Fixing a cupped iron??

[Steve N]

Wilbur, I may be totally wrong in how my mind is seeing this iron, but I'm seeing an iron that will not touch wood completely across it's width, due to the cupping. I wonder, are you seeing this like a Japanese chisel?

[Admiral]

I'm thinking some shims and a large machinists vice would be your best bet, as opposed to hammering it out. Or a combination of both, starting with the vice. Another avenue might be heating it to hammer it then reharden retemper, but I'm way, way out of my league with this sort of thing.

[enjuneer]

If the cupping is not severe (less than 0.005"), the back could be flattened on a surface grinder in a matter of a few minutes. Only about the bottom two inches or so needs to be machined. If I recall correctly, Tablesaw Tom offers this service.

[AHill]

How many blades are we talking about and what sizes? I might have some spare irons I could send you. Alternate to the Hock / Lee Valley / Lie-Nielsen route, Stanley still makes planes and the blades for the el cheapo Home Depot kinds are probably better than some of the vintage planes, and they should fit. A blade for a No. 4 is currently selling online thru Walmart for $13.55.

[Admiral]

I think Dave wants to fettle what he has go, not replace.

[DaveParkis]

I would prefer to keep the planes as close to original as possible, but I also need to be at least somewhat realistic. I think I'll just try putting one in a vise and trying to straighten it that way. They seem to be concave on the bevel side. Thanks!!!

[Admiral]

Do let us know how it worked out, and exactly how you did it.

[DaveParkis]

Will do. Right now, I have it clamped in a good size machinist vise. I'll be trying to close the jaws a little bit more every day. Thanks!!!

[Wilbur Pan]

Steve N said:

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Wilbur, I may be totally wrong in how my mind is seeing this iron, but I'm seeing an iron that will not touch wood completely across it's width, due to the cupping. I wonder, are you seeing this like a Japanese chisel?

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Although Dave has indicated that he has the opposite issue with the concavity being on the bevel side of his plane irons, here’s what was going through my little brain.

This is what the back side of a Japanese plane blade looks like.



The concavity makes it easier to “flatten” a Japanese plane blade, since all you really have to do is make sure the area behind the edge is flat, as opposed to flattening the entire back. Japanese planes are bevel down, as all proper planes should be. ***ducks*** So even though the concavity is there, where the blade touches the wood, the entire edge is engaged.

[Steve N]

Gotcha. The pic in my mind is it was arched up with the cup so the leading edge wasn't touching all the way across.