Flattening longer plane soles
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Flattening the sole of a #4 plane is easy. It’s short, so not only there’s not so much material to remove, and the surface with sandpaper is reasonably sized.
What about longer planes? I’m already finding it hard to flatten my #5, can’t imagine owning a #7 (I have a wooden one). Are there different flattening techniques than rubbing it on sandpaper glued to a flat surface?
I am having two problems with my #5 (or I wouldn’t bother):
– Joined edges always rock when put together. There’s always a bump in the middle and gaps at the ends.
– I cannot plane to a line parallel to an opposite edge. In the middle of the length of the edge, the plane can’t reach the lines without passing the ends.I used it to flatten my jointer wooden plane and that one produces the opposite effect on boards.
So I have a concave sole.
I’ve been considering sanding the ends freehand, checking a lot, and then doing a final truing up on a no-so-long flat surface.
Does anyone have suggestions on how to make this less annoying?
I had to flatten a #7 after I had it welded ( broken cheek) that had a 1/16+ Concave bow in it. I had no qualms about using the belt sander on the ends until it got in hand sanding range. Just don’t let the iron body get too hot, and use something like a 36 grit belt.
When I switched to hand sanding the sole, I went to the glass shop and asked for a 1’x2’ piece of float glass, which is very flat. And used psa sandpaper strips. It still took a couple hours going through the grits.
You can also go to a granite counter shop and ask them for a sink cutout. They usually send those to the landfill and will likely give you one. Black granite tends to be harder and flatter, because a not flat piece show odd reflections.
Technique also counts in jointing edges. You need pressure on the front of the plane at the start and at the rear of the plane at the end of a swipe. Pretend you are trying to scoop out the middle.
Though I appreciate your logic, I’m not sure you have the problem with edge jointing analyzed correctly as due to a concave sole. Rest the plane on a flat surface like a table saw table. Can you see the concavity? My planes have been carefully flattened, and it’s still easy to wind up with a high spot in the middle when joining boards, which probably has a lot to do with the pressure one is exerting. It’ easy to get more pressure at the beginning and end of a board. It can also be difficult to not weight the plane to one side or the other which also screws up the jointing. And grains can affect the whole process, leading to high spots close to where knots were, etc.
Check out Paul’s video on edge joining two boards: https://www.youtube.com/watch?v=h-vMtS_j4cY This is the technique I use to edge joint and it works great. But I’ll add that after a first try I often have a high spot in the middle of the two boards. I then put the two boards back in the vice, take a couple of passes to make sure the boards are back in alignment, and start making a couple of passes just over the center few inches. Then I gradually increase the length of the passes (maybe a total of 4 or 5 times) until I’m almost at a full pass, and then do one final full pass. I’m doing all this with the plane adjusted to take a very, very light shavings. I’ve also found it important to make sure the plane blade is adjusted to be dead on 90 degrees to the sole. If you’re not familiar with how to do this Paul has excellent videos on adjusting the blade with the lever, and testing it by taking shavings from both edges of the plane. You listen for the sound to tell if the shavings are equal in thickness.
Also, I get the board edges individually to 90 degrees to the face using a shooting board before doing the edge jointing, so I’m just fine tuning in that step. I know it’s not necessary (as you’ll see in the video), but it works for me and makes me more confident that the edge jointing will work out. And good luck Roberto – I’m sure you’ll get this problem figured out.
Fritz Walker
Sandpaper to a flat surface is a pain, but also very simple. It’s worth to check the sole with a straightedge and mark any hollows or high spots. Then, if you do have a curve on the sole, you can buy sand paper in roll form (usually used for the large floor sanders) and use that on a non-textured piece of kitchen worktop to give a longer flatter area. You could also fix your wooden plane with this as well. You don’t need to glue the sandpaper to the worktop, just restrain it so that it does not move. This also means that you are left with a reasonably reliable flat plate that you can use for levelling chair legs etc. if your workbench is not perfectly flat (just remember to store it vertically).
My local Obi sells offcuts, but I am not sure what happens in other big box stores in other countries (take or buy a long ruler and check the worktop for flat before you buy).
I have had success with this in the past. (Also, I usually use fresh new pieces of MFC as mounting for sanding at 1500 and 2500 grit on some of my blades and chisels.)Colin, Czech Rep.
I’ve flattened the sole of my #5 and my #5 1/2 using 80, 180 and 320 grit sandpaper in roll firm on a piece of 14 mm thick plate glass. The measures of this glass are 115 x 15 cm. I,ve checked later with a feeler gauge (0.05 cm) and the gauge didn’t pass under the sole.
I’ve controlled carefully the pressure over the plane, mounted completely but with the blade retracted, and i’ve used only the forward stroke. You must try not to hold the plane too strong because you cant flex the sole or even break the glass.
I tried to do this using an offcut of kitchen counter, but it wasn’t flat and the sole ended with a concave shape.
I’ve uploaded three pics of the process. The grid on the sole allows to control your progress. It’s a slow and, tedious process and the sandpaper wears quickly, but the results are great.
By the way: I apologize for the MDF top of the bench (LOL), but it was made from offcuts for the garden shed. In fact, we could call him “the Paul Sellers-inspired Frankenstein bench” (LOL).Thank you all for the replies. I guess flat surface it is. I wanted to avoid acquiring such piece as I don’t know what else I’d use it for and I don’t want to store more junk. I’ll figure it out.
Fritz, I am aware of how to plane correctly and how to edge joint boards. The hump in the middle is not the only symptom I’ve described: Not being able to plane parallel lines (plane will not cut down to the line in the middle) and having my wooden jointer, which I flattened with my #5, do the exact opposite (leaves a hollow). Resting the plane on a guaranteed flat surface and using a feeler gauge is not the only way to diagnose it.
Right you are Roberto. I focused just on the edge joining. My apologies.
Fritz Walker
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