drill bit helix

[mikechoochoo]

Why do a few drill bits have a helix with more turns than the standard ones. Are these for some special use.
Mike.

[EricM]

From Viking Drill and Tool's website:
Helix Angle (Spiral Angle)

An essential feature of a twist drill is the helix angle (spiral angle). It determines the process of chip formation. Larger helix angles provide effective removal of soft, long-chipping materials. The high helix brings the stringy chip up and out of the hole for easy disposal.
Smaller helix angles, on the other hand, are used for hard, short-chipping materials.
Twist drills that have a very small helix angle (10° – 19°) have a lengthy spiral. In return, twist drills with a large helix angle (27° – 45°) have a rammed (short) spiral. Twist drills with a normal spiral have a helix angle of (19° – 40°).

[BadDog]

High helix drills also provide shorter spacing between the lands, so somewhat less prone to wander in deep holes. But as noted, depending on material, can exaggerate chip packing problems.

[mikechoochoo]

The reason I asked is that I have a 3/8 drill with a fast twist the came with a can of drills and I just wanted to know what it might be useful for. Its not unusually long or special in any other way.
The mention of drilling long holes reminded me of gun barrels and the time I was offered a 38 caliber revolver that someone had sort of converted to 38 special by drilling out the cylinder chambers. Of course they were oversized and off centered. I passed on that one.

[Harold_V]

The mention of drilling long holes reminded me of gun barrels and the time I was offered a 38 caliber revolver that someone had sort of converted to 38 special by drilling out the cylinder chambers. Of course they were oversized and off centered. I passed on that one.

Heh! Likely a wise move.
When I was a young lad, my father had a Spanish made 38 special. The cylinder suffered from slight misalignment with the barrel, resulting in the shooter getting sprayed with lead with each shot. He didn't have it long.

H