Metallurgy for Woodworkers

FWW Bench Chisel Test

Steve Elliott

>I'm going to leave it to the experts to address most of the issues you raise. I'm interested in which Fine Woodworking bench chisel test you think is good. There was one in issue 139 (November/December 1999) that rated Japanese chisels the best, and one back in issue 51 (March 1985) that tested a number of chisels for grain size, among other things. Have there been more recent reviews? I'm not a subscriber, and may have missed one.

Re: Metallurgy for Woodworkers

Todd Hughes

>First I don't think many if any of the old chisels that people today are fond of were hand forged.That Swann or witherby that is so nice were made using a drop hammer and dies in as few operations as posiable The steel was not worked much at all esp. in these chisels where the body is iron.I have never heard of any blacksmith worthy of the name that would work steel cold, or work the piece hot again after he quenced it unless forced to because of a mistake. Working the steel cold is about the worst thing you could do and can see no advantage in quenching somthing befor it is done being worked on.This is even frowned on when working with mild steel or wrought iron never mind High Carbon steel.

I know lots of people get all excited about laminated tools.I don't know how many 100's of laminated tools I have made but has been many and if anybody should be telling you how a big advantage they are you would think it would be me...but its not. You can think so if you want to, thats fine but I don't see how the wood you are cutting knows if the steel that is cutting it goes back only an inch in the chisel of if the entire chisel is made out of steel.In both cases the same steel is doing the cutting.Maybe a very small augument could be made that a laminated chisel is easier to sharpen but boy I don't think it could be much.On laminated chisels you are still sharpening the edge which is mostly still steel and the back of the chisel if you flatten it is all steel ...Wheres the advantage? I believe as many others do that it was done to save on the cost of expensive steel.Once steel got cheaper All steel tools came out and was proudly marketed as being solid steel.Several large disadvantages with laminated chisels, first once you sharpen back past the steel bit you no longer have a viable tool to use working wood. Wrought iron is very soft and iron body chisels can be bent, also how many times have you seen a laminated chisel whose bit has cracked and started to come out because of a poor weld. I know I have seen many.

I think the reason that old laminated chisels have such good cutting edges isn't because they are laminated persay but because they could have cutting edges that were tempered harder since the body was iron. An all steel chisel that was tempered to the same hardness all over to the same hardness as the steel bit used in a laminated chisel would be prone to snap during use.If tempering is done by hand it is easy to just harden the cutting end of a all steel chisel but is harder to do on a mass production assembly line and I think esp. with later cheap chisels it was a comprimise and do the entire chisel so that the cutting edge was softer....Todd

Re: Metallurgy for Woodworkers

Adam Cherubini, NJ

>Todd & c,

If you've got a thick plane blade, mortise chisel, framer or the like, you could have 1/2-3/4" long bevel. If that bevel is solid hardened steel, you may be honing for a while. If it was hardened to 63-65, you'd wish is wasn't. You may have to grind to avoid dubbing the iron (dubbing isn't always a bad thing).

When the blade is laminated, its like sharpening an old stanley .08" thk blade with a perfectly aligned, always attached, .5" iron honing guide!

We should not underestimate the advantages when sharpening:

dramatically faster honing

less grinding

wide foot print (bevel) acts like honing jig

Adam

Todd

Adam Cherubini, NJ

>Todd,

Would you mind telling us the difference between drop forging, die forging, hand forging? Would you also include your thoughts regarding when each was used or on what chisels? I think that would be very helpful information.

Also, do you know the difference between cast steel, crucible steel (I think they are the same) blister steel, and german steel? Have I missed any?

Adam

Answers from your friendly neighbourhood metallurg

Andrew F in Australia

>Adam,

I typed this up once but lost it before posting, so I'll just dot point some replies.

I've got a very busy Saturday ahead of me so there are rough and ready answers - I'll probably make at least one mistake in these

- I've previously typed up what you're looking for and posted on this board, but I'll search later and put up the link.

- Rob Lee (Veritas) has a good summary on the articles section of the Lee Valley site

- Toughness is more important than hardness, as the chisel is not subjected to load in one direction, but is also subjected to torsional and lateral force (twisting and levering)

(definitions: hard = resistance to indentation; tough = resistance to deformation)

So, the hardest possible chisel is not necessarily the best. You're looking for a chisel with high hardness and high toughness.

eg: the hardest chisel is one quenched and not tempered. This will shatter when you lever with it for the first time, either at the edge or in the blade of the chisel.

Lamination:

Helps with vibration dampening - Japanese chisels are also laminated in structure.

Rockwell:

This is simply a measure of how far a steel or tungsten carbide ball is pressed into the surface of a piece of material. The material determines the test result (eg: Rockwell A, B, C,D, E etc....).

The less distance the steel ball is pressed into the surface, the harder the material

Heat treating

THis is the black art that separates the various manufacturers making something out of an identical starting alloy, and alot of it is proprietary knowledge. eg; O2 steel quenched at 20 degrees C gives different results from O2 steel quenched at 24 degrees C in the same oil

So an alloy comparison is a bit subjective, depending upon who did the heat treating.

Re: the edge fineness vs sharpening direction, I'm also a trade cabinetmaker. As long as the edge is sharp enough to pare the end grain of pine or cedar, it's at a fine enough level for me.

Anyway, must run, I've spent 25 minutes typing then retyping this and running late (&10am Sat)

Hope that there's not major typos as I haven't proofread.

Cheers,

Andrew

Re: Metallurgy for Woodworkers

Todd Hughes

>Actually I would think on a solid non laminated chisel the top of the bevel being hard would enable you to more easly keep your corect angle when sharpening.On a laminated chisel the top being softer would wear faster throwing your angle off.After saying this In the real world probaly not much to worry about. I could see how a laminated Big chisel would be somwhat easier to sharpen if you were starting from a square edge[like you snapped the end off] but how often does that happen and why ain't you using a grinder anyway? But for maintenance of an edge?....just don't see it....Todd

Re: Todd

Todd Hughes

>I think most if not all old chisels you are likey to see today were made using water or steam powered drop hammers.A work man took a billet of steel or iron and held it between two dies that formed it to shape in a few hits.Basically the same as they are made today.I would not be surprised if some small chisels were made esp. in England like this but by hand with two workmen using hand held hammers hitting the forming dies as this was how knife blades were made.I would be very surprised if any chisels were shaped by hand and hammered out either by hand or using power hammers with out dies.To many chisels that had to be uniform had to be made for them to be made like this.Just to slow

I'm not home now to look up the difference types of steel but I do know that Blister steel is an old type of steel where thin sheets of iron is basically baked in crucibles containing a source of carbon so that it absorbs the carbon and turns into steel.I have done this befor with thin sections of wrought iron and cooking them in an iron pipe containing bone dust.The trouble with Blister steel,[which gets it's name from the blistering appearance on the surface] is that was hard to get consistant quality.One part might be good but section next to it no good.One way they tried to get around it was forge welding pieces of blister steel together,[sort of like Damascus] and working it out.This was Shear Steel.Ones worked longer was better and called Double Shear Steel. Still find old English knives marked Shear steel ocasionaly. Fellow named Bessamer[sp?] came up with a way to make better steel reliably in a cruciable ,[wanted to make clock springs and needed steel with out soft spots] that could be cast into ingots this was Cast Steel and is the steel used in most of the old chisels we like today. German, Silver, London,Spring, are all variations with maybe added ingrediates, probably the biggest being a good bit of Hokum.....Todd

Re: Metallurgy for Woodworkers

Bob Hackett

>Adam,

As you`ve seen this can be like the LA/BU vs BD plane issue,many different theories and opinions.

As an alternate solution I would suggest posting a list of references that could be useful to any WWer interested in metal working.My list would be;

Machinery Handbook,Pick up an old copy if the newest one is too pricey for you.It`s the bar none most comprehensive reference I know of for all things metal related.

Tool Making for Woodworkers by Ray Larsen,Ray explains eveything from what to look for at the scrapyard to how to build a coal fire to heat treating to step by step making of 4 different woodworking tools.

Any book by Alexander G Weygers,The 3 volume series is out of print but the compilation I believe is still out there.

ABANA(Artist-Blacksmiths` Association of North America) puts out a newsletter which includes articles on toolmaking.

Many of the knife maker`s guilds put out newsletters that contain info we can use for our purposes

New Edge of the Anvil by Jack Andrews was recently recommended by a fellow toolmaker.I plan to add it to my bookshelf.

What most of these references have done for me is to give me information I can use and apply in my own shop to make tools for myself and my friends.

There are other books out there that tell about the chemical/physical process of turning austenite in to martensite(or is it the other way around)or building a brick forge or the proper gas mix for GTAW welding or heattreating in inert atmospheres with computer controled furnaces but is it something I`ll ever use?

Perhaps we could have a challenge involving metalworking similar to your chest challenge only this time we could aim toward a useable WWing tool as the end result?I`d be glad to help set it up in any way I can,I`m walking some stoneworkers thru a similar process as we speak.

I think it`s a valid and important skill for a WWer to master.If nothing else it`ll show you how to bring those sub-par chisels up to snuff yourself.

Mainely,Bob

Article on Tool Steels *LINK*

Steve Elliott

>The link below is to an article that describes the properties of tool steels, namely hardness, toughness and wear resistance. Although the article is intended for metalworkers, the properties are the same for woodworking tools.


Selecting High-Performance Tool Steels

Re: Metallurgy for Woodworkers

Dennis McDonaugh

>I've seen gouges labeled "cast steel". Wnere do they fall in scheme of things?

Re: Metallurgy for Woodworkers

steve knight

>it is difficult when grinding lamianted tools to get a good grind. when I use my makita with sandppaer the blades tend to grab. and you have to be careful to maintain the correct bevel angle or it is easy to get a steeper angle after awhile.

Re: Metallurgy for Woodworkers

steve knight

>it's fun to play with heat treating. but to get consistant results it takes a lot of skill. even if it was cost effetive I would never try to heat treat my blades myself.

you should see the effort the japanese put into heat treating to get great tools.

laminating steel does more for plane irons then chisels. a solid steel chisel and a laminated one will cut the same. though the edge may laster longer and other thigns make it better. but in a plane iron you get several good things from laminated steel. first the blade vibrates at a higher pitch and that makes it have less tearout (I think) and cuts a cleaner surface. but it also makes the tool easer to move through the wood. and when talking japanese steel it usualy holds an edge a fair time longer too.

Re: Todd *LINK*

joel

>Cast steel is a different thing than bessemer steel. the latter is a mild steel and isn't used for tools. See the link below for dates and inventors.

While the very largest makers of edge tools might have drop forged thier tools into dies most didn't. For two reasons:

Cost - the size of a hammer that can reliably forge a tool into a die is big and expensive. Also tooling is expenseive.

"grain of steel". Michel Auriou, who makes really fine edge tools in addition to his rasps says that the reason drawing of the steel from a billet was used also has to do with the "grain of the steel" apparently you get a better edge retention this way. He pointed out that other top makers hand forge (with drop hammers) for the same reasons - Ashley Iles for one. (AI has a few short videos of the process on their web site).

For carving tools especially using formed dies just isn't practical. there are over 500 different carving tools.

I don't know how bevel edge chisels used to be made but these days the bevels are always ground in from square blanks. I don't know how much forging the blanks go through.

The tang and bolster of the tools is always forged seperately and at the start of the process so that for the rest of the process the toolmaker has something to grap onto.

One advantage of making chisels from modern alloys is that you don't need to do any forging. since it's skilled work it makes a difference in cost.

I just remembered that Two Cherries forges each chisels in a series of steps. In my office I have a step by step board of a chisel at each phase of manufacture (I also have one for an Ashley Iles gouge). No drop forging for either company.

Is there a difference in the quality of a drawn out chisel versus one not forged (both in carbon steel). I would say yes.


http://www.davistownmuseum.org/lecShipbuildingTools.htm

Interesting stuff Joel...

Christopher Fitch @ Memphis

>

Re: Metallurgy for Woodworkers

Bob Hackett

>While all this batting back and forth of info about grain size and cryo tempering of alloy steel is useful in that it helps us make informed decisions about what to buy I was hoping to post info folks could use to make and modify thier own tools themselves.

I`d like to see more info from folks like Mr Horn about tapping out a japanese plane iron(if I can sweat thru it surely others can with the CORRECT guidance),or Bill Tindal about how to make informed decisions on what CPM alloys to buy,where to buy it and who to trust to heat treat it at the upper level of skills.

At the lower level I`d like to be able to put in the hands of entry level metalheads things like working metal parts useing WWing tools.How to anneal,harden and temper found or purchased HCS in your own shop,etc.

At the mid range of skills simple forge construction and use comes to mind.

Any interest in something like this or am I veering off on a sideroad nobody but me finds interesting again?

Mainely,Bob

Chisel Toughness

Don Thompson - Cutler Ridge, Florida

>So, the hardest possible chisel is not necessarily the best. You're looking for a chisel with high hardness and high toughness.

That would seem to indicate that the FWW article of a few years ago in which they rated chisels by hardness was flawed.

Re: Metallurgy for Woodworkers

Adam Cherubini, NJ

>Bob,

I was hoping to post info folks could use to make and modify thier own tools themselves.

Any interest in something like this or am I veering off on a sideroad nobody but me finds interesting again?

I'd like to answer that. My primary interest is in harnessing the mental horsepower here to help woodworkers sort out truth and hype. At least a WC article could bring everybody to the same place in terms of basic terminology.

In my opinion, its important to know (and we haven't discussed this yet) whether you need a Tormek grinder or not. We need to know what it means and what to do if an edge turns blue. If its a LV A2 plane blade, what does it mean? If its a cast steel chisel, what does it mean? What tool can we hit with a hammer?

I like your idea of including references. I have Larsen's book.

Adam

Re: Drop hammer forging

Larry Clinton - Frankfort, Indiana

>I operated a drop forge hammer & die forged brush cutter blades when I was about 18 years old.

I did this at Tuthill spring company in Momence, Illinois. Speaking from experience and also as an Engineer, (Process and Quality for 38 years), I would venture to say the main reason the drop forge has been discontinued is safety.

The hammer I ran had a head (flat die) weighing over 1,000 lb. It was lifted about 12 feet by 2 rubber coated rollers driven by an electric motor. The rollers closed on 16" laminated maple 2 X 4's. Six of these were inserted into a slot the top of the die and wedges driven in to secure them. They did come loose occasionally - causing the hammer to fall and the 2 X 4's to exit via the roof.

The lower die had the form machined into the surface to shape the end of the cutter blade. The blades were 5/8 thick 4 inches wide and about 4 ~ 5 foot long. The end of the blades were heated in an open furnace until bright red / orange. You then removed the hot blade, inserted the end in the die and pressed a foot pedal to drop the hammer.

As can be surmised, a lot of people misplaced the blade in the die (would lift you right off your feet), injuries were frequent. The hammer also was so loud most of the personnel who had ran it for more than 6 weeks suffered permanent hearing loss. Once the hammer was released there was no way to halt it till it hit the bottom.

Granted this was one of the larger units, but I think the safety issues remain in the smaller units for chisels etc.

hardness, toughness, wear discussed

bill tindall

>I can't comment on the evaluation as I did not see it but one can't ignor toughness. In use an edge will fail by wear, deformation (bending, crumbling) and/ or chipping. The alloy composition as well as the heat treating will all have an effect on these properties. All three properties must be optimized to be as high as possible. If one is weak the tool will fail in normal use(think cheap chisels).

If the metal is not tough enough it will be brittle and it will chip. Japanese chisels are a notable example. If they are sharpened at too acute an angle the edge chips. If they were tougher they would not chip, but the only way to make their metal tougher is to make it softer. If it was made softer then the edge would deform in use and not wear as well. Someone decided that for these chisels and this metal that they would be made hard and sacrifice some toughness. The result is a chisel that performs well when sharpened properly. If someone came up with a better heat treatment or different composition to toughen these chisels while maintaining the same hardness, then they would not chip as readily.

Sorby chisels rarely chip, but they fail by deforming(crumbiling). Likely the metal used in these chisels can't be made any harder, or it would be.

Glass and carbide are both hard, but brittle (not very tough). So they are useless for chisels.

I believe that CPM 3V offers the best combination of toughness, hardness and wear for a chisel, but we have already plowed that ground.

In the above context "hardness" is resistance to bending. The Rc hardness commonly measured is a resistance to penetration. It is indirectly related to bending resistance and wear resistance. So, two chisels each at Rc 60 may perform very different in terms of wear and crumbling. Toughness is measured by wacking a test piece ever more severly until it breaks. There are numerous toughness tests, each a better predictor of performance of a metal for a particular application.

Andrew questions

bill tindall

>1. Heat treating: My limited experience in this technology is a result of contact with a steel supplier and three heat treating operations. In my case the heat treating schedule was developed by the steel supplier and the heat treaters tried to convince me that they would faithfully follow the directions of the steel supplier. It did not seem to me that there was any "black art' and nothing propreitary involved. The heat treating schedule is on the steel suppliers web site. I was led to believe that the steel supplier had investigated with designed experiments the heat treating variables, came up with what worked best, provided this information to heat treating shops, and expected them to follow directions. I came to believe that the only variable among heat treaters would be how well they could follow the steel manufacturer's directions(care and equipment). Did I get the wrong impression?

2. I believe that you may have defined toughness incorrectly. Toughness tests measure resistance to impact-how much force does it take to break-not bend- the test piece. My steel supplier defined "hardness" as resistance to bending. Rc hardness is resistance to penetration as you stated and it is related to, but not the same as bending resistance. Summary-if it is hard it resists bending. If it is tough it resists fracture(is not brittle) Obviouls one would like to have each property as high as possible to minimize chipping and crumbling failures at the edge.

What is 'Swedish Steel'? NM

Tom Colligan, Peoria

>

Re: hardness, toughness, wear discussed

Don Thompson - Cutler Ridge, Florida

>Thanks for the info, Bill.

BTW, it may not have been the FWW article. There were a couple of articles about two years ago, and one of them just tested the hardness of the chisels in two or three places. I questioned the conclusions using that methodology. Sometimes it seems that magazine writers think they have achieved the be-all and end-all of fair, impartial testing when they have not. Remember the FWW sharpening methods test last year?

Re: Andrew questions

Andrew F in Australia

>Hi Bill,

It's late at night here (11pm) so a quick reply -

You'll find that even if the different heat treaters follow a set schedule, there is a good possibility of a variation in performance. Just my experience as well as training - reasons previously stated. You mnay have a different result.

Yes, steel suppliers provide heat treating schedules. As you said, some heat treaters are able to perform to tighter tolerance levels and with more consistency than others.

The black art that I refer to is the proprietary knowledge that allows the manufacturer to develop their published heat treatment schedule, or, more commonly, how a plant that makes (for instance) gears is able to improve the wear resistance and life of their gears compared to the competitor down the road - initially, they follow the mfg's schedule, but then improve upon it as necessary. The same would apply to toolmakers.

Toughness I defined simply. Strictly, one of the best measures of toughness is the integration of area under a stress/strain curve.

As you said, glass is hard but brittle, and we know it isn't tough.

Silicon rubber is anything but brittle, but not hard, and it isn't tough

Steel is a comnbination of the above and is moderately tough. Other metals are similarly tough.

Toughness is usually measured by swinging a large hammer (held in an accurate and precision machine) at a sample of accurate and specified geometry, thus snapping the sample and measuring how far the hammer goes beyond the sample. The less distance the hammer travels, the more energy absorbed in the fracture = a tougher material. This is called "notch impact" testing and the most common versions of this are the Izod or Charpy test.

The dictionary definition of hardness is resistance to indentation.

The 'stiffness' you refer to is related to hardness, and is called the 'modulus of elasticity,' often in charts as E. This is a measure of how much force is needed to deflect something to a certain level and then have it spring back to it's original shape. Higher force needed = higher value of E. Hope that this helps clear things up if you're talking to your supplier again

Trust that this clears things up somewhat. (11:20pm)

Cheers,

Andrew

Bill, dictionary definition of toughness *LINK*

Andrew F in Australia

>Hi again Bill,

Attached link from on-line dictionary of metallurgical terms.

Toughness is the energy absorbed in bending and breaking the metal (it bends some before it breaks, depending on the metal)

Cheers (I'll be off to bed soon),

Andrew


http://metals.about.com/library/bldef-Toughness.htm