Flattening Plane Soles - Block and Bullnose Planes

[Don Penniman]

I have read many articles regarding flattening soles of planes, many or most stating that flattening is essential.

I have a Stanley #60 1/2 block plane and and Stanley#90 bullnose plane that I am expecting to use a lot in the near future. My general question - how essential is it to flatten the soles of small planes? The block plane is used for trimming the edges of small pieces, trimming small areas of gnarly grain, and rarely for trimming end grain. The bullnose plane is used for trimming in tight spaces. In the long term, I plan to use both for shaping the braces and sides of guitars (my long-term pipe dream). Using an accurate straightedge, I see less than a hair's breadth of light along the length of the block plane and virtually no light along the length of the bullnose plane. I am going to upgrade the block plane with a Hock iron.

If I venture into flattening the soles, what grits of sandpaper are recommended? (I have seen lots of conflicting info on-line) Any pitfalls I should be aware of?

(As an aside, many years ago I foolishly bought a Stanley #75, which I have never gotten to work acceptably. It seems lots of other woodworkers have had the same experience. I was thinking of experimenting on the #75 before I started working on my valuable planes)

[Andrew Seemann]

Some people view sole flattening as an essential part of woodworking. Others think sole flattening is a pointless waste of time and far more likely in practice to mess up your plane than make it better. I tend to be in the latter camp.

I definitely wouldn't bother flatting the sole on a block plane. If you did have one that was so messed up that the sole rendered the plane unusable, I would just use that for a parts plane and find a better one. Old Stanley block planes are relatively cheap, and there usually is no reason to spend a lot of time fixing one up unless you are really attached to it, like if it was your great grandfather's.

[Jim Koepke]

Don, it is likely true more people actually make their plane worse by trying to lap the sole than actually improve the plane's performance.

Before taking any action on a planes sole, it is necessary to determine if there is really anything wrong with it. If no problem can be found and defined, there is no reason to attempt to correct it.

jtk

[Jason Buresh]

I also am in the if it ain't broke don't fix it camp. I've had one plane in my lot that must have exclusively been used on narrow boards and that is the only one that has needed lapping. Try your plane before you start to attempt to flatten it. And don't think if a plane isn't performing it's always the soles fault. Sometimes it's a finicky lateral adjustment. Sometimes it's a poorly fitted chip breaker. There are many variables, but rarely is it the sole.

As a side note, I have a 75, and I love it. I actually just used it tonight to trim a piece i already installed on my bookcase but needed a slight tweak.it can be a handy little plane

[James Pallas]

Don, Don’t do it. If you see no light or very little there is not much to improve. As far as your #75 goes go back and look at my posts from a year or more back about that little plane. It was never a “bull nose” plane. And yes the nose of the plane was intentionally made out of plane with the sole. Great plane when used as intended. It’s been about a year now so the little #75 needs to get lambasted once again��
Jim

[Brad Roof]

Don,
I would try and use each plane on some scrap boards. With your block plane you should be able to get a very thin (transparent) full width shaving. If you are having a hard time accomplishing that then try flattening it. I use 120 and 220 grit sandpaper on something flat.... whatever that flat thing is check it with your straight edge. If it's better than the plane sole than go for it...a block plane is easy to do...I spray the sand paper with a light adhesive and stick it down...use window cleaner for some fluid and go for it...it doesn't take long...you will not do anything that can't be fixed ..but I think the important thing is let the performance of the tool guide the amount of tuning you need to do.

[Scott Clausen]

I think on a smaller plane the risk of rounding the bottom is significant. On a larger plane I don't think it is required unless it is really whacked out. That said when I do a full restoral and want to make it shinny I will flatten the sole. I don't think I can blame any of my plane errors on the sole flatness. This give me an idea for next time I screw a board up I will loudly proclaim, "It's this damn plane sole not being perfectly flat that made me do this".

[Jim Koepke]

With your block plane you should be able to get a very thin (transparent) full width shaving. If you are having a hard time accomplishing that then try flattening it.

It might be prudent to check the blade first. It isn't uncommon for people to have cambered the blade to prevent a full width shaving. Sometimes it is an unintentional cambering. Make sure the back of the blade is flat across the full width. A small bevel on the back (aka "ruler trick") can cause problems with a bevel up blade.

To repeat, if the plane is working without any discernible problem(s), then it is unlikely abrading the sole will make it any better.

jtk

[Luke Dupont]

Be very careful not to round the bottom, whatever you do.

The No. 5 1/4 that I have now -- my primary plane -- came with a very rounded bottom. The edges -- all of them, were high, and pretty significantly so. The bottom around the mouth wasn't making full contact, either. The bottom was patina'd, but I've never seen a Stanley like that before. My guess is that someone in the distant past tried to flatten the sole and just rounded it.
I've thus far managed to correct the majority of it. Half an inch at the toe and heel, and maybe 1/4 of an inch around the edges are still a tad low, but it's use-able and much, much better than it was.
I only did this because the plane was significantly out of flat when checked with a straight edge, in all directions, and with a belly in the center.

So, yeah. If it ain't broke, don't fix it. But if you do need to fix it, be really careful, especially if there's a belly. It's easy to just rock along that belly and make the problem worse. I had to work on the center with a coarse stone and sandpaper to create a flat registration face first.

If you have a perfectly flat diamond stone (check it), that should be preferable to sandpaper and the like for flattening the bottoms of small planes, as it's less likely to round over. But the rocking problem still exists if the plane already has a belly.

[Brad Roof]

For those that have rounded the bottom of a plane...can someone explain how it happened? I have flattened the soles of a handful of planes and I have never done that. I typically lap in a criss cross direction with even pressure...I am curious if someone could articulate the common reason why this happens?

[Luke Dupont]

For those that have rounded the bottom of a plane...can someone explain how it happened? I have flattened the soles of a handful of planes and I have never done that. I typically lap in a criss cross direction with even pressure...I am curious if someone could articulate the common reason why this happens?

I've never rounded one myself, but I have accentuated the problem by starting with a rounded bottom and just pushing back and forth. If there's a hump in the middle, and you just push back and forth / criss cross / whatever, the plane will just rock on that hump and you won't be fixing anything.

Other potential causes would be:

1. Not using a perfectly flat surface
2. Using a surface (ie sandpaper) with too much give, ie, if the sandpaper and doublesided tape or whatever you are using compresses under the weight of the plane
3. If there's any twist in the surface you're using (a lot of people tend to neglect checking for twist, even when they check for flatness in all directions)

Not sure what else, but a variety of abrasives, surfaces, and starting condition of the sole can lead one to accidentally round the bottom. The remedy, of course, is to just keep checking your progress with a straight edge (and maybe winding sticks even), rather than just trusting that all you need to do is get scratchmarks along the entire surface.

[Brad Roof]

At the end of the day...you need to keep track of your references...if you show a straight edge to your plane...then show that to your lapping surface.....keep checking that master reference and things should be ok...I concur with the check for twist if you are trying to lap across a large surface area...even pressure...and error on the side of a courser grit.....it's a pretty straightforward job...and keep in mind the critical areas that need to be in plane...the toe area before the mouth and some reasonable area after. A little hallow in the middle of the back is typically not a problem...

[Bob Jones 5443]

I don't know, this seems a simple operations to me. Get a flat reference surface: a granite surface plate would not be overkill. Maybe you know someone who has one for his or her waterstones.

Then get a length of pressure-sensitive adhesive (PSA) sandpaper. You'll be fine with some 80 grit and some 220 grit. This supply can be pricey.

Now blacken the sole with a thick Sharpie. Retract, but don't remove, the blade, and tighten in place. Then run the plane over the 80 paper a few times –– straight forward and back –– taking care to balance the downward force left and right. Lock your elbows and arms and move with your legs.

Take it up and see where the black is. Where it's still black, you have an indentation, a belly. Mostly you don't want it black just behind the mouth. Stay with the 80 grit until there's no more black.

Switch to the 220 grit. Clean and then re-blacken the sole. This time you can just use an outline around the perimeters of the fore and aft sections, plus a line down the middle, with a little extra just before and after the mouth. Once all the black is gone, you're done.

No need to go to 320 grit, although some do. You can finish with some Autosol metal polish. It's overpriced on Amazon.

https://www.amazon.com/Autosol-Utoso...a-563996090104

But it's cheaper elsewhere, and it lasts forever. Apply it and work it with 0000 steel wool and you can get a near-mirror finish.

I was much too scared to consider doing this myself until I was coached by a master who took me through the above steps. OK, I'll name-drop: it was David Charlesworth in his workshop in Hartland, North Devon, England. Best woodworking week of my life. I was royally hesitant to take the first swipe, but there he stood, smiling and encouraging me. Soon the 60-1/2 and my Lie-Nielsen 4-1/2 were entirely flat. (OK, the LN was nearly perfect to start, but not "perfect.")

I just looked and variations of this procedure are all over YouTube, but I'd look for someone reputable. Paul Sellers is a good bet, but he takes forever in his videos.

For as simple as this operation is (especially with a little block plane), I wouldn't vacillate about whether it's "necessary" to flatten the sole. The operation itself is a diagnostic. If you have a belly behind the mouth, your plane is going to be trouble.

That's my two cents, going against the herd here, it seems.

[Jim Koepke]

For those that have rounded the bottom of a plane...can someone explain how it happened? I have flattened the soles of a handful of planes and I have never done that. I typically lap in a criss cross direction with even pressure...I am curious if someone could articulate the common reason why this happens?

Luke mentioned a few possibilities.

Another might be due to not clearing the swarf from the abrasive material.

It is also wise to remember, cast iron cuts fast. That is one of my reasons for not starting with an 80 grit abrasive. That is almost like spending time getting your plane sharpened and smoothing a panel to a fine shine and then going over it with coarse sandpaper.

For as simple as this operation is (especially with a little block plane), I wouldn't vacillate about whether it's "necessary" to flatten the sole. The operation itself is a diagnostic. If you have a belly behind the mouth, your plane is going to be trouble.

Using the plane is a good diagnostic. Despite common belief, cast iron does flex. One plane purchased many years ago was "fixed by lapping" by previous owners. The sole became too thin. The sole flexes in use and with changes to the season or adjusting the blade. My intent was to take a picture of it while in the shop today but it slipped my mine. Oil seeps through one of the frog screw holes, making a round stain on the sole.

If the plane has a problem, describe it as best as possible and likely someone can help with it.

Having lapped a few plane soles it can be said they all have their different angles of attack to bring them flat.

If you can get a nice thin shaving out of your #60-1/2 block plane, it doesn't likely have a problem.

jtk

[Tom M King]

I have four Stanley block planes. Two are kept with cambers, and two with straight across edges. One of the 9/1/2's wasn't quite right, so I checked it, and it did have a hump a little behind the throat. I did flatten that one, but it's been so long ago that I don't remember what sandpaper I used on the 12x18" granite surface plate.