Stanley 1-12-020 block plane bevel angles

[WoodMangler]

I have a Stanley 1-12-020 adjustable mouth block plane (as per http://www.power-tools-pro.co.uk/images/1-12-020-plane-500.jpg) The specification iron angle is 21degrees, to what angles should I grind the primary and secondary bevels ?

 

[AndyT]

Your "specification" 21 degrees is the angle between the body of the blade and the horizontal, which is much lower in this style of plane than it is in a bench plane.
Normal advice for sharpening the blade for a block plane is actually the same as for bench planes - grind at 25 degrees and hone at 30.

This gives an "effective pitch" of 21 + 30 = 51 degrees which is fine.

 

[WoodMangler]

Your "specification" 21 degrees is the angle between the body of the blade and the horizontal, which is much lower in this style of plane than it is in a bench plane.
Normal advice for sharpening the blade for a block plane is actually the same as for bench planes - grind at 25 degrees and hone at 30.
This gives an "effective pitch" of 21 + 30 = 51 degrees which is fine.

Thanks very much - that's what I needed to know.