Flattening the back

[jppierson]

OK, sometimes I wonder just how far to go. Renovating a Millers Falls 90. I've got the back back of the blade flat... except about 3-4 scratches left over from the factory grind. It had a hollow that is now gone. I've only gone as far as emory paper "Fine" since I intend to put a slight back bevel on it using the ruler trick. These scratches end about 1/8th inch from the business end. So do you go the extra mile and bring it to perfection? Leave well enough alone? If you were shopping for one, would it make a difference as to whether you buy it or not? The sole of the plane itself is pretty flat (I'm no Tablesaw Tom) the sides are straight, and 90 to the bed, and I lapped the frog and the contact points. So it should end up being a decent user.

[barryvabeach]

OK, sometimes I wonder just how far to go.  Renovating a Millers Falls 90.  I've got the back back of the blade flat... except about 3-4 scratches left over from the factory grind.  It had a hollow that is now gone.  I've only gone as far as emory paper "Fine" since I intend to put a slight back bevel on it using the ruler trick. These scratches end about 1/8th inch from the business end.  So do you go the extra mile and bring it to perfection?  Leave well enough alone?  If you were shopping for one, would it make a difference as to whether you buy it or not?  The sole of the plane itself is pretty flat (I'm no Tablesaw Tom) the sides are straight, and 90 to the bed, and I lapped the frog and the contact points.  So it should end up being a decent user.

Since you are using the ruler trick, it is good to go.  Even without that, it will still work fine.

[Handplanesandmore]

The real test is how it cuts in use. Put it in use (true an edge, eg) for some empirical feedback.

Simon

[bandit571]

hmmm..
 
[attachment=24929]
Seems to work well enough....

[adamcherubini]

The ruler trick is just a way to get some kind of repeatability. Otherwise, you could just free hand a back bevel every time. Flattening the back is no less arbitrary. We only do it because we feel its a way to repeatedly get back to that surface. In terms of cutting, it just needs to be controlled and polished. Whether its 1 degree or 10 doesn't really matter.

Almost no matter what you do, you will invariably round over that back edge. And honing the entire surface to it is laborious.

I do it two ways - 1) with a worksharp or something like it to grind that back down until its flat all the way to the edge. 2) Sometimes I just grind the edge off to get rid of the last 1/16 or maybe 1/8 so I have a flat back.

If you are comfortable with the ruler trick, why bother flatten the back at all. Just try to keep rust off it.

I think it was Ron Hock that told me about edge morphology years and years ago??? As I (probably mis-) understood it, honing side to side encourages the grains to realign that way. At the very least, it leaves scratches in the wrong direction And that weakens the edge. Front to back honing results in a stronger edge. Scratches are longitudinal. My guess is DC doesn't care. He probably hones often enough that this doesn't play a role.

I think my advice would be, if the blade has lots of length, I'd do my level best, then grind it off then hone however you want.

[AHill]

[quote pid='7833554' dateline='1584450799']

I think it was Ron Hock that told me about edge morphology years and years ago???  As I (probably mis-) understood it, honing side to side encourages the grains to realign that way.  At the very least, it leaves scratches in the wrong direction And that weakens the edge.  Front to back honing results in a stronger edge. Scratches are longitudinal. My guess is DC doesn't care.  He probably hones often enough that this doesn't play a role.  
[/quote]

Grains won't realign depending on what direction you hone.  (I'm a metallurgical engineer - trust me.)  Sharpening is basically removing material by abrasion.  The grains don't go anywhere.  The only way you can realign grains is to deform it by whacking it with something hard, or heat treat it.  Sideways sharpening will indeed leave micro-scratches across the edge.  Interestingly enough, this is how Harrelson Stanley was taught in Japan to hone an edge - sideways.  He even invented a honing guide that facilitates sideways honing.  Just before he finished, he would hold the edge dead on perpendicular to the finest grit waterstone, and with only the weight of the blade, slide it sideways across the stone.  He claimed that removed the portion of the edge that would otherwise break off during use due to those sideways scratches.  He called it jointing.  He then would do a couple of very light strokes more of honing and declare it done.

[wmickley]

[quote pid='7833554' dateline='1584450799']

I think it was Ron Hock that told me about edge morphology years and years ago???  As I (probably mis-) understood it, honing side to side encourages the grains to realign that way.  At the very least, it leaves scratches in the wrong direction And that weakens the edge.  Front to back honing results in a stronger edge. Scratches are longitudinal. My guess is DC doesn't care.  He probably hones often enough that this doesn't play a role.  

Grains won't realign depending on what direction you hone.  (I'm a metallurgical engineer - trust me.)  Sharpening is basically removing material by abrasion.  The grains don't go anywhere.  The only way you can realign grains is to deform it by whacking it with something hard, or heat treat it.  Sideways sharpening will indeed leave micro-scratches across the edge.  Interestingly enough, this is how Harrelson Stanley was taught in Japan to hone an edge - sideways.  He even invented a honing guide that facilitates sideways honing.  Just before he finished, he would hold the edge dead on perpendicular to the finest grit waterstone, and with only the weight of the blade, slide it sideways across the stone.  He claimed that removed the portion of the edge that would otherwise break off during use due to those sideways scratches.  He called it jointing.  He then would do a couple of very light strokes more of honing and declare it done.
[/quote]

I met Ron Hock in 2011 just before his book was published. I didn't know if I should buy the book so I asked him a question to see how much he knew. I don't want to tell the question, but here is his answer:

"Absolutely not! The only way ...... now wait a minute....... I better ask someone about that."

I met Harrelson Stanley two years later. As I looked at his side sharpening jig he told me I would never be able to to learn to sharpen without his jig, that freehand sharpening did not work. I was trained to freehand sharpen before little Harry was born.

Sharpening is very much more complicated than you suggest. (Trust me, I am a woodworker.)

[jppierson]

Thanks all for the feedback. I think I will leave well enough alone, he back should be fla enough for good chip breaker contact, new owner will do their own thing with sharpening anyway.

[Handplanesandmore]

I really consider myself lucky that I learned how to plane and sharpen long before I came across forums and read threads like this.

Once again, sharpening advice is made out to be so unnecessarily complicated that one might never start planing while trying to figure out how to sharpen. 


 

Simon

[jppierson]

I took the flattening a little farther, it still has some grind scratches. Went through the grits beyond the fine emery paper using worn 400, 600, 1000, 1500 these I did length-wise to the blade. Only took about 50-100 strokes each to remove previous grit scratches Did the Rob Cosman method on the sharpening using only 1K and 8K stones (best I have). I sure like not having to set up a sharpening jig. Back bevel on 8K stone only took 10 secs this is done along the width of the blade. Put it together and pulled less than a thou see through pine shavings, not bad for a mid-level grade plane. Good enough. The reason I decided to go a bit farther was following the old saying that a shiny thing is worth more in a buyers eyes than one that ain't.