Hand Tools Archive

Some quick tests (lots of pictures) *PIC*
Response To:
Weaver chisel grind *PIC* ()

I did a little bit of testing with using a buffing wheel on chisels. Short version: like David and Bill, I have gotten greatly increased edge durability, but unlike them, my buffed blade takes a bit more effort for cutting (he had the reverse). It's likely that the difference is due to differences in equipment and technique.

For testing, I used a cheap Buck Brothers chisel I got from Home Depot ($21 for a set of three). Normally when I use this chisel, I'm surprised at how quickly the edge gets damaged and folds over, probably because I've gotten used to my nice chisels.

I got a drill-mounted buffing set made by Ryobi, which was only $10 from Home Depot. It came with three wheels and three different compounds. I used the largest wheel, which is 4 inches in diameter, and the finest compound, which is white rouge, and mounted to my drill, which supposedly goes up to 2000 RPM. The wheel is a cushion-sewn wheel, which is softer than the sisal wheel that I saw David use in his scraper video.

The Buck Brothers chisel was sharpened with a 30-degree bevel using a honing guide, with the final stone being a Shapton Pro 12000. Then I used the buffing wheel on it, for about five seconds on the bevel side, and then about half a second on the back.

For comparison, I used a Veritas PM-V11 chisel, also sharpened to 30 degrees with 12000 grit, but I didn't use the buffing wheel on it.

Both chisels were at the same level of sharpness before I took the Buck Bros chisel to the buffing wheel.

Here's what I've found. First, some of the initial observations:

- The buffed chisel had a hairline of reflection at the edge, similar to what David showed in his picture. More on this later.
- Just by feeling the edge with my finger, the buffed chisel did not feel as sharp as the unbuffed one.
- The unbuffed chisel easily shaves hair and can pop off hairs, the buffed chisel could only shave hair with some effort.
- With a push-cut across the grain of printer paper, the unbuffed chisel cuts easily and cleanly. The buffed chisel did not cut as cleanly, but it still could do it. Given the previous observations (about the edge feel and shaving ability), this was quite surprising to me. When I sharpen on just stones, if a blade can't easily shave hair, it won't be able to do this type of push cut. So this is one place where the behavior of a buffed chisel is quite different from a stone-sharpened one.

I then used each chisel to cut endgrain of a small piece of oak, and then chunk of pine. Here are my observations about that:

- The buffed chisel had more resistance in both the oak and pine. The unbuffed chisel cut more easily.

- Both chisels were able to cleanly pare oak end grain.

Paring oak end grain with buffed chisel:

Paring oak end grain with unbuffed chisel:

- However, with pine, the unbuffed chisel cut noticeably more cleanly.

Paring pine end grain with buffed chisel:

Paring pine end grain with unbuffed chisel

- After doing this work, the unbuffed chisel had some edge damage that was visible to the naked eye (this chisel is PM-V11). The buffed chisel looked exactly the same to the naked eye (this chisel is the cheap Buck Brothers chisel that normally folds over very easily).

- With the buffed chisel, I chopped through more of the pine, and it still looked exactly the same.

After doing this, I looked at the edges under a microscope. The appearance of the blade is very sensitive to the direction of the light, so I've included multiple pictures, with the light source in different positions.

- Here's what the unbuffed chisel looked like (after being used). This is the most damaged part of the edge.

- Here's what the buffed chisel looked like. In the second picture, I moved the light so that you can see the reflection off the buffed edge. This is even after the additional chopping through pine. As far as I'm able to see with the microscope, the edge still looks undamaged.

In terms of the angle, you can get an idea of the angle by looking at how light reflects off of it. The angle of the buffed edge in my case is at least 45 degrees, and I think slightly higher. To measure the angle, put the chisel down so its back is horizontal (you'll need to support it with a block because otherwise the handle will get in the way of it being horizontal). Then look straight down at the edge and shine a small handheld light at the edge. Move the light up and down and observe what position lets you see the reflection of the light.

The reason I know that the buffed edge was 45 degrees is because when I did this and held the light directly horizontal to the cutting edge, I could see a reflection. I was actually able to move the light a little lower and still see a reflection, but I didn't have things set up to measure the exact angle.

Edge reflections, with the light positioned horizontal to the edge:

A closer look at edge reflections. Visible edge damage to the unbuffed chisel:

I suspect that the very cutting edge is not just more obtuse, but actually rounded over from the buffing. That's exactly what I'd expect a soft buffing wheel to do to the edge, and it would also explain the increased durability. It makes sense that a uniformly rounded edge would be durable, since the forces from cutting would be spread more evenly. (This is different from an edge that is sharpened with a coarse grit, which would have a ragged edge with little peaks that can bend and break.)

I don't know if it makes more sense to describe the edge as being rounded over, or as having a more obtuse angle at the edge. Let's say the edge had a 1 micron-wide apex before buffing. I'm certain that after buffing, the apex would be much larger than 1 micron, and behind the edge, the blade would be convex.

From my small amount of testing, I agree with what David and Bill have observed, that the buffed edge will be much, much more durable than a regular one that comes off of stones. I suspect that something similar is achievable with a strop, but I don't know for sure.

For me, the edge was noticeably less sharp, but much more durable. I'd like to be able to do what David has done, which is achieve an edge that is both sharper and more durable. It's possible that a harder buffing wheel and/or different compound would work differently. Or maybe I just need to buff it for less time.

I'm guessing that if the soft Buck Brothers chisel can become so much more durable with buffing, a high-quality chisel can be even more durable with buffing. Or, one could buff the high-quality chisel for less time and have less edge rounding (or increase in edge angle), and therefore cuts more easily, and still end up with a very durable edge.

Here are some pictures of the microscope setup. It's a regular microscope, with a phone mount on it.

Messages In This Thread

Weaver chisel grind *PIC*
Some quick tests (lots of pictures) *PIC*
Some chisel pictures *PIC*
Re: Some chisel pictures
Re: Some chisel pictures *PIC*
astonished by picture quality *NM*
excellent pictures!
Another test *PIC*
Re: Another test
Re: question *PIC*
Re: question
could be a database issue...
Second try for picture *PIC*
yellow pine *NM*
Those pictures..
Nice piece of work
Re: Nice piece of work
Light source?
Re: Light source?
I've made a video.....
video...not for the meek...
It's a very funny video
comments on the two pictures.....
bevel width
It's the scale that escapes me
Re: It's the scale that escapes me
Looking forward to it, thanks! *NM*
More on the Weaver Bevel
Re: More on the Weaver Bevel
the premise is different in this case
I don't agree with limitation of your premise
You nailed it
This is hilarious
Jim - here's your guy
Well that escalated quickly.
Moving the needle
Re: Moving the needle *LINK*
Thanks for the memories *PIC*
Absolutely *LINK*
Positioning *LINK*
Where to find unhndled Narex chisels? *NM*
Taylor Tool Works
narex and their hardening....
how I achieved the Weaver Bever
Weaver Bevel
Further defining the Weaver Bevel
perception of penetration?
solving a problem, not creating one...
Re: solving a problem, not creating one...
rolling over edges....
On secrets, incantations and open source
Weaver grind—how is convexity added?
Marc Adams
Could've been felt...
Re: Weaver grind—how is convexity added?
The world is upside down :)
I took a nine day Sellers course
Re: I took a nine day Sellers course
it makes sense
How about making a video?
Period costume?
Re: How about making a video?
Trying things out
Re: Trying things out
Re: Trying things out
failed to figure things out...
Re: How about making a video?
Re: How about making a video?
variations on the already done...
thoughts *PIC*
Re: Weaver grind—how is convexity added?
Re: Weaver chisel grind
making peculiar names
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