blade back question

[Steven Lee, NC]

For cambered blades how important is it for a "mirror finish" flat back for Chris Schwarz heavy/medium tool stage? I am thinking not too important to waste time on achieving.

thnx

[Bill Houghton]

It's always true that a sharp edge is created by two surfaces meeting at an angle, and that the level of sharpness is affected by the smoothness of the surfaces. Even at heavy stages, sharpness increases your efficiency.

Having said that, I've never tried to go berserk on my scrub plane, heavily cambered.

[David Weaver]

The best way to find out is to do a partial job, put a good sharp edge on the bevel side and give it a run.

I have a couple of planes that aren't polished backs yet, but no smoothers like that. If the iron is geometrically OK (i.e., the edge isn't rounded over really steep) it'll probably be fine. Easiest way to tell is to hone it and try it, though.

Otherwise, all of my irons are honed to sharp, coarse or not. There's no great reason not to as the bits of the process that make the iron really sharp are not significant in terms of time compared to what it takes to stop your work rhythm and take a plane apart and put it back together.

[Archie England]

I've moved from beginner to intermediate (at least) status in sharpening my blades. When I started, my blades cut well enough...until I learned what better was. Now, my blades easily slice or pare endgrain and gnarly grain with little effort and leave a great finish. That said, getting blade backs flat (at least the last 1/2" or so) is truly important for "better" cutting; but, getting the bevel cleanly honed is the major part of the journey. I sometimes feel a tad anal about working the blade backs (and I never do all of one), but it genuinely makes some difference--especially if the back has convex areas or lows at the edges. I use slow grinders and my beloved Tormek for establishing bad edges, but my preferred medium are water stones (though I do enjoy my oilstones, as well, when working O1).

Happy New Year

[Jim Koepke]

I use slow grinders and my beloved Tormek for establishing bad edges,

LOL!

Mostly wood will do that to my edges without having to pay for a grinder. :D

jtk

[Kees Heiden]

It depends (as always). If the back is smooth, all I need is enough of a flat to be able to knock of the wireedge. But if there is any pitting involved, then I have to remove that first. Pitting makes the edge impossible to get sharp. And of course, most edge tools accumulating in my shop suffer from pitting, so usually that means an extended session on coarse diamond stones. As soon as the are flat it's not much more work to polish them up a bit.

[Archie England]

LOL!

Mostly wood will do that to my edges without having to pay for a grinder. :D

jtk

:) Yep, sorta dropped a "re-" in that sentence....

[Winton Applegate]

I mirror polish every blade.
Why ?
I may be part raven. I like shiny metal things.
I will say that my scrub plane blades cut cross grain for like EVER between sharpenings even in the purple heart and bubinga.
With the grain I think it is pretty important to go VURY sharp. Cross grain or diagonal not so much.
To use a Roy ism cross grain may be more WEDGE than EDGE.

There were never wiser words spoke than Davids :
TRY IT AND SEE FOR YOUR SELF.

[Derek Cohen]

For cambered blades how important is it for a "mirror finish" flat back for Chris Schwarz heavy/medium tool stage? I am thinking not too important to waste time on achieving.

thnx

Hi Steven

I think that there is a misunderstanding why we polish blades. I believe that most think that the best finish for the wood comes from the smoothest blade. And if you believe this, then it would be natural to question why use a smooth edge to create a rough surface, such as with a scrub or jack plane. That surely it should be reserved for finishing, not starting?

In my opinion, the smoothness of the edge is not for the wood but for the tool, whether chisel or plane. A smoother/sharper edge will penetrate wood more easily than a less smoother/duller edge. A sharper edge is easier to work. It is safer since you do not have to force the cut, which puts one at risk for slipping. Note that I have not referred to a cleaner finish since this is not relevant here.

Further, the hard work in sharpening lies with the coarser grits. The 1000 waterstone may take 75% of the time, the middle 5000 about 15%, and the final polish only 10% (which may amount to a few strokes). It hardly seems worthwhile not to go the whole hog.

Regards from Perth

Derek

[george wilson]

I polish my edges until I have to put them under a box to watch the Sun come up!!

[Steven Lee, NC]

thanks, I'm convinced, I'll try to finish this blade back as best that I can