So now, in my opinion (!), my answers would be cutters 1,2 and 6. All the heads have a helical design, but these three are the only ones where the cutter is at an angle to the direction of rotation, producing a slicing motion.
The rest are perpendicular to the direction of travel, producing a chipping action. (However you may see something in the image that gives you that same opinion).
There is another identifier that you can use. A helical head that chips will have straight-sided cutters. A helical head that slices will have mild convexly curved edge. If they don’t, you can experience a slight ridging running the length of the machined board. Reading around on the forums, this seems to have caught a number of people out where they have what is meant to be the best thing since sliced bread (a helical head) and they are getting results worse than a straight-head planer. They (or the manufacturer/supplier) hasn’t realised there are carbide inserts, and then there are carbide inserts.
Straight-sided cutter for chipper-helix heads
Radius-sided cutter for slicing-helix heads
Exaggerated radius (not for a helix head, but it is easier to see the radius so you know what I'm talking about!)
Guess it comes down to brand – if you buy something made by a (overseas) company that doesn’t actually understand what they are copying, they might have produced a helical head (with a slicing angle) and assumed straight carbide bits can be used. Or they have avoided the problem by making something that looks like a helical head, but still chips away, rather than slicing so they can use the straight sided carbide bits.
If you want quality, unfortunately the old sayings remain true – “if you want quality, buy quality” and “quality costs”
Filed under: Tools Tagged: | best thing since sliced bread, carbide bits, carbide inserts, Helix, Sliced bread, straight head
