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What would chip M42 steel?

Jamie Straw

Jamie Straw

Joined
May 28, 2015
Messages
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Location
Bainbridge Island, WA
My D-Way spindle gouge got a tiny chip in the edge today. Really surprised me! Of course, the edges are sharper now, what with my new(ish) CBN wheel:D, but what would cause a chip (tiny, but noticeable)? I've been spindle turning cocobolo and bubinga.
 
Depends on a lot of things. Most tools are hardened to 58 rockwell or harder. If the edge is thin it will chip quite easily if you hit something hard. My bowl gouge is ground to about 55 degrees and the edge is really tough. It's a Thompson particle metal steel and I believe at that time he was hardening them to 60 Rockwell. My spindle roughing gouge is a no name High Speed Steel tool that I had sharpened to a 35 degree cutting edge. I used it that way for years but lately it seems like it's chipping easily so I backed it off to 45 degree grind. I seems to be holding up much better now. Don't know what caused it to start chipping unless the hardening through the bar was not consistent and since it's about 20 years old and I've ground away about an inch and half this new are simply might be harder and more brittle than the edge when it was a new tool.
D way tools I'm sure are quite well made so it's possible that you hit some small hard particle buried in the wood. A lot of woods have sand imbedded in them and will really beat up a tool edge.
 
To echo what john lucas said about the angles, I have had a couple of small chips on my M2 tools lately. I'm pretty sure it correlated to me changing to a steeper angle. Not just that the metal has a steeper angle, but I'm likely presenting them to the wood differently as a result. This seems to be happening more with my gouges than my skew chisels, although I've been experimenting with steeper angles on both types.
 
If the tool has a very thin edge like one of mine that I use for finial and similar work the edge doesn't have much supporting metal behind it which makes it more susceptible to chipping. M42 is a high cobalt steel that is very hard. It is more chip resistant than most other high speed steels, but it can still chip especially from impacts that might occur during interrupted cuts of hard wood.
 
I have chipped edges or rolled over a tiny bit of the edge most often from not commanding my tools to hit handle first while they are in the air above my concrete floor. I have also chipped tools once or twice by whacking the edge against the ways, whacking the edge against the tool rest, hitting a hidden nail in a piece i'm turning, hitting them with another tool......

Sharpening after a chip takes a lot more passes on the wheel than a normal sharpening.
If you did not notice the chip and sharpened the tool you will still have the chip and maybe no clue as tto where it came from.
 
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I also have some of those unruly gouges that will dive head first into whatever there is, and only one time did I try to prevent that by catching a skew, trip to emerge (almost severed a tendon) and lessen learned, let it fall let it fall let it fall :oops:.

I tend to have an acute angle on my tools, as they just cut better, (pluck sometimes though) but the thin edge is weak and can/will chip when hitting anything like lathe or tools or god forbid the concrete floor, but even a hard knot in the wood can do this, or like was said imbedded sand particle etc.

Just keep on turning it was probably just a onetime event, if not you’ll find out if it is just one particulate tool that does it or more :).
 
Leo Van Der Loo said:
.... and only one time did I try to prevent that by catching a skew, trip to emerge (almost severed a tendon) and lessen learned, let it fall let it fall let it fall :oops:.
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:eek:

I have a bad habit of trying to cushion the fall of dropped things by "catching" it with a foot. So far I have resisted the urge to catch a turning tool with a foot.
 
Well I've had 2 interesting skew accidents over the years. The first one fell and stuck point first in the arch of my foot. Hurt like hell. I do catch things that fall with my foot. Learned that as a photographer and saved many a lens. However I did have to learn there are certain things you simply watch where it lands rather than trying to catch it with your foot. The other unusual skew accident was when it fell of the back of my lathe. landed point first right on the 220 cord that goes to the lathe. The arc cut 2 nice deep nicks in the blade and of course kicked the circuit breaker.
I finally figured out how to make your tools not land point first. Ever try to throw a knife and stick it in a board. It always lands butt first. Same is true with tools. Of course in TV no matter what distance it is they knife they throw always lands point first.
 
Jamie Straw said:
My D-Way spindle gouge got a tiny chip in the edge today. Really surprised me! Of course, the edges are sharper now, what with my new(ish) CBN wheel:D, but what would cause a chip (tiny, but noticeable)? I've been spindle turning cocobolo and bubinga.
Click to expand...

There are lots and lots of potential causes. The Steel itself can be flawed. The kinds of flaws can range from heat treating problems to insufficient mixture of the alloy creating weak or brittle areas. As many have stated the angle of the grind can contribute.
Better Alloy mixture is supposed to be one of the benefits of powdered metal.

If you are into reading up on things like this here's a PDF
https://www5.kau.se/sites/default/files/Dokument/subpage/2010/02/93_1343_1362_pdf_76008.pdf
 
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john lucas said:
My spindle roughing gouge is a no name High Speed Steel tool that I had sharpened to a 35 degree cutting edge. I used it that way for years but lately it seems like it's chipping easily so I backed it off to 45 degree grind. I seems to be holding up much better now. Don't know what caused it to start chipping unless the hardening through the bar was not consistent and since it's about 20 years old and I've ground away about an inch and half this new are simply might be harder and more brittle than the edge when it was a new tool.
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I have read that the cheaper HHS tools can be "less hard" past the first part of the tool, e.g., only a portion of the working end of the tool is tempered well. The D-Way tools, and other quality HSS, are quality steel all the way to the top. I recently reground the spindle gouge to be closer to 40 degrees (rather than 45), so the edge was thinner, no doubt, might be a combination of that and wood contamination (and user technique?).

john lucas said:
D way tools I'm sure are quite well made so it's possible that you hit some small hard particle buried in the wood. A lot of woods have sand imbedded in them and will really beat up a tool edge.
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I remember seeing a glint or two in the bubinga after turning the lathe off. Must have been something evil in there.

john lucas said:
Most tools are hardened to 58 rockwell or harder. If the edge is thin it will chip quite easily if you hit something hard.
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Dave's tools are 64-66. I know some people think that's "too hard" but I don't hear complaints from the people who've used them for a long, long time.
 
Bill Boehme said:
If the tool has a very thin edge like one of mine that I use for finial and similar work the edge doesn't have much supporting metal behind it which makes it more susceptible to chipping. M42 is a high cobalt steel that is very hard. It is more chip resistant than most other high speed steels, but it can still chip especially from impacts that might occur during interrupted cuts of hard wood.
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"Interrupted cuts" normally being like a natural edge bowl and such? For sure, I wasn't trying to make interrupted cuts on my bottle stoppers, but ya never know.:rolleyes:
 
Leo Van Der Loo said:
...or like was said imbedded sand particle etc.
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Looking back on the bubinga, that may be it.

Leo Van Der Loo said:
Just keep on turning it was probably just a onetime event, if not you’ll find out if it is just one particulate tool that does it or more
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I've been using that tool for quite awhile now, this is the first nick in the edge, so I think it's OK.
 
I'm voting for something in the wood. I recently bought a three of Dave's gouges for finishing and have the finest sharpened at 35°. I haven't had any issues. Come to think of it, I've cut through rocks with my Thomson gouges and often times there is no nick, though the edge is dull.

Another thing I've noticed about Dave's gouges, and I can't really substantiate it, but I think they sharpen a little faster. The edge seems to last well.

Speaking of dropping sharp tools...being a commercial fisherman, my feet have learned (sometimes the hard/sharp way) to get out of the way. You should see the flying sharp knife in big seas dance.
 
Zach LaPerriere said:
Speaking of dropping sharp tools...being a commercial fisherman, my feet have learned (sometimes the hard/sharp way) to get out of the way. You should see the flying sharp knife in big seas dance.
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Sounds like an episode from "Deadliest Catch".
 
Oh, my. There are a myriad of ways to drop tools. Murphy's Law prevails but, to me, Murphy was an optimist. I was wrapping a guide on a fishing rod and dropped the Xacto knife. It had a #11 blade which is pointed. It hit my leather slipper so I thought everything was OK until I too off the slipper. Thought I would never stop the bleeding!
Jamie, not an expert on turning tools, but if the grind is very thin, anything real hard could cause the chip. BTW, lots of good information. I'm just trying to sharpen my tools to cut half decent!
 
Hard to say what could cause a chip. I would consider that there is a difference between a 'chip' and a 'ding'. For a chip, either you hit some thing really hard, or it is a weak spot in the metal and/or a very thin bevel/wing angle. The HSS is soft enough that if you hit some thing hard, you will get a ding, but it shouldn't chip some metal off the tool. Hitting it on another hard tool, or carbide might provide a good ding, but chip??? I don't know.

robo hippy
 
Sounds like we need the double chain link foot coverings of the knights of st. John......I try not to lay tools on the ways, but use the basket under the ways......the angle u sharpen to I agree has a effect on chips and the unusal stuff found in wood.....
 
Zach When I was doing my sharpening test too see how sharp I could get the 3 different types of steel I noticed that it took longer to get a super sharp edge on the Thompson tools than HSS tools. Now I didn't have a sample of Dave's tools and don't really know what type of steel he uses. However there is a factor in some tools that they call toughness that makes them harder to grind. That is a factor of what is in the steel.
 
john lucas said:
Zach When I was doing my sharpening test to see how sharp I could get the 3 different types of steel I noticed that it took longer to get a super sharp edge on the Thompson tools than HSS tools. Now I didn't have a sample of Dave's tools and don't really know what type of steel he uses. However there is a factor in some tools that they call toughness that makes them harder to grind. That is a factor of what is in the steel.
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Thanks, John. That's sure interesting. I love the Thompson steel, but as far as I can tell Dave's holds up just as well. I love that Dave's sharpen a bit faster, since I've been sharpening at 800-1000 on the CBN wheels for final finish cuts. Between the quality of the steel and Dave's very polished flutes, I'm using his gouges exclusively for finish cuts.
 
john lucas said:
Zach When I was doing my sharpening test too see how sharp I could get the 3 different types of steel I noticed that it took longer to get a super sharp edge on the Thompson tools than HSS tools. Now I didn't have a sample of Dave's tools and don't really know what type of steel he uses. However there is a factor in some tools that they call toughness that makes them harder to grind. That is a factor of what is in the steel.
Click to expand...

Dave's tools are made of M42 which is a high cobalt HSS. M42 is primarily used to make machine tool cutters that can withstand very high temperatures without dulling. D-Way has their tools tempered to a hardness between Rc 64 and Rc 66 which is a bit less than a file. Thompson tools use A11 (CPM 10V) vanadium steel and tempered to Rc 62 - 64. Toughness is one factor that determines the durability of the edge. I haven't noticed any difference in sharpening between the various tools that I have (M2, M4, M42, A11, and a couple unknown). However, I think that I can get some of my tools sharper.
 
I've been following this thread, and can't contribute much......mainly because I don't recall of ever experiencing a "chip" in the cutting edge of any of my tools. Most of my tools are M2 steel, and I'm not sure what the hardness factor is for the tools I most commonly use.

I am wondering if factors like heat from sharpening, and thinness of the steel at the cutting edge (from acute ground cutting angles) might be considered as factors that may effect the brittleness of the very tip of the cutting edge......? Now, if that were so, then a chip could be in the cards, if these conditions were, in fact, a part of the reasons why it could be induced by other factors......such as a grain of sand, or other "hard spot" in the wood......?

ko
 
robo hippy said:
Hard to say what could cause a chip. I would consider that there is a difference between a 'chip' and a 'ding'. For a chip, either you hit some thing really hard, or it is a weak spot in the metal and/or a very thin bevel/wing angle. The HSS is soft enough that if you hit some thing hard, you will get a ding, but it shouldn't chip some metal off the tool. Hitting it on another hard tool, or carbide might provide a good ding, but chip??? I don't know.

robo hippy
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Jamie Straw said:
I considered this a chip -- or perhaps a "nick." Right at the cutting edge, could fit my pinkie fingernail just into it (perpendicular to the cutting edge). If I had had our new camera when it happened, I could have taken a macro, but alas....
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Chips, dings, and nicks ... this is getting complicated. :D I really like Reed's distinction between a chip and a ding and I am more inclined to think that might be what Jamie is seeing. I prefer Jamie's suggestion of "nick" rather than "ding", but I can't explain why. Even though the D-Way tools are hard, I think they would need to be at least as hard as a file (even brittle as Odie suggested) before the edge would actually chip. Every time that a tool decides to take a dive off the bed of my lathe onto the driveway the nice sharp edge gets nicked, but I don't see that any metal actually flaked off which is what I would call a chip.
 
They definitely don't need to be as hard as a file to chip. Drop one of your tools on the concrete tip first and you will usually get a small chip. none of our woodturning tools are even close to a files hardness.
 
john lucas said:
They definitely don't need to be as hard as a file to chip. Drop one of your tools on the concrete tip first and you will usually get a small chip. none of our woodturning tools are even close to a files hardness.
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I say nick, you say chip. I think that we may just hav different definitions of the same thing.
 
Bill Boehme said:
:eek:

I have a bad habit of trying to cushion the fall of dropped things by "catching" it with a foot. So far I have resisted the urge to catch a turning tool with a foot.
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One of the few things I learned (and remember) from shop class.
"If something goes flying - DUCK! And just let it fly!"

Tools, blades, wood etc. Its all replaceable.
Some of the messiest accident are when stuff comes loose, starts spinning out of control - and someone tries to stop it by hand....

(I'm pretty good with that rule, but still need to fight the urge)
 
My son in law is a NASCAR fan. I was watching a race with him when Danica Patrick spun out towards the infield. The camera in her car showed her clearly holding her hands in the air, nowhere near the steering wheel. I asked my son in law why she did that, and he said there is no way to control a car in that situation. Her best bet is to not also break her wrists or arms.

We should learn from that. When something lets loose, get out of its way and let it fly. After everything calms down, then you can see what happened.

This is also why I modified my lathe to have the controls be remote from the headstock.
 
RichColvin said:
Her best bet is to not also break her wrists or arms.
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Yikes! Makes sense, though.

RichColvin said:
This is also why I modified my lathe to have the controls be remote from the headstock.
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Yep. I love the little Comet lathe, with the OFF/On switch on the right. I have a remote switch box to mount to the Jet 1236 with magnets, will place it where it's appropriate for each activity. The stock switch on that lathe is very, very sticky, so not only will it be nice to have a switch away from the headstock, but also to have one that's easy and quick to flick.
 
Yep. Learned that many years ago apprenticing in kitchens. If you drop a knife, your foot probably isn't the best thing to catch with.

Which reminds me of a saying…

If it first you don't succeed, maybe skydiving isn't the sport for you. :)
 
Bill Boehme said:
or ....

If at first you don't succeed then maybe losing is more your style. :D
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Bill, that was seriously funny!

Reminds me of Jerry Seinfeld remarks on second-place: "of all the losers, you were the best"
 
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