Thread: Chisel Hardness Study, the first step.

What I'm trying to get to is something somewhat different. To illustrate let me use a figure from my study of Disston saws. If you'd like to see the thread discussing this data in more detail look here: Hardening of sawplates

This plot shows the mean + the standard deviation of the hardnesses of the blades of 116 Disston saws spanning the period from the inception of the company until the beginning of the HK Porter era. The upper row of dots is the mean + S.D. and the lower row is the mean - S.D. for each saw. The black lines are the second order polynomial fits to each set of points.

Disston saws over time STDEV 031018a.jpg

The dates are binned and denoted by a year marking that approximates the centerpoint of the medallion era's as described on the Disstonian Institute website (Online Reference of Disston Saws -- The Medallions).

Observations:

1) The hardness of Disston saws really didn't vary very much over the approximately 100 years of production.

2) The variability in the hardness, expressed as standard deviation, did however. It was relatively high in the early days and got progressively better until it was lowest during the 1896-1918 production period - The Golden Era. After the Golden Era the variability in hardness increased.

3) Overall, Disston made the best saws in regards to blade hardness variability of all of the major manufacturers, see link above.

Golden Era saws are generally held to be among the most desirable of production periods in regard to their quality as tools and their aesthetic characteristics. After the Golden Era the consistency of the blades decreases over time until the end of the Disston family ownership period.

Given the number of saws we have it's really beyond doubt that Disston was a mass manufacturer or saws over all production periods except the very first in the 1840's.

The quality of saws made in each of the post-WW1 era's decreased over time, i.e. the steel became less consistent, and as anybody can appreciate the aesthetics deteriorated.

I think a similar situation probably exists in chisels, particularly the mass marketed chisels. I don't have enough data to show it in the detail that I did for saws but I do know that the very poor Sorby chisels were hardness tested because each bears a single indenter mark from a 150 kgf HRC machine on the back side of the blade, so at least they tried. Further I know that the other manufacturers aren't a using a similar QC program including hardness testing because none of the other chisels bears the tell-tale marks of hardness testing. The various custom manufacturer chisels I've tested that have hardnesses that vary from their stated ranges or that have high inter and or intra chisel hardness variability speak to the lack of QC as well. Poor, inappropriate or no QC makes for bad products.

I used one of my new sets of sorby chisels this weekend to make a cart for my vac and trash can setup (for years, I've left them stationary, because pulling the hose at the top of the can tips the can, and "dopily" never did anything but sweep dirt to the vac range if it was out of range).

At any rate, I used cheap wood from HD - stair treads with knots, and dovetailed them knots and all.

While those chisels are soft, I'm almost certain that's sorby's choice. That sort of tool tempering goes all the way back to r. sorby irons, even the ones they made for norris.

They won't fare well in this test, but I quite like them in use. I can refresh them on oilstones in about 30 seconds, and they grind quickly. The only thing they're really missing in that context is their finish level is off a bit, but the boxwood handled chisels of the base-model type are about $123 for 5 if ordered with a discount code from hartville here.

Some will debate they're not worth it, but I think they're probably intended for skilled users, and not beginners who can't improve their sharpness cycling time. They do love the shallower primary and then tiny rounded bevel that I favor, which is excellent for everything except mortising (the bevel needs to be more blunt to ride it).

Rob, your finding about disston's saws being consistent while while the brand was going strong matches my finding with older chisels. They vary by maker a lot, but not necessarily within maker. Each had a target they were aiming for.

If you were to get a bunch of ward chisels, you'd find them to be as hard as most modern offerings, ex. japanese chisels, of course. Probably harder than a lot of modern chisels. If you get turn of the century chisels marked "buck brothers cast steel", they're more in the range of the newer sorby chisels, but consistent.

I can't help but think this idea of "poor quality control" of very old chisels due to lack of technology won't be thought about the current chisels if someone 100 years from now gets a few sorby chisels and a couple from lie nielsen.

(in the back of my mind with the varying hardness of chisels still retailed, and the preference for harder chisels, the only ones that I have that I really can't get on with are the 5001 stanley chisels. They can be bent by accident and then bent back and they give no indication of iffy feelings - too soft. That and the two blue-handled marples sets I had. Each had four good chisels and one soft one. No clue about that. Not minor soft, but like saw temper - very low 50s at most).

I suppose what is of vastly more importance to me is that a full 50% of chisels tested fall out between Rc 58-61... 3 points! And yet within that 50% of chisels tested - there is a gigantic spectrum of performance on the wood... Ranging from immediate edge failure to beautiful high performance magic...

Why?

What is fundamentally different between the good ones and the bad ones at the same hardness?

Look at the Sorby Firmer and Sorby bench chisel? 1 failed miserably in pine and one is still kicking it's way through the test... Or the Craftsman vs the Narex? Both fairly cheap.. One didn't even make it through pine and another is showing solid performance on oak? And what happened to the Berg? These are all nearly the same hardness... But the edges perform vastly differently..

And so this would take me to:
Alloy and Heat Treatment... And I would be very surprised to find out that the alloy is significantly different between the Sorby chisels tested...

Now... 1 interesting observation is that Berg and Narex chisels are Austempered to reduce problems with warping.. Makes me wonder if that is the difference between the Sorby chisels as well.... Was 1 austempered and the other conventionally quenched and tempered?

Austempering is turning to look like a benefit for manufacturers and a dud for woodworkers. Of course, most would say the same thing about the sorby chisels in general (even though I like them so far).

In terms of hardness, if you're doing cross grain work in oak, there will be miles of difference (if the quality of steel is good and the heat treat also good) between a 58 and 61 chisel. The former is sorby territory and the latter is ashley iles. Iles chisels do magnitudes better in that kind of work.

there still is the 2 degree rule, though (my rule). If a tool doesn't hold up, add two degrees and it probably will. Just not the whole bevel (so as to avoid the wedging).

Rob's findings mirror what I've seen in the chisels that he's tested that I've also used. The chisels in the softer group are sometimes one part lack of initial success and a second part screwing around and finding out what they like. Sometimes, they're so soft that what they like isn't very desirable (e.g., if you have to chase the initial edge up to 35 degrees to get it to hold up, it's going to seem like a chisel that does OK in light work, but in punching off waste to get to a marking line, it's going to feel like a cold chisel).

Originally Posted by NeilS

Yes, any Kiyotada that can still be found are in collector territory now.

Japan Tool - Chisels - Kiyotada Oiire Nomi (collector's item)

Japan Tool - Chisels - Kiyotada Oiire Nomi 2

And, as they say, if you have to ask for the price you can't afford it!

But, Rob's chisels may also become the province of collectors at some time in the future...

I have three kiyotada chisels, and two (maybe I said this above, I'm sure I thought it already) are chisels that were somewhat improperly cared for paring chisels, but i"ll get them back into order over time (the cardinal sin on one was the move to leave half of the chisel hanging off of a stone so that the thin sides of the ura are cut partway off). Those two originated from So, and the person who sold them to me suggested he was "passing them along", meaning I paid close to what he paid. About $100 per chisel. The third is an NOS 15mm mortise chisel that was $225. It's really nice. It's still a chisel (still gets dull, you can still chip the edge if you're breaking rules, but it's still a really good chisel and the finish work on it is perfectly plain like the current kiyohisa offerings). Perfectly plain being a good thing - japanese understated, and not tasai westerner-favored bling.

Anyway, i saw that set but never asked so. He says he spends an inordinate amount of time when he prepares anything used, so I'd guess he wants way more than I'd be willing to pay.

I don't know what he does to "adjust" his chisels, he says a month. It would take me about two hours to get a forlorn set into that condition. Perhaps four if they were awful, but I am an amateur toolmaker and have done that work a lot. The last set of 12 older chisels that I bought took 45 minutes to prep (though the aesthetic requirements aren't quite as high as these.

They're quite short from use, too (the handles).

Anyway, even at that, i'd be surprised if they were less than $3000, and not surprised if they were $5k. Suehiya in Tokyo may still have some NOS chisels. That's where my mortise chisel came from thanks to a generous tokyo resident fetching it and sending it. As good as they are, the results are the same as they are with iyoroi chisels (at least with the three I have), and I still prefer western parers, even to the kiyotadas.

Some of the things that come up, I often wonder if it's just a "nail the gaijin" type of thing. I can't remember the name of the dealer (it's ten years on now), but there used to be someone whose prices on the English side of their site were 50% higher than on the japanese side. And seeing what tomohito iida is doing with ogata and nakano planes (driving them up to close to $800) makes me think he's got a little of that, too. I doubt the stock cost him more than a quarter of that, or a third at the most.

Here is one of my parers:
Japan Tool - Chisels - Kiyotada Usu Nomi

Here is the other:
Japan Tool - Chisels - Kiyotada Shinogi

The first one is markedly harder than the second one.

(I didn't get them from so, I got them from a customer of his, but those are unmistakably my chisels - warts and all - and short handles).

Originally Posted by D.W.

Perfectly plain being a good thing - japanese understated, and not tasai westerner-favored bling.

Yes, and that is why I sent that 'pretty' Tasai to Rob, which he has kindly agreed to include in his testing regime. Its only saving grace on the sartorial side is that it didn't have that mokume-gane treatment that adds absolutely nothing to its performance.

Appearance and reputation often come at a premium and I will be the least surprised if the Tasai under performs relative to its price.

Originally Posted by NeilS

Yes, and that is why I sent that 'pretty' Tasai to Rob, which he has kindly agreed to include in his testing regime. Its only saving grace on the sartorial side is that it didn't have that mokume-gane treatment that adds absolutely nothing to its performance.

Appearance and reputation often come at a premium and I will be the least surprised if the Tasai under performs relative to its price.

Someone in tokyo told me that his local dealer thought tasai were well-made chisels, but said something along the lines of "it's a shame that they are so flashy".

Presumably, most of tasai's chisels sell to gaijin, just like iwasaki kamisori.

Tasai's stuff is horribly marked up in the united states, too, I guess due to the distributor here (as well as the retailers being piggies).

https://www.japanwoodworker.com/prod...-in-signed-box

that's a horrible joke. $400 a chisel for a set of bench chisels? I doubt tasai sees half of that - perhaps a third.

The market that they're aiming at must be uneducated, because they can't even both to specify which blue steel. (I understand that tasai sometimes states that they specialize in a forge purified blue steel, but for $4k, I'd expect to know where the stock originated from and what it is).

Separate and aside, I did run into my second set of too-soft chisels, but they're not vintage (at least not in a sense). They are more modern sheffield made marples chisels with boxwood handles. A lovely profile, unused (finish a little rough, but given when they were probably made, excusable).

All I've tried so far have been too soft for actual use. One of them denting visibly to the naked eye when paring a piece of cherry. The others still wearing quickly and forming a wire edge from a few paring cuts. It'll be interesting to see what happens when I reharden a couple using what I would do for O1.

The only other thing they're suitable for at this point is re-selling - they're incapable of work, but I'm not the kind of person who would do that. If I manage to break, crack or warp a couple of them beyond repair, I'll chalk it up to learning.

Apologies for the delays gentlemen, I've had an issue drop on me that demands the majority of my attention. I may get a break in a week or so.

Originally Posted by D.W.

Separate and aside, I did run into my second set of too-soft chisels, but they're not vintage (at least not in a sense). They are more modern sheffield made marples chisels with boxwood handles. A lovely profile, unused (finish a little rough, but given when they were probably made, excusable).

All I've tried so far have been too soft for actual use. One of them denting visibly to the naked eye when paring a piece of cherry. The others still wearing quickly and forming a wire edge from a few paring cuts. It'll be interesting to see what happens when I reharden a couple using what I would do for O1.

The only other thing they're suitable for at this point is re-selling - they're incapable of work, but I'm not the kind of person who would do that. If I manage to break, crack or warp a couple of them beyond repair, I'll chalk it up to learning.

Well, stuck making a lending library for the neighborhood (out of plywood no less, with hand tools). But I did get a chance to reharden one of these tonight. I have a coffee can forge, two torches and then an outdoor 500k btu open setup, so nothing at all precise. The handles are on these (tang chisels) and they're bound to get a bit scorched.

That said, the first one was the softest I had, I heated it a bit past where you'd heat O1 (going a little too hot is better than not going hot enough, and who knows what they are and what they need to be heated to). Handle on also means tempering the chisel at the opening of the forge, which I did to dark straw and then quenched quickly again.

It's still a touch soft compared to a lot of modern offerings, but I pared an eighth of an inch off of a cherry stick and then malleted with it a little bit and it is surprisingly good! No nicks, no lines, etc, the edge stayed perfect.

https://s14.postimg.org/7nykfki35/20180331_000557.jpg
https://s14.postimg.org/4tvf24vch/20180331_000612.jpg

Not exactly a torture test, but a single paring pass rolled the edges badly on these chisels, creating what felt like a significant wire edge.

The only marks on the end of this stick after paring an eighth of its length off are just from the edge of the chisel.

I have seven more that will probably need the same treatment, and it looks like I'll need to track down a wet towel to wrap around the handles so as not to scorch the ends of the rest of them.

Did a second (tested very soft, unusable) chisel from that set again today in the coffee can forge and it, too, turned out great. Wet rag around the handle kept the handle cool as well as preventing burning up at the front edge.

I drove the heat up a bit higher on this chisel before quenching it (medium bright orange), and it seems to be a bit harder off of the same tempering colors.

David,

That may he a sign that the steel needs to soak a bit longer at temperature to get all the C dissolved. They typically recommend 20 minutes at 1475F or so for O1.. These longer soaks are pretty critical with typical 1%+ Carbon steels used in chisels... Pretty easy to do in a temperature controlled kiln... Not so easy to keep the temperature that stable with a torch..

This sort of behavior would make sense if these were normalized but never got hardened in the first place.