How can you make a correction for minor out-of-square situation?
Is it best to make minor corrections with a honing guide?
At what point is it necessary to grind back to squareness and then resharpen?
Is a slightly out-of-square chisel a problem to work with?
The use of a marker pen on the bevels of the blades has helped me to both adjust and avoid out of square when sharpening. Despite a wide wheel honing guide I constantly tend to take off more to the right of the edge. When it happens, I adjust the pressure and check for equal loss of ink along the bevel.
I always switch to a guide when correcting squareness because a substantial amount of grinding time (by hand) will likely be required rather than just a few minutes.
For a bench plane, it is necessary to grind back to square when the lateral adjustment lever can no longer achieve a useful set on the blade. For a joinery plane, like a shoulder or rabbet plane, the blade must generally be maintained square all the time.
A chisel being out of square usually does not bother me. It would be fine, if not improved, for most paring. It would likely bug me most for chopping a mortise because it increases any tendency to twist as your start or not enter square to the walls, but I’ve chopped quite a few with out-of-square chisels, so it’s not impossible.
I agree with the advice so far about minor out-of-square not being a big problem (otherwise hand sharpening would be an impossible discipline), and correcting by additional pressure on one side during sharpening or using a a jig to re-establish on low grit paper.
For very seriously out-of-square blades it can be difficult to reestablish the squareness as the blade tends to rock onto it’s existing bevel, even when used in a jig, and this tends to perpetuate the error forever. I wasted a lot of time and blade length learning that one time when refurbishing old basket-case planes.
I can already sense the disapproval, but…
In very out-of-square cases it can be easier to draw-file or stone the blade square at 90 degrees (check progress often) and then reestablish the bevel as desired and sharpen (jig or freehand) until the bluntness is gone across the whole width of the bevel. It sounds really brutal and wrong as you are deliberately blunting the blade initially but it works very well. Filing square especially works wonders with softer steel, antique blades (which are also a joy to sharpen freehand btw). If anyone else tries this, maybe don’t use your best file for this, and maybe don’t try this on a modern super-hard steel blade YMMV etc 🙂
What Mikes says (shape near 90 degrees) is how I was taught to shape cutting tool profiles on a grinder. If you are making a light grind, e.g., grinding a well shaped bevel, then you can do it at the bevel angle, but taking care about heat. If you have enough metal to remove that you are changing shape, then get to your new shape at or near 90 degrees. This keeps you from developing heat when the metal comes to a thin edge, which will be more likely to overheat. So, get to shape, then as a separate step, work to get your bevel. Once you have the shape, bring everything to a uniform edge thickness (still blunt), then work the whole edge to sharp uniformly so that it all comes to an edge on the same pass (ideally).
For the situation being described here, though, I think one can just keep an eye on the tool over days and weeks. Never let it get so far out of square that you cannot grind back to your desired shape by hand in 10 minutes or so.
I have seen a very simple method for slightly (but seriously) out of angle or out of shape edges: Use a stationary disk grinder, rest the blade on the table of the grinder and push it against the disk. Of course, this is very hard on the abrasive, so push lightly only and consider, which corner will touch the disk first. If the upper corner touches first and the disk is moving down there, you will get trouble.
I have re-squared some chisels from flea markets on my stones. First, I used a very high angle while abrading on the bevel side and watching my progress on the back of the chisel. Once the back was square again, I rebuilt the bevel.
This took a lot of time, and if you have a power grinder, I think, there is no reason not to use it. Only be careful not to overheat the blade.
By the way, I correct my blades whenever I have the time. It seems, that all my chisels get shorter on the same side, so it is part of my sharpening routine and will always get worse if I don’t take care of it. I can’t see it, when I sharpen once, but after 10 times or so, it gets visible.
Out of square plane iron is a great way to get the feeling of your body position, finger pressure.
I restored several planes and used many methods… bench grinder was less preferable, because I was found it freehand and wasn’t very accurate with the result.
Sandpaper worked great.
I also tried reshaping the iron with a diamond hone. It cut faster, but totally ruined the hone.
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