Secondary bevel on Chisels or not?
ronco71 | Posted in Power Tools and Machinery on
Hello,
I am new to fine woodworking and recently purchased a set of Sorby Cabinetmakers Bench chisels. I am wondering if it is common practice to create a secondary bevel. I don’t really want to create one and then find out later that I shouldn’t have.
I will mostly be working on hardwood and making coffee tables, sofa tables, end tables, etc.
I would appreciate your feedback and comments on the pros and cons, etc.
Thanks a lot!
Ron Thibault
Replies
The answer, Ron, is "Yes, but only on the bevelled face."
I'm not saying why, though. I'll be really intersted to see how many actually know why.
This should be a great thread...
Lee
Furniture Carver
A chisel will never perform well unless the back is perfectly flat or slightly hollow. Creating a secondary bevel on the back of a chisel is disastrous because you lose the large flat surface as a guide for your cutting edge (with no bevel on the back they are one and the same). No bevel on the back gives you control because you don't have to raise the chisel to cut. Imagine trying to pare a tenon or the inside of a mortise with only the top bevel touching the wood (in other words, using the chisel up-side-down): you would have to constantly maintain the chisel at exactly the same angle as the bevel, at exactly 25 or 30 degrees. Putting a bevel on the bottom of a chisel amounts to the same thing (on a smaller scale).
What a lot of woodworkers don't realize is that a hollow stone can create a bevel on the back of a chisel without them knowing it (when they try to flatten the back of a chisel), so keep your stones flat or those nice Sorby chisels won't quite perform as they could.
Edited 1/16/2003 9:31:28 PM ET by PLINTHE
Edited 1/16/2003 11:56:49 PM ET by PLINTHE
Edited 1/17/2003 10:09:49 PM ET by PLINTHE
The secondary bevel allows for a thicker blade cross section close to the cut. This increases the strength of the blade and reduces the possibility of chipping the blade while clearing chips. It also makes the final honing faster as finer grits cut less slowly.
TDF
Edited 1/16/2003 10:22:02 PM ET by Tom Ferreira
Because the furniture gods will smite thee with all of their rage and fury.
A number of woodworkers, myself included, will re-grind a new chisel to create a 'hollow" grind. In that case, it makes sense to put a secondary bevel on the edge so that you're not undoing the hollow. It's also simpler to re-sharpen the secondary bevel than to sharpen the whole edge. At first, you might want to experiment with the secondary bevel without re-grinding. The secondary bevel is very slight (1/64" -1/32") so it won't be all that much work to un-do it if you decide you don't like it.
Thanks Lee and CHIPTAM.
CHIPTAM,
If you don't mind me asking, what is the purpose of the "hollow" grind?
Ron
Ron,
The idea behind the hollow grind on a bench chisel is that you'll have less steel behind the cutting edge creating a tool better suited for operations like paring and other fine work. On the other hand, you don't want a hollow grind on a mortise chisel where the extra meat behind the edge is needed when you're pounding vigorously on the tool with a mallet. Finally, as Lee mentioned, the secondary bevel should only be on the bevel side. The back side should be perfectly flat.
Thanks everyone for your comments. I really appreciate it!
Ron
So Lee, Has this petered out enough for you to give us the real answer?
TDF
I'm quite surprised this thread petered out so soon, I'd guessed it would attract far more attention.
A secondary bevel, also known as a "microbevel" and "bezel" are necessary to a bench chisel used for general woodworking. The secondary bevel has three main purposes.
Tom, you're right in that a secondary bevel will allow for a much stronger cutting edge. A quick angle to the cutting edge leaves more metal behind that edge. A chisel with a straight grind, or worse in this condition a hollow grind, leaves a much weaker edge without this secondary bevel. The big advantage to the hollow grind is ease of sharpening since you have to remove less metal, and you can get more honings before regrinding.
The point right between the regular bevel and the secondary bevel is the fulcrum. Without this fulcrum control over the chisel when used with the bevels down is nearly impossible. With motions of the handle, either up or down, the depth of cut is controled by sliding along on the fulcrum and changing the angle to the cutting edge. I would guess everyone who has used a chisel instinctively knows this but it is so important to the function of a chisel it should be stressed more than it is. Without this fulcrum a chisel is simply a knife and good for little more than whittling when the bevelled side is the side being used.
It kills me when I read "Already sharpened and ready to use" in a catalog. Hogwash! Without a secondary bevel bench chisels are only half ready for use.
When used with the back side down the secondary bevel also acts as a chipbreaker. Actually, you don't want to see the beautiful ribbon of wood from your chisel similar to that from a plane. A secondary bevel will break the underside of the chip as it forms and this makes control of the chisel easier and it makes the wood itself less likely to tear if large slivers aren't allowed to reach the point where the main bevel begins.
There are few exceptions to the secondary bevel, mortising chisels are one. But, for bench chisels...they should all have a secondary bevel. I do a fair amount of carving and every one of my tools have secondary bevels on at least one side. Of a hundred-plus carving tools all but three or four have secondary bevels on both sides.
Now then, I wonder if this will fire this thread up again...
Lee
Lee Grindinger
Furniture Carver
My opinion is that a secondary bevel has little or no effect on how a chisel cuts, as long you're comparing chisels with the same bevel angle at the cutting edge. The main thing the secondary bevel does is make it easier to sharpen the chisel. Given a choice between honing the entire bevel face or honing a secondary bevel 1/32" wide and the length of the edge, which one do you think will get you back in production sooner?
BTW, when I first started reading about this issue, I saw frequent references to a microbevel. This confused me at first because I thought they were talking about a secondary bevel too small to see, and I wondered what would be the point.
Hi everyone, I’m a hobbiest woodworker in my sanctuary garage and my question is to the one gentleman who saws hogwash to a chisel being ready to go. I recently purchased a couple of Matsumura bench chisels. It’s incredible how sharp they already are and the ease of using.they are razor blades still after several uses on dovetails. Your saying I should do something more to these even of such quality chisel? That will improve them? I’ve heard of touching up other chisels but can’t say I’ve ever come across anything needing to be done in regards to a Matsumura. I’m really curious to know and thank all in advance for any responses to the subject.
The angle produced on the chisel honed with a secondary bevel is bigger and therefore marginally less sharp but stronger and therefore less easy to dull. It is easier to hone because one is not removing from both ends of the hollow bevel. The hollowed bevel is a purely incidental result of the pure and simple fact that the grindstone is round! Short of grinding the bevel on a belt sander (which is not the usual way of sharpening tools) there is no way to avoid the hollowed bevel. To speak of it as somehow cleverly advantageous is in my opinion to miss the point.
While one does create a stronger edge with a secondary bevel the danger is, if one doesnt have a honing guide that one creates a rounded edge over time. Ive seen many chisels which have honed repeatedly with a secondary bevel over time and consequently the straight angle of the edge has been lost making them less sharp. For this reason I prefer to balance the chisel on the entire length of the bevel while honing (which guides the chisel at a reliable and sharp angle) thereby avoiding any rounding. This is how I learnt to hone while on my apprenticeship in Hamburg, Germany. It does take a bit longer to hone chisels this way and does definitely mean it is best to use a strop afterwards but there is next to no danger of rounding.
As far as I can tell it is totally common practice in Germany (unlike the UK and most, but not all, of the US) to hone WITHOUT a secondary bevel. One of the things I have never understood is that clearly one is effectively creating a blunter angle by honing to a secondary bevel. Noone who swears by their secondary bevel seems to recognise this.
Admittedly the sharper angle created by honing without a secondary bevel will, if not looked after properly, create chisels that don't always hold their edge as long but they are MUCH easier to sharpen without a honing guide because you're not guessing what the angle is and consequently you're less likely, without a honing guide, to round the edge. The whole business about breaking the chip with a secondary bevel has clearly never been of concern to German Carpenters and Joiners so I confess I'm totally unconvinced by that argument.
Yes you should put a secondary bevel if the primary bevel is flat ground. It just takes less time to sharpen. If the chisel is hollow ground there is no need for a secondary bevel. You only need a single bevel at the chisel edge. And as others have said the back should be flat.
Most folks put a 30 degree primary angle on their chisels then a 35-ish degree secondary bevel on top of that. The actual number of the angle isn't that important, but that's a decent rule of thumb. For dovetail work some like a 22 degree angle, which gives better access to the narrow spaces, cuts well, but does make the edge a little more susceptible to dulling or, Lord forbid, breaking. Although I'd think anyone who can do dovetails isn't going to be that ham-handed.
So the number isn't critical but the two faces coming to a point is the critical bit. I always use a secondary bevel AND strop all my blades after sharpening, as it polishes the metal and makes the edge even more of a point. You can see it under a microscope but not with your naked eye.
I recommend reading Ron Hock's book on sharpening; he goes into metallurgy, various angles, honing, hollow grinds, the whole banana.
Some do and some don't put a secondary bevel. Both ways seem to work.
I don't create a secondary bevel for any reason other than ease of quickly resharpening/honing while I'm working. I create the initial bevel to suit the kind of work I'm asking the chisel to do: 25-ish for paring, 30-ish for chopping. For plane irons, the range is more like 25-50 degrees. A one or two degree secondary bevel doesn't really change the working characteristics or durability of the tool to any significant degree, but makes it real easy to return to the fine stone or strop for a minute or two when I first notice the tool is losing its mojo, rather than enduring a dullish tool and a big sharpening job.
The back of the chisel or plane iron is also simple. Take the time to make it perfectly flat and polished once---at least from the leading edge back to where you will be shortening it during your expected lifetime of sharpening it and you're done. This can take some time, but you only have to do it once.
Don't make this more complicated than it needs to be.
I don't add a secondary or micro bevel.
Everyone seems to say "it takes less time to resharpen", I don't get it.
If I take the time to sharpen to a certain degree properly, that's what I want, I see no need to try and outsmart the steel by adding an unnecessary extra bevel to be able to "quickly" resharpen.
Secondary bevels are best suited to plane irons on bevel down planes to add mass behind the cutting edge and not change to cutting angle.
I see no need for them on chisels.
JMHO
The primary bevel on the chisel I'm holding is 1/2" wide. I add a secondary bevel that starts out at maybe 1/64 or 1/32. It takes just a few strokes on 8,000 grit to get a crisp edge on 1/64th of steel. It takes a lot, lot more to try to polish the entire 1/2" at 8,000 grit. And it's completely unnecessary. All the wood cares about is what's at the very edge.
Except if you hone without a secondary bevel (or to the primary / hollow ground bevel) you don’t hone the ENTIRE bevel—you just hone enough to get it sharp. The added advantage with honing to the primary bevel is that you don’t need a honing guide because the primary bevel
is a ready made guide. It’s a different technique but a lot easier to perfect without creating a rounded edge which is what often occurs when honing to a secondary without a guide.
Plus you get a sharper edge. Win win.
If you aren't honing the entire primary bevel, then you are, actually, creating a secondary bevel. You are.
If the cutting edge is polished, but the rest of the primary bevel is not polished, you have made a secondary bevel. If you're doing it freehand, it's just a slightly rounded end.
If you keep the angle provided by the arc of hollow ground surface of the chisel you are not creating a second angle or bevel. Just to be clear (not sure but perhaps you've never tried it which might explain the misunderstanding) when honing on the primary bevel you rest the chisel on what is effectively a tangent of the circumference of what is created by the circumference of the grinding stone--so both ends of the angle (where they meet the circumference) are touching the wet/oilstone. To create a secondary bevel you have to lift the chisel away from the known second point on the circumference. This means the chisel relies on you / the honing guide supporting it to keep that secondary bevel. When you hone to the primary bevel you keep to the angle created by the grind stone. Albeit an angle not created along a straight line --because the grind stone is round.
It actually not compulsory to add a secondary bevel. I've seen design with secondary bevel and I've seen design without secondary bevel. I think the main essence of the secondary bevel is for thickness.
Boy, this one gets a lot of comments!
Before I had a roller sharpening guide, I hollow ground all my chisels, and honed them using the front and back edges of the hollow as reference surfaces. I ground them to the angle I wanted at the edge, balancing the angle between ease of entry into the wood and durability, always the determining factor in the angle you choose.
After I got a roller guide (basic Eclipse), I ground to a slightly smaller angle, then used the roller guide at the angle I wanted for strength at the edge, which essentially produced a secondary bevel. As others have mentioned, this makes honing quicker. In fact, unless I am repairing a damaged edge, when I regrind I don't grind all the way to the edge, just narrow the secondary bevel to speed honing.
When I started woodworking 45 years ago, the books of the time said to grind to 25º and hone to 30º. This is fine for basic bench chisels, but I would go to 35º for mortising chisels that take a lot of malleting, and 25º for paring chisels that are only pushed by hand, and aren't used to lever out chips.
Carving chisels are a completely different animal, as they are rarely hit hard with a mallet, and are mostly pushed by hand. Typically both sides of the edge are gently curved, with the angle at the edge just enough for durability. This allows for the control of the depth of cut that Lee talks about. A youtube video on sharpening them recommends a 22.5º angle for the major bevel, and enough on the minor bevel to strengthen the edge (probably about 5º). I have several flea market chisels that had minor rust pits that I have sharpened as carving tools, as the minor bevel puts the edge in a rust free zone. You can also sharpen a narrow one as a skew, which is very handy for cleaning out the bottom corners of half blind dovetails. I ground/sharpened one with equal bevels just for this purpose, so it would work either left or right.
Many seem to add somewhere within their responses, something like "for a quick hone or sharpening. This usually implies that there's no time to sharpen the way you want to but just touch up the edge.
No matter what method you use or what micron or grit level you want to achieve, I suggest make a dedicated sharpening station.
If the sharpening supplies are readily available to use, most people are more apt to do it more often. If all the supplies are in a drawer or cabinet out of sight, the tool tends to go longer in between sharpening and just gets "touch-ups". Sometimes this goes on for far too long and when you finally drag out the sharpening supplies, you have to entirely re establish the primary grind or at leat a portion of the grind to get back to a starting point.
I use a granite surface plate which is not overly heavy but at 26 lbs you don't want to have to lug it out each time you need to touch up a tool. If it's out sitting on a cabinet ready to go, it's a different story. then you tend to not let it go for tooo long
Just a suggestion
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