6-facet SPA style or 6-facet tertiary relief style?

[aquataur]

I would like to bring up some subjects, but since there is tremendous uncertainty about the terminology of 6-facet grinds I would first like to clarify that.

There is no consensus as to what a 6-facet grind is. Some think it is a 4-facet grind plus SPA´s (and indeed Mazoff in his well-known article speaks of a 6 faceted drill with secondary point angles (SPA) which could be interpreted this way), but others speak of added relief facets extending the primary and secondary relief planes by a even steeper relief plane, sometimes called tertiary.

The 11/32" drill shown at right has small SPA's added making it 6 facet.

( GadgetBuilder alias John Moran on Drill Sharpening Etc, chpt. ,,Honedrill")

An article by Derek Brown appeared in Model Engineer issue #4025 describing some additional jigs for the Quorn to facilitate "6 facet" sharpening. This process extends the 4 facet process, adding another secondary relief (ternary relief?) at 45 degrees, again arranged so all intersection planes meet precisely at the drill axis.

(Ron Chernich on Drill Sharpening On The Quorn chp. "Six Facet Sharpening")

Four facet drill sharpening (...) Secondary Point Angles (SPAs) can be added to extend drill life, improve hole finish and minimize the exit burr on through-drilled holes.

( GadgetBuilder alias John Moran on Drill Sharpening Etc, chpt. ,,A Powered 4/6 Facet Drill Sharpener"

So by now it should be clear that SPA´s are not limited to a certain sort of grind.
Neither are methods for web thinning like splits.

The point can be split on 4 facet or conical drills.

( GadgetBuilder alias John Moran on The Home Shop Machinist post#8: "4-facet" vs. "split-point" drill grind definition)

(Note the great compilation by Arthur Marks in the end of this document.)

I will address both subjects individually in following threads shortly.

Having that cleared, I would like to bring the tertiary facet to your attention.
Ron Chernich mentions this extra facet in the link given above, but he is not very clear on the purpose of this added complexity.

The secondary relief is commonly said to be about 20° (Chernich: 25-30°). I believe this is not critical, since with the DBS-22 it will have slightly different angles dependent on the drill size.
The tertiary relief according to Chernich is 45°. Akin to the seconary facet, it has to be carefully ground up to the tip.
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(Source: http://modelenginenews.org/meng/quorn/images/q6f_2.jpg)

Now on the DBS-22 you change from grinding the primary facet to the secondary by advancing the pin vise assembly one notch, after tilting the whole jig. The resulting relief angle remains to be determined.

Logic tells that repeating this step again by advancing the vise even further will produce a third facet – and this works. I encourage you to try this, but be careful and hold the vise firmly, it tends to get caught by the wheel. Let us know about your results, folks.

I recommend reading the pages on Gadgetbuilder´s drilling adventures linked above, particularly the ZIP file containing the sharpener plans., which is full of information on SPA´s, facets and splits.