Bad Axe Saws – Mark Harrell on Hybrid Filing

Some candid notes from Mark Harrell when we asked him “why hybrid filing?”

Hybrid-filing: we all wonder—‘surely one thing can’t do two things incredibly well,’ because that is true about 99% of the time. Not so with a hybrid-filed Bad Axe saws, 90% of customers go for hybrid-filing and never look back.

  • Geometry: All we’re doing is making what is essentially a rip-filed saw with a little bevel thrown in to clean up the end grain. Geometrically, our hybrid-filing technique calles out 10 degrees of rake (compared to 5-8 degrees with dedicated rip) and 10 degrees of bevel (compared to 20-25 degrees with dedicated crosscut).
  • Dedicated Crosscut saw is a waste of time: Frankly, dedicated crosscut is a waste of time at the expense of edge retention and accuracy. All it does is make clean end grain with far too many strokes. You really don’t need a lot of bevel to prevent blowout on the far side of the cut and create incredibly smooth end grain. We experimented with 15 degrees, 12, and finally 10—and 10 degrees delivers an expedient cut with clean end grain when employed in crosscut mode than any other bevel setting we’ve used. We also dress both sides of the toothline with a sharpening stone and literally dial in a precise amount of set appropriate to the gauge of metal in the saw. This also serves to clean up end grain.
  • Rates of Cut: So what all this means is that with one of our hybrid-filed saws, one generally slows down just a tad when ripping—for every 5 strokes in dedicated rip, you’ll take 6, maybe 7 when ripping with hybrid-cut. For every 10 strokes in dedicated crosscut, you’ll easily get the cut done in 5-6 strokes, and with incredibly clean end grain and little to no blowout on the far side of the cut.
  • Consider the physics involved: .018 is a really thin piece of metal. Sawing a chunk of wood at the end of the day is about shoving a wedge of chisel-edged metal through wood fiber, so the thicker the plate, the harder the cut. We relax the rake of the 1st two inches of our toothlines to about 15 degrees, then modulate that to the dedicated hybrid rake setting of 10 degrees. This allows the sawyer to dive into the cut on the push stroke and then the rest of the toothline takes over.
  • Sharpened to joint: on a final note, it’s not about making a sawtooth sharp. Think about it—one shoves a file through a gullet and creates two sharp edges. We’re not talking about plane irons finessed with a Japanese Waterstone here. File-sharpening in fact is quite barbaric. What make a saw ‘sharp’ so to speak, is that we sharpen our toothlines to joint, such that we have no ‘big-tooth/little-tooth’ syndrome. Every tooth in a Bad Axe severs wood fiber right alongside its fellow tooth in a 196-count toothline (for a Bayonet). And that is what make a saw ‘sharp.’