Re-hardened inexpensive chisels vs "good" chisels

[John C Cox]

Hey guys. New guy here.

My primary wood hobby is building acoustic guitars - so I primarily use chisels for paring sort of things, not pounding sort of things. And hard exotic woods are commonly used...

As such - I generally feel like my chisels are too soft, not too hard...

I have recently chased down the rat hole of re-hardening chisels... Without too much preamble here - I found that the Buck Brothers chisels found at the local BORG harden fabulously by heating a smidge past nonmagnetic and then quenching in olive oil. My older Footprint chisel did as well.. They are made of some sort of oil hardening good steel...

(Narex, some sort of German chisel (probably W1), and Harbor Freight wood chisels require water quench.. After making a bunch of banana chisels and cracked chisels - I have decided that water quench is too much trouble)

I decided I liked them much better when not crumbly hard - so I tempered them back at 375F to 400F to get a nice hard edge that doesn't chip immediately.. They are certainly harder now than out of the box - I can easily scratch a box chisel with one of mine now.. And the standard chisels don't mark mine.

But... This whole thing has me thinking..

Is the performance of these re-hardened chisels any better than "Good" chisels? Is Quenched and Tempered $10 Buck Brothers chisel steel anywhere close to that of Veritas O1 or Hirsch steel right out of the box?

I know I am not the only one who has ever tried this out... I know that several of you guys here have done this... Is this something worthwhile...

Thanks

[Jim Koepke]

Howdy John and welcome to the Creek.

I have no idea about comparing the modern soft chisels to harder modern chisels.

I have very few new chisels. Only a few of my older chisels have any problems with edge retention. They tend to get set aside and not used.

Most of the 'hardware store' chisels may be soft for a reason. It has been suggested there may be legal aspects involved. The makers do not want to get sued if some nimno ends up injured because a chisel shattered when he used it to open a paint can.

There is also the idea of some customers, without knowing prefer the easier to sharpen soft chisels since they are only using them to install a couple of hinges and edge retention isn't as important to their work.

For my use my old high carbon blades are fine. They may need a honing or two during a project, that doesn't bother me as much as it seems to bother others. A few minutes on the stones is like a quick breather for me.

jtk

[Larry Frank]

I think rehardening those chisels is a shot in the dark. For Veritas, when they heat treat something like O-1, they know the grade of steel and exactly what heat treatment is needed. In addition, their control of times and temperatures are much better.

When you just reharden the chisels you bought, you really do not have any idea what grade of steel it is. I am glad that your heat treatment works for you. Be careful you do not get them too hard or they could fracture.

[Frederick Skelly]

I can't answer your question, other than to say that if they work - use them.

But I wanted to say 'Welcome John!' And that we're glad to have you join us!
Fred

[John C Cox]

Yes - the hardware store chisels do seem to be tempered soft out of the package... For all the reasons listed.

I tried out the Harbor Freight wood chisels - they won't oil harden - even in warm canola. They will water harden - but they crack and warp badly. Narex will water and warm canola quench.. Water takes them harder. They warp badly if you harden any more than about the first 3/4". Unfortunately - doing that looses all the benefits of isothermal tempering...

The Buck Brothers chisels are very well behaved. They will quench to really hard in room temperature oil. They warp a little - but it's nothing they can't be flattened back out on the stones.

What works best for me is to only harden the last 3/4" to 1" of the chisel. That reduces the amount of warp you have to deal with. They all warp...

If if any of you guys are interested in trying it out - I can post a brief write up with pix. It takes longer to write it up than to actually do it start to finish.

[Warren Mickley]

For a beginner there is a narrow window between too hard and too soft. Too hard and the chisel is liable to chip and too soft and the chisel tends to fold at the edge. An experienced worker has a much larger window because with cleaner technique he can avoid the inadvertent abuses that cause these failures.

I have some chisels that are lightly tempered like yours and I use them but I prefer 19th century chisels because they are so nice to sharpen. I get good sharpness and retention.

It would not surprise me if your chisels were a bit more like the Japanese chisels and harder than many of the premium chisels. So you might be disappointed in some of the brands you mention.

[John C Cox]

When I first quenched them and left them full hard - they would slice right through anything and still be shaving sharp. Bubinga, Jatoba, White oak, rosewood - and then shave transparent shavings of spruce with no hairs of torn grain.

The problem was that the edges would chip if your technique wasn't perfect. If you twisted or levered even a tiny bit - they would chip out. And after going round and round - back to the coarse stones to get the chips out, I decided to temper them back a bit.

[Mike Henderson]

Yes - the hardware store chisels do seem to be tempered soft out of the package... For all the reasons listed.

I tried out the Harbor Freight wood chisels - they won't oil harden - even in warm canola. They will water harden - but they crack and warp badly. Narex will water and warm canola quench.. Water takes them harder. They warp badly if you harden any more than about the first 3/4". Unfortunately - doing that looses all the benefits of isothermal tempering...

The Buck Brothers chisels are very well behaved. They will quench to really hard in room temperature oil. They warp a little - but it's nothing they can't be flattened back out on the stones.

What works best for me is to only harden the last 3/4" to 1" of the chisel. That reduces the amount of warp you have to deal with. They all warp...

If if any of you guys are interested in trying it out - I can post a brief write up with pix. It takes longer to write it up than to actually do it start to finish.
Sure, post pictures. It's a lot easier to see and understand with pictures.

My understanding of hardening steel is that you trade off between hardness and toughness. Too hard and the edge chips, as you discovered. You have to go a bit softer to get the toughness in the edge.

I suspect most commercial chisels are tempered a bit on the soft side to make sure they won't break in half in use. If you're willing to go a bit harder and understand the tradeoffs, you can get a longer lasting edge.

Japanese chisels go to the hard side with one layer and then use a layer of very low carbon steel to provide some toughness - to keep the chisel from breaking in half.

Mike

[Jim Koepke]

Yes to pictures. Doesn't everyone love pictures?

jtk

[george wilson]

The problems with trying to re harden chisels and plane irons are these:

1. You don't know the type of steel they may be made of. There is air hardening, oil hardening, and water hardening.

2. Steel starts doing strange things when repeatedly re hardened. It needs to be NORMALIZED before re hardening. GOOGLE "normalizing steel" and proceed from there.

3. If your chisels have beveled edges, or a plane iron has its beveled cutting edge, it will WARP. This is because those bevels make different amounts of surface area on either side of the tool. Wider bevel edge chisels will warp more than narrower ones. Plane irons need the BEVEL EDGE GROUND SQUARE, totally eliminating the bevel before you go quenching it.

4.You cannot go using quenched but not tempered steel. It has NO mechanical strength, and will shatter like glass. That's WHY it is TEMPERED!! I had just hardened a plane iron years ago, and it was laying on the bench. I was as yet too young to know better, and the plane iron had not been TEMPERED. I noticed a FLY had landed on the bevel of the blade, and was walking along it when:PING!!!!! The bevel shattered into several pieces. The fly was killed by the concussion!!!! O.K.,I made up that last story :) but,you will soon find out WHY you should have tempered that tool!

5. You do not know the hardening medium, and neither do you know the tempering color. (And,the use of tempering colors is NOT the most accurate means of tempering tools as the steel's chemistry makes those colors a different temperature for different steels).( It works well enough for simple steels like W1 or 01.) For most ordinary quality tools though, it should be sanded bright,and carefully heated SLOWLY to a medium brown color. There are many steels that this will not apply to,but it is a decent guess for most tools. High Speed Steel will not respond to that color,but FEW ordinary wood worker's tools are made from HSS. The only ones I am aware of off hand, are some WOOD TURNING chisels. And,believe it or not,some cheap CHINESE chisels,














Sorry,my little dog laid her head on the keyboard!! She always manages to push some key that messes up a posting!





with crudely brazed on tips. (I do not refer to metal turning lathe tools. I mean wood cutting chisels) Even Sears Craftsman offered a set of HSS wood turning tools.

I used to make steel spinning chucks for all the major golf trophies. I would rough them out as much as possible. I made a drawing of the spinning chuck,accurately drawing in "Stair steps" along the curved bodies. Then,I turned the stair steps as drawn(this HAS to be drawn ACCURATELY!!!!! After I had stepped in the body shape,I'd use carbon steel,or High Speed Steel wood lathe chisels to smooth away the steps. The HSS tools lasted longer between sharpenings,but men used carbon steel for centuries . Thousands of years, even! So,a decent carbon steel chisel would work. Especially if I was making the chuck out of LEADED STEEL. Turns wonderfully, but keep it off your skin, and wash your arms afterwards.

Why did I throw in that story? I tend to wander into a related story. But,save that tidbit. If your lathe will run SLOW enough, you can turn steel freehand perfectly well, to make missing bits and pieces you need.

Leave out SORBY lathe tools. They are disgustingly SOFT!!!(That's my opinion anyway,and they can't SUE me for my stated OPINION!! I HAVE re hardened Sorby lathe tools(who knows WHAT they are made of?) and did make them better at least.

[Pat Barry]

4.You cannot go using quenched but not tempered steel. It has NO mechanical strength, and will shatter like glass. That's WHY it is TEMPERED!! I had just hardened a plane iron years ago, and it was laying on the bench. I was as yet too young to know better, and the plane iron had not been TEMPERED. I noticed a FLY had landed on the bevel of the blade, and was walking along it when:PING!!!!! The bevel shattered into several pieces. The fly was killed by the concussion!!!!
Thanks George!

[Ryan Mooney]

First, interesting to know that the Buck Bros retemper fairly easily, thanks for taking the plunge and passing the info along!

As for comparison the only way to really know for sure is to take them head to head, you know what you have to do :) Practically speaking though if what you have is working well why look further unless its for abstract knowledge (worthwhile if that's the goal)?

My first pass guess is that you're leaving yours somewhat harder than most of the commercial ones. Assuming the steel is O1 you would be in the Rc60-63 hardness, but whether its O1 (and indeed where in the O1 line it falls as there is a substantial variation) is anyones guess (so you may well be harder or softer).
http://www.buffaloprecision.com/data_sheets/DSO1TSbpp.pdf
The veritas O1 are claimed Rc58-60 and the PMv11 are claimed Rc61-63 (but that's a completely different type of steel so apples to apples its not). Hirsch claims Rc61 but again may not be apples to apples..

I suspect you might get slightly better results on the warping issue annealing the chisels first and then re-hardening but you'd have to trade that off against the risk of slightly more decarburization from the repeated heating.

[Jim Koepke]

Leave out SORBY lathe tools. They are disgustingly SOFT!!!(That's my opinion anyway,and they can't SUE me for my stated OPINION!!

I will be a material witness on your behalf. My Sorby lathe tools seem to be challenged at holding an edge.

jtk

[george wilson]

I forgot to mention that just leaving hardened, but un tempered steel, parts laying about,is that they have been well known to suddenly pop into two or more pieces. Fully hardened steel is just full of high stresses. So, always temper your hardened tools ! I made up the bit about the fly,but it was based on the fact that fully hardened parts can ,sometimes violently go POP. You don't want your eyes near them when they suddenly blow up.

Jim: it is just too bad that Sorby tools,with their nice London Pattern boxwood handles lack in the performance of their blades. The OLD Sorby tools of the 19th. C., with their figure of Punch stamped upon their blades, were among the finest English tools.

[John C Cox]

mI suspect you might get slightly better results on the warping issue annealing the chisels first and then re-hardening but you'd have to trade that off against the risk of slightly more decarburization from the repeated heating.

George covers this pretty well - but the issue is the bevel edges on the sides and tip. About 100% of the chisels warp towards the back. And the reason is that there's more steel on that side. But - this outcome is preferable (to me at least) to the chisel taking a belly.

2 things seem to make for less clean up work subsequent...
1. Prep the back of the chisel prior to hardening. They almost always come out of the box warped a bit towards the back/tip. This clean up doesn't reduce the warpage - but it's easier to grind a softer chisel than a harder one. And so the subsequent cleanup effort is less than if you just heat straight out of the package.

2. Only harden the last 3/4" to 1". Don't get greedy and try to harden 2+ inches of chisel - that is almost guaranteed to leave you a hard steel banana that's going to take hours and hours and hours to clean up (if possible).

[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/robert-sorby-chisels-compete-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.

[John C Cox]

I wanted to circle back around to this thread a year later with some things I have learned...

1. The Buck Bro's chisels I rehardened were all very chippy after this. Even when I tempered them back softer.. I have been unhappy with their performance - as sections of the edge can flake right off.... Compare this to ONE single Buck Bro's new chisel I received which was very very hard out of the pack (I estimate in the Rc 62 range vs their typical at Rc56 range). That hard factory chisel is quite hard but very tough and holds up well on the wood without chipping. Since this road leads nowhere for me - I am done fooling with these for now....

2. I finally figured out that the Cheap Chinese "Chrome Vanadium" Harbor Freight chisels problems are because of being extremely shallow hardening even though the carbon content appears to be there... A typical brine quench of a cup of salt in about a gallon of water (give or take) only fully hardens them around 1/32" deep... This is a problem because they run almost 1/4" thick... Of course the obvious consequence is that a good round of prep to get them ready can burn right through the hard layer into mush.... And that's how I figured it out.. I ground some warp out and hit mush...

Onwards and upwards... Next item of business - can I figure out how to get them to harden more deeply....

This may point to some of what George was getting at but never said outright... Heating up a little past non-magnetic and quenching to reset the heat treatment assumes they were properly heat treated in the first place... And if they simply started with a fully annealed/spherodized structure with no normalization, induction heat, and spray quench... They may not have gotten the crystal structure into the right form to take hardening properly.... Thus their strange behavior...

[ken hatch]

I know different strokes for different folks and all that rot as well and it is good to post about things that blow your skirt as well as things you question. So good on all y'all tool players, I enjoy reading your posts and sometimes they can be enlightening. Here's the question, other than mucking around fooling with tools.....Why? There are very good tools to be had for little more than the cost of the cheap ones and tons of time to saved. In the end you have wasted time and money. BTW, when you are older than dirt time is much more important than money because like that roll of TP when you get near the end it sure goes fast. :D

Anyway, I get a kick out of 'em in a head shaking way and of course YMMV.

ken

BTW, I wanted to see how many cliches I could get in a single post and still make some sense. I did ok. :)

[John C Cox]

Why? Because it's there of course. ;). And because they are "Sunk cost"... They are basically useless to me as chisels as is... So if I can get something better out, I win... And if I wreck them - I have lost nothing because they already aren't useful as chisels..

And perhaps I might also have and ulterior motive behind trying to sort out how to properly through-harden these low alloy water hardening steels... ;)