Replies

1. 
   LeeGrinding1 | Jan 16, 2003 11:27pm | #1

   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

   Lee Grindinger

   Furniture Carver

1. 
   plinthe | Jan 17, 2003 05:30am | #5

   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

2. 
   TomFerreira | Jan 17, 2003 06:20am | #6

   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

2. 
   ChipTam | Jan 16, 2003 11:28pm | #2

   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. 

1. 
   ronco71 | Jan 17, 2003 01:39am | #3

   Thanks Lee and CHIPTAM.

   CHIPTAM,

   If you don't mind me asking, what is the purpose of the "hollow" grind?

   Ron

1. 
   ChipTam | Jan 17, 2003 03:30pm | #7

   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.

1. 
   ronco71 | Jan 18, 2003 01:23am | #8

   Thanks everyone for your comments. I really appreciate it!

   Ron

1. 
   TomFerreira | Jan 18, 2003 04:05am | #9

   So Lee, Has this petered out enough for you to give us the real answer?

   TDF

2. 
   LeeGrinding1 | Jan 18, 2003 06:27pm | #10

   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

3. 
   UncleDunc | Jan 17, 2003 02:12am | #4

   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.