Hi

A small back bevel, all that is needed, of a degree or two makes little 
difference to the cutting geometry.

However, to put a small back bevel on the iron you really need to jig 
the process.

On my sharpening pages I have a section on flattening the back and why 
it is a waste of time.

A couple of notes:

  1 diamond abrasives on steel - iron has an affinity for carbon with 
the result that a chemical reaction (not a physical breaking, a chemical 
removal) dissolves the diamonds. diamonds work well on most everything 
but ferrous metals.

  2 coarse abrasives shatter the crystal structure of the hardened iron 
well below the base of the scratches. using 40 grit on the back will 
mean you have less durable steel on the working edge until you sharpen 
past the flattened section of the blade.

  3 a small microbevel on the back, created with sub 6 micron abrasives 
will not shatter the crystal structure of the steel and will give you a 
durable edge that is flat on both sides.

  4 flattening once does nothing to remove the wear bevel created on the 
back face during use. Lee Valley giving you a very flat back lulls you 
into having half sharp plane irons forever. to have a plane iron with an 
edge that is flat on both faces you have to work both faces every time 
you hone. if done correctly this can add up to 1 minute to honing time

Sharpening well with the best abrasives is faster, lasts longer and 
simplifies tool mastery.

However, you needn't worry. People have been doing good work with 
dullish edges since tools were invented.

On 2017-06-02 08:55, Kirk Eppler wrote:
> BTW, putting a back bevel on changes the cutting geometry, effectively
> giving you a high angle plane. Can be a benefit, can be a curse.
> 
> On May 31, 2017 7:33 PM, "Christopher Dunn" 
> wrote:
> The smart thing to do is to put a back bevel on the iron and call it a
> day (like the last guy who owned the plane), but I now consider this a
> challenge and want it the back flat.

Brent
-- 
Brent Beach
Victoria, BC, Canada