Reason for secondary bevel ?

[lou Brava]

I've only used bench chisels always sharpened using Japanese stones completely honing the entire face, as you can imagine this process takes a lot of time & effort especially if there's a nick. I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face which makes sense, the other is the edge will stay sharp longer but that part really doesn't make sense to me. Is there some science behind that or is it just expert wood workers and experience that claim this ? Either way I'm going to try the secondary bevel just for ease of sharping.
Thanks

[Tony Wilkins]

It’s just one option among many. The ‘science’ is that you’re only honing the small amount of steel at the tip. Of course you can continue to do he whole face but know that whereas the oire nomi has the soft steel on top the other will be all harder steel. Some use hollow grinding to provide a quicker hone. I learned from Charlesworth and the Schwarz so I use a micro bevel.

[Kendall Scheier]

The reason that the edge lasts slightly longer is that the angle of the steel is more obtuse providing more support to the cutting edge making it less likely to chip or fracture…. It’s a small incremental difference but we all live that kind of stuff lol

[Eric Brown]

I've only used bench chisels always sharpened using Japanese stones completely honing the entire face, as you can imagine this process takes a lot of time & effort especially if there's a nick. I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face which makes sense, the other is the edge will stay sharp longer but that part really doesn't make sense to me. Is there some science behind that or is it just expert wood workers and experience that claim this ? Either way I'm going to try the secondary bevel just for ease of sharping.
Thanks

The shorter bevel is stiffer, meaning that it is stronger. Downside is that it is also harder to use. (The higher the angle the more force required to use). These very slight differences are not noticeable to most of us. When looking at bevel angles there are two things to consider. One is clearance. We all like to think that when the edge cuts the surface doesn't change, but there is some compression that happens. That is why you don't use a 45 degree bevel on most hand planes. The other thing to consider is that it can be compared to a screw thread. The finer the thread the easier to turn but the slower it progresses. Skewing a plane has the same effect as a lower angle. Yes it's easier but the cut width is reduced. All the angles are compromises. The ideal angle will probably be different depending on the blade thickness (thicker doesn't vibrate as easy), the type of wood. Even how the chip breaker is set. Over the years the 45 degree angle of most planes is an angle that will work for most woods. When working with difficult grain, or super hard woods, different approaches might need to be utilized. Another downside of a secondary bevel is that eventually you will be required to grind the primary bevel back to where the secondary is easier to maintain. So when looking at the time it takes it really depends on your sharpening routine. Do you sharpen after every use? To you just want to do a quick sharpen to get some work done?

Personally I do both except I don't sharpen after every use but once a month I check all the blades and spend the time to sharpen what needs it. If I'm working and the blade seems dull I sharpen the secondary.

There are also those that don't grind flat but put a hollow grind on. This makes the number of secondary sharpenings greater.

Confused? Lost Art Press has a book on sharpening I would recommend.

[steven c newman]

There are some out there that even put FOUR bevels on an iron.....

Then, there are some like me that only use a single bevel...

All depends...as to where one wants to spend their shoptime at......at the sharpening "bench", or...simply put the plane to work...

[Edward Weber]

The reason that the edge lasts slightly longer is that the angle of the steel is more obtuse providing more support to the cutting edge making it less likely to chip or fracture…. It’s a small incremental difference but we all live that kind of stuff lol

+1
My understanding is that the secondary bevel was developed for use with plane irons, which are thinner than chisels and have little support behind the cutting edge.

[mike calabrese]

Here is some info on the secondary bevel applied to plane blades and chisels
calabrese55


https://www.youtube.com/watch?v=t-Vwlbi0hcQ
https://www.youtube.com/watch?v=m7xNQ-XEoNI
https://www.youtube.com/watch?v=Q4f4d3VRqY4
https://www.youtube.com/watch?v=m7xNQ-XEoNI
https://www.youtube.com/watch?v=N6qa9kkfA2Y

[steven c newman]

Delaware County, NY? have relatives buried up there...Abner Newman's Father is Buried there. Abner Newman bought "Government Land" down here in Ohio...1792...and moved to the Logan County area...One of the first Methodist Churches was set up on his land..1822...

Just getting old and set in me ways...

[Tom M King]

My reason for almost never using a secondary bevel is that you almost never have to use a grinder. None of my plane irons have visited a grinder in more than a few years, and only the chisels that have damage from some use other than cutting wood. Still only a few minutes from scraping paint off of brick to more than razor sharp. Much less for an undamaged edge.

[Jim Koepke]

My tendency is to maintain a flat bevel on my chisels.

Using a chisel bevel down is a bit tricky with a secondary bevel.

A secondary bevel may have less area to work, but it is difficult to hold such a small area flat on a stone when freehand sharpening. Eventually the small area gets bigger and needs to be reground. Like Tom, my blades seldom get near a grinder.

My mortise chisels may have a different setup than my plane blades, chisels and gouges.

There are also different sets of chisels in my shop. One set is ground at a very low angle for paring. Another set is ground to a steeper angle for rougher work or being struck by a mallet.

jtk

[Rafael Herrera]

Japanese chisel have a very thin layer of steel forge welded to a wrought iron backing (i.e. soft), so sharpening them maintaining a single bevel is practical. Most modern western chisels are all hardened steel, so using the single bevel approach would take a very long time and not be practical.

One of the many methods of sharpening bench chisels or plane irons (mind you, not mortise chisels) is to grind a shallower main bevel, around 25 degrees or less, by some means, not something done every time. When honing the edge, one lifts the chisel a bit above 25 degrees and works the edge. One does this until the secondary bevel is too big or takes too long to work, that's when the main bevel is reground.

On mortise chisels, which are subject to prying, the apex at the edge needs to be an angle more obtuse than what you would use on bench chisels. That prevents the edge from chipping when you pry. One uses a mallet with the mortise chisel, so they need to be sharp, but not at the level of bench chisels.

Prying will damage an edge, so you have to adjust your sharpening according to what you will do w the chisel. If you're going to pare, you can go pretty shallow. If you're going to chop, you can't go as shallow. Your baseline is around 25 degrees, start there.

[Jimmy Harris]

For me, secondary bevels make sharpening harder, not easier. For one, you don't have the big flat surface to reference against. And a sharpening jig adds unnecessary time, cost, and complication. And two, if you only ever sharpen the secondary bevel, eventually you'll find yourself in a situation where you have to regrind the primary bevel once you worked that secondary bevel far enough back. And then you've got a ton of work on your plate, because you're having to remove A LOT of material. So to avoid that, I sharpen both the primary and secondary bevels on my mortise chisels every time I sharpen them. It doubles my sharpening time, but it prevents me from having to grind the chisel down at some later date. And this is why I only use secondary bevels on mortise chisels, since they're the only tools that, in my opinion, take enough advantage of a secondary bevel to be worth the hassle.

But that's just my opinion. Other people have no problem taking their chisels over to a bench grinder and regrinding the primary bevels once in a long while. And there's no right or wrong way to go about it, so long as the way you choose works for you. It's all a tradeoff, and we each get to decide which qualities are most and least important to us. I get paid the same no matter which method you choose, so I have no incentive to convince you my way is right for you.

[Mark Gibney]

I might be confused but it looks to me like the OP asked about putting a secondary bevel on a chisel, not a plane iron, in place of flattening the entire face.

I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face

I would never put a secondary bevel on the face of a chisel. Am I misinterpreting the question?

[mike stenson]

I might be confused but it looks to me like the OP asked about putting a secondary bevel on a chisel, not a plane iron, in place of flattening the entire face.

I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face

I would never put a secondary bevel on the face of a chisel. Am I misinterpreting the question?

On the face? I absolutely do, especially on say a2 steel. It's no different than a hollow grind. On the back? No.

[Rafael Herrera]

I might be confused but it looks to me like the OP asked about putting a secondary bevel on a chisel, not a plane iron, in place of flattening the entire face.

I just ordered a set of mortise chisels (Narex) and reading about secondary bevels being the way to go. From what I gather the big advantage to a secondary bevel is you only have to sharpen a small part of the face

I would never put a secondary bevel on the face of a chisel. Am I misinterpreting the question?

The references to plane irons were included because they can be sharpened in a similar manner. I always think of the "face" of a chisel or plane iron as the flat side of the tool, so the bevel side is the "back". Some people refer to them in the opposite way, the OP may be one of them, who knows. It helps top think that the face is what makes contact with the wood.