Replies

1. 
   SgianDubh | Nov 17, 2002 08:45am | #1

   DW, pointy ended V shaped teeth with a knife like face have a slicing action designed for crosscutting.

   V shaped teeth with a near vertical leg of the V and a straight chisel like  profile at the pointy end are designed for rip cutting with the grain.

   The same basic patterns can be seen in handsaws, bandsaw blades, circular saw blades, etc.. Slainte.

   Some stuff I've made.
2. 
   GregB126 | Nov 17, 2002 09:56am | #2

   DW,

   Here's a way to visualize the difference and understand why.  Take a wide chisel (wide only because it helps illustrate better) and a regular (not push) broom.  Hold the broom horizontally so the straws are near you, with the tips pointing away from you.  The handle is now pointing straight back, as if you are jousting backwards.  Present the chisel to the straws, not at any angle, but with the cutting edge straight across and perpendicular to the straws.  You can see that the cutting edge could theoretically cut the straws, just by pushing through, if it is nice and sharp.  If you held the chisel at an angle, though, it would slide in between the straws and do a pretty bad job cutting.  This non-angled presentation, with the cutting edge straight and perpendicular to the straws (or fibers, in the case of wood) is the profile of the rip saw.

   Now turn the broom sideways to you, sort of as if you are about to lie it down crossways on a counter in front of you.  The handle is now pointed off to your left and the tips of the straws to your right.  Now, if you thrust your chisel straight out from you, as in the above rip profile, the cutting edge slides nicely between the straws, cutting nothing.  If, however, you angle it a bit, then present it to the broom straws, the cutting edge of the chisel is presented to the straws in such a way that it can cut them, rather than sliding through between them.  It isn't exactly perpendicular to them, but more so than the straight presentation of the rip saw.  This is the theory of cross cut saws.  They make a cut with an angled, slicing action.

   Make any sense?  Or have I just completely muddled it up?  Once you can picture this, you can see why L-N, as just one example, sharpens their dovetail saws on a rip profile.  Pins and tails are more ripping operations.  The shoulder at the half pin is not, but I guess you could use a cross cut tenon saw at another $125 a copy for that.  Just kidding.

   Cheers,

   Greg

1. 
   DWRead | Nov 17, 2002 09:08pm | #3

   Great explanations, thanks to both of you.

2. 
   charlesm | Nov 18, 2002 05:51am | #4

   That's the best analogy Ive ever heard to explain this! Can I borrow it (with due credit, of course)?

   Charles M

   Freud, Inc.

1. 
   GregB126 | Nov 18, 2002 07:38am | #5

   Go ahead.  I saw something like it on pbs some years ago.  It was a guy, maybe visiting Roy Underhill, who used a broom to represent wool fibers and a 2x4 cut in such a way to represent enlarged handsaw teeth.  I've always used a wide chisel since, because the sharp edge actually can cut a straw or two, vastly improving the illustration for an in person demonstration.  Few people actually ask about that one, so I'm still on the same broom.

   Cheers,

   Greg