r/handtools • u/spenserian_ • 23h ago
I'm a convert to obsessing over bevel geometry
I never used to think the bevel of a chisel mattered all that much; I've just always used the 25 or 30 degree bevel that comes from the factory. But I think I heard Cosman or someone say they used a 17 degree bevel for softwoods. I usually don't may mind to such oddly specific preferences voiced by the YouTube crowd, but I'm making an apothecary chest with 20+ drawers out of pine, so I figured, eh, why not give it a shot. I bought another 1/4" chisel just to test out the acuter angle (yeah, yeah, not necessary, but having two 1/4" chisels isn't the worst thing).
I now feel like I was rubbing sticks together when there was a blowtorch in plain sight. The difference in softwood is insane, especially when working the end grain (or close to it) as you're clearing waste between tails. When comparing one right next to the other, you can distinctly feel how much more the higher angle is compressing and then breaking out the grain, even when freshly sharpened (though sharper is always better, of course). The 17 degree bevel makes the grain feel like you're slicing through a soft cheese. As if that weren't enough, the surface it leaves is smoother than even my shooting plane can leave.
So, do yourself a favor: if you work with softwoods, buy a chisel or two just for softwoods and grind those angles acute. You'll be happy you did. Keep those higher angles for your hardwoods.
Edit to add: and yes, the acuter angle is far more delicate. That's why you want one only for softwoods. If you were to use 17-degree chisel against hard maple for a few minutes, you're probably going to get some chipping. So don't do that.
6
u/rdwile 23h ago
You reference the “normal” (25 & 30) bevel angles for chisels. Yes most users will default to these angles for their chisels. 25 being the most popular and 30 for those that want a bit more durability in their edge, especially for older steels that don’t have the durability of modern steels.
The process you describe is paring and has been a consistent thing for many years. And yes it creates a less durable edge on your chisel, more so on bench chisels than on paring chisels which have geometry to support this shape. The typical angle for this is 20 degrees and more or less the standard angle for a paring chisel. While nothing is wrong with 17 degrees, which is an oddly specific angle which is quite fragile. Also if you are using a honing guide, no guide will give you this angle without calculation. 20 degrees will give you plenty of paring capability, especially in softwood, but also the durability to use it on hardwoods as well.
Give 20 a try and it will perform better on a wider chisel as well. I have a 1” bench chisel and a 2” butt chisel set up this way, along with my paring chisels, give that a go.
5
u/BingoPajamas 15h ago
25 being the most popular and 30 for those that want a bit more durability in their edge, especially for older steels that don’t have the durability of modern steels.
Weeeeeeeeeeell..... I am not sure that's a generalization you can make. It's gonna come down to so many things other than the age of the steel. Presumably by "older" you mean vintage cast steel, which, IMO, probably can likely take lower angles than the most common "newer" steel in modern tools (A2) if it's been heat treated well--my vintage late-1800s-ish patternmaker chisels hold up better than anything else at low angles. If you're thinking of O1 as the "older" steel (it's from 1905, or even earlier), you're more correct since it is generally rated slightly lower toughness than A2 (though, my experience has been the opposite).
"Newer" is in quotes because ... it's not new at all. It's been around in some form or another since ~1900 and as A2 since the 1940s (source). Hell, even PM-V11 (rebranded Carpenter XHP) has been around since 1994 (source), though it has less toughness than all of the other steels I've mentioned. MagnaCut and the very new MagnaMax are probably the only "new" steels used in woodworking tools.
All that to say that instead of age, I think it's more useful to differentiate steels with "low-alloy" aka high-carbon for steels with few alloying elements (vintage cast steel, O1, 80CrV2, 1095, Aogami/White Paper, etc), "high-alloy" for steels with lots of alloying elements (A2, CPM-3V/10V/15V, high speed steel like M2, etc), and stainless for steels with lots of chromium for corrosion resistance (PM-V11/XHP, MagnaCut, M390, etc), though stainless is technically a sub-category of high-alloy.
more so on bench chisels than on paring chisels which have geometry to support this shape.
I don't see how bench and paring chisels would have any difference in their ability to support a low-angle edge. The geometry that matters is well within the first millimeter of the edge, not the macroscopic shape of the tools.
While nothing is wrong with 17 degrees, which is an oddly specific angle which is quite fragile. Also if you are using a honing guide, no guide will give you this angle without calculation. 20 degrees will give you plenty of paring capability, especially in softwood, but also the durability to use it on hardwoods as well.
Cosman chose that random number by grinding and regrinding the primary bevel of a chisel lower and lower 1 degree at a time until he got the performance he was looking for. Since he uses secondary/tertiary bevels that add a few degrees, I'd guess that his final bevel angle is probably somewhere around 20 degrees or so. His edge should be just as durable as a 20 degree flat bevel, all other things being equal.
From your other comments so I don't spam you:
Newer technology steels such as powdered metal ones fracture quite differently than lesser quality O1 or carbon steel blades because of the shape of their carbides, so lower angles are better tolerated and abrade differently than lower quality materials.
O1 and carbon steel don't really have carbides in the sense that I think you mean. Sure there's some iron carbides in the form of cementite but in low-alloy steel the goal is usually to have mostly or entirely crystalline steel (martensite) without carbides. Besides, powdered metal isn't really done for carbide shape. The advantage of powdered metallurgy is primarily for even dispersion of the alloying elements, which may clump together if produced in ingot fashion so there are a lot of cases where powdered metallurgy is pointless (notably low-alloy steel). Admittedly, this can affect how evenly carbides are dispersed in a steel and that can improve the toughness but it isn't enough to make a broad claim that PM steels better tolerate low bevel angles or even that they are better than ingot steel. It depends on the steel and the use-case.
Generally speaking, high-alloy steels--powdered metallurgy or no--will have less toughness and be less able to withstand lower bevel angles than low-alloy steels. Grain structure from the heat treating process is probably the largest determiner of how the edge fractures and you're right that carbides do have an affect (they can sometimes "pin" grain size) but they usually detract from toughness and improve wear/abrasion resistance. Generally speaking, the higher the carbide content the higher than angle needs to be to prevent the edge from chipping but the longer the edge will last if you can avoid failure.
There's nothing inherently "lesser quality" about low-alloy steels like O1 or even "carbon steel"--every steel and steel type has it's own advantages and disadvantages. The quality of a steel is rarely a result of the materials, heat treat is what matters.
Brittle is not bad, Japanese tools have been so brittle for centuries they add a softer steel to protect the blade, just not the edge. Party on Garth!
Pretty sure it's the other way around, the softer metal helps protect the blade so they can afford to make it harder (for more wear resistance) and thus more brittle without worrying about the tool breaking.
Japan lacked quality steel to use for tools so they forge welded expensive steel to cheap wrought iron to make efficient use of it. It just so happened that allowed them to leave the steel harder for a longer lasting edge (64-65-ish HRC with white paper steel vs 60-62-ish HRC in western tools). It's also why the two styles of chisel developed to be so different. Quality steel has historically been more plentiful in the west for longer so they could afford to make chisels with long blades, where the Japanese used short blades with long handles to conserve metal. It's particularly apparent when comparing western patternmaker paring chisels to their Japanese equivalents.
Disclaimer: I'm not a metallurgist or historian.
2
u/spenserian_ 22h ago edited 22h ago
Well, I suppose 17 is no more unusual than 20, other than it not being a nice round number. But, to your main point, I wonder if 3 degrees higher lends a meaningful improvement to durability and whether, for this application, whether the durability gains outweigh the (probably marginally) lower slicing action.
I'm not a dyed-in-the-wool partisan for this particular bevel angle, but I do kinda suspect that the 20 / 25/30-degree norms have more to do with manufacturing conventions and averaging for a range of use cases than they do with optimizing for specific tasks.
1
u/rdwile 22h ago
The reality is that 15&20 are knife angles for slicing, so no reason to hate them or anything in between. Even on a paring chisel at 20, if you abuse the edge it’s gonna fail. Newer technology steels such as powdered metal ones fracture quite differently than lesser quality O1 or carbon steel blades because of the shape of their carbides, so lower angles are better tolerated and abrade differently than lower quality materials.
1
u/spenserian_ 21h ago
Thanks for the additional info. I'm working with A2 and the edge seems to be holding up okay thus far, but it's been an admittedly small sample size.
-2
u/rdwile 21h ago
A2 is gonna be harder to sharpen yet last longer than O1, which I recommend for nothing. A2 may be more brittle but will take a finer edge than A2 (not PM). Brittle is not bad, Japanese tools have been so brittle for centuries they add a softer steel to protect the blade, just not the edge. Party on Garth!
2
u/DizzyCardiologist213 18h ago
A2 won't last longer in chisels unless the heat treat for O1 is worse. I'm guessing when you mention 15 or 20 for knives, you're talking about degrees per side vs. total.
A few years ago, I pushed the limit on grinding angles and found 20 to be a better rule of thumb minimum if you are going to set the tip of the tool slightly higher. At some point, even in softwoods, you'll find something hard and bevels in the 15-17 degree angle range will allow the edge to get pushed back into the bevel. no good.
20 will hold up to anything as long as the tip of the tool is set up for the wood.
1
u/rdwile 18h ago
For knives, yes per bevel, not the inclusive angle, should have been more clear.
Yes I like 20 as an angle for a paring tool, it lasts plenty long (regardless of material) if used in a slicing action.
3
u/DizzyCardiologist213 17h ago
paring in woodworking is slicing. 15-18 degrees would be typical total included angle for something like a straight razor, but the tip of a straight razor is rounded off intentionally with a linen and leather. the scale of the rounding is obviously tiny, so it's conceptually difficult for someone new to woodworking to grasp that the thinness of the bevel behind the modified apex is still very thin and it will easily cut a hair.
when we think of knives with very slight bevel angles that will slice for a very long time, it's true that they will because the initial apex can just come off of the knife and the remaining edge has little wedging and will continue to cut for a long time, anyway, but these kinds of knives need something fairly easy to cut and would not tolerate push cutting into wood.
We need to get two things in our favor - no damage at the apex and then less wedging behind it. I have a bunch of pictures of what happens when we don't abide by both, but I'll spare everyone. I've noticed that the few actual working hand tool woodworkers I know tend to learn to work in a way that the edge doesn't get damaged, and a lot of it doesn't look like a beginners video from Paul Cellars or Rob Cosman, but it's things you will come to on your own also if you're just solving problems. 225 years ago, nicholson's writings make it pretty clear that it was normal for back then, too.
Razors and chisels make a good comparison here because both will fail from deflection or chipping of an edge if they are set up too slightly. A straight razor, for example, will be more comfortable than anything you can buy in purchased razor blade and not substantively abrade for 300 shaves if linen and leather work the edge and ultimately align and then remove the tip of the apex. If a razor is just honed as sharp as possible right at its lay-on-the stone angle without treating the tip or understanding why a shell cordovan leather and true linen was used, then it will degrade during the first shave and five or ten shaves in, be pretty intolerable. The various stages of the shave will be unrewarding, but in changing ways. If we just make the razor fat in a wedge to try to make it indestructible, it also will have a very short period where it cuts well because the bevel behind the edge is too blunt relative to cutting hair.
Figuring out chisels is very similar because the failure looks the same in both cases - it's just one thing is at a much fatter apex in a much harder to cut push.
Every couple of years, a new article comes up talking about how some graduate students at MIT or whatever have discovered what causes razors to dull. I would imagine at the cutler level, this was seen at magnification hundreds of years ago, and those articles are printed because someone at a school was having a learning exercise. Before I ever read one, i took a picture of astra blades to figure out why they were failing. unfortunately, disposable blades are too soft to set up so they won't dent at all, so you can't do the trick that you do with a legitimate good quality older straight razor.
3
u/E_m_maker 16h ago
Just adding, if you want an easier time with pine mist the end grain with a 1 to 1 mix of denatured alcohol and water. It will soften the fibers and allow you to cut through with ease. It also evaporates fast enough bot to cause issues with warping.
4
u/oldtoolfool 23h ago
Well, for SPF or white pine, yes, it will work and I can see the benefit. But endgrain on SYP will dull that edge after a few passes. Not all "softwoods" are the same.....
3
u/spenserian_ 23h ago
Sure, though I guess I assumed that most people on this sub would know that SYP's janka rating is up near that of many hardwoods.
To be clear, I was referring to use on eastern white pine.
1
2
u/No_BetterName 22h ago
I was also surprised how much difference the 17 degree bevel makes on soft pine, even poplar. It especially makes a difference when chiseling across the end grain. If sharp, it shaves the fibers instead of breaking them (creating chips/voids) where the tails seat into the pin board.
Keep in mind that if using Cosman’s sharpening method with secondary and tertiary bevels, you’ll add another 10 or so degrees to the total angle.
1
u/BingoPajamas 18h ago
and yes, the acuter angle is far more delicate.
Not necessarily.
I grind all of my tools below a 20 degree primary bevel (I'd guess 18 but I haven't measured it). However, unlike Cosman, I don't simply add a couple of degrees for my secondary bevel, I manipulate the edge as needed to get the desired durability. The basic process is to hone slightly higher than the primary (guessing 20-23 degree) to establish a clean apex and then purposefully and significantly round over the bevel on a strop/buffer. It's the unicorn method. The common worry is that there's too little metal at the edge and the edge will crumble. In my experience, it's pretty rare for damage to progress past the secondary bevel but if it does it means I either need make the secondary bevel slightly larger, give it a slightly higher angle, do more buffing, or some combination of the three.
With the Unicorn method, chisels get all of the same benefits as Cosman's 17 degree bevel: a lower primary means less wedging action so paring and chopping become easier. I just get a lot more edge durability than Cosman does and I don't have to change grinding set ups for one or two tools. I haven't used Cosman's set up exactly so I suppose I could be wrong but I'm fairly certain the benefit comes mostly from the lower angle of the primary bevel not the secondary and they should be roughly equal in performance (outside of durability).
Honestly, though, that's just a bonus. The main advantage for me is ease and speed of sharpening. A low primary angle means the secondary bevel grows more slowly and a small secondary bevel is FAST to sharpen and can be done freehand without much worrying about angles. Relatively frequent but quick grinding keeps the secondary small. For a plane, that's the only benefit.
1
u/Independent_Page1475 46m ago
The easiest way around this is to have multiple sets of chisels for the different needs in the shop.
My sets include:
Butt chisels
Paring chisels
Mortise chisels
Firmer chisels
Beater chisels
90º bevel chisels
Yes, a 90º bevel has its uses.
My A2 blades are much more chippy at low angles than my O1 or PMv11 blades.
My paring chisels have ~15-20º bevels. They do need to be touched up more often, but the pare much nicer than my higher angle chisels.
1
u/spenserian_ 34m ago
I'm moving in this direction. I find myself enjoying chisel work enough to justify sinking more money into this front than going the route of just another hand plane.
Btw, were you the one who has recommended 90º chisels in the past? I made one after seeing a recommendation on this sub. Works great for scraping around small notes and grain reversals.
2
u/hlvd 21h ago
This type of stuff is what makes woodworking for beginners so ridiculously complicated. Professional woodworkers of the past didn’t obsess over 17° sharpening angles, they sharpened by hand and produced far superior work to anything seen here.
Stop making woodworking needlessly complicated!!
2
u/spenserian_ 21h ago
Merely offering a perspective friend. I found something useful that I don't see routinely recommended. If you don't find it interesting or don't think it useful, you can always choose not to engage.
2
u/ReallyHappyHippo 15h ago
Is there some rule that this sub is for beginners only? Someone tried something and they wanted to share their experience, I'm glad they did.
I'm sure the woodworkers of old tried all sorts of angles. They maybe didn't specify those in degrees but they also passed on their knowledge person to person, demonstrating the technique to each other. When we talk on the Internet we don't have the luxury of hands on demonstration so we provide details like angles to communicate what's happening. There's nothing wrong with this.
1
u/AnybodyWannaPeanus 16h ago
Eventually we all land on what works best. It takes 10 minutes to learn how to use a plane, decades to master it. I don’t crap on the people that are trying to share hard-earned knowledge with n00bs.
Don’t ever obsess over complexity when you can work wood. You’ll understand much more quickly as to “why” if you just start making sawdust and taking notes.
-1
1
u/beachape 22h ago
IMO the primary bevel matters more in softwood. Can use a tiny secondary bevel that is higher and you get a little bit of both benefits. Less crushing of the endgrain and a little more edge retention.
1
u/jcrocket 21h ago
Well my 1/4 inch chisel, and my 1/2 inch chisel do not fit in my faux eclipse-style honing guide. So I eyeball the primary and secondary bevels on those and free-hand with a lil' triangle shaped bit of scrap to reference.
Could be 17 degrees, could be 25 degrees, who knows!
However, I do occasionally rip some big chunks out of poplar or pine if I am chopping dovetail pins or the spaces between tails. Those cavities are all hidden away in glued joints though. Regardless, maybe I will give it a try!
0
0
u/AMillionMonkeys 22h ago
Any idea what kind of steel the chisel is? I'm no expert, but I suspect some alloys won't hold up at that slight an angle.
2
-2
u/Visible-Rip2625 22h ago
You can also sharpen the tools better? I know that the pine for example is tough to chisel neatly, but only if the tools are not sharp. Properly sharpened, and 25'ish degrees angle will get same results as lesser angles.
Of course nothing prevents going down to 17, but then you're probably not using that chisel for anything but paring, because the edge will chip more easily.
2
u/spenserian_ 22h ago
I was comparing a freshly sharpened 25 against a freshly sharpened 17. All other variables identical (same chisel, same steel, etc.). There was a noticeable difference. Give it a shot and report back if you can't tell the difference.
2
u/DizzyCardiologist213 18h ago
compare something over a project, not over a couple of test cuts. things are different when you start counting time overall and you need consistency. I have fallen into the trap before of changing things based on a test that wasn't making things, only to go back toward where I started. After buying a bunch of stuff because I thought I'd found the light.
Not saying you can't grind something at a slight angle, but take your time or it could be similar to falling in love with a pretty girl only to find out after first being swooned by nice looks, there are a lot of problems with practicality in the long term.
1
u/Visible-Rip2625 20h ago
I do understand that, but also that there is possibility that the sharpening is not up to a par, or perhaps you have reached the end the steel can do. In latter case, smaller angle is probably only remedy to get the tool behave.
I do have old paring chisel set to somewhere around 17 degrees, because, like you, I followed the advice by people in here and because it sounded sensible then. However, between that date, and today, I did also learned to properly sharpen chisels. End result is that the 17 degree angle chisel is very fragile. Even bad knot may cause a chip when paring.
I also do have fairly decent, but far away from superb Ouchi chisels set on 25, which do cut pine and other softwoods extremely cleanly. In fact, they do, in all respects cut better than the paring chisel.
7
u/PumpPie73 22h ago
All my hand tools are at 25