Broken Tip R Iles Mortise Chisel

[David Eisenhauer]

I was chopping 1/4" wide x 3/4" deep mortises in some pecan (hard) and broke the tip off on my 1/4" Ray Iles chisel on the beginning of the 2nd pass through the 8th mortise I worked on for this project. The tip broke off when I levered back to eject the debris after the mallet strikes and looks like I broke the last 3/16" - 1/4" off of the length. My first pass yielded an approx. 1/4" deep mortise as I don't normally try to drive a chisel as deep as it can go, just tend to strike the chisel with two solid blows (using a 20 oz Wood Is Good mallet) per movement every time. This pass was probably going to yield another 1/4" of depth (see the "hole in photo 2 where I was able to extract the tip from). This pecan is hard, maybe I struck the chisel a little harder than I normally do? Maybe there was a hard(er) spot in the timber?, maybe I powered up on the lever jerk more than usual? (pretty sure this was not the case this time and the "pop" of the break occurred immediately after just starting my first lever pull). Maybe there was some type of minor flaw in the metal? Who knows, I don't have any magnification equipment to take a close look at it and most likely would not know what I was looking at any way. The end of the remaining chisel is approx. 1/8" thick (doesn't sound like a lot, does it) but this will require an amount of grinding to bring it back down to a useful thickness for final hand sharpening. This chisel is only a couple of years old, not much use to date, but used enough to have honed the working tip at my version of a 35 deg angle many times on a couple-three projects. 372220372219372218

[Pat Barry]

Time to put the grinder to work :)

[Phil Gaudio]

I had the same experience: very nice chisels, but poor choice of steel.

[ken hatch]

I was chopping 1/4" wide x 3/4" deep mortises in some pecan (hard) and broke the tip off on my 1/4" Ray Iles chisel on the beginning of the 2nd pass through the 8th mortise I worked on for this project. The tip broke off when I levered back to eject the debris after the mallet strikes and looks like I broke the last 3/16" - 1/4" off of the length. My first pass yielded an approx. 1/4" deep mortise as I don't normally try to drive a chisel as deep as it can go, just tend to strike the chisel with two solid blows (using a 20 oz Wood Is Good mallet) per movement every time. This pass was probably going to yield another 1/4" of depth (see the "hole in photo 2 where I was able to extract the tip from). This pecan is hard, maybe I struck the chisel a little harder than I normally do? Maybe there was a hard(er) spot in the timber?, maybe I powered up on the lever jerk more than usual? (pretty sure this was not the case this time and the "pop" of the break occurred immediately after just starting my first lever pull). Maybe there was some type of minor flaw in the metal? Who knows, I don't have any magnification equipment to take a close look at it and most likely would not know what I was looking at any way. The end of the remaining chisel is approx. 1/8" thick (doesn't sound like a lot, does it) but this will require an amount of grinding to bring it back down to a useful thickness for final hand sharpening. This chisel is only a couple of years old, not much use to date, but used enough to have honed the working tip at my version of a 35 deg angle many times on a couple-three projects. 372220372219372218

David,

Look at the break, if there is an area of dull gray it will indicate a fault in the steel. Stuff happens. If not, but I expect you will see a old fault, then I'd look at how I was using the chisel. BTW, I'd contact TFWW if I found an area with a fault, I expect they would like to know about it and from my experience working with TFWW they will replace your chisel even if there is not a fault in the steel.

ken

[ken hatch]

I had the same experience: very nice chisels, but poor choice of steel.

Care to tell us more?

ken

[Larry Frank]

How would someone know if it was a bad choice of steel without knowing the grade, chemistry and heat treatment. I could break the tip of almost any chisel in that way.

By the way, I am a metallurgical engineer so I have some basis for my comments.

[Pete Taran]

A more accurate statement might be great choice of steel, but poor heat treating.

[Brian Holcombe]

I think an adjustment if technique is needed for this material. I don’t lever but instead chop the waste with another round of chopping before lifting the waste out. You might try something similar when working in pecan.

[Larry Frank]

I think it is impossible at this point to say either poor steel or heat treatment. Most of these steels have a hardness in the upper 50s or higher. Since sharpness and maintaining a sharp edge is important, there is less ductility. Bending them like the OP did put very high stress on them and a brittle fracture happens.

Think about what would happen if you stuck 3/16 - 1/4" of your 1/4" wide chisel into a vise and then pulled back on the chisel. Most likely the tip would break off.

Before anyone makes guesses, it would be great to see a close up of the fracture surface. To really find out what happened, you would need several metallurgical tests.

[Pete Taran]

Larry, I’m pretty sure if you took a piece of hardened steel and clamped it in a vise and bent it, it would break. But that’s not what the OP was doing, he was using a mortise chisel to chop a mortise in wood, the exact purpose it was designed for. I’ve never worked in pecan, but I’ve chopped tons of mortises in hard maple with no damage. If the chisel failed using it for what it was designed for, then I’m putting my money on the tool, not the user.

[Phil Gaudio]

Sure: these were made of D2. I suspect if they had chosen A2 (or O1) which exhibit better toughness, these fractures would not happen. I've seen these metallurgical discussions go down hill fast (sort of like a sharpening thread), so I am not going to bother posting graphs, etc. At the time my chisel fractured, I did a brief search and found a number of similar incidents with the RI chisels. As I said: nice chisels with a great design, but poor choice of steel.

[Patrick Chase]

How would someone know if it was a bad choice of steel without knowing the grade, chemistry and heat treatment. I could break the tip of almost any chisel in that way.

By the way, I am a metallurgical engineer so I have some basis for my comments.

Those specific chisels are D2, though Iles doesn't specify hardness/tempering. I suspect based on comparison to other tools with similar steels that they're around Rc61-62. D2 is commonly used for punch and die work, so I don't think that it's fair to describe it as a poor or unusual choice for an application like a mortise chisel.

Note also that PM-V11's apparent creator has stated that "it can be considered ... a corrosion-resistant D2 tool steel", and Veritas uses it in their mortise chisels, so RI's choice isn't terribly unusual.


A more accurate statement might be great choice of steel, but poor heat treating.

Quite possible, but I don't think the OP has provided enough data to make that call. Certainly something went wrong, probably in fabrication/treatment.

[Stewie Simpson]

Alarm bells should be ringing;


The primary bevel on the chisel is ground to a very narrow 20 degree angle. This of course is not a strong enough angle to hold up to vicious chopping, but it's historically accurate because the narrow angle lets a blow on the chisel push the chisel very deep. And that's what we want - to go as deep as possible with each blow. But of course we have to strengthen the tip or it will bend. So mortise chisels need a hefty secondary bevel at the tip or around 35 degrees. It turns out with D2 steel (see below) we can use a very tiny secondary bevel. It works great and it reinforces the shallowness of the primary angle so these chisels can get even deeper per blow than the old antiques. All you need is a tiny secondary bevel, even a 1/16" is fine. In general we recommend that when you sharpen just sharpen the secondary bevel and it will grow wider. If it gets annoyingly wide just regrind the primary bevel at 20 degrees.
https://www.toolsforworkingwood.com/store/item/MS-MORT.XX/English_Mortise_Chisels_by_Ray_Iles

[Larry Frank]

When one breaks or damages a tool, the first response typically is to blame the tool rather than the user.

Stewie has pointed out that the 20 degree angle is very narrow. Along with the width of the chisel, there is not much support for the tip. If you embed the tip in hard wood and bend the chisel much the tip could fracture.

Without much more information, it is difficult to blame either a mfg defect (wrong steel grade or heat treatment) or user technique.

[Pat Barry]

It wouldn't be surprising to have the combination of levering the tip back and forth repeatedly in hard wood such as this to cause local work hardening of the steel and subsequently resulting in fracture.

[Phil Gaudio]

These pics were still in my photobucket account:

372259

372260

This was cherry, and I had just started working on this mortise. I do recall it did take a while to extricate the errant tip, but I did salvage the mortise. The chisel: not so much.

[michael langman]

Using D2 in forging,punching applications, we always had it double and even triple tempered because it was needed to prevent fracturing under stress.
Maybe Isles doesn't know that.

[michael langman]

Also D2 does not have the toughness of other steels so it is more prone to fracturing under stress, especially with such a small cross section as the tip of that chisel.

[michael langman]

Although S7 tool steel would not hold an edge as long as A or D series steels it would hold up well under the strain of leverage. Easy to sharpen.
I don't know why it isn't used more in wood tools.

[David Eisenhauer]

Just re logged back in and read all of your comments - thanks for the responses, but, for my own taste, I tend to fall more into Ken's line of "stuff happens". I have used the same mortising technique since the 1980's or so (albeit not at all in an all day-everyday situation at all) and have been working my way through way too much left over pecan from a partially aborted commercial cabinetry job from several years ago, but the use of this particular chisel is the new (so to speak) part of the equation. My initial, on-the-spot reaction to the incident was that something was "brittle" because I really just had started my lever pull. I position the tip, two strikes, then one lever pull (push away actually) to loosen the debris and move the tip ahead for the next go around. I don't pry back and forth, don't try to achieve maximum depth per mallet blow. I re hand sharpen the tip at a 35 deg angle any time I feel like it will benefit the operation and don't use dull chisels. Previous to acquiring the Ray Iles chisel, I used a Sorby registered type firmer chisel for many, many years and have been getting used to the differences between the two chisels. I have had the feeling that the Ray Iles chisel was quite a bit beefier in general than the Sorby (Sorby is much more flexible in the 1/4" size) and, with the meat of the Ray Iles chisel running "north-south" in the mortise, felt that it was a more robust chisel although (to my hands) a more "club like" or not as user friendly chisel when first picking it up. I used the Sorby to clear out the broken tip and finish the mortise I was working on and noticed that I tended to pay closer attention to the lever operation than I had been with the Ray Iles. More attention due to the recent breakage or more attention because the Sorby is a different chisel? Don't know. I stand by my initial assessment in the original post - who knows why it broke, but I will grind and re sharpen the broken end for continued use. I will try out Brian's suggestion of a double chop pass before starting to clear (lever) the debris out if I can break myself of 20-30 years habits (I tend to get into a "zone-mode" when chopping mortises) and see how that goes. I'm thinking if it is good for Brian, it might be good enough for me. If I break it again, I will probably discontinue use of the chisel. Actually, the larger question remains - is this incident worthy of promoting a CBN grinder wheel purchase? What say you Derek?

[Patrick Chase]

IMO mortising chisels and wheel grinders don't mix very well. The last thing you want is to be levering on a concave bevel, such that the bevel angle closest to the edge is even less than the average (20 deg in your case).

I use CBN wheels on most of my tools, but the mortise chisels only see belts and flat diamond disc grinders (mostly the latter nowdays).

[David Eisenhauer]

I will use the grinder to get some of the now-way-too-thick end off (of the 20 deg face) before using sandpaper-rough diamond-800/1,000/6,000/13,000 water stones to shape and then hone the final working end of the chisel. You did not answer the most important question, though - does this event warrant a CBN wheel purchase? And if not, what do I have to do to justify a CBN wheel purchase?

[Pat Barry]

I will use the grinder to get some of the now-way-too-thick end off (of the 20 deg face) before using sandpaper-rough diamond-800/1,000/6,000/13,000 water stones to shape and then hone the final working end of the chisel. You did not answer the most important question, though - does this event warrant a CBN wheel purchase? And if not, what do I have to do to justify a CBN wheel purchase?
It all depends on who the decision maker is and what your track record is with previous purchase decisions.

[Patrick Chase]

Back to the topic of geometry, I've always used 20 deg primary bevels on my mortise chisels (initially Narex, now a mix of RI and LV), though with a 35+ degree secondary bevel about 1-2 mm tall at the tip. I have never had issues with fracture, though I also treat levering as a (sometimes very) necessary evil rather than as a "go-to" means of material removal.

More broadly I think that the faster/easier chopping one gets with a 20 deg primary is worth having to take a little care.

I also think that the OP should get in touch with TFWW (assuming they were the source of the chisel). That doesn't look like an expected failure mode to me, and I suspect Joel will make it right unless there's clear evidence of abuse.

[ken hatch]

I will use the grinder to get some of the now-way-too-thick end off (of the 20 deg face) before using sandpaper-rough diamond-800/1,000/6,000/13,000 water stones to shape and then hone the final working end of the chisel. You did not answer the most important question, though - does this event warrant a CBN wheel purchase? And if not, what do I have to do to justify a CBN wheel purchase?

David,

You should know by now, never pass up an excuse to buy a tool no matter how weak :D.

One of the things usually missed on the TFWW blurb about RI chisels is putting a convex bevel on the chisels. Back in the day it was common for mortise chisels to have a convex secondary bevel. I think it makes a stronger chisel and makes it easier to lever.

ken

[Nicholas Lawrence]

For whatever it is worth, I have two antique mortise chisels. One is a 3/8 Sorby. The other is a 3/16 I. Sorby. Both are ground at approximately 30 degrees. I say approximately because both have a convex bevel. It is very slight, and I had never noticed it before putting the protractor on it, but it is definitely there. Neither is anything close to 20 degrees. I have used them both quite a lot, and they work very well.

[Jerry Olexa]

Time to head to the grinder methinks.

[Roger Nair]

David, I suggest that the whole discussion on metallurgy is a mute point since it's the chisel in hand that has failed. The corrective measures should be geared towards your most severe service the chisel must perform. Since the original profile has failed, I would alter towards blunter angles. If you can, I would increase the primary bevel by 5 degrees and have a secondary bevel at least 5 degrees more. A rounded secondary bevel heel seems likely to increase strength at the tip by giving a gradual path for stress to be relieved. I would not hollow grind the finished profile.

If pry and scrape is a desired chisel function, get a lock mortise chisel or a swan neck chisel. Save the mortise chisel for chop and counter-chop and chip clearance.

[Patrick Chase]

David, I suggest that the whole discussion on metallurgy is a mute point since it's the chisel in hand that has failed. The corrective measures should be geared towards your most severe service the chisel must perform.

Given that this is a $70-ish chisel sold by a dealer who stands by their products, I think that any discussion of topics other than contacting the dealer is moot (not "mute", though I'm continually amazed at how many people mess that up).

[Pat Barry]

Given that this is a $70-ish chisel sold by a dealer who stands by their products, I think that any discussion of topics other than contacting the dealer is moot (not "mute", though I'm continually amazed at how many people mess that up).
Considering that the said chisel was used for quite some time doing mortising work in relatively hard material with some significant levering taking place, I'm not so convinced this was a manufacturing defect at all. Perhaps the supplier will be willing to take it back. If so, it would be interesting to hear back what their findings were regarding this particular breakage.


I was chopping 1/4" wide x 3/4" deep mortises in some pecan (hard) and broke the tip off on my 1/4" Ray Iles chisel on the beginning of the 2nd pass through the 8th mortise I worked on for this project. The tip broke off when I levered back to eject the debris after the mallet strikes and looks like I broke the last 3/16" - 1/4" off of the length.

[Roger Nair]

Given that this is a $70-ish chisel sold by a dealer who stands by their products, I think that any discussion of topics other than contacting the dealer is moot (not "mute", though I'm continually amazed at how many people mess that up).

Yes, oops, on the other hand the point could be mute because it does not speak to effect. The dealer should be out of the picture after a few years after sale and the tool has been accepted.

The tool as provided may have been optimized to woods that are on the soft side of the spectrum. It is up to the craftsman to adaptively sharpen tools to the materials used in a project. My suggestion is all about getting to work and adaptation is an iterative process to find an ideal in use. Whatever input a dealer would have is questionable since the dealer normally is remote from the bench.

[David Eisenhauer]

Thanks for the responses. I will not (never considered) send the chisel back for a refund/replacement. etc. I think, perhaps, that some of you may be making more of this than I am and I am not driving any metallurgy talk or unduly unhappy with the chisel. It happened. If it happens again with the same chisel, now perhaps there really is a problem with this particular chisel. I merely thought it may be of some interest to any who had not seen a broken tipped chisel before and related the events that resulted in the break. I saw a couple of opinions expressed as to my mortising technique, but I believe my technique is fairly consistent with traditional methods with the exception of my mallet work - I do not attempt to achieve maximum chisel penetration on each strike at all. Pat - I don't believe that I am performing "significant levering", with a 1/4" depth achieved per (total of two mallet strikes) chop and a single pull/push on the chisel to loosen (not eject) the chip. I scrape/clear debris with a bench chisel when I complete a run through the length of the mortise. I believe someone wrote of creating a final working edge with a convex profile that sounded interesting, but I do not know how to create a convex profile. I have continued using my former mortising chisel (registered/firmer type Sorby chisel with an assumed O-1 steel) that is more flexible by far than the R Iles, but works well using the same technique as when I use the R Iles. The Sorby has a 25 deg primary bevel and a 35 deg secondary or micro bevel. I tried it out a few years ago on some of this same pecan with a 30 deg secondary bevel, but I encountered excessive edge rolling so I steepened the final cutting angle up and the rolling disappeared. As I originally stated, maybe I broke it, maybe it broke, but, at any rate, I will re shape/sharpen it back to the same profile I originally had on it and re use it to see what it does. I will try to go to Brian's suggestion of a double pass down the length of the mortise and only lever on the second pass. That should prevent any future breakage.

[Nicholas Lawrence]

David, the only thing I can add is that I learned a lot from watching the mortising video Paul Sellers has on Youtube. Your mortise looks pretty even in depth all the way across. When I do them, I do more what Sellers shows in that video, with the mortise increasing in depth as you go along. With the bevel, that results in the chisel “pushing” the waste to the side, into the space left by the prior cut, so there really is not a lot of pressure or stress involved. What is being levered out is already broken loose.

I have seen others (can’t remember where unfortunately) do something similar by drilling a hole at one end of the mortise. The waste is then forced sideways by the bevel into the hole, and again pretty much broken loose before you get to the point of trying to lever any of it out.

I am curious how you managed to get the broken tip out? I broke a drill bit in a project once, and was never able to get the broken tip out.

Don’t know if any of that helps or not, but good luck once you get it ground back the way you want it.

[David Eisenhauer]

Nicholas, the photo of the mortise was taken after I used an upside down 1/4" bench chisel to clear out and level out the bottom surface of the mortise to better expose the broken piece for removal. After cleaning and levelling the mortise bottom, I chopped in front of and behind the piece with another 1/4" chisel and used a bench chisel in the front/back chops to create a little "wiggle" room for the broken piece. I then was able to pull the piece out pretty easily. I have seen the Paul S videos and my technique is pretty much the same (only he is a lot quicker). My mortises also go deeper as I progress along the length of a mortise. This pecan seems to create individual chunks when chopped as I progress along the length and Brian's suggested double chop technique should result in smaller/less dense chunks for clear out.