Ray Iles Pigsticker review

[Patrick Chase]

This is a quick review of the Ray Iles mortise chisels sold at TFWW. I have a set of Narex mortise chisels, but decided to upgrade to a "real" pigsticker in my most commonly used size (5/16" - don't ask). As background, I cut mortises using the following technique:


Mark out using a 2-wheel (actually dual-arm) cutting gauge
Chop out the entire mortise to a depth of ~1/16". I do this to establish "guide walls" on both sides so that I don't have to worry about positioning once the serious cutting starts.
Work from the center out with the bevel facing outwards, alternating orientations. This technique makes a "V" profile cut that grows from the center out.
Upon reaching the end, chop the bottom out vertically to true up the ends of the "V".

It's basically a combination of the "layered" technique advocated by Kirby and others (step 2) and the traditional "center-out one-pass" technique (steps 3-4). I don't pre-drill on a press. I always configure mortising chisels with 20 deg primary bevels and fairly sizeable 35 deg secondaries. That's the as-shipped configuration for the Ray Iles pigstickers but requires some work on the Narex chisels.

The short summary is: The Ray Iles chisel works extremely well. Other than the obvious differences in configuration and bulk, I notice 3 main differences between it and the Narex ones:


For whatever reason I'm about 50% faster with the pigsticker even when all else (wood, mallet, starting sharpness) is held constant. I think that some of this comes down to the fact that I rapidly figured out that I could take more aggressive cuts without rolling the edge over (see 3 below), and part comes down to stiffness and impact transmission.
They're more accurate, at least for me. The Narex chisels are tapered both in profile (~1 deg/side or so) and along their length (~0.25 deg/side), while the Ray Iles is only tapered in profile. This means that the sides of the Narex ones aren't a reliable reference for vertical, and will allow the cut to change direction a bit if you're not careful. It also presents some issues when levering material out. Admittedly we're not talking about a whole lot of taper here, but even so I can see it reflected in my results when I check accuracy with a square (I use the Vesper double square with a thin blade to check mortise sides). It took a little bit of practice to *not* correct for the tapered side edge though.
The edge lasts longer in the Ray Iles chisel, and when it fails it doesn't require as much material to be removed as the Narex chisels do to get back to a clean edge.

Some random notes about the construction and materials in the Ray Iles chisel:


The D2 steel works surprisingly well in this application. Because it contains a lot of chromium carbides I sharpened it using diamond media (plates/pastes for back, lapping film for bevel) in the hopes that I could sharpen the carbides in situ instead of just knocking them out. It seemed to work - I wouldn't describe the edge as terrific, but it was better than I've seen from D2 in the past (admittedly honed with waterstones in previous instances) and more than good enough for chopping. The edge life was extremely good given the pounding it took, and noticeably better than the "Cr-Mn" steel in the Narex chisels
The pigsticker is TALL in cross-section, at just under 1/2" at the top of the primary bevel, and just over 3/4" at the bolster. The only honing guide I have that works with it is the old Veritas Mk I top-clamp guide. The slightly tapered sides foil side-clamp guides, and the chisel is so tall that it contacts the roller in the Veritas Mk II guide.
The blade geometry is accurate as-shipped, with very slight lengthwise concavity and crosswise convexity in the face, and moderate crosswise convexity in the bevel. None of those matters much for a mortise chisel, but my OCD compelled me to flatten the first couple inches of the face and the entire primary bevel. Doing so took ~10 min.

The bottom line is that while the Narex chisels are unbeatable for the price, you do get what you pay for in this instance. Don't be surprised if a full set of Narex mortise chisels appear in the classified before long.

[ken hatch]

Patrick,

Welcome to the club. Over the years I've tried most ways and types of chisels for chopping mortises and for one off work nothing beats a good English style pig sticker. With the cost of vintage pig stickers, the Ray Iles are a no brainer.

ken

[Patrick Chase]

Patrick,

Welcome to the club. Over the years I've tried most ways and types of chisels for chopping mortises and for one off work nothing beats a good English style pig sticker. With the cost of vintage pig stickers, the Ray Iles are a no brainer.

ken

Yeah, I see that now. I think the Narex chisels are a decent "value" option as they have a similar blade configuration
. I'd take them over a registered sash mortise chisel a la L-N, but as you say there's no comparison to the real deal.


Other than the lengthwise taper, which I've always found sort of baffling. It's sort of like investing in CNC stitching machines for your new line of rasps, and then using them to create perfectly uniform tooth patterns. Oh wait, they did that too...

[Jim Ritter]

Patrick I just sent you a PM.
Jim

[Frederick Skelly]

Good review Patrick. Thanks!
Fred

[Charles Bjorgen]

Thanks for the review, Patrick. Last year I picked up a couple vintage "pigsticker"type chisels off the bay and planned to reshape them in the Ray Iles style. Was advised not to use a hollow grind by other forum members so will probably use a power belt sander. I was not aware of the profile tapering so I will check to see if these old-timers have that.

[Pat Barry]

Hey Patrick, what material were you chopping those mortices in? How long, how deep? It sounds like these chisels are pretty substantial in construction? Is the Ray Iles 'ferrule' solid to the main chisel iron or just a separate decorative piece? Any idea of the tang dimensions inside the handle?

[lowell holmes]

Comparing a Narex pig sticker to a Ray Iles pigsticker is like comparing a Volkswagon to a Sherman Tank.
Pat, I'm not Patrick, but I will answer your question. The ferrule is solid to the main chisel.

Holding the Ray Iles pigsticker is a pleasant experience. You realize that you have a substantial tool in your hand. Also, the fit and finish of the chisel is absolutely superb.

[Patrick Chase]

Hey Patrick, what material were you chopping those mortices in? How long, how deep? It sounds like these chisels are pretty substantial in construction? Is the Ray Iles 'ferrule' solid to the main chisel iron or just a separate decorative piece? Any idea of the tang dimensions inside the handle?

I chopped some maple I had lying around, about 3" long and 1.5" deep. They're VERY substantial.

The Ray Iles chisels don't have ferrules on either end. The ferrule at the base of a handle prevents a smaller bolster (one that isn't as wide as the handle) from being driven into the base of the handle and thereby splitting it. The Ray Iles chisel has a full-size bolster (as wide as the handle) that is integral with the blade. Because it supports the entire base of the handle the bolster only applies vertical loads to the handle during chopping, so there's no need for a ferrule to prevent splitting.

A ferrule at the top of the handle prevents splitting due to mallet impacts. In that case the pigstickers appear to rely on sheer mass.

I don't know about the tang configuration, but if it's like everything else about these chisels it's massive.

[Patrick Chase]

Thanks for the review, Patrick. Last year I picked up a couple vintage "pigsticker"type chisels off the bay and planned to reshape them in the Ray Iles style. Was advised not to use a hollow grind by other forum members so will probably use a power belt sander. I was not aware of the profile tapering so I will check to see if these old-timers have that.

Yep, I leave the bevels on most tools hollow-ground, but not mortise chisels. If you use the "inside-out V-cut" technique like I do then you then that face must slide against the newly cut surface, and that doesn't work very well if it isn't flat. If you use the "layered" technique then it doesn't matter, but if you're going to do that then you don't really need a pigsticker to begin with.

Note that I said "leave the bevels hollow ground". If I'm doing something that requires bulk removal (for example changing the primary bevel of a Narex from 25 to 20 :-) then I often use a bench grinder to do the bulk of the removal (usually in multiple passes such that I end up with a series of 2-3 scallops that each bottom out along the desired final face) and then finish on diamond discs or belt sander. Doing it that way is efficient but requires careful mark-out and grinding.

[Tom Vanzant]

Patrick/Ken, I'm still in the Narex phase. The few mortises that I make are in walnut, cherry, or yellow pine, so the Narexes work fine. OTOH, I don't know any better...

[Niels Cosman]

I love my Iles pigstickers. I have most of them from the svelte 1/8" to the beefest vampire-slaying 1/2".
They are perfect for what they do.
One thing that I did notice on two of them was that the edge did not hold up very well until I resharpened it 2-3 times. The first sharpenings wouldn't last a single mortise in maple or ash. After that I have had no problems and I've been happy as a clam.
I suspect this could have been some tempering variation from the factory grind and/or my bevel angle increased as I sharpened it.
I sharpen them free-hand or with my Kell jig (which is perfect for the shape of these blades. When I bought the first couple directly from Joel in Brooklyn. I asked about the "ideal" secondary bevel, and he said "whatever" almost anything will work. So I haven't sweated maintaining a super precise angle as long as the edges are wicked shaaap.

[ken hatch]

Patrick/Ken, I'm still in the Narex phase. The few mortises that I make are in walnut, cherry, or yellow pine, so the Narexes work fine. OTOH, I don't know any better...

Tom,

Pick the chisel you use most....Buy that one. The others will soon follow :D.

ken

[Patrick Chase]

Tom,

Pick the chisel you use most....Buy that one. The others will soon follow :D.

ken

Me last week: "I'll just buy the 5/16" one"

Me this week: "If I order the rest will you give me the set discount?" (for the record the answer was "yes").

[Keith Mathewson]

The Ray Iles chisels have a long primary bevel which is good for deep mortises but not for shallow ones, the fulcrum for levering is too high and leads to bruising of the mortise. The handles can split if one is overly aggressive, I've broken 2. Not something to be proud of but after 4 or 5 hours of chopping mortises I tend to hit harder than I should. The good news is that Bob Scott in Boston can make replacements.

[Tom Vanzant]

Patrick/Ken, lol... Isn't that the usual result? When the time comes, the 1/4" Ray Iles will be first.

[Pat Barry]

Interesting thread made me wonder what the only pigsticker I have was. It is stamped "GEBR. vom BERG CAST-STEEL". The steel is about 5 inches long and it is a 1/8" (approx) chisel with a very similar to the Ray Iles chisel with the integral bolster. I have never used it as a 1/8" mortice is a bit small compared to what I typically need.
336451

[Mike Cherry]

The Ray Iles chisels have a long primary bevel which is good for deep mortises but not for shallow ones, the fulcrum for levering is too high and leads to bruising of the mortise. The handles can split if one is overly aggressive, I've broken 2. Not something to be proud of but after 4 or 5 hours of chopping mortises I tend to hit harder than I should. The good news is that Bob Scott in Boston can make replacements.


I gotta say your the first person I've seen that busted one of these, much less two. Did you notice a relation to the lumber used when breaking the handles? What type of instrument do you use to to strike the chisels?

[Randy Karst]

Hey Keith, do you have contact info for Bob Scott?

[Keith Mathewson]

Mike,
I had made a large joiners mallet which as too large for the job at hand. While it took a couple of hundred mortises to break the handle, it was a case of force instead of technique.

Randy,
Send me a PM with your number and I'll forward it to him. Don't expect anything soon, he broke his arm a few weeks ago.

[Mike Cherry]

Ahh thanks for the additional info Keith!

[Patrick Chase]

Interesting thread made me wonder what the only pigsticker I have was. It is stamped "GEBR. vom BERG CAST-STEEL". The steel is about 5 inches long and it is a 1/8" (approx) chisel with a very similar to the Ray Iles chisel with the integral bolster. I have never used it as a 1/8" mortice is a bit small compared to what I typically need.
336451

Out of curiosity have you ever tried a lower primary bevel on that chisel?

That looks to me like ~35 deg. I saw a pretty significant improvement in mortising speed when I dropped my Narex chisels from 25 to 20, and the Ray Iles also ships at 20 deg. I use a 35 deg secondary bevel on both though.

[Robert Engel]

Why do I hate the term "pigsticker"?

It seem so "unwoodworkingish".

[Pat Barry]

Out of curiosity have you ever tried a lower primary bevel on that chisel?

That looks to me like ~35 deg. I saw a pretty significant improvement in mortising speed when I dropped my Narex chisels from 25 to 20, and the Ray Iles also ships at 20 deg. I use a 35 deg secondary bevel on both though.
I got this at a garage sales a couple years ago and actually have never used it, primarily because at 1/8" its a bit slim for the typical mortice work I have been doing it seems, but what you say sounds like a good idea. I'll give it a shot.

[Charles Guest]

Ian Kirby does describe the layered technique but actually uses what he calls the 'full depth' method (it is better IMO):

http://www.woodworkersjournal.com/hand-cutting-mortise-and-tenons/

[Patrick Chase]

Ian Kirby does describe the layered technique but actually uses what he calls the 'full depth' method (it is better IMO):

http://www.woodworkersjournal.com/hand-cutting-mortise-and-tenons/

I like (and follow) Kirby's advice on dovetailing, but he seems to have his head shoved somewhere when it comes to mortising.

The big problem here is that he insists that the chisel must have parallel sides, i.e. sash mortise configuration like the L-Ns (and you can see in the picture that he's using a lightweight sash mortise chisel). He justifies this by arguing that tapered sides will allow the chisel to rotate (true to some degree), and then insists that rotation will make the mortise WIDER than the chisel. 9th-grade geometry tells us that the cut width will be chisel_width*cos(rotation_angle), which can never be greater than chisel_width. Also, for a tapered pigsticker the maximum rotation angle (before it's stopped by the chisel side) is about 1 deg, so the minimum mortise width is 0.9998*chisel_width. Put another way, the worst-case error is 0.02% of the mortise width.

I recall seeing a FWW article that compared his opinions on mortising side-by-side to Klausz'. Klausz advocated side-tapered pigstickers like the Ray Iles ones, and pretty much annihilated Kirby's arguments. I suppose that his techniques makes sense if you limit yourself to toy chisels, though even then I'd probably go with Paul Sellars' technique (https://www.youtube.com/watch?v=q_NXq7_TILA) instead (second half of the video).

EDIT: And then in his description of the "full-depth" method he doubles down on the rotation/width canard. Ugh. It occurs to me that with a registered chisel such as he uses rotation *does* increase the mortise width, so in that sense he's causing the very problem he claims to be avoiding.

[Warren Mickley]

I recall seeing a FWW article that compared his opinions on mortising side-by-side to Klausz'. Klausz advocated side-tapered pigstickers like the Ray Iles ones, and pretty much annihilated Kirby's arguments. I suppose that his techniques makes sense if you limit yourself to toy chisels, though even then I'd probably go with Paul Sellars' technique (https://www.youtube.com/watch?v=q_NXq7_TILA) instead (second half of the video).

I laughed when I read Klausz's method for mortising back in 1979. It was obvious that he had been making mortises by machine and not by hand. Thirty years later he had a better method. Even an "old world cabinetmaker" can learn to do hand work here in America.

Whether or not a parallel sided chisel works well is dependent on how fine the tolerances are. A perfect chisel would be fine; you really want all four corners of the chisel involved. However a tiny taper helps insure that the chisel is not wider at some point than the edge or the back. And a taper in length likewise helps insure against clearance problems. A bulge an inch from the cutting edge would make the chisel difficult to withdraw from deep in the cut.

I like as little taper as possible (in both directions) for myself. And I work on the chisel based on how it performs in use, not some predetermined set of specifications.

[Patrick Chase]

I laughed when I read Klausz's method for mortising back in 1979. It was obvious that he had been making mortises by machine and not by hand. Thirty years later he had a better method. Even an "old world cabinetmaker" can learn to do hand work here in America.

Whether or not a parallel sided chisel works well is dependent on how fine the tolerances are. A perfect chisel would be fine; you really want all four corners of the chisel involved. However a tiny taper helps insure that the chisel is not wider at some point than the edge or the back. And a taper in length likewise helps insure against clearance problems. A bulge an inch from the cutting edge would make the chisel difficult to withdraw from deep in the cut.

I like as little taper as possible (in both directions) for myself. And I work on the chisel based on how it performs in use, not some predetermined set of specifications.

Yeah, it occurred to me that I should have heeded my own maxim that "there's usually more than one way to do it" when I wrote that post.

FWIW I've developed a preference for slight (~1 deg/side) taper in profile but none lengthwise.

[lowell holmes]

I have to ask :). Craftsman style rocking chairs have 1" square through mortises in the front post to arm joint.

The largest mortise chisel I've seen advertised is 1/2". How would you chop the mortises through the arm?

Paul Sellers has been conducting classes for these chairs for 20 years that I know of.

[Warren Mickley]

I have to ask :). Craftsman style rocking chairs have 1" square through mortises in the front post to arm joint.

The largest mortise chisel I've seen advertised is 1/2". How would you chop the mortises through the arm?

Paul Sellers has been conducting classes for these chairs for 20 years that I know of.

"Craftsman" style furniture was made a century ago by machine. A hand tool woodworker would usually do something different, like two narrower tenons or a round tenon.

In the hand tool era narrow mortises like 3/8 were done with mortise chisels and wide mortises like in timber framing were done with framing chisels while the bulk of the waste was bored or coarsely chopped out. If I were asked to make a 1"x1" mortise I would probably make two parallel 3/8 mortises and then chop out the 1/4 strip in the center.

[Reinis Kanders]

Would not making a V in the center approach to mortising be somewhat inefficient because it either requires to shift the grip or change a stance for every chop?
In this video Follansbee is using similar approach and it seems that he has to shift his stance frequently.
https://www.youtube.com/watch?v=N1bo6NVYCc0

On the other hand Follansbee must have settled to this method after some exploration and it must be pretty fast because most of the stuff he makes (chests, chairs) requires a lot of chisel work.

[lowell holmes]

I learned to chop 1" square mortises in two Paul Sellers classes. We chopped the mortises with 1" bevel edged chisels. I've built five chairs since then, using bevel edged chisels.
That is the reason I posted my comment. I have mortise chisels and sash chisels as well as numerous sets of bevel edged chisels.

That makes seven chairs. My whole point is that
it is interesting to divine the historical precedent, but that is a different interest than making chairs.

I feel like it is good to be able to use historical precedent, but making chairs is more fulfilling. I had an issue with one of the chairs I made, and there was not room for 1" through tenon,
but there was room for 15/16". I was able to grind one of my chisels to 15/16" and the chair is now rocking two great grandchildren.

[Patrick Chase]

"Craftsman" style furniture was made a century ago by machine. A hand tool woodworker would usually do something different, like two narrower tenons or a round tenon.

In the hand tool era narrow mortises like 3/8 were done with mortise chisels and wide mortises like in timber framing were done with framing chisels while the bulk of the waste was bored or coarsely chopped out. If I were asked to make a 1"x1" mortise I would probably make two parallel 3/8 mortises and then chop out the 1/4 strip in the center.

FWIW my first thought upon reading Lowell's post was similar, but with narrower parallel mortises and then a coping saw to rough out the center, leaving some paring work on the ends. If I remember the design of those chairs correctly there's more than enough room to access the mortise with a coping saw or fretsaw.

[lowell holmes]

Just for fun, lay out a 1" square mortise in a scrap of 3/4" wood. Reinforce the limits with a 1" chisel by placing it in the scribe marks.

Then, start chopping the mortise using Paul Sellers technique. You will probably enjoy the exercise. You just nibble away it.

OBTW, I love my Ray Iles pigstickers and I use them every time I have need for them. They are everything they are supposed to be.

[Patrick Chase]

I feel like it is good to be able to use historical precedent, but making chairs is more fulfilling.

What do you think has changed that makes historical precedent invalid or irrelevant in this case?

The wood hasn't, the chisels haven't (Sellars uses classic Marples bevel-edged chisels made of plain old HCS), and human anatomy hasn't. I believe that covers all the bases, so pigstickers are as relevant and useful now as ever.

I think that Sellars' technique is useful, and that's why I linked to his video earlier in this thread. I don't think it reflects any sort of progress though. It's just yet another way of doing things, that has likely been practiced all along.

[Charles Guest]

I like (and follow) Kirby's advice on dovetailing, but he seems to have his head shoved somewhere when it comes to mortising.

The big problem here is that he insists that the chisel must have parallel sides, i.e. sash mortise configuration like the L-Ns (and you can see in the picture that he's using a lightweight sash mortise chisel). He justifies this by arguing that tapered sides will allow the chisel to rotate (true to some degree), and then insists that rotation will make the mortise WIDER than the chisel. 9th-grade geometry tells us that the cut width will be chisel_width*cos(rotation_angle), which can never be greater than chisel_width. Also, for a tapered pigsticker the maximum rotation angle (before it's stopped by the chisel side) is about 1 deg, so the minimum mortise width is 0.9998*chisel_width. Put another way, the worst-case error is 0.02% of the mortise width.

I recall seeing a FWW article that compared his opinions on mortising side-by-side to Klausz'. Klausz advocated side-tapered pigstickers like the Ray Iles ones, and pretty much annihilated Kirby's arguments. I suppose that his techniques makes sense if you limit yourself to toy chisels, though even then I'd probably go with Paul Sellars' technique (https://www.youtube.com/watch?v=q_NXq7_TILA) instead (second half of the video).

EDIT: And then in his description of the "full-depth" method he doubles down on the rotation/width canard. Ugh. It occurs to me that with a registered chisel such as he uses rotation *does* increase the mortise width, so in that sense he's causing the very problem he claims to be avoiding.

I've used both types -- parallel sided and tapered. I honestly couldn't tell that much difference. The difference for me in speed and overall quality came with I started going full depth in the middle and then working back to the ends with each blow going all the way to depth. Releasing a parallel sided chisel seems much less an issue with this method.

[Patrick Chase]

I've used both types -- parallel sided and tapered. I honestly couldn't tell that much difference. The difference for me in speed and overall quality came with I started going full depth in the middle and then working back to the ends with each blow going all the way to depth. Releasing a parallel sided chisel seems much less an issue with this method.

Interesting - I have almost the opposite subjective impression.

I lever waste out using the top of the primary bevel as a fulcrum, so the back<->side edges are the ones doing all the work. I find that in a parallel-sided chisel the top<->side edges just tend to get caught above the fulcrum (i.e. they engage on the lip and upper sidewalls of the mortise) if the chisel is rotated even the slightest bit, and that slows me down. A small amount of bevel therefore helps, because it keeps those top<->side edges disengaged while still being close enough to perpendicular to prevent any serious twisting.

[lowell holmes]

I didn't say it is invalid, but when I have a joint to make, I will use what's available to me. There is only one way to make 1" square mortise in a 1" board that I know. I'm sure if I were clever, I would find another way to make it. The task at hand is to make a difficult visible joint that has to be near perfect. To me, that is sharply defining the limits of the mortise, make it leaving no splintering nor bruising.
The through tenon has to match it perfectly. Remember the 1" tenon has to be as perfect as the mortise, and it is cut on the top end of fatter leg.

Actually, I am following historical practice that is about 20 years old.

Google "Brazos Rocker" and you will come up with pictures of guys with the chairs they built.

[Warren Mickley]

Would not making a V in the center approach to mortising be somewhat inefficient because it either requires to shift the grip or change a stance for every chop?
In this video Follansbee is using similar approach and it seems that he has to shift his stance frequently.
https://www.youtube.com/watch?v=N1bo6NVYCc0.

Yes it is probably a little faster not to keep changing position like that. You might remember a video David Weaver showed of a Chinese fellow mortising. He doesn't go back and forth like that and neither do I. But I think that if that is the only thing that is inefficient about one's mortising technique it isn't too bad.

[Warren Mickley]

There is only one way to make 1" square mortise in a 1" board that I know.

Actually, I am following historical practice that is about 20 years old.


Only one way that you know? I just wrote you another method in response to your question in #30 of this thread. Did you not bother to read it? For the record I made a 15/16 X 1" mortise with a 5/16 mortise chisel (two mortises and chop out the center) and a 1x1 with a 1" bevel edge chisel in 15/16 thick oak. My method was slightly faster, a bit neater, and less tiring.

Historical practice that is 20 years old? I used your method to make 1" mortises in 1979 when I only had five chisels.

[Steve Voigt]

I like (and follow) Kirby's advice on dovetailing, but he seems to have his head shoved somewhere when it comes to mortising.

The big problem here is that he insists that the chisel must have parallel sides, i.e. sash mortise configuration like the L-Ns (and you can see in the picture that he's using a lightweight sash mortise chisel). He justifies this by arguing that tapered sides will allow the chisel to rotate (true to some degree), and then insists that rotation will make the mortise WIDER than the chisel. 9th-grade geometry tells us that the cut width will be chisel_width*cos(rotation_angle), which can never be greater than chisel_width. Also, for a tapered pigsticker the maximum rotation angle (before it's stopped by the chisel side) is about 1 deg, so the minimum mortise width is 0.9998*chisel_width. Put another way, the worst-case error is 0.02% of the mortise width.

I recall seeing a FWW article that compared his opinions on mortising side-by-side to Klausz'. Klausz advocated side-tapered pigstickers like the Ray Iles ones, and pretty much annihilated Kirby's arguments. I suppose that his techniques makes sense if you limit yourself to toy chisels, though even then I'd probably go with Paul Sellars' technique (https://www.youtube.com/watch?v=q_NXq7_TILA) instead (second half of the video).

EDIT: And then in his description of the "full-depth" method he doubles down on the rotation/width canard. Ugh. It occurs to me that with a registered chisel such as he uses rotation *does* increase the mortise width, so in that sense he's causing the very problem he claims to be avoiding.

Funny, I've read the Kirby article before and I found it to be a perfectly good description of efficient technique, apart from one or two oddball things. A couple notes.

First, I suspect that when he's talking about the importance of square sides (note that he says square to the face, not parallel sides), he's comparing mortise chisels (of any type) to bevel edge chisels. I don't think he's making the "LN sash-style vs. Ray Iles pigsticker argument" that you are. Vintage mortise chisels, whether pigstickers or sash, are all over the map in terms of whether they're truly parallel-sided or slightly trapezoidal in section. I have a number of both style and there's no consistency (and some are tapered the wrong way, which obviously needs fixing before the thing will work at all). Kirby learned to chop mortises decades ago, when an argument over minutely tapered vs. perfectly parallel sides simply couldn't have happened.

Second, it most certainly is possible to enlarge a mortise in a most unfortunate way by twisting the chisel. It is not a question of trigonometry; it's because whatever force (or bad technique) that causes the chisel to twist also knocks it out of plumb, so you are driving or levering at an angle, which will scar the walls and enlarge the top of the mortise. If this has never happened to you, either you are very talented, or you have not cut many mortises! I would have thought it was an issue that one needs to learn to overcome, just like cutting dovetails without gaps.

I think Kirby gets lost in the weeds a bit when talking about the "layered" vs. "full-depth" methods; that stuff isn't very important. But before that, he does a good job of hitting the most important points, namely riding the bevel (excellent description of that), stance behind the mortise, levering technique, etc. The article reads like it was written by someone who's chopped a lot of mortises and is good at it, which is more than one can say for a lot of woodworking articles out there.

The only thing that's weird is when he talks about using two hands to position the chisel. I have to assume that he's writing this as beginner's advice; surely he doesn't do that himself. Actually, that's one of the more difficult things to learn about mortising. Positioning the chisel quickly and accurately on the gauge marks, while holding it by the handle and not like a pencil, is quite difficult to learn but imo it's one of the keys to working efficiently.

[Patrick Chase]

Yes it is probably a little faster not to keep changing position like that. You might remember a video David Weaver showed of a Chinese fellow mortising. He doesn't go back and forth like that and neither do I. But I think that if that is the only thing that is inefficient about one's mortising technique it isn't too bad.

FWIW I cheat a bit and do a couple/few chops per direction before reversing. It's not like there's any rational reason why the bottom of the "V" has to be centered or even stay in the same place.

[Steve Voigt]

I learned to chop 1" square mortises in two Paul Sellers classes. We chopped the mortises with 1" bevel edged chisels. I've built five chairs since then, using bevel edged chisels.
That is the reason I posted my comment. I have mortise chisels and sash chisels as well as numerous sets of bevel edged chisels.

That makes seven chairs. My whole point is that
it is interesting to divine the historical precedent, but that is a different interest than making chairs.

I feel like it is good to be able to use historical precedent, but making chairs is more fulfilling. I had an issue with one of the chairs I made, and there was not room for 1" through tenon,
but there was room for 15/16". I was able to grind one of my chisels to 15/16" and the chair is now rocking two great grandchildren.

I would hate to have to regrind the size of a chisel every time I wanted a different size mortise. I would think one would have to have an awful lot of chisels for that.

I regularly chop square mortises, usually around 13/16ths, with whatever chisel is closest. Mine are turned at 45° to the edge of the stock, which makes it a little easier. But they are highly exposed mortises that need to look good. It's not a problem.

That said, regrinding is not a bad idea if you are chopping lots of mortises at the same size. If I can ever settle on a consistent size, I might have to try that!

[Patrick Chase]

Second, it most certainly is possible to enlarge a mortise in a most unfortunate way by twisting the chisel. It is not a question of trigonometry; it's because whatever force (or bad technique) that causes the chisel to twist also knocks it out of plumb, so you are driving or levering at an angle, which will scar the walls and enlarge the top of the mortise. If this has never happened to you, either you are very talented, or you have not cut many mortises! I would have thought it was an issue that one needs to learn to overcome, just like cutting dovetails without gaps.

Oh, I've certainly had that happen many times, but IMO straight vs tapered sides don't matter there, at least for the range of bevel angles we're discussing in this thread. I was specifically objecting to Kirby's contention that a parallel-sided chisel would mitigate that (IMO it doesn't).

I've also read Kirby's FWW article a couple times, and based on both sources I'm pretty sure that he means NO taper - he specifically rejects tapered-side pigstickers IIRC. I'll go back and reread though.

As I said in another reply, I realized almost immediately after writing the post you replied to that I had been too inflexible.

EDIT: The exact wording from Kirby's FWW article is "[the mortising chisel's] blade is perfectly rectangular in cross section". He clearly means registered.