Hand Tools Archive

Subject:
Shooting with a buffed blade in a bevel-up plane *PIC*

Winston
I have a shooting board for squaring and cleaning up right-angle cuts, but I mostly stopped using it a while ago, because the blade would get damaged pretty quickly, and using it involved a lot of sharpening. To be honest, I solved my shooting edge damage problem already: I bought a table saw and built a cross-cut sled for it.

Still, I've been wondering how well a buffed blade would hold up when used for shooting, so I did some tests. I used a Veritas low-angle jack with an A2 blade, and I tested by shooting the end of a maple board that was 3" wide.

The blade was sharpened with a 25-degree bevel on a Shapton Pro 1000, then I worked the back on a Sigma Power 6000 to help remove the burr, then I buffed the bevel side, and finally I ran the back of the blade quickly over the corner of the buffing wheel to remove any tiny remaining burr. When sharpening chisels with the buffer, I don't touch the back to a stone, but I did for this plane blade because I wanted to make sure I had a very straight, clean edge, and because with the burr (mostly) gone, it allows you to do less buffing, which means that the edge angle doesn't need to be increased as much. (This is the same reasoning that David used for his procedure buffing bevel-down plane blades.)

Here's what it looked like to start out with, looking at the bevel and back. I think the little bits sticking up are carbides in the A2 steel:

I also got a profile pictrure:

As I made the cuts, I tried to get shavings .0025" to .003" thick, according to my calipers.

After 100 passes, it was still cutting well. No visible damage, but there was a bit more resistance when pushing, and the part of the blade that was doing the cutting felt a bit less sharp.

After 200 passes, still no visible damage. There was a bit more resistance when pushing, but still not bad. This is what it looked like:

There's one visible defect on the back side of the blade. Maybe it got nicked there -- or maybe a carbide popped out?

The piece of wood looked flawless. If you look closely, you can see the rays, perpendicular to the growth rings.

*****

I also tested a blade that was honed to 32 degrees and finished with a Shapton Pro 12000. Here it is, with the bevel and back side:

No carbides (or whatever they were) sticking up this time.

I noticed that I had a harder time getting the edge as uniform and straight, compared to when I was sharpening the cheap steel and PM-V11 chisels. I don't know if it's because of the A2 steel, or because the plane blade is significantly larger than the chisels, and harder to sharpen completely.

After 100 passes, there was a tiny bit of edge damage. It was barely, just barely visible to the naked eye.

After 200 passes, there was still only a small amount of damage. This was barely visible to the naked eye.

The wood in this case also looked flawless.

After 200 passes, I think that the flat-32 blade had slightly less resistance to being pushed than the buffed-25 blade. This is negligible when you're doing normal woodworking tasks, shooting here and there, but it's noticeable when you're doing 100 passes without stopping.

In summary, the flat-honed 32 degree blade did great -- much better than I expected.

****

At this point I wondered why I ever had problems with edge damage from shooting. Then I remembered that I used to use a lower angle for shooting. I think it was 25 degrees. So I sharpened the blade to 25 degrees, finishing with the Shapton 12000. Again, I had a hard time making a straight uniform edge for some reason. The raggedness is nothing you'd be able to see with the naked eye, but it's there.

After 20 passes, it was getting harder to push the plane smoothly -- it would catch and skip a bit, and the blade was already leaving tracks in the wood:

Edge damage after 20 passes with this flat 25-degree bevel was visible to the naked eye. It was greater than the damage after 200 passes with the flat 32-degree and buffed 25-degree conditions.

This is the edge after 100 passes:

I stopped at this point, because it was getting difficult to push the plane smoothly through the cut and I didn't want to do 100 more passes with it. It was already obvious that 25 degreees is just too low.

This is what the blade looked like at a more normal scale. The edge damage is visible on the right side.

*****

In summary, a buffed 25-degree bevel held up great. A flat 32-degree bevel also did very well -- better than I expected. A flat 25 degree bevel didn't hold up nearly as well.

This is with A2 steel. I don't have any other kinds of blades for this plane, but I wouldn't be surprised if other steels had roughly similar behavior.

Regarding sharpening: I was reminded why people complain about A2. I usually start sharpening on the Shapton 1000, but this blade kind of felt like it was skating on it, and it worked slowly. After a bit I switched to the 1000-grit diamond plate, which worked much more quickly. For other blades that I've sharpened recently, there wasn't such big difference between the Shapton 1000 and the diamond plate.

Someone on another forum mentioned that it looked like the unicorn profile required removing significantly more material at each sharpening. I said it was about the same or only slightly more work each time. For chisels, the dramatically increased edge life more than offsets the possibly slightly increased sharpening time.

In this case, because sharpening the A2 plane blade was so slow on the Shapton, sharpening out the buffed bevel took noticeably more work than sharpening out normal damage in a flat bevel. (But keep in mind that I sharpened the buffed bevel not because it was damaged, but because it was time to reset the blade for another test.)

Incidentally, I can't imagine using these A2 blades without a powered grinder, and even with a bench grinder, the grinding is annoyingly slow. I wish they had blades that were half as thick -- I doubt the extra thickness does anything helpful for these bevel-up planes, and it just makes for more work when it's time to sharpen.

This was just part of the way through the testing:

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