Hollow grinding an LV skew rabbet blade.

[Chris Griggs]

Hey folks,

I'd like to put a hollow grind in the blade on my LV skew rabbet, as it is currently the only blade holding me back from selling my MKII honing guide. Actually, I can hone it freehand fine without the hollow grind but I would like to put one in it to make things quicker. Also, if I mess up the geometry a bit from several honings I want to be able to correct it on my grinder. At this point the only thing keeping me from selling the MKII is my fear that I will mess up the geometry while grinding or freehanding and be unable to correct it without the guide.

Is there any reason I shouldn't attempt to put the skew blade on my grinder. I imagine if I messed up the geometry I could just mark a 30 degree line across the back and and grind to it in order to make the correction. Or is there something I'm missing? If I mess up the geometry will it be difficult to correct? People used skewed fillisters for centuries before the MKII guide was available, so I can't imagine it's that difficult to get the geometry correct??? Thoughts?

[Marc Jones]

Hey Chris,

I'm no sharpening guru, but I have the LV skew rabbet and I sharpen the blade exactly as you're suggesting - hollow grind followed by honing on stones. I haven't had any problems with the grinder - just lined up the blade so the cutting edge is perpendicular to the wheel. And you right, if you wanted to alter or reestablish the angle of the skew you can just mark the back of the blade and grind the edge of the iron to that line. In my mind it's definitely worth it to facilitate freehand honing.

Marc

[Derek Cohen]

I'm another doing exactly as Chris described. I do have the advantage of a Tormek for grinding. This protects the sections of steel that are more vulnerable to overheating, such as the thin, pointy bits. What out there. Go very slowly and cool the steel frequently.

Regards from Perth

Derek

[Russell Sansom]

I also have used a Tormek on several of these, including a Stanley #140 whose blade had been rendered inoperative by one of those people who've been doing it for centuries. In fact, when was the last time you saw a properly sharpened used skew iron of any kind? Outside of this forum, I mean, of course. These edges on my skew planes seem to get beaten up in a hurry in the line of duty, so a hollow is essential for the quick and often deep edge touch up.

My favorite method is to make the back into a mirror, paint it with Dykem Layout fluid. Then scribe a thin line on the back at precisely the correct angle. I put this line as close to the leading edge as the messed up geometry will allow. I then grind a hollow, until I'm within 1/64th or so of the line on the back. Here's the fun part. Joint the "cutting" edge on a diamond stone until you almost reach the line ( hold the blade upright on the stone ).
At this point there's a flat where the cutting edge would be. It's easy to look at the flat face on and see exactly what slight adjustments are needed on the Tormek to get it all square. One last light grinding session should take you down to the line just as the last of the flat disappears. Getting the precision I want is a squirrely proposition on the Tormek, but it's the best method I've found. As simple-minded as it sounds, the trick is in the perfection of the scribed line.

[Chris Griggs]

Thanks guys! Exactly what I wanted to hear... great advice on all counts. I will definitely grind it - fortunately i don't need to correct any geometry (yet), just match what is already there.