I was rather tempted to try jumping in the deep end with the new Tormek Drill Bit Sharpening jig, but decided to err on the side of caution, and rtfm.
Probably a good thing – it is a significant jig, and able to achieve a lot more than standard drill bit sharpening systems. The ability to produce a 4-facet point is significant, and only available on more expensive systems, such as the top of the range Drill Doctor models, and of course the Tormek.
A standard sharpened bit (and typically as a bit comes when it is new) has 2 facets, coming together as a chisel tip. These cannot self-centre, and slip around badly on harder materials. For these bits to cut, that chisel has to be pushed into the surface to expose the cutting edges. This significantly decreases bit life (blunting the bit), and results in a higher temperature for the bit.
The four facets come together at a point, so immediately the drill bit is able to drill into the surface rather than simply rub against it.
The formation of the four-facet tip using the Tormek seems more sophisticated and controllable that the 500X and 750X of the Drill Doctor, (the 350X cannot produce one at all). The significantly different radius of the cutting wheel is another point (excuse the pun!) to compare the two systems. I’ve never had an opportunity to try the Drill Doctor, so can’t say how well that system works in practice.
The Tormek controls point angle (from 90 degrees to 150 degrees) and lip clearance angle (7 to 14 degrees). There are also adjustments to limit the total amount of material removed
Unlike some other systems, the formation of the primary bevel (the actual cutting edge) is given the attention it deserves, with the secondary bevel formed to produce the 4-facet tip – it serves no other purpose, so why focus on it for the majority of the operation? You can even grind away quite a bit of the heel (the back half of the secondary bevel) to minimise the total amount of material that needs to be removed on the Tormek.
There is a little setting up involved, but after doing the first time following the instructions, it will soon become intuitive, and quick. Typical of Tormek, all the variables are controlled – there is nothing left to chance, or eyechrometer. Other than one – setting the drill bit at the right degree of rotation in the holder, but a magnifying glass with a reference post ensures even that is as close as is needed for the operation. (Given the bit is round, being slightly out isn’t critical – it affects the look, rather than the function of the bevel).
Next step will be to actually do the grind, but that will be the subject of another article :)