chisel sharpening

[Brian Keith]

I have a set of fairly new and lightly used chisels that need to be sharpened. Im using the varitas honing guide with 3 different grit diamond stones. They dont say what grit they are just coarse,fine,extra fine. My plane blades came out good and I was able to shave the hair on my arm but the chisels are different story. I cant seem to get them sharp. I have flatten the backs and have gone through all the stones but seem not to get that sharp. When using on wood they seem to push through the wood instead of cutting. What am I doing wrong? Thanks

[David DeCristoforo]

Well, you know the problem is not the stones or the guide or your "technique" (or the hair on your arm either!). So that pretty much leaves the "fairly new and lightly used" chisels which I suspect are poor quality steel. Are you the first owner of these chisels? If not, the previous owner may have overheated the steel by grinding them improperly, ruining the temper.

[Brian Keith]

I bought them new and it says forged alloy steel on them. Now the bevel, do I need to grind a new bevel? These seem to be alot more than 25 degrees?

[Wilbur Pan]

If you are using the chisels for paring, 25 degrees would be a better angle for them.

One other thing to keep in mind is that an "extra fine" diamond stone is about equivalent to a 2000 grit waterstone at best, so your chisels may not be as sharp as you think they might be.

[Ruston Hughes]

My plane blades came out good and I was able to shave the hair on my arm but the chisels are different story.

I also use the 'shave test' and if your chisels won't take the hair off your arm as easily as your plane blades then they are not as sharp, regardless of the bevel angle.

On your finest stone are you alternating between bevel and back to make sure you are completely removing the burr?

[Brian Keith]

yes I can feel the wire it creates and taking it off as I go. I measured the bevel and its around 40 degrees on all 5 chisels. Should I grind this to 25?

[David DeCristoforo]

Instead of re-grinding the bevel, try "hollow grinding" the bevels and then re-sharpen. The bevel angle is really not going to affect the ability of the blade to take a razor edge.

[Wilbur Pan]

Oh, definitely. A bevel angle of 40 degrees is past mortise chisel territory.

Just a rule of thumb for bevel angles on chisels:

Paring chisels: 20-25 degrees
General use/light chopping: 25-30 degrees
Mortising: 35 degrees

These angles also depend on whether you are working with softwoods or hardwoods, and if you are paring/chopping with the grain or across end grain.

[Will Blick]

> Paring chisels: 20-25 degrees
General use/light chopping: 25-30 degrees
Mortising: 35 degrees

These angles also depend on whether you are working with softwoods or hardwoods, and if you are paring/chopping with the grain or across end grain.

Wilbur, can you elaborate on this? I assume the harder the wood, the lower the angle? But within the range you are suggesting above? I never considered altering bevel angles on chisels, but just like planes, why not?

[Mike Henderson]

What I do is sharpen almost all my western chisels to a 25* angle and then use a secondary bevel to increase the angle. I increase the angle when the edge is not holding up in use. That way, you aren't measuring things, you just adjust until things work for you, hardwood or softwood, face grain or edge grain.

I do the same with mortise chisels. On a mortise chisel you want a low angle so the chisel can penetrate the wood, but a higher secondary bevel so that the edge holds up.

Mike

[Wilbur Pan]

Wilbur, can you elaborate on this? I assume the harder the wood, the lower the angle? But within the range you are suggesting above? I never considered altering bevel angles on chisels, but just like planes, why not?
Hi Will,

Again, those are just guidelines. I probably should have provided more detail, but softwoods and end grain tend to do better with the lower end of the range of bevel angles I had mentioned above.

As Mike mentioned, using a secondary bevel is a good way to try out different bevel angles without completely changing the profile of your chisel. Just to show you an extreme case, the Ray Iles mortise chisels (http://www.toolsforworkingwood.com/Merchant/merchant.mvc?Screen=PROD&Store_Code=toolshop&Product_Code=MS-MORT.XX&Category_Code=TBMC) have a 20 degree primary bevel, but has a secondary bevel of 35 degrees(!).

Having said that, I don't use secondary bevels on my Japanese chisels, which all seem to be close to 25 degrees, except for my mortise chisels, and I use them for both hardwoods and softwoods. But many roads to the same destination, and it just goes to show that bevel angels are not the be all and end all of chisel performance.

[Jim Koepke]

But many roads to the same destination, and it just goes to show that bevel angels are not the be all and end all of chisel performance.

This is correct. Sharpness is the end all and be all.

Inside of a range, it becomes preference and how often one is willing to pay honedge to the stones.

Lower angles will need more touch up than a high angle. After a point though, a high angle is not going to have much cutting action without a lot of effort.

Like so many things, there is give and take involved.

jim

[Will Blick]

I always wonder why some chisels I can get sharper than others.... this set from LV is the by far the sharpest chisels I own.... maybe its the 02 steel, or the way its tempered, but they are like a surgeons scalpel .... no other chisels can I get this sharp.... it appears the angle may be part of the reason?

http://www.leevalley.com/images/item/woodworking/chisels/05k0470s1b.jpg

[Zahid Naqvi]

you will be surprised how much difference bevel angle makes. For starters do what Mike Henderson suggests, but only on one chisel. Grind a primary bevel at 25 degree and then a secondary at 30/35. Get it as sharp as you can using your stones and compare this chisel with the another one you have ground at 40.

[Will Blick]

This is a good point.... I may try this... just like LA planes cut smoother than high angle planes (assuming the wood is cooperative) then I assume the same would apply to chisels...

[Jim Koepke]

I am not a regular user of secondary bevels.
This is not an argument against secondary bevels, it is just how I have done it.

I may start using them, just haven't yet. My favorite chisel has a bevel at a little less than 15°. That is the way it came, with a bunch my brother picked up for me at a flea market. It is not one to be pounded on, but it seems to stand up to it.

IMO, it is the long shallow bevel that makes this curl making bench chisel my favorite.

This is also a good reason to have multiple chisels of the same size. Then they can all have a different bevel for different uses.

jim