Thread: Chisel Hardness Study, the first step.

It's the one that Stu sells. Stu and I used to do trading of things, so except for whatever it cost me to get the trade fodder, I didn't pay for it (the trade fodder probably did cost me more than the chisel, though...who knows. I don't keep score).

I'll go look it up so that you have a name to attach to it.

It's the ones that Stu has titled as "'Funmatsu-Nezumi' oire-nomi."

(the maker is fujikawa).

I just looked up the definition of horse trading. That's not really an accurate description, it's more like screwing each other around trading things that weren't available in country. Stu would ask for norton this or that, or DMT, and I'd barter or bargain other stuff. Kind of fun - not mean spirited or trying to get one up on each other.

Okay, here's the hardness testing results. The Group St. Dev. and Average St. Dev. are the same in the case of the Funmatsu-Nezumi chisel because only one chisel was tested. Nonetheless, it's the hardest chisel in this set. It'll be interesting to see how it cuts.

Sharpness testing results 030218a_Page_076.jpg

Yikes! Rc 65-66! Most likely I could not get any work out of a chisel that hard. I just don't have the right skill/technique. It would be chip city..

I'm sharpening it now.

It was sharp on arrival but I decided to take it through my usual procedure to keep as much as possible constant.

SUPER tough chisel. Cuts well with diamond and up to 1000 grit water stones but after that it's really, really abrasion resistant. I'm on 3000 now and have been for the past 30 minutes.

Originally Posted by truckjohn

Yikes! Rc 65-66! Most likely I could not get any work out of a chisel that hard. I just don't have the right skill/technique. It would be chip city..

Yet, that is not quite up there with some PM turning tools that come in at 66-68 on the Rockwell C scale. They sharpen readily on a diamond or CBN wheel (in a matter of seconds and as I can see Rob is finding with the Funmatsu-Nezumi on diamond plate) and the PM composition brings down the grain size to give an acceptably sharp edge. We try not to bury them in wood and then lever/twist them (aka a catch), so there is usually not the same forces involved with a struck blade. The only time I have observed a chip in one of these PM edges is when I have dropped the tool on the concrete floor...... : ~{

I appreciate that Rob's study is about carpenter's and cabinet maker's hand chisels and not about turning tools or knives, or hatchets, etc., so my comment about the HRC of PM HSS turning tools is somewhat irrelevant to his purposes. However, there is a continuum on which the hand chisels for various uses sit and an understanding of what is happening with the outriders on that continuum may be of some value.

PS - the PM blades may hold their edge for longer, but most experienced turners find that the PM blades don't hold their edge as long as the manufacturers claim, which then calls into question their additional cost.

PPS - as would be expected, the performance of PM blades depends on the tight control of tempering (Cryo or otherwise) and variable performance is experienced between and within makers. So, just because the blade is made from PM doesn't ensure better performance.

Finally got the FN chisel as sharp as I can get it. With just over 100 grams of cutting force on the HTSTD (as described above and previously) the FN PM chisel has shown that it will get as sharp as any other, just takes a lot of effort to get it there.

Originally Posted by rob streeper

SUPER tough chisel. Cuts well with diamond and up to 1000 grit water stones but after that it's really, really abrasion resistant. I'm on 3000 now and have been for the past 30 minutes.

My HSS tools are one of the reasons I went with some Sigma Power 'Select II' waterstones that Stu sells. They are softer stones than most people prefer, but perform well on HSS and PM.

Sigma Power 'Select II' stones. : Tools from Japan, Japanese woodworking tools direct from Japan.

However, if you prefer harder stones and don't have many HSS blades, it may be hard to justify them for just a few blades.

Do you ever look at the real Scanning Electron Microscope pictures, real pictures, of the edges?
No back shed guess-work, will save you bags of time and money.
Steels shred. They have zero crystalline stricture like a flint or a diamond edge.
I discovered that I was knee deep in modern mythology. Saved me quite a lot of money.

Originally Posted by Robson Valley

Scanning Electron Microscope pictures, real pictures, of the edges?

At this point EM is beyond the budget. I could get it done if I wanted to pay about $1300/specimen. Maybe later.

I sharpened that powder HSS chisel on a medium crystolon, fine india and then probably rubbed it on a hard arkansas followed by japanese whetstone dust on jasper. Rob isn't afforded the biases that I am, because each chisel needs to be identical. As I sent it, it had a very lightly convexity on the edge, but nothing like paul sellers does. If it wasn't HSS, I would sharpen it flat as that's japanese tradition.

The crystolon is extremely strong cutting (faster than any waterstone on the market in the 220+ range, and with better swarf clearing because it's in oil), but the rest of the stones are not so much, they're just removing scratches. A refreshing routine in regular work with fine india, arkansas and whetstone dust on jasper would be two or three minutes. It's actually quite a practical chisel, and I expect that given the condition of the edge under a microscope (uniform with no strange behavior at the edge - I didn't take a picture, but should have), it should last well in actual use. The same hardness bound for carbon steel doesn't apply to it.

It's bizarre how well a marginal cutting stone works if you sand the dust off of it and put it on an extremely hard surface. The dust that I have is from old japanese barber hones that I had to lap flat to sell. I just decided when it started to pile up, I'd keep some of it (free) to try on a leather strop (that was pointless). On jasper, it can be crushed down to its actual particle size in use and make a very fine edge, but also cut well, and to my surprise, it worked well even on this.

The total time to grind and hone it setting the initial bevel and all was about five minutes, but I'm afforded the ability to do it freehand and keep the biases in my favor, and spend the time with the dust only at the very edge.

Originally Posted by Robson Valley

Do you ever look at the real Scanning Electron Microscope pictures, real pictures, of the edges?
No back shed guess-work, will save you bags of time and money.
Steels shred. They have zero crystalline stricture like a flint or a diamond edge.
I discovered that I was knee deep in modern mythology. Saved me quite a lot of money.

I'm curious about what you mean. I don't think an SEM is helpful, other than to show what you describe. They certainly do have a crystalline structure, but it's over-discussed with tool steels, especially the plainer types, which have a fairly small grain size, and can be abraded fairly easily.

I'm curious about the comment that knowing that saved you a lot of money, though. The best data available is generally what you hear from experienced users, past or present (but that can be hard to find, because they're past the point of talking much about chisels in a sea of newbie purchasers who just want something that they think will hold an edge forever or that will fit in a guide easily).

Carving in very soft woods requires very sharp edges. At the same time, there has to be enough steel behind the edge to support it in service.
When I was taught freehand sharpening ( full-time professional carver), the concept was to keep going to 8000 or 12000 on water stones.
Therein lies a considerable investment.

I "feel" about 30-40 minutes service from edges in western red cedar and in yellow cedar with Pfeil gouges. They are of consistent quality.
The harder steel of some crooked knives (5 brands) performs about the same. That is comfortably subjective!

Then I bought and read Leonard Lee's book. The National Science and Engineering Research Council of Canada did all the SEM as your CSIRO could do.
From the micrographs, I could see that 1500 grit then a final treatment with CrOx/AlOx was going to be about as fine an edge as I would ever find for my application.
So I did that. Instead of shaving arm hair protein, I tested my edges in my wood carvings as progress.
I got as far as buying some 4k waterstones but they have been boxed up for a few years in favor of the 3M wet & dry fine automotive sandpapers.
I stick them down with masking tape. I never find their use as objectionable as many people do.

Freehand sharpening comes from knees, not elbows. I use 30, 28, 25, 20, 15, 12, 10 & 6 degree angles, depending on the tool.
I confess that I actually do have some straight edges (draw knife, spoke shaves and carver's stop chisels) , they are hand work as well.