jamil mehdi
10-03-2020, 9:43 PM
This is a public service announcement:
A lot of people use the terms "helical head" and "spiral head" interchangeably. I think it's important to know the differences between the two.
A helical head has cutting edges in line with the helix, so when the cutter hits the workpiece, it slices off a shaving.
442559
A spiral head has cutters at a 90 degree angle to the workpiece, and arranged in a helical pattern, so when a cutter hits the workpiece, it scoops, exactly like a 1/2" long jointer or planer knife.
442558
So what does that actually mean? Without going into it too deeply...
A helical head will cut more quietly because it's slicing wood fibers rather than gouging them. It will also retain it's edge longer than a spiral cutter will because there's less initial impact against the work surface. A helical head cutter will last longer than a spiral head cutter before it needs to be turned.
A spiral head is better than straight knives because if one gets dinged, you can turn it. It's also slightly quieter than straight knives because the cutting action is segmented across the whole diameter of the cutter head rather than at two or three specific points. But that's it. Beyond those two factors, there is no difference between a spiral head and straight knives.
If you want a helical head because you've heard about how quiet they are and how nice the finish is, and how long they last, you're going to be pretty let down if you get a spiral head because you think they're basically the same thing.
A lot of people use the terms "helical head" and "spiral head" interchangeably. I think it's important to know the differences between the two.
A helical head has cutting edges in line with the helix, so when the cutter hits the workpiece, it slices off a shaving.
442559
A spiral head has cutters at a 90 degree angle to the workpiece, and arranged in a helical pattern, so when a cutter hits the workpiece, it scoops, exactly like a 1/2" long jointer or planer knife.
442558
So what does that actually mean? Without going into it too deeply...
A helical head will cut more quietly because it's slicing wood fibers rather than gouging them. It will also retain it's edge longer than a spiral cutter will because there's less initial impact against the work surface. A helical head cutter will last longer than a spiral head cutter before it needs to be turned.
A spiral head is better than straight knives because if one gets dinged, you can turn it. It's also slightly quieter than straight knives because the cutting action is segmented across the whole diameter of the cutter head rather than at two or three specific points. But that's it. Beyond those two factors, there is no difference between a spiral head and straight knives.
If you want a helical head because you've heard about how quiet they are and how nice the finish is, and how long they last, you're going to be pretty let down if you get a spiral head because you think they're basically the same thing.