A theory..

[steven c newman]

In the quest to get the back of a plane iron flat, is it possible to remove too much in just that small area? Without the rest of the iron being done, soon the iron will be thinner right at the edge, making it not bed properly as the rest of the thicker iron would hold the thinner from any contact with the mouth opening. May be a cause of the mythical chatter one hears about. At least for a bevel up iron.

Also, does anyone flatten the area right behind the bevel? Same as above. If that area is not flat like the back is, how can it mate to the planes bed? You may have a case of a flat back mating to the chipbreaker, but a convex side behind the bevel not allowing the iron to mate to the bed. Or, it may be concave, letting the middle of the iron a space to chatter in? Case of mate to the Chipbreaker, AND the bed of the plane.

Since the only irons I use are the original ones the planes were sold with....including the bevel up block planes. Might be something to look into?

[bridger berdel]

The only time I work on the area just uphill of the bevel on a bevel down plane is rehabbing a seriously fuxxored tapered iron. I've only had to do that a couple of times, and the softer backs of laminated irons means it's not so bad to do. The only bevel up planes I have are block planes (though I have a *few* of those). I think that in the end it isn't much of a problem.

[Pat Barry]

The plane blade should be flat in the area contacting the frog. That is important.

[Andrew Pitonyak]

I was wondering the same thing while working with a blade that had one corner that was far more out than the rest.

I decided that if it was just close to the edge I should grind the blade back, or, if not way too far out, I would essentially use the "ruler trick", which is what I did and it worked well in that one instance. Also, I did not want to take that much of the blade down on an odd-ball blade that I thought would be tricky to replace. It was a new plane given to me after the previous owner died.No name on the plane, but it was made in India.

http://www.sawmillcreek.org/showthread.php?234851-Identifying-hand-plane-made-in-India

[steven c newman]

Would seem that IF there is a big cavity on one face of a blade, there should be a corresponding hump on the other side to match. On a bevel down plane, that hump part may cause the iron to rock from side to side...just a thought..

[Kees Heiden]

Yes, but. The chipbreaker pulls the blade hollow anyway.

[steven c newman]

Have seen quite a few planes come through this shop. About half have wear in the center of the iron, but not the center of the sole......why would that be? The other ones with wear look like this ~ Then I find a hollow in the back of the iron that matches that pattern. Again, the soles are almost flat across the width.

When I rehab a plane, and start on the iron.....I try to spend the same amount of time on the front and the back. Seen a few where a nice shiny spot will appear behind the center of the beveled edge, and shiny spots to the outside corners of the back of the same iron. After a hundred or so planes, one begins to see a pattern.....