Sometimes I get curious about the origin of things. In this case, I was curious about how Forstner drill bits came to be. I did a little digging and came up with a tidbit of information on Wikipedia and woodworkinghistory.com. Seems there was this gunsmith named Benjamin Forstner.
Benjamin Forstner
Source: http://www.auroracolony.org/old/families/forstner_family/
If you know anything about guns, you know that during the early years of gun manufacturing, gun stocks and grips were fitted by hand to each gun. This required great skill and accuracy in drilling the recesses necessary to accommodate the barrel and stock of the gun.
To quote Wikipedia:
The Forstner bit was “patented on September 22, 1874, [and] was to make him a rich man. Without the lead screw (which Forstner called the “gimlet-point”) and cutting lips of more conventional wood boring bits it would prove especially useful to gunsmiths like himself and other high-end woodworkers. The bit was unsurpassed in drilling an exceedingly smooth-sided hole with a flat bottom. It was better than the Russell Jennings twist bits for boring at an angle and not following the grain of the wood.
Forstner bits are unique in their ability to drill overlapping holes, notches on the edges of a workpiece, and angled holes on the face of a workpiece (pocket holes, for example). The bit will cut whether or not the center spur is engaging the workpiece. This feature is unique to the Forstner bit.
Colt Forstner bits sold by Infinity Cutting Tools excel at drilling clean, flat-bottom holes, even in the edge of a workpiece.
As time wore on, patents expired, and dozens of manufacturers sought to improve on the design. One of those companies is Colt, based in Germany. They manufacture a unique Forstner-style bit in France.
Colt Forstner-Style Bits by Infinity Cutting Tools
Unlike your run-of-the-mill Forstner bit, Colt bits have a unique geometry that creates a clean, flat-bottom hole without burning and clogging.
The first thing you’ll notice is that the entire circumference of the bit isn’t a cutting edge as it is on cheaply made bits. Colt bits have sort of a scoring tooth that quickly scores the outside diameter of the hole. This prevents burning.
Then if you look at the flat cutting edges on the inside that actually do the bulk of the cutting, you’ll notice some differences there, too. The cutting edges have notches cut into them. The result is small shavings that are less likely to clog the bit.
Another benefit to this unique cutting edge geometry is that it facilitates sharpening the bit when needed. And because there’s less tendency to burn, the bit will stay sharper longer.
Finally, and I know it’s a small detail, but the center spur on Colt Forstner bits is shorter than you’ll find on a lot of Forstner-style bits. This means there’s less of a dimple at the bottom of the stopped holes and there’s less likelihood the spur will break through the opposite side of the workpiece when drilling deep, stopped holes (recesses for hinge cups, for example).
Infinity Cutting Tools carries a full line of Colt drill bits. I use them. And I highly recommend them.
Carbide. Another improvement in Forstner bits over the years has been the introduction of carbide for the cutting edges. The Infinity Tools 7-pc. Carbide-Tipped Forstner Bit Set offers a good value. The tough, carbide edges will last many times longer than conventional steel bits. I keep a set on hand when drilling tough materials.
The cutting edges on these bits are tipped with carbide for long life and easy drilling in tough materials.
