Hand Tools

Re: Questions on sole flattening

Sgian Dubh
I suspect it's sometimes the case that rather more effort goes into perfecting plane soles than is required. In general I've found that getting a plane sole acceptable for work isn't overly difficult or daunting.

A sign in use that there's an obvious problem with a plane sole, for both experienced and inexperienced users is that a plane, in all other ways, set up 'right' for planing tends to take a cut at only the beginning and end of a cut; I'm thinking here primarily of longer planes such as a no 5 up to try planes (no 7), but this can also apply to smoothing planes. I'm also referring to trying to plane a piece of wood that's already reasonably flat, although if starting with rough sawn successive strokes eventually lead to only being able to take shavings at the beginning and end of a stroke. The problem indicated by this phenomenon is generally a concave sole, but whether an inexperienced user would recognise this I suppose is debatable.

The reverse of this lack of flatness (concavity) is plane sole convexity, but in my experience convexity in a plane sole is relatively rare, and if the plane sole is only slightly convex it's frequently reasonable usable anyway, and more often than not very usable.

But to fix a concave sole I simply attach a long length (maybe up a metre [~3 feet] long) of 60 or 80 grit Aluminium Oxide abrasive paper to a flat surface such as a saw table or surface planer bed and use this to flatten away. The abrasive comes in rolls 5m long x 115 mm wide, and are made by such people as Norton. After fixing down the abrasive, usually with masking tape at either end I set up the plane as if for work, withdraw the blade well into the plane's body, grab the handle and knob and rub the plane up and down the abrasive. 60 or 80 grit abrasive very quickly takes off any high spots. Five minutes or less usually creates an at least figure of eight 'flat' that encompasses the toe, the heel, along both edges, and a patch encircling the mouth.

At that point the problem should be solved and the plane workable, but most people like to refine that coarse figure of eight scratch pattern and flatten more, plus go up the grits to something finer. I've never gone above 120 or 180 grit.

Is the above technique perfect? Maybe not because it's likely the paper wrinkles up as the plane passes back and forth probably or possibly leading to some convexity of the sole, but I've always found this rough and ready methodology generally works. I've seldom come across a plane sole that is hopelessly convex and/or badly in winding (twisted), and on the exceptionally rare occasion I've dealt with such a case the tool went to a machinist for flattening.

Of course, none of the above deals with other problems that can show up on planes, e.g., cap iron and blade not meeting tightly, grinding and honing the blade correctly, and other faults. Slainte.

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