones, extra fine diamond stones, 2000 grit abrasive paper on glass, and the Tormek with 6000x grit on the leather wheel. Diamond paste was also tried on a steel lapping plate and on MDF. These surfaces produced results worse than the diamond on maple. But the article did not say how these two compared to all the methods tested. Unfortunately other methods were not tested: 0.25 micron diamond paste on a cast iron plate, 0.5 and 0.3 micron 3M abrasive paper on glass and 8000x, 12000x, 15000x and 30000x Shapton stones. These newer products have some good user feedback. The article author, Amie Ontario Fraser, has since switched to Shapton stones. See the note at the bottom in the section Other People's Conclusions.
In a 2002 post on rec.woodworking Steve Knight wrote:
"for real world use there are oil stones, scary sharp and waterstones. diamonds [lapping plates] are not cost effective to sharpen steel with as they wear I bet 10 times faster sharpening steel over carbide and such. I have worn out several. I wear out a diamond lap with 30 or so plane irons. ceramic stones are really slow and small. the norton stones if you want diamonds are the way to go. they are the best quality out there. but if you want speed then you want these http://www.japanesetools.com/tools/sharpeningstones/sharpeningstones.php a set of shapton waterstones 1000 5000 and 12000. these are the fastest and least wearing waterstones I have found. So far it is the fastest way to sharpen I have found. If I find anything faster I will use it as I make my living selling planes and they all come sharpened."
Waterstones are popular. They cut fast because the surface wears away quickly and exposes fresh, sharp abrasive particles. This means they cut as quickly at the start of a sharpening session as they do at the end. However they can wear unevenly and require maintenance to keep them flat and some are messier than others depending on how much water they require. However, a water pond will contain the mess. Man-made stones are the most common and predictable but natural waterstones are also available. Stone quality varies and one company's 1000x stone may cut faster, leave a better finish and/or require less maintenance than another company's 1000x stone. Reports say that some stones, especially the 8000x and up, will last a lifetime for most people. (Even though the Shapton stones are ceramic they are generally grouped with waterstones.)
Scary Sharp (abrasive paper glued to glass) has a large following but is not as popular as waterstones. With Scary Sharp you do not have to worry about keeping stones flat. But the paper can wear unevenly and result in curved blade edges which you may want for some applications. The paper "dulls" and that means it cuts slower the longer it is used. Some think scary sharp is less messy than other methods. Some think its more messy. It depends if you like a water mess, oil mess or a steel dust mess. No matter what there will be some mess. However unless you use PSA backed abrasive paper you will have to deal with glue for attaching the paper to glass and probably use solvent to clean the glass after removing the paper. In place of the glass you can use a granite surface plate, jointer or table saw surface. Dave Wright wrote in a post on the Woodcentral message board that he glues abrasive paper to MDF and throws it out when the paper dulls. Scary sharp is initially cheap but in the long run may be more expensive than waterstones.
Oil stones are not popular these days because their round shaped particles take a lot of time to hone the metal. The particles do not break free from the stone to expose fresh, sharp particles. But the stones stay flat a long time and may only need flattening every few years depending on how you use them. Some people think they are less messy than waterstones even though a cutting fluid is required. The Museum of Woodworking Tools website says to "mix 3 parts kerosene to 1 part heavy mineral oil or 2 parts kerosene to 1 part light mineral oil. The more kerosene, the faster the stone will cut. The more mineral oil, the less it will clog."
Diamond Stones are expensive and Steve's comments above suggest they are not very compatible with steel. Monocrystalline stones are more expensive and apparently cut faster than polycrystalline stones. Diamond stones cut very aggressively when new but after the loose diamond crystals are removed the stones cut in a more controlled fashion (that is how the DMT website states it). One nice thing about diamond stones is if they start out flat then they will stay flat. Apparently it is a good idea to check the stone when purchasing it to make sure it is, in fact, flat.
In a post on the Woodcentral message board, Bill Tindall wrote "Diamond powder on cast iron is fast cutting and the cheapest abrasive available for final edge preparation (honeing). The serious limitation of this approach is that the cast iron pieces are not readily available at woodworking sources. Diamond on acrylic may be an acceptable alternative." By diamond powder I think Bill means diamond paste and the lapping plate from Harris Tools. Apparently diamond paste comes from various suppliers in water or oil based versions. This system is like the maple board used in the Fine Woodworking #157 article but the cast iron plate requires less maintenance and does not warp with changes in humidity.
Yet another method is described in Fine Woodworking #165, October 1993, "Sharpening---A different approach" by William Duckworth. He uses wet abrasive powder on a granite tile. See details in Other's Conclusions section below. This method is much like flattening oil stones with abrasive powder on glass. I always wonder how long the flat surfaces will stay flat in these methods. It was explained to me that a cast iron lapping plate or a mylar laminate on glass works differently than a hard surface like glass or granite. Since cast iron and mylar are softer materials, the grit embeds in the surface instead of rolling around. So the surface is not worn. However it may be hard to get all the embedded grit out before you move to a finer grit. Lee Valley sells a lapping kit and PSA backed plastic sheets.
Stropping on leather might be a bad idea compared to 0.5 micron abrasive paper on glass. Brent Beach says that the green stropping compound contains particles larger than the 0.5 microns stated on the package. If this is true and 0.5 micron paper would perform better in the same tests that Fine Woodworking did then potentially 0.5 micron paper might produce a better edge than 0.5 u diamond paste on maple. Also, when stropping, the leather is compressed under the blade but not beside the blade. This rounds the edges which increases the included angle. If this is planed into the system then it could be like a microbevel on a double bevel blade. This is the same as discussion above about finishing on a belt sander.
In Kingshott's Sharpening: The complete guide he discusses how Japanese woodworkers match each of their tools to one of there many waterstones for best performance. This could be for many reasons. One is harder steels require softer stones to reduce the chance of micro fractures in the cutting edge and subsequent chipping. On his website, Steve Elliot has come to the same conclusion. Steve finds a particular blade performs better with a particular sharpening abrasive.
Back to geometry considerations...
So now it is down to hollow grinding followed by freehand flat honing or the double bevel. For blades 1/8" and less the difference in geometries is minimized. But freehand honing is difficult for these thin blades; it is easy to rock the bevel off the heel or toe. For any thickness blade, if each method is done with care, then I doubt there is a performance difference for most tasks.
Other considerations and preferences are probably more important in choosing between the geometry options, a sharpening method and equipment. Here are some.
When using the double bevel or hollow grinding followed by freehand honing you can monitor how much metal you are removing when you regrind. You do not have to regrind the entire bevel. Just reduce the size of the honed portion enough to regain the advantage of having to hone only a small amount of metal.
Free hand honing means the abrasive isn't crushed by the honing guide but some guides don't ride on the abrasive surface. Mine doesn't. This proposed crushing may not be real or may not matter in practice. I have read mention of narrow wheels on honing guides wearing a groove in a soft stone (perhaps a natural waterstone).
Free hand honing allows you to use the entire stone surface to even out wear. Only the honing guides that ride on the surface do not allow this but you can rotate the stone 180 degrees once in a while to even out the wear. With free hand honing or a guide that does not ride on the stone you can take longer strokes which would speed honing.
Free hand honing is very flexible and lets you put curves on the blade. But this can be done with a honing guide. It may be easier to hone a curve with a honing guide that has narrow wheel compared to one with a wide wheel. See the section on David Charlesworth in the Other's Conclusions below.
For creating the primary bevel in the double bevel method you can use a belt sander, platter grinder (or even a wheel grinder) so the speed of the wheel grinder is not an advantage to hollow grinding followed by flat honing method as advertised. According to Steve Knight, the wheel grinder is slower and hotter than abrasive paper. However, in a post on the Woodcentral message board, Bill Tindall counters "I strongly disagree that belts are either faster or cooler than a properly chosen grinding wheel. By their nature wheels are considerable less heat generating because properly chosen wheels continuously refresh the abrasive edge that does the cutting. It is dull abrasive particles that is responsible for a good part of heating." You could use the curved wheel portion of a belt sander for the hollow grinding followed by flat honing geometry.
If using a bench grinder for any part of the sharpening process use one of the white, aluminum oxide wheels that grind cooler than the grey wheels. In Lee's The Complete Guide to Sharpening he says the Norton brand 38A80-H8VBE "is the best all-purpose stone for dry grinding in a woodworking shop." Now I have also heard of people using the pink wheels which apparently run even cooler than the white wheels. I do not know anything about these pink wheels. At some point, a wheel refreshes quickly enough to run cool and more friable wheels just wear unnecessarily fast.
A major consideration is how quickly you can re-hone the blade to a sharp edge. A quick method means you will be more likely to keep your blade sharp. Using a honing guide is not really slower than freehand honing. It takes me less than 30 seconds to set the blade in my guide and after that I can hone faster without worrying about rocking the blade off the heel or toe of the bevel. Also using a guide allows more predictable results than freehand honing the microbevel on a double bevel and certainly takes a lot of the concentration out of the process for a beginner.
When using the hollow grind followed by flat honing method you remove metal at the toe and heel. Since their is more metal in the heal, this wears your abrasive more than twice as fast as a double bevel and presumably is slower. The single bevel method wears the abrasive even faster.
Use a sharpening method that fits in your shop. It is better to have the sharpening station set up permanently then to have to set up before each sharpening.
Also consider the other tools you might sharpen with your equipment, how much maintainance the abrasives require, the mess they make, the costs and how much sharpening you do.
Expensive electric sharpeners (platter or tormek) do not produce a quality cutting edge for plane blades used in demanding woods and grains. Instead, it is sufficient to use something cheeper like a bench grinder or belt sander to do the rough shaping. In any case follow by hand honing.
Hollow honing would produce the best geometry and could be very fast but cannot produce the finest edge. It might be possible to produce the finest edge with some homebuilt equipment.
Single bevels take more time to maintain but with good sharpening stones that may not be very much time. If inferior geometries, which are faster to maintain, did not produce satisfactory results then I would try a single bevel.
Without doing stress analysis in the blade metal the following are the things I would try after my study comparing the double bevel with hollow grinding followed by flat honing.
Blades 1/8 inch and thinner: Sharpen with a double bevel where the primary bevel is only one or two degrees less than the microbevel. Optionally use a honing guide to accurately control the angles. Alternately grind with a 5 to 6 inch wheel and either carefully hone freehand or set the blade in a honing guide so both the heel and toe are honed as they would be for freehand honing.
Blades 3/16 inch: Same as for 1/8 inch and thinner. The optional honing guide is probably unnecessary for honing the hollow grind method.
Blades 1/4 inch: same as for 3/16 inch blades but perhaps use a 7 to 8 inch wheel if hollow grinding. If using a double bevel try to keep the primary bevel only one degree less than the microbevel as contact height is exaggerated for these thick blades.
As long as the results remain satisfactory then I will continue to use a double bevel by grinding the rough shape on my bench grinder followed by 40x or 60x paper and honing with 15, 5 and 0.5 micron abrasive paper from 3M on glass with a 28 degree primary bevel, 30 degree microbevel and a tiny 2 degree back bevel back bevel as described on Brent Beach's page. My blades are only 0.080" thick. I am very tired of the dull abrasive paper, glue and solvent.
When I build myself some Krenov style planes with 3/16" thick blades I would like to buy 1000 or 2000, 5000, 8000x Shapton stones and freehand hone but a set of Shapton stones are expensive to start. After watching a little video on the Shapton site, I would really like to get the Shapton DRLP as well. I am learning with an inexpensive 1000/4000x waterstone for chisels. I will not be trying oil stones. I may use a diamond stone for flattening waterstones if I do not purchase one of the Shapton lapping systems.
From David Finck's excellent book Making and Mastering Wood Hand Planes:
For blades 1/8" thick or less he recommends the double bevel technique. For blades thicker than 1/8" he suggests a 5 to 7 inch "friable-bond" aluminum oxide wheel (preferably on a hand grinder) to hollow grind followed by freehand honing on waterstones up to 8000x.
On April 11, 2005 I emailed David asking which brand of stones he uses and if he ever uses grits finer than 8000x waterstones. He replied:
"I use King Stones and am happy with them -- I haven't tried the Shapton stones but have used a variety of others. I will occasionally strop with 14,000 mesh equivelent diamond compound on a hard leather strop."
Steve Knight doesn't seem to like wasting time or money on sharpening but values a high quality cutting edge because that is part of his business and reputation as a quality plane maker. From Steve's posts on rec.woodworking about sharpening his 1/4" blades with a single bevel:
"...when I make irons I grind the bevel at 30 degrees before heat treat. then I use the makita [9820-2] freehand with the [PSA backed] zirconia paper at 120 grit to flatten the back and get the bevel accurate. then I free hand on my shapton stones. from the makita to sharpened takes me at most two minutes and usually less."
"...plus it's easier to free hand sharpen when you do the whole bevel. if you use good fast sharpening tools like shapton stones the speed is not really a issue."
"I use 120 grit zirconia on the makita then 1000 5000 and 12000 [Shapton waterstones]. I have the hippo stones and they are the normal shapton's not the pro's. even with my use I show very little wear on them. I can go pretty far between flattening's with those big stones. but I would prefer the 8000 over the 12000 but they don't make that grit in a shapton hippo stone."
To keep is stones flat, Steve uses the Shapton Compact Lappping System with lapping powder. He flattens the stones after about 10 blades worth of sharpening. He says that one container of the Shapton powder lasted him two years. Now he bought a 10 lb bag of 220x powder (same stuff used in rock tumbling) for $5 on ebay.
From Fine Woodworking #157 article "Sharp and Sharper" by Amie Ontario Fraser:
"In my shop, I use Norton waterstones for most sharpening. In demanding situations, I go though the trouble of getting out the diamond paste and maple to polish both sides of the edge to a mirror finish. I also use diamond stones to keep my waterstones flat and to rapidly flatten the backs of new plane irons and chisels."
She used a Fast Track honing guide to create 30 degree bevels. Norton waterstones are available up to 8000x and the diamond paste used in the article is 0.5 micron from Beta Diamond Products.]
On April 11, 2005, I spoke on the phone with Harrelson Stanley who imports Shapton stones. He spoke with Amie Ontario Fraser at a woodworking show the previous weekend. He says she did not know about Shapton stones when she wrote the Fine Woodworking article. At that time, Harrelson had only been importing the stones for about a year and they were not widely known yet in North America. Amie told Harrelson that as of April 2005 she hasn't used her Norton stones or diamond paste for a long time. Currently she has the Shapton Professional stones up to 30000x and the Shapton Diamond Reference Lapping plate. [A total investment of around $1550 US. This estimate would include stones 320x, 1000x, 5000x, 8000x, 15000x, 30000x. The 30000x stone is $636 US and I think could be omitted for most uses. Harrelson did not make a big objection when I suggested omitting the 30000x stone.]
On the Shapton website there are pictures of Frank Klausz using Shapton stones at a woodworking show to sharpen a chisel. The caption says that Frank likes the 1000x, 5000x and 15000x set of professional series stones.
Harrelson Stanley imports Shapton stones from Japan
In a video clip on the Shapton site, Harrelson demos sharpening a (Japanese?) plane blade. He uses the Shapton DRLP to flatten the bevel and stones, then he uses 2000, 5000, and 8000x stones. When removing the burr at each stage he uses the 8000x stone which avoids scratching the back of the plane. The whole process only takes a few minutes. Harrelson uses the DRLP to flatten the stones frequently (every 30 strokes) and claims the DRLP and frequent flattening has reduced his shapening times by 70% because he does not have to chase around for missed spots on the blade. The blade and stone are flat and make contact along the entire width.
To keep stones flat, the Shapton website recommends that the abrasive you use to flatten a stone must match the stone. Fine abrasives must be used to flatten fine stones so as not to leave deep grooves. The unsupported particles beside these deep grooves would crumble very quickly and the stone would wear quickly and require reflattening sooner. The DRLP is only for stones 1000x and finer. For the Shapton Compact Lapping System they sell course powder for 120x, 220x, and 320x stones; medium powder for 1000x, 1500x and 2000x stones; and fine powder (approx 4000x powder) for stones 5000x and finer. The Shapton site says that you can use up to 400x paper on glass but finer papers will clog. For the 5000x and finer stones the Shapton site does not recommend using sandpaper on glass because the paper will not produce a smooth shiny surface which is efficient for sharpening.
From David's article "A User's Guide to Waterstones" in Fine Woodworking #169, April 2004 which focuses on chisels:
David uses 800x, 1200x, and 8000x Japanese synthetic waterstones. He stores the 800x and 1200x stones in water. He sprays the 8000x stone with water and uses a Nagura to create a slurry on the stone. He likes the "cheap Far East copy of the Eclipse" honing guide and uses only a pull stroke to avoid digging into the stone. To make a micro bevel on chisels, he makes only three or four light pull strokes on the 8000x stone. David flattens the stones after 100 strokes with water-soaked, 180 or 220 grit wet-dry sandpaper on 1/2 inch glass. He marks the stone with a pencil grid to monitor when the stone is flattened. It also shows him how the stone wore during use.
From David's article "Handplane Tune-up" in Fine Woodworking #172, October 2004 has a sidebar on sharpening plane blades:
David uses the same equipment to sharpen plane blades as described in the FWW #169 article. He flattens the back of the blade on the 800x and 1200x stones. However his method is very different on the back of the blade when he uses the 8000x stone. I would have to repeat the article to explain his "ruler trick" well. Essentially when working on the back of the blade on the 8000x stone, he puts a 1/32 inch thick ruler between the blade and the stone. The ruler is parallel to the cutting edge and back from the edge by about 2 1/2 inches at the start of the stroke and 1 3/4 inch at the end of the stroke as he pulls the blade across the stone and ruler. This angles the blade to the stone surface and produces a 1 degree back bevel on the blade which he says has no real affect on how the plane functions. This is much like Brent Beach's method but Brent goes a little further with this idea and never flattens the back of the blade even with course abrasives.
This article also describes how David puts a slight crown on the blade. First he uses a black marker on the bevel so he can easily see the results. Then, with the blade in the Eclipse type honing guide (which has a narrow wheel) and using the 800x stone, David focuses pressure with one finger on the left end of the cutting edge for eight pull strokes. Similarly for the right side. Then he focuses pressure half way between the left edge and the middle for four strokes. Similarly for the right side. Then only one stroke with pressure directly in the middle of the cutting edge. Repeat this with the 8000x stone and remove the wire edge on the 8000x stone using the ruler trick.
Notes from his book Sharpening with Waterstones:
Use a 100/220 combination waterstone to flatten the back of the plane blade. Then 800, 4000 and 8000 waterstones on the bevel and back. He suggests the 800 as an optional fourth stone. He implies that if you do not have the 800 stone then perhaps have a stone lower in the 1200-4000 range instead of the 4000 stone. Ian keeps stones flat by using abrasive paper on glass. He recommends 120 grit paper for course stones, 220 grit for medium stones, and 320 grit for fine stones. He also says that it's time to flatten the stone with there is a 1/16" dip in the stone surface.
Lee is the founder of Lee Valley Tools and Vertias. Many regard Lee's 1994 The Complete Guide to Sharpening as the bible of sharpening. There have been advances in sharpening equipment since he wrote the book however.
To speed the general shaping process Lee says nothing is safer than using a wet grinder with either an 800x or 1000x wheel. He prefers the vertical wheel style (with at least a 6" wheel but preferably a 8-10" wheel) over the horizontal wheel style. The vertical style is easier to true and more versitile. Alternately he suggests a bench grinder with 80x aluminum oxide wheels or vertical belt sander with belts as course as 60x for grinding. He prefers the vertical belt sander to a bench grinder because it is more versitile and runs cooler.
For honing, Lee likes waterstones and recommends using an 800x stone for basic shaping and a finishing on a 4000x to 8000x stone. He does not like hollow grinding and recommends the double bevel technique with a primary bevel between 30 to 35 degrees and a microbevel that is only one degree more than the primary bevel. He suggests using a honing guide (Veritas or Eclipse both sold by Lee Valley) because it allows you to maintain the correct angle with greater pressure to reduce sharpening time.
To keep the stones flat Lee says a course diamond plate is "a wonderful luxury". He suggests some of the other usually methods: Lapping powder on a glass plate, or better is lapping powder on mylar laminate on glass (sold by Lee Valley), or rubbing three stones together in rotation.
Notes from Kingshott's 1994 Sharpening: The complete guide
Kingshott liked a watercooled grinder for shaping. For plane blade honing he used manmade waterstones 1200x, 4000x, 6000x and 8000x. He also liked diamond stones made by DMT (the perforated stones) and Ezelap but was not specific which grits. He lubricated the Ezelap with light oil and the DMT with water. He did say that the waterstones were used to produce the final cutting edge. To flatten the waterstones, Kingshott allowed the stones to dry overnight and then rubed them on aluminum oxide abrasive paper taped flat to a piece of glass.
Mike Dunbar is the head of the Winsor Institute. From an article in Fine Woodworking that may still be available here:
Mike glues 80, 120 and 320 grit sandpaper (the dark red coloured paper) from rolls to 3/8" glass. Then he holds a piece of 600 grit wet-dry paper (the black stuff) on top of the 320 paper. Sometimes he will continue with 1000 and then 2000 grit papers.
Info from Brent Beach's site:
Brent doesn't keep the back of his plane blade flat, He puts a very low angle back bevel (discussed below) but this probably doesn't change performance too much. He grinds a 25 degree primary on a 1" belt sander and then, using a home made honing guide, puts three microbevels with 15, 5 and 0.5 u paper from 3M stuck to glass with baby oil for lubricant. His final micro bevel is around 31 degrees.
In his inspirational The Fine Art of Cabinetmaking Krenov describes his use of oil stones. This book was first published in 1977 and he may have changed his methods as better equipment came on the market. David Finck was a student of Krenov at The College of Redwoods and perhaps David's method above better reflects Krenov's current system. For the record here is a summary of what Krenov wrote in The Fine Art . . . .
Use a hand grinder with a 5 or 6 inch, fine grit, carborundum wheel grinding with a medium spin speed. The fine wheel will leave small scratches which are quickly honed away with an india or soft arkansas stone. Because little metal must be honed to remove the grinding scratches you can re-hone the blade more times before needing to re-grind. Finish on a hard arkansas stone. Lubricate the stones with kerosene. Occasionally flatten the stones with grinding powder on glass.
The Hock website says that Krenov specified a 30 degree bevel angle.
I have read many people's suggest that oil stones do not put a fine enough edge on a plane blade. But Krenov is famous for his hand planed finish (i.e. no sanding) so the oil stones must have been doing a pretty good job for him. I have also read in several places that Krenov likes working woods that plane well. Perhaps with a sharper blade more woods would plane well. Just a guess on my part.
Garrett Hack has written books about hand planes and hand tools for Taunton Press which publishes Fine Woodworking Magazine. From the same article explaining Mike Dunbar's paper on glass use:
Garrett uses an "agressive cutting" diamond stone to lap plane blades flat and a lot of water to keep the stone clean. To sharpen he starts with a manmade India oil stone with kerosene as a honing oil. Then a hard, black Arkansas stone with kerosene. For the last step Garrett mixes a "half pea" amount of 4 micron diamond paste with kerosene on the fine stone.
See also the updated information below.
From Fine Woodworking #165, October 1993, "Sharpening---A different approach" by William Duckworth.
He uses 220x, 320x, 500x silicon carbide abrasive powder and 12 and 5 micron aluminum oxide lapping powder from Willmann-Bell. These powders are probably available at rock hound shops. He spray's a little water on a granite tile ($12 from a home centre---don't use an expensive granite surface plate) and then adds a bit of powder to create a slurry. Between each grit he wipes the tile clean with paper towel. He suggests that you probably will not need it but you could continue to finer abrasives like jeweler's rouge on a leather or cloth wheel on a grinder.
Lee Valley bench plane instructions:
"The Veritas bench plane blade comes honed ready for use, with a 30 primary bevel and a 35 micro-bevel. This configuration provides a strong, long-wearing edge that can be quickly honed many times before the primary bevel needs to be reground. The 35 micro-bevel leaves a 10 relief angle; more than adequate to accommodate the springback of the wood fibers."
"Your Lie-Nielsen Bench Plane is ready to cut wood out of the box. The blade is ground sharp at a 25 degree bevel. You may wish to give it a light honing before use. We recommend water stones used with a honing guide to provide good control. A secondary bevel of 1 to 2 degrees helps achieve a razor edge."
See also the updated information below.
Date: Mon, 2 Jun 2008 Subject: Sharpening article and current practices for LN, Garret Hack, etc From: Steve Hamlin To: Peter Michaux Hi Peter Thank you for taking the time to put together your article on plane blade sharpening (http://members.shaw.ca/petermichaux/workshop/BevelDownSharpening.html) I was at a hand tools show here in the UK this weekend, and saw several wizards and warlocks approach to sharpening which I thought might be of interest: Deneb Puchalski of LN - using Eclipse-style guide, Shaptons and the ruler trick Mick Hudson of Clico (Clifton Planes) - using Veritas Guide, Norton waterstones and a leather strop (with his own blue rouge) Garret Hack - finishing with a Norton 8000 and honing on hardwood with diamond paste when the application requires it (David Charlesworth was there but didn't see him sharpening) Thanks again, Steve Hamlin
Excel worksheet for the calculations in the tables.