What is the advantage of hollow grinding chisel and plane blades?

[Ron Kanter]

Here is my question: why is it faster to sharpen a hollow ground blade?
Don't you still have to move the blade over the stone the same number of times? Clearly, there is less metal to remove, but the energy required is all about the number of strokes or the time devoted to sharpening.
I can't understand how the effort is really any different when moving 1/8" or even 1/4" of steel over the stones versus moving two 1/16" ridges with a hollow ground space between them over the stones. I hope my description makes sense.
Another way of picturing the blade to be sharpened is to think of it as one relatively thick line of steel versus two thin parallel lines of steel with a narrow, empty space between them. Would the two narrow lines get sharp faster? If so, why is that so?

If I am wrong, I hope you can help me understand what I am missing.

I can understand that less steel would offer less resistance when slicing wood, and there may be some small reduction in wear on the stones, but my question is about the ease of sharpening. Thanks for your thoughts.

Regards from Philadelphia,
Ron

[ken hatch]

Here is my question: why is it faster to sharpen a hollow ground blade?
Don't you still have to move the blade over the stone the same number of times? Clearly, there is less metal to remove, but the energy required is all about the number of strokes or the time devoted to sharpening.
I can't understand how the effort is really any different when moving 1/8" or even 1/4" of steel over the stones versus moving two 1/16" ridges with a hollow ground space between them over the stones. I hope my description makes sense.
Another way of picturing the blade to be sharpened is to think of it as one relatively thick line of steel versus two thin parallel lines of steel with a narrow, empty space between them. Would the two narrow lines get sharp faster? If so, why is that so?

If I am wrong, I hope you can help me understand what I am missing.

I can understand that less steel would offer less resistance when slicing wood, and there may be some small reduction in wear on the stones, but my question is about the ease of sharpening. Thanks for your thoughts.

Regards from Philadelphia,
Ron

Ron

You really know how to step in it.

Bottom line it isn't the number of strokes on the stone but how much metal needs to be removed. Hollow grind will need less metal removed by the stone.

ken, where is my popcorn when needed.

[Carl Baker]

I'll start by saying that I cant answer your question. BUT whether you know it or not, you've started a sharpening thread! That means we all get to weigh in! Like most of them, it will probably go a whole lot of different directions before it comes back to a question of how you work and the best way for you to stay sharp.
I see the logic in having less area to hone and I can imagine it would be quicker but i can't see it saving THAT much time. I have been reluctant to hollow grind simply because, and ironically because, I don't want to take the time to hollow grind the blade in the first place. I also use a hand crank grinding wheel for "heavy" work. If I spent the money on a nice machine, I would probably change my tune... if nothing else, just to get my money's worth! I also want to believe that less steel equals less strength... but that may just be me further justifying my own opinion.

[Stanley Covington]

Ron

You really know how to step in it.

Bottom line it isn't the number of strokes on the stone but how much metal needs to be removed. Hollow grind will need less metal removed by the stone.

ken, where is my popcorn when needed.

Ken:

Do you have the popcorn concession for SMC? (ツ）

Ron:

Ken has it right. It takes time, and effort, and worn-out stones to remove the metal. A hollow-ground blade has less metal to remove, so the job gets done sooner and at less cost.

A second important point is flatness. If you really pay attention, you will will notice that working a chisel or plane blade's flat over a stone to sharpen it almost always tends to make the flat curved instead of flat. This makes it harder to keep the area directly at the flat's extreme edge in contact with the stone. Until this area is sharpened its full width, the blade is not as sharp as it can be. Once again, wasted time, effort, and stones, and too often, a ratty cutting edge.

The hollow makes it much easier to keep the flat in a single plane (or close to it), at least the flat defined as the lands around the hollow, one of which is right at the cutting edge. Its just a better design. But a lot of people have lesser standards for sharpeness, or don't notice these small details. How small is your cutting edge's width, Ron?

Stan

[Derek Cohen]

It is all about surface area. The hollow grind has significantly less than the flat bevel.

Regards from Perth

Derek

[John C Cox]

The simplest answer is this.....

Hollow grinding ensures there isn't a hump in the middle of the back you will have to battle when setting up the chisel... Simple as that. As a result - you are flattening the cutting edge and sides sooner....

When you have a hump (or humps) in the back somewhere - you spend eons of time flattening out the hump before the sharpening process finally makes it to the edge.... I battled this out with a new set of Two Cherries chisels Friday evening... I finally broke down, dug out my surface plate and roll of 100 grit PSA and I made war...

Patrick has pointed this out - but it appears that most manufacturers are now grinding before heat treatment to save manufacturing time - which means you will have to deal with some warp... Some have sorted out how to do it right so you aren't grinding the backs for 4 hours on Friday night... Some have not...

It was worth it for the Two Cherries - as I was rewarded with fantastic steel that sharpens beautifully and holds an edge really well... Other chisels have not gone so well.

[ken hatch]

The simplest answer is this.....

Hollow grinding ensures there isn't a hump in the middle of the back you will have to battle when setting up the chisel... Simple as that. As a result - you are flattening the cutting edge and sides sooner....

When you have a hump (or humps) in the back somewhere - you spend eons of time flattening out the hump before the sharpening process finally makes it to the edge.... I battled this out with a new set of Two Cherries chisels Friday evening... I finally broke down, dug out my surface plate and roll of 100 grit PSA and I made war...

Patrick has pointed this out - but it appears that most manufacturers are now grinding before heat treatment to save manufacturing time - which means you will have to deal with some warp... Some have sorted out how to do it right so you aren't grinding the backs for 4 hours on Friday night... Some have not...

It was worth it for the Two Cherries - as I was rewarded with fantastic steel that sharpens beautifully and holds an edge really well... Other chisels have not gone so well.

John,

One modern maker (that I know of) still hammer forges their chisels and after heat treating looks for the "hollow" before grinding the bevels. Ashley Iles chisels are fair priced and really good chisels with a flat to hollow back. Now as to the hollow grinding I think you are thinking about the wrong side of the chisel.

ken

[Robert Engel]

You essentially get a secondary bevel with one effort.

I sharpen freehand and it helps me register the angle.

Now here's something to consider [with a mouthful of poplcorn LOL] -- a reduced wedging effect when chiselling.

[John C Cox]

John,

One modern maker (that I know of) still hammer forges their chisels and after heat treating looks for the "hollow" before grinding the bevels. Ashley Iles chisels are fair priced and really good chisels with a flat to hollow back. Now as to the hollow grinding I think you are thinking about the wrong side of the chisel.

ken

Nobody said anything about the bevel... The back is really where I want to see a bit of a hollow grind..... Not only for initial setup - but ongoing maintenance is easier as well..,,

The only reason I hollow grind the bevel is if I need to remove a lot of steel for some reason or another. It allows the Dremel to do the majority of the work without as much risk of drawing the temper or otherwise gouging the edge and ruining the edge geometry.. Chipped, rounded, or badly skewed from the factory is where I end up pulling out the grinder when I need to battle the initial setup as it comes to me... Just Saturday I hollow ground a badly chipped thrift store Stanley iron....

But if you like to hollow grind your bevel as a normal part of your use - have at it...

[Jim Koepke]

Here is my question: why is it faster to sharpen a hollow ground blade?

As said above, in theory there is less metal being removed. Creating a secondary bevel could possibly match this for the fast factor.

A hollow grind is created when the outside, curved surface of an abrasive wheel is used to remove metal. When using freehand sharpening, the hollow ground blade actually "clicks" into place on a stone. One of my books somewhere states in times of old it was not only an embarrassment to have a convex grind on an edged tool it was considered a sign of poor practice. So it became standard practice to 'hollow grind' every edged cutting tool in order to avoid having a product that didn't meet the expected standard. Since abrasive wheels were a standard item, this went on for a few centuries.

As times changed so did methods. There isn't an electric bench grinder in my shop. My electric sharpening system is a disk style machine from Veritas. It produces a flat bevel. It works fine for me. Touching up a flat bevel is not a horrendous task. Some folks make it even quicker with a micro bevel.

In my opinion bench grinders are often over used and shorten the life of many good tools by removing more metal than necessary.

For me, simple often works best. No worries about micro bevels, hollow grinds or many other "tricks of the trade" to distract me from enjoying time in the shop.

As per usual, a reminder... 379405

jtk

[Patrick Chase]

Patrick has pointed this out - but it appears that most manufacturers are now grinding before heat treatment to save manufacturing time - which means you will have to deal with some warp... Some have sorted out how to do it right so you aren't grinding the backs for 4 hours on Friday night... Some have not...

A lot depends on the HT process. Narex are well regarded despite doing that, because they use a fairly exotic HT process that inherently produces lower warp than conventional quenching. This enables them to skip post-machining without aggravating customers for any but their longest (paring) chisels. Some other (lower end) makers seem to use any old HT process and skip the post machining, with fairly disastrous results.



One modern maker (that I know of) still hammer forges their chisels and after heat treating looks for the "hollow" before grinding the bevels. Ashley Iles chisels are fair priced and really good chisels with a flat to hollow back. Now as to the hollow grinding I think you are thinking about the wrong side of the chisel.

The breakpoint between post-machined and not seems to be around $25/chisel right now. AI is north of that, and makes a quality post-machined product.

$70/chisel or so gets you a dead flat post-machined and then lapped back with perfectly machined side bevels extending all the way to the sole :-)

[Stanley Covington]

Here is my question: why is it faster to sharpen a hollow ground blade?
Don't you still have to move the blade over the stone the same number of times? Clearly, there is less metal to remove, but the energy required is all about the number of strokes or the time devoted to sharpening.
I can't understand how the effort is really any different when moving 1/8" or even 1/4" of steel over the stones versus moving two 1/16" ridges with a hollow ground space between them over the stones. I hope my description makes sense.
Another way of picturing the blade to be sharpened is to think of it as one relatively thick line of steel versus two thin parallel lines of steel with a narrow, empty space between them. Would the two narrow lines get sharp faster? If so, why is that so?

If I am wrong, I hope you can help me understand what I am missing.

I can understand that less steel would offer less resistance when slicing wood, and there may be some small reduction in wear on the stones, but my question is about the ease of sharpening. Thanks for your thoughts.

Regards from Philadelphia,
Ron

I guess I am confused. Are you talking about a concave grind on the cutting edge's bevel? Or a hollow grind on the blade's flat?

If a hollow flat, then my answer above is good.

If a concave bevel, then I think it is simple expediency. I don't use this technique on blades worth owning.

[ken hatch]

I guess I am confused. Are you talking about a concave grind on the cutting edge's bevel? Or a hollow grind on the blade's flat?

If a hollow flat, then my answer above is good.

If a concave bevel, then I think it is simple expediency. I don't use this technique on blades worth owning.

Stan,

Join the club. If I read the OP's post correctly he is asking about hollow grinding the bevel, some of the answers are about hollow grinding the back. But then I'm only fluent in Texan, never did figure out English.

ken

[Patrick Chase]

Join the club. If I read the OP's post correctly he is asking about hollow grinding the bevel, some of the answers are about hollow grinding the back. But then I'm only fluent in Texan, never did figure out English.


Y'all're incomprehensible! :-)

[Stanley Covington]

Your English maybe not plum but pert near.

[ken hatch]

Y'all are too much....ROTFLMAO

MsBubba is Scottish, we've been together going on 15-16 years and she still doesn't understand a thing I say.

ken

[Stanley Covington]

Y'all are too much....ROTFLMAO

MsBubba is Scottish, we've been together going on 15-16 years and she still doesn't understand a thing I say.

ken

A Scots wife? that explains the combination of tacos and whiskey!

If the control tower can understand you, that's goods enough.

[Pat Barry]

I certainly did not think this was about hollow grinding the backs of chisels. Why in the world would anyone hollow back their chisels? Hollow grinding the bevel, as Derek and others have noted, makes perfect sense ...
Yes, by the way, I know the Japanese do this as a design practice. I'm not talking about those.

[Stanley Covington]

I certainly did not think this was about hollow grinding the backs of chisels. Why in the world would anyone hollow back their chisels? Hollow grinding the bevel, as Derek and others have noted, makes perfect sense ...
Yes, by the way, I know the Japanese do this as a design practice. I'm not talking about those.

If you know it, then please don't bother responding with "Why in the world would anyone hollow back their chisels?"

There are plenty of people that grind a hollow on the flats of their Western planes and chisel blades... even the soles of steel bodied planes. It works. Don't knock it if you haven't tried it. Makes sharpening those LN A2 blades a lot easier.

[Pat Barry]

If you know it, then please don't bother responding with "Why in the world would anyone hollow back their chisels?"

There are plenty of people that grind a hollow on the flats of their Western planes and chisel blades... even the soles of steel bodied planes. It works. Don't knock it if you haven't tried it. Makes sharpening those LN A2 blades a lot easier.

I guess I'e not seen that type of thing even discussed here in all the time I've been reading. Does Warren do that? Who really does? If anyone does this routinely it would be enlightening. Otherwise its just more bs as far as I'm concerned. Of course, thats most of what seems to be discussed here these days.

[Stanley Covington]

I guess I'e not seen that type of thing even discussed here in all the time I've been reading. Does Warren do that? Who really does? If anyone does this routinely it would be enlightening. Otherwise its just more bs as far as I'm concerned. Of course, thats most of what seems to be discussed here these days.

If you imagine that all of woodworking is discussed on this little forum, and in the woodworking press/blogs, then you know a lot about BS.

[Prashun Patel]

[BS alert:] I hollow grind sometimes for simple convenience when re-establishing a bevel. It's just fast. It has the nice benefit of giving a nice crutch (2 point reference) for free-hand sharpening, but even the necessity for this goes away with time and practice. I am unsure if it's accepted practice, but I tend to hollow grind mortise chisels the most. I definitely appreciate the 2-point reference for quick and frequent freehand honing. I find it tricky to use jigs on those thick, narrow blades.

[Chet R Parks]

Prashun
You may want to read a resent thread Ray Iles Mortise Chisel (https://sawmillcreek.org/showthread.php?262295-Ray-Iles-Mortise-Chisel) post #9-12 about hollow grinding mortise chisels.

[Prashun Patel]

I read that, to my chagrin. But I have not noticed that it is a problem. My chisels seem to work fine.

[Vincent Tai]

379487
I suspect I might get in trouble for doing this to a western blade (and on my first post here too good going me) but I ground out the back of an old vintage blade last year; mostly for ease of sharpening and just plain experimenting. I had already ground out a slight hump a few years ago and left about an inch of untouched flat steel from edge upwards and 3/4” from the sides in. Unsightly and still a massive amount of steel to flatten. I didn’t touch it for years then one night I rigged up a jig (tape and an failed woodie prototype) on my bench grinder (CBN wheels and no I didn’t overheat the blade even a smidge) and went at it. I tried ura-dashi and it actually worked rather well, didn’t take much to flatten. Finished honing it on a Jnat, haven’t got around to making a body for it. I’ve convinced myself to think of the look as a multiple hollow Japanese chisel style but evidently it’s a far cry. The ridges in between grinds also do not touch the stone whereas multiple hollow chisels do (I think). While it may look like a big multiple hollow chisel the grind is entirely geared for a plane blade, the ridges won’t touch the stone in most of my lifetime. Along side the real deal the looks don’t hold up but function wise it’s improved. I would do the same to a lot of other western chisels and irons if warranted and on tools I make, laminated or not.

As for hollow grinding bevels if you have a 1/4” thick blade you’re not sharpening a face that’s 1/4” widthwise unless you’re sharpening a Bevel at 90 degrees. Even then I’d hollow grind that. With a 25 degree bevel on a 1/4” blade (shooting plane) your looking at a surface area that’s more like 7/16” in width. At this point two 1/16th strips sound pretty nice — it actually takes a while with a nicely ground blade to get to that point (assuming you pop out the blade enough for touch ups and don’t let the edge get too deteriorated. When sharpening you try to abrade the bevel so it moves past the wear and then repolish it. If you tried to take a 1/64” in thickness off your workbench that’s going to be slower then taking off a 1/64” off two 1” wide strips of wood (same length, species etc) If you have less metal on the bevel your’re going to get past the wear faster. It’ll also polish up a lot quicker. Imagine having to hone a flat ground straight razor. That would take forever from your first stone to the last. Below is a picture of my shooting plane iron (taken for social media so filtered to look hipstery). On the bottom pic you can see the bevel right after a grinding. On the top pic hopefully you can see two tiny strips that are polished. They’re hazy because I finished up on a Jnat and a bit bigger than what one could get off a fresh grind; I was experimenting with a few different stones. So speed is one thing but self jigging, accuracy, etc are all benefits. A nice CBN wheel goes a ways for speed and peace of mind too. At this point I’m rambling but hopefully sounded coherent. Let me know if pictures won’t enlarge, I’m still figuring out how to post.

379482

Vincent Tai

[Jim Koepke]

Howdy Vincent and welcome to the Creek.

You touched lightly on my biggest problem with a flat bevel. My #62 has a thick blade. When my water stones are relatively flat the bevel tends to get stuck on the stone due to the water's surface tension. Usually this can be dealt with by sharpening side to side.

jtk

[Warren Mickley]

The cutting edge is only one part of a chisel. Its job is to sever fibers. The chisel also acts as a wedge, pushing material aside as it goes in. A hollow ground bevel makes a poor wedge and it makes the edge vulnerable because it fails to open up a good pocket for easy exit of the tool. The edge penetrates deeply and gets stuck deep in the cut. Then it is vulnerable to chipping and bending.

Some think it wise to use an exotic steel to resist edge deformation. Then the steel sharpens poorly so they hollow grind. A vicious cycle.

[Vincent Tai]

Thanks for the welcome Jim!
I had a really rough time with sticky flat bevels. Still do on my Japanese chisels, and some of them have microbevels out of frustration. Side sharpening really works for me too, I guess all that’s left for me is to sharpen some more and let time do it’s thing.

Vincent

[Chris Parks]

Howdy Vincent and welcome to the Creek.

You touched lightly on my biggest problem with a flat bevel. My #62 has a thick blade. When my water stones are relatively flat the bevel tends to get stuck on the stone due to the water's surface tension. Usually this can be dealt with by sharpening side to side.

jtk

More heresy but something I have tried recently with no disastrous results. Soak the stone than remove the visible surface water and go at it with the blade as per normal. The sky won't fall in and the sun will still rise in the east and you will be surprised at the result I know I was.

[Todd Zucker]

My brain is beginning to hurt a little, but this is a fascinating discussion.

I do have a question. If you have a hollow ground bevel and are chopping, or are paring with the bevel up, wouldn't the flat side act as the lever and keep the blade from digging in?

[Jim Koepke]

My brain is beginning to hurt a little, but this is a fascinating discussion.

I do have a question. If you have a hollow ground bevel and are chopping, or are paring with the bevel up, wouldn't the flat side act as the lever and keep the blade from digging in?

No, it still acts like a wedge.

jtk

[Stewie Simpson]

I guess I'e not seen that type of thing even discussed here in all the time I've been reading. Does Warren do that? Who really does? If anyone does this routinely it would be enlightening. Otherwise its just more bs as far as I'm concerned. Of course, thats most of what seems to be discussed here these days.

Pat; you raised a very valid question. Who hollow grinds the backs of their western chisels and plane irons. And who would go to that trouble of hollow grinding the soles on their western metal bench planes. imo the smell of BS is not coming from your direction.

Stewie;

[Todd Zucker]

I am not trying to weigh in here, but just trying to learn from the debate. The reason I am interested is that I have been intending to hollow grind my Western chisels on a Tormek for the first time, and I don’t want to screw things up.

Derek and others present an argument that I can grasp, that the hollow grind makes it faster to sharpen what would normally the primary bevel, but is in fact both the primary and secondary bevel. And easier to do freehand because it provides two reference points.

On the Japanese chisels, the hollow grind is not recommended, and a single bevel is suggested if IIRC. But I understood that the reason was not because of the geometry of the wedging action, but instead because there is less non-hardened steel to support the hard flat edge on a Japanese chisel, and it would chip.

The last point made, as I understood it (and might have misunderstood) was that the hollow grind would not make a proper wedge sufficient to shear off the fibers. I am thinking this is related somehow to the chipbreaker concept in the video I watched that explained why the chipbreaker’s placement close to the edge of the plane blade helps prevent tearout on difficult woods.

On a Western chisel with the exotic metals, though, if the hollow grind isn’t going to cause the chisel to chip, then it seems like it comes down to two other factors. The geometry of the blade and the forces they create (wedging action) and the properties of the wood.

In that case, it seems to me that if you have a hollow grind, the leading edge of the chisel (i.e., the wedge”) would have much less influence because it is much narrower than a single-bevel Japanese chisel. You would be able to steer the tool straight when paring or chopping more easily than with a Japanese (or mortising) chisel. That would be the case at least until you got deep enough into the wood for the far edge of the bevel to come into play. If you were paring straight into the grain, you might have problems with the tool following the grain of the wood instead of the direction you intend. But if cross grain paring or chopping, then it wouldn't be as much of a factor.

Am I way off base on this? Again, just trying to understand and learn, not debate.

[Patrick Chase]

Pat; you raised a very valid question. Who hollow grinds the backs of their western chisels and plane irons. And who would go to that trouble of hollow grinding the soles on their western metal bench planes. imo the smell of BS is not coming from your direction.

Stewie;

Narex now sells Western "dovetail chisels" with hollow-ground backs. I think they're sort of silly looking myself, but that's just me.

I don't know if this counts as a plane iron, but I've seen several low-angle spokeshave irons (most notably everything from WoodJoy) with hollow-ground backs. In that case the hollow grind serves a dual purpose: It makes the iron easier to sharpen and increases clearance just behind the cutting edge.

There's somebody out there who will try just about anything you can imagine. Patrick Leach tells a great story (http://www.supertool.com/StanleyBG/stan1.htm#num2c) of "hollow grinding" of plane soles gone horribly awry. Start at the paragraph that begins "and now for something completely different", next to the picture.

[Jim Koepke]

In that case, it seems to me that if you have a hollow grind, the leading edge of the chisel (i.e., the wedge”) would have much less influence because it is much narrower than a single-bevel Japanese chisel.

A wedge is still a wedge. It will react pretty much the same whether it is hollow ground, flat ground or convex ground. It will have different reactions based on the bevel angle.

Maybe someone who is good at the maths can break it down into a formula.

jtk

[steven c newman]

How strange.....someone out there will spend "hours" to make the back of a blade "perfectly" flat......then turns around and wants to grind a "handi-grip" hollow into the perfectly flat surface......? Weird Science Project?

[Derek Cohen]

Actually there is sense to hollowing the back of a Western blade. However this is only done under specific circumstances.

The circumstance is that the back of the blade is not flat and needs to be made flat. The example that comes to mind is when I needed to flatten the back of a drawknife. Grinding a slight hollow made it easier to do, and the hollow was lapped out anyway. I think that this is the point - that one is not seeking to create a hollow ala a Japanese blade, but remove the high points and speed up a flattening process. Note that this is not about polishing, which is a different area.

Regards from Perth

Derek

[William Fretwell]

I have never hollow ground a chisel blade because I've had no need. My chisels sharpen just fine. My Barr timber frame chisels are just the opposite, he recommends convex ground for strength.
I have had to concave grind my A2 BU plane blades so I can sharpen them before I die. I used to think I would like to use them but I've just replaced them all with BD 01 blades attached to different planes. Not entirely without some pain as the new blades are thicker but a huge improvement.
My 10" wet wheely thing can now usefully grind stainless steel edges to some useful purpose.

[Stanley Covington]

Shakespeare wrote “Home-keeping youths have ever homely wits.”

There is a similar saying in Japanese that translates to “A frog in a well knows nothing of the wider world.”

BS meters require constant adjustment.

[Stewie Simpson]

“He has all the virtues I dislike and none of the vices I admire."

Winston S. Churchill (https://www.goodreads.com/author/show/14033.Winston_S_Churchill), Wealth, War, and Wisdom (https://www.goodreads.com/work/quotes/2249483)

[Pat Barry]

Go ahead and put a hollow grind in the back of your chisel if you feel that its necessary. Just keep in mind the future when you have consumed the metal up to that hollow and try to figure out some fancy tapping out procedure to get metal back where you need it. Perhaps some of our experts could comment on the proper location and depth of this back hollow from their own tremendous experience / knowledge with doing so. I'll meanwhile stick to the basics thank you.

[Prashun Patel]

Reminder to Everyone: keep it civil, please. This sounds like it can get personal quickly.

[Brian Holcombe]

My brain is beginning to hurt a little, but this is a fascinating discussion.

I do have a question. If you have a hollow ground bevel and are chopping, or are paring with the bevel up, wouldn't the flat side act as the lever and keep the blade from digging in?

Very little of my chopping uses the blade back as a reference. I typically only do this on the last chops of a mortise wall or when shearing off the waste which remains after coping between dovetails.
As Warren mentions, picture the chisel as a wedge. If you utilize the bevel to help in cutting, you will be shearing off a consistent portion of waste as the chisel is driven down into the work and out from the work. The work is used as support for the cutting action which pushes the waste away while shearing the fibers below it and splitting the waste out as it travels. Consider the section view of that waste, it forms a triangle for the first chop, and progressive chops are a consistent thickness section. After this is all removed and you are out to the baseline, what remains is a small interior ramp of waste. This can be chopped into with the bevel facing away from the work and it will be easily removed when clearing the floor of the work.

If you reverse the chisel and work with the bevel facing away from the work (and toward the waste) as you chop the wedging action will be driving the chisel toward the baseline of the work. It will attempting to shear an excavate an increasing large section of material. It is much harder on the work, harder on the chisel and harder on the user.

[Todd Zucker]

Thank you, Brian. Very helpful.