Thread: Your experiences with re-hardened chisels

Originally Posted by truckjohn

.......I am a bit surprised over there at the amount of hostility and hand wringing over the idea of a non-professional trying to heat treat a $10 BORG chisel.... I suppose I was expecting that more people had done it and would offer some useful advice... Nope... Instead, I got the equivalent of a lecture by my mom.....

Seems like an odd reaction to me, John. A debate on whether it's worth it, by all means, but can't see it's anything to get worked up about. The worst that can happen as far as I can see is a couple of worthless chisels will remain worthless. If you are having fun & learning something in the process, what's not to like?

I lived in Nth America for a while, & it seemed to me that we Aussies are a bit more likely to have a go at cobbling up tools & gear to get the job done. I had a couple of colleagues who were also keen woodworkers, and they always seemed surprised that I made or modified many of my tools. At the time I put it down to our being a generation or two closer to the pioneering days, plus tools (particularly power tools) were relatively quite a bit more expensive in Oz.

But there are many factors that influence our approach. I grew up in the immediate post-WW2 years, when there wasn't a lot of choice, the tools that were available weren't cheap, and my parents' generation was still smarting from the 'great depression'. My dad & uncles made all sorts of gear, mostly pretty crude, but one uncle was a fitter & could make very 'professional' looking stuff, which gave me a bench-mark to aim for. We had the basics for fooling about with metal on the farm, like a forge & welding equipment, which was necessary when the nearest repair shop was 25 miles away, & a long round trip on a pretty basic road. Parents back then allowed kids to do things modern parents no longer seem to, so my brother & I were happily shaping hot metal by the time we were 12. Apart from a nasty burn or two, no great harm befell us, & I think we learned a little.

Over the years I've acquired a pretty decent tool kit, yet some of the tools that perform best & give me the most pleasure to use are ones I've made or modified. So please feel free to experiment with your cheap chisels & tell us what you discover!

Cheers,

Originally Posted by truckjohn

I am a bit surprised over there at the amount of hostility and hand wringing ... I got the equivalent of a lecture by my mom.

On this site the anti-investigational and or anti-intellectual currents are nil (almost) compared to that other site.

I wont be increasing the hardness of steel on my earlier manufactured chisels and plane irons. I have a personal preference for a tool steel that can be worked easily on the stone, that wont force me away from using natural honing stones , that wont make it more difficult to raise a burred edge, that when required can have its longevity of the edge improved upon by simply increasing its secondary bevel by up to 5 degrees. There are those that think like a woodworker, and there are those more inclined to think like a metal worker.

Originally Posted by auscab

My son does have a set of Irwin's I think . And they are crap . The edge is soft and folds just like Trevor describes in his hardening thread.


Rob

I said this back in post 22 and its not fair on Irwin . Sorry Irwin .
My Son has a set of cheap chisels bought from a Big store and they are not Irwin's. I checked.
They have been suffering from a folded , what looks like a soft edge though.

Someone had a set of Irwin chisels in my workshop a long time ago and I do remember not liking the feel of the handle .
That's just a personal thing I suppose.

With the cheap store bought set, I gave them a bit of a file test and compared them to my old Stanley set, which are good. I also compared them to some vintage Eskiltuna . I was surprised, they feel just as hard . Some of the vintage ones feel soft ? probably from over grinding and losing the temper ? Now I'm thinking I better check how they are being sharpened , It could be the user ?

When I do prove I have a soft one to myself, maybe a vintage chisel. I want to give it a try with the same hardening colour and an Oil . I wont be out buying any oil at the shop to try it though . I'm hoping second hand oil from an oil change will be OK . And some fire wood brought down to Charcoal on the charcoal forge. I'm out of Gas.

Ill put up pics for the fun of it. If I get around to it soon .


Rob

Improving the longevity of the edge by applying a steeper bevel is nothing new. Most bench chisels are supplied a flat primary bevel angle of 25 degrees. It is then left to the user to increase that bevel angle via a secondary bevel to a nominal range of 28- 30 degrees, or 32 - 35 degrees for mortise chisels. Parring chisels being the exception with a primary bevel of 20 degrees.

Bevel down plane irons are no exception to this rule, generally supplied with the similar manufactured bevel angle of 25 degrees, requiring a steeper secondary bevel to improve the longevity of cutting edge.

Most of the work to apply that secondary bevel is done via the stone, invariably starting with a coarse stone, a medium stone, and ending with a finer grit stone. The requirement for a tool steel that can be easily worked on the stone, that will show tell tale signs of a burred edge being formed, have traditionally been a pre requisite within the type of tool steel required within woodworking. If we select a time period of post WW2, the suggestion that steel producers did not have the knowledge or know how to produce a more wear resistance tool steel than of 01 and W1 is rather questionable, given the fact that molten steel technology during that same time period was well advanced when compared to decades prior. More likely, those same steel producers were well in touch with the requirements of the professional woodworker, and were supplying them with a tool steel that best met their needs. Very few would disagree with the fact that 01 steel can still provide a slightly superior cutting edge to that being offered as an alternative on today's market.

I have little knowledge on pm steel, but can add some comment from what I have read regarding A2 steel. Online tests comparing the longevity of the cutting edge to 01 steel do favor A2. One should bear in mind a some important factors. 1st , that A2 steel requires a higher 32-35 degree secondary bevel to form an edge that's not prone to premature failure. 2nd, results by the tool manufacturers make no mention if the secondary bevel angle on the 01 steel was worked to a similar 32-35 degree secondary bevel to allow a fair comparison. 3rd, being a more wear resistant steel A2 will need additional time to be honed compared to 01 steel. 4th, water stones are recommended by the tool manufacturer to work A2 steel. 5th. 01 steel can be honed on either water or oil stones.

Nothing further to add.

The onus is left to you, and not the manufacturer, to select the right type of tool steel that best suits your own personal needs.

Stewie;

Originally Posted by planemaker

The onus is left to you, and not the manufacturer, to select the right type of tool steel that best suits your own personal needs.

Unfortunately - there is nowhere near this level of transparency among manufacturers of edge tools. Only a very few publish anything useful about their alloy, hardness specification, and other information relating to how their tools will hold up in specific applications.... Those few that do use that as a selling point.

And to your point - that sort of information is useful when you are trying to match the right tool for what you want to do.

An anecdote I heard some years ago referring to graduates of the North Bennet Street School ...

all graduating students know how to use a chisel and select an appropriate sharpening angle. Those who used carbon steel chisels (and plane irons) also knew how to sharpen an edge tool. Those who used HSS edge tools -- at the time primarily A2 -- didn't.

It occurs to me that one of the most difficult aspects of Truckjohn's quest is determining exactly what steel you have. I guess that if you are good at identifying steels from grinding sparks you may be able to make an assessment.

I have no knowledge of how to heat treat modern alloy steels so I cannot offer an opinion there, but high carbon steels are easy: This is the sort of steel used in the leaf springs on automobiles and quite a ready source of material for those wanting to make up their own tools including chisels, plane blades, draw knives etc.. Old circular saw blades are a good source of steel for thinner tools such a knives.

If you have obtained an old tool, let's say a chisel, you can easily rework it and keep doing that until it reaches the right degree of hardness for your purpose. Heat to cherry red and quench (I use oil because I think it is more gentle, but that is a subjective view, not objective, and I have no data to back that up). Now clean the chisel until you will be able to see colour change on the steel. Heat the chisel again but very gently because the light straw colour will appear very suddenly. Quench again.

On the subject of quenching and the distortion some people have experienced we need to take a look at how the knife makers heat treat. The trick is to rapidly plunge the hot steel directly up and down in the quenching medium and in a slight different spot each time so that relatively speaking you are in a cool place within the oil. Do not move the tool from side to side. I use a twenty litre bucket so there is plenty of oil, but this is also dictated by the size of the steel you are treating.

So nice big firmer chisels are robust, but extra long paring chisels will need more care.

I have heard of the old steel, which is primarily high carbon steel, as being called pre-nuclear steel. In other words before WW2. I once read in a woodworking magazine a comparison test between three chisels. The test involved paring a section of end grain timber. The modern chisel (bear in mind this was back in the eighties so at least 30 years ago, maybe more) which I think was a Stanley, but I can't be certain, cut a miserable 6mm before the edge developed a visible "light" to it. The Japanese chisel I think managed about 17mm, but the "pre-nuclear" chisel pared off a creditable 25mm!

i would expect the most modern alloy steels would be able to achieve at least that, but it does point to some very good quality tools around before the onslaught we called WW2.

My point here is that if you have some older tools that need some rehabilitation I think it is well worth while and if it does not work as well as you hoped there is very little lost.

Regards
Paul

Interesting facts on tempering steel.

Definition of Tempered Steel | Sciencing