Plane with a bowed bottom. Is that normal?

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Forum topic by botanist posted 04-23-2012 02:16 PM 1111 views 0 times favorited 7 replies Add to Favorites Watch
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167 posts in 3561 days

04-23-2012 02:16 PM

I’ve got what I believe is a Stanley #5 that I inherited from my father. It was pretty neglected the past few years so I’ve been trying to get it cleaned up. The bottom has some pitting on the bottom that I wanted to take care of and pulled out my granite surface plate and some wet/dry sandpaper and started getting to work. I noticed that the front and back of the bottom were getting some attention from the sand paper, but not the center. I laid the plane on the granite and noticed that there was a slight bow to the bottom. Is that normal?

7 replies so far

View Smitty_Cabinetshop's profile


15367 posts in 2641 days

#1 posted 04-23-2012 02:32 PM

Nope, not normal.

The #5 doesn’t need to be absolutely flat to work, it’s the ‘jack’ of all planes and brings stock into decent shape for follow-up with the jointer and smoothing planes. But shouldn’t have a noticable bow to it. You can safely use the larger grits to get it flat, finers to smooth up, then put it to work!

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View Loren's profile


10476 posts in 3670 days

#2 posted 04-23-2012 06:10 PM

It may not be normal but it’s not uncommon. How flat plane soles
need to be is a matter of debate. A “slight bow” of 1/100th inch
is unlikely to be a problem. A bow of 1/16” probably will be. Between
those two it’s a matter of how fussy you are. Good work can
be done with wooden planes that are not what I would call
examples of straightness.

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David Craig

2137 posts in 3131 days

#3 posted 04-23-2012 08:43 PM

I have flattened planes before that were somewhat concave. I lowered the grit, when flattening, to make the process a little less time consuming. Take a marker and run it up and down the plane. When you start flattening, you will probably see the marks on the front, back, and sides go away while the hollow remains. When the marker is all gone, it is pretty much flat. Move to finer grits from there.


-- There is little that is simple when it comes to making a simple box.

View stefang's profile


15881 posts in 3357 days

#4 posted 04-23-2012 08:48 PM

A bow concave shape on the sole between the toe and the heel might have been done on purpose to minimize friction while planing and to make eventual re-flattening quick and easy.

-- Mike, an American living in Norway.

View Loren's profile


10476 posts in 3670 days

#5 posted 04-23-2012 09:07 PM

Oh you know the plane may bulge a tiny bit behind the
mouth when the blade is clamped in. Normally this is
not noticeable with metal planes but it does occur
I think. So work your plane to flat with a blade and
chipbreaker in there to emulate working tensions on
the plane body.

View russde's profile


104 posts in 2862 days

#6 posted 04-23-2012 09:10 PM

You didn’t mention it…but Don or Dan (both excellent resources) recommend flattening planes with the blades/chip breakers attached but retracted as the tension will affect the sole plate.
I just got a Craftsman #5 with a corrugated bottom that had been neglected for 30 years, and tested this. It’s true. With the plane ‘empty’ the marks I placed on the sole changed when the blade was installed.

View ShipWreck's profile


557 posts in 3775 days

#7 posted 04-25-2012 10:33 PM

Botanist: You did not say how much of a bow. Can you take a reading with a feeler gauge with the plane fully assembled? If it is within a couple thousands, I would leave it alone. Checking flatness by light can make a thin gap look 10 times larger. The critical area for being flat is about 1”-1 1/2” before the mouth anyways. Edge dings are another story….... you should always file/hone those.


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