Re-hardened inexpensive chisels vs "good" chisels

[John C Cox]

So.. To go after the comments about "Oh - you don't know the steel so you can't harden it.."

Really? How did smiths ever learn how to deal with steel except for doing it and figuring out what worked.

First off - this is hardening chisels that are already chisels... That these have already been made into chisels by a bona fide manufacturer says that they already did the first pass due diligence and selection of the alloy... These are modern chisels made of modern steel - not mystery metal laying around in a barn.. I am not fooling with miscellaneous scrap steel bits or trying to make mild steel into chisels (I had a good laugh reading that thread and I do understand George's frustration..). Yeah - I know that some manufacturers made chisels out of junk - but they don't oil harden to any useful degree.

Next - my experience from this is that you are more likely to find out it won't harden than that it will. Water hardening steel won't harden in oil (not well at least). If it gets file hard in oil - then you know it's some flavor of oil hardening steel.. If it gets file hard in water - then you know its some sort of water hardening steel... If it won't get file hard - you are SOL..

As for A2 - so far, except for chisels advertised as such (Blue Spruce, LN) - I haven't ran into any that would air harden... That stuff doesn't really cooperate with current high volume production methods... The hardening process just takes too long vs an oil or water quench and temper process.

After fooling with water hardening - I have no desire to fool with that stuff anymore... Too much fall out to warp and cracking.

I agree on tempering. Danger of cracks notwithstanding - I don't like chippy or crumbly edges. I think an oil hardening chisel tempered back to 400F - so it's softer than full hard, but still harder than right off the hardware store shelf makes me happy for what I do with them....

[Warren Mickley]

There are some weird notions in this thread. Two people suggested that Sorby lathe tools are too soft. I have four Sorby tools that I purchased in 1981. They do a fine job. I wish I could buy something of this quality today; there are a few more gouges I would like to have. I have no trouble turning woods like dogwood, persimmon. Osage, rosewood.

I also have a skew chisel for turning that had been in a fire so I hardened and tempered it myself. Still going strong 36 years later. As John mentioned, we were hardening and tempering this stuff for quite a while, long before Fahrenheit and Rockwell were born.

[Larry Frank]

Concerning...you do not know the steel grade comments

Please, do not listen to me as I am a Metallurgical Engineer who made all types of steel.

Also, do not listen to George as he has many years of practical great experience.

Buying the chisels you mention, you could run into a wide range of chemistry and hardening properties. If you had a large amount of a single type of steel, you could figure out how to treat it properly. Blacksmiths generally only dealt with a few grades of steel generally varying in carbon content. They did not have to deal with the types of alloys that are put in modern steels.

I saw in your other thread how you were heat treating and IMHO you are over heating it as it appears to be almost yellow. This can damage the steel and make it prone to fracture.

If you want to learn about heat treating, you could take a blacksmithing class or even a basic heat treating class. Good Luck and be careful.

[Robert Engel]

I use both Marples and Narex chisels. I've never given a thought to what you're talking about.

I probably don't know any better, I just sharpen them when they need it. However, I do think there are differences in brands regarding edge retention but so much depends on how sharp the chisel is, the wood, and what you're doing with it.

For all the reasons mentioned by George and Larry, I think you're taking a big risk so if you have to, do it on the cheap ones I guess.

[John C Cox]

I have a great deal of respect for Larry and George - but I am quite confused.... These guys talk about all sorts of existential "risks" ... But yet what specifically are those risks of rehardening an actual chisel (not mystery scrap) by heating it to nonmagnetic and quenching in oil?

The process I listed is literally plastered all over the Internet, and is in various blacksmith/knife making books... It's not like I invented this...

I went through my Machinerys Handbook and I just don't see the problem. There are many pages of steel that requires heating a bit past nonmagnetic followed by an oil quench... For the most part - they also have fairly similar tempering requirements.

Like came up with 3 risks...
1. The main "risk" I see from miscellaneous alloys is that it won't harden to any useful degree because it is the wrong steel for the process.
2. The second risk is warping and cracking.
3. The last "risk" really isn't a risk - it's that rehardened junk steel is still junk steel... Harden 1050 and it still won't give good edge retention because of the low carbon....

Tell me what I am missing and why this should not be attempted except for illuminati?

[Warren Mickley]

John, you hardened and tempered a few cheap chisels. You were happy with the results. Now people who have never tried your chisels suggest that what you did really did not work. This kind of thing happens all the time. The proof is in the pudding, not in someone's imagination.

I have a neighbor who had a cherry tree. It did not self pollinate, so every year he would get a flowering branch from another tree and stick it in a bucket of water under the tree. Then he got the bright idea of grafting on some twigs from another tree. He got some sticks from a yellow cherry and I showed him how to graft, I think six little branches. Then some farmer came around and told him grafting doesn't work any more. Really? Of course it worked.

[Kees Heiden]

John I don't see the problem either. You had fun and learned a lot along the way. Seems like a valuable use of your time.

I've got a little experience with hardening too, and indeed water hardening is risky! I cracked a uselessly soft old chisel too.

[lowell holmes]

This thread makes sense if your into salvaging old chisels. I prefer to work wood, so chisel hardening is way down on my list.

I have new Lie Nielsen chisels which come shiny and sharp. I use them. I have a collection of old Stanley chisels and if the metallurgy of a particular chisel is good, I use will it.

I sometimes will alter an old Stanley chisels and sometimes it is successful. I needed a 15/16" chisel one time and I ground down on old 750. Old 750's vary in hardness. If you get a good one, it is a good chisel.

[Pat Barry]

Curious about oil vs water hardening steel and need some education. Does the oil actually contribute something to the steel (carbon?) to aid in its hardening effect? Water wouldn't have any carbon to contribute so it wouldn't have the same result? Why does the steel care what fluid its being hardened in? Without any better knowledge than my own intuition I have always thought it had to do with the heat transfer of the liquid - water might draw the heat out too quickly for example and this might not be the best thing for hardening some steels.

[John C Cox]

It's the rate of heat transfer during the quenching when hardening steel. There are 3 basic classes:

Slow quenching - these are called "Air hardening". These steels are quenched in still air to reduce the temperature slowly. D2 and A2 are like this. The quenching here could take a couple hours.

Medium speed quenching - these steels harden well with a slightly slower quench than water. These are generally called "oil hardening". They are quenched in oils to reduce the temperature at specific rates that are faster than air but slower than water. O1 falls into this category.. But many alloy steels quench well in oils.

Fast quenching. These steels require a very fast quench to make the steel hard. These are generally called "water hardening". They are typically quenched in water or brine mixtures. Most plain carbon steels fall into this. 1095 is a good example.

There are are heat treatment books full of tables that show what sort of treatment you use for what type of steel.

[John C Cox]

This thread makes sense if your into salvaging old chisels. I prefer to work wood, so chisel hardening is way down on my list.

Whats this whole working wood thing you speak about. I thought the purpose of the Neanderthal Haven was to talk about sharpening, old tool collecting, the merits of egg beater drills vs braces, and sorting out old planes and saws...

And arguing about how you can't harden chisels.

[lowell holmes]

I admit, some of my old Stanley's need to be hardened. I'm not at the point I want to do that yet.

IIRC, I did harden a chisel one time by boiling it in hot water and then quenching.​ I would have to re-visit that to be sure.

[John C Cox]

I have worked my way through a couple more white papers on the subject of hardness, carbon content, and edge tool life...

I think I am starting to get what George and Larry were maybe trying to say but didn't say..

Its not just the pure "hardness" that matters as much as getting the correct conversion of crystal types within the steel.. (That's probably not the correct terminology.)

so.. You can have 2 otherwise identical steel alloy samples - hardened and tempered to the same test hardness.... One was done "right" and the other "wrong".... And the "wrong" one may well have half the wear resistance of the "right" one... Even though the "hardness" and alloy are the same.

And so that's why you don't necessarily know if you accomplished anything worthwhile until you test them out a bunch.

George/Larry - Is is this a more accurate statement?

[John C Cox]

So here's a promising result. I am not necessarily ready to declare this a sows ear to a silk purse.. More like a sows ear to a nice sow ear purse.

So here I am - channeling my inner Derick Cohen to run some tests of my own. I am making a quick and dirty chisel holding plane to do some of my own tests.. But I needed to chop and pare out some waste in the process of making the plane.

The wood is some sort of exotic HARD pallet wood from the hardwood lumber place. It's pink, very dense, and hard. Reminds me of some sort of eucalyptus.

Anyway.... Here's what happened.

Paring out the waste - the rehardened Buck did very well. Right up there with my Blue Spruce. Harbor freight made it 1 pass before rolling the edge and wouldn't cut. Stanley fat max - useless because it's too short.. Unhardened Buck - would at least pare some... It did a little better than HF but not as well as hard.

Chopping. I didn't have the heart to pound my Blue Spruce paring chisels. The hard Buck made it through over 3/4 of the job before chipping too much. Switched to HF - the edge rolled bad on the first hammer whack. The second whack broke off the whole edge about 1/16" back.. Useless. Unhardened Buck made it 3 chops and gave up. Stanley Fat Max finished the job. It rolled bad the first chop - but then the rolled edge broke off and it stabilized to a ragged edge at about 45 degrees that would chop through given sufficient hammer...

I don't usually chop anything with chisels... These were ground at 27 degrees or so... The chopping would probably have gone better with a 35 degree bevel. I probably would have had a shot at wearing the edge instead of destroying it.

And then I spent another 2 hours grinding all the gouges and dings back out.

Conclusion...
Hardening and tempering the Buck Brothers chisels did something useful.
Sorry - no pix of the edges...

[James Waldron]

Several years ago, I was given the opportunity to buy a few things from the estate of an old-timer who was quite a good woodworker. Among the things his widow was just sure I would want was a box of 9 pristine Sorby 167 bench chisels (the ones with the London pattern boxwood handles and the ornamental brass hoops that always fall off until a fix is employed) - at a very nice price. I wasn't in need of chisels and I hesitated, partly because of poor marks given by some. Then again, there have been a few people that really like them (https://paulsellers.com/2012/12/robe...with-the-best/). Since she was so generous with the other things I wanted and needed the money, I decided to take on the Sorby things as well.

It turned out they appeared "factory fresh" in a faded red box and it appeared that none of the chisels had ever been removed from the cardboard insert in the box. When I got them out, I confirmed they were indeed unused, with factory grind intact on back and bevel. At the time, I didn't have a 1/8" chisel, so I was glad to get that. But first thing, I prepped the 1/2" and gave it a try. It was a fine tool, took a very sharp edge that lasted a pretty good while chopping waste and trimming dovetails for a couple of boxes. I was pleasantly surprised, given the negative reviews. So I tried the 1/4" and the 1/8" and then the 3/4", all with very good results. Over time, I worked up the entire set and they have become my primary workers for fine work. (I passed my old primaries on to my son, who then had them stolen, along with a number of other things a couple of years later. Of course!) For rough work, I have a set of old Bucks that do pretty well and several old, beat up Stanleys as beaters and loaners.

I've never found out when my Sorbys were made and I have no substantive information to offer on why mine seem to be better than the experience others have had. I can say that they aren't the hardest edge tools I have, or the longest lasting edge sharpness, but they are enough to get me through a pretty full day of dovetailing with no more than a 10 pass touch-up on my ultrafine Spyderco stone and a half dozen wipes over my strop (0.5 micron paste on mdf) at lunch time. I don't use them for mortising; I have mortise chisels for that. I do use them for paring, and they can shave end grain better than most.

Was my set just a lucky fluke? Was there a time when Sorby hardening and tempering changed for the worse? Is there something else in play? At one time, Sorby published that they hardened to Rc 60-62; currently their web site (http://www.robert-sorby.co.uk/) is entirely silent on any quantification of hardness as far as I can see. What they do say about hardness is, "Every tool has a small indentation, our ‘hallmark’ and your guarantee, that each chisel has been diamond hardness tested before it leaves the factory." I'd be interested in learning more, but the information available from Sorby seems rather scant. I have noticed that a lot of retailers carry Sorby turning tools but only a few carry their bench chisels.

If anyone has any more information, it would be good to know.