Mission: Grind Secondary Point Angles (SPA) on Drill Bits

[Ken S]

Rick and Rich,

I finally had the chance to quietly study this topic. (a great read with early morning coffee before my family arisen).

In both cases, I am impressed how you were able to achieve a goal beyond the original usage design parameters. Rich, you were able to use the DBS-22 for a very accurate, smooth hole in wood. Using the 4000 grit SJ wheel to finish would go far beyond the practical time for standard bit sharpening. You recognized a need for this one particular drill bit and took the time and effort to achieve that need.

Rick, your particular need went both beyond the standard parameters of the jig and the limits of both the SG and SB wheels. You even went to the extent, like Elden had, of modifying your jig and working outside the standard projection.

At this point, I would like to interject a compliment for support. This is exactly the way I hope support will work. When Stig ran support, I always knew I could count on his considerable knife sharpening experience. Much of Stig's expertise, like more sophisticated use of the stone grader and using lighter touches, carries over into other areas of sharpening. Expecting a knife expert to have that same level expertise sharpening special purpose drill bits seems a very tall order. I am pleased that Tormek support had the wisdom to bring in one of their production employees who is more familiar with the deeper workings of the DBS-22. Bravo to Tormek for giving you a useful answer beyond a canned general purpose reply.

Rick was sailing in uncharted waters with changing the bit projection. I sailed in similar waters when I standardized on 139mm as the projection length with the kenjig. I was fortunate enough to have Dutchman's grinding tables as a reference and guide. 139mm is not a magic number; it is a workable projection length within the limits of the knife jig and the sizes of typical kitchen knives. Jan recognized this logic and adopted the 139mm standard. He and others improved the basic jig. Wootz computerized the process, allowing greater precision and a wide choice of angles, projections and distances. In all cases, both with drill bits and knives, forum members did not have the operating constraints of Tormek engineers. We did not have to design something which would be stone simple for thousands of users. We could design something to fit a particular need, knowing that forum members who had the same need would expend the effort to follow the directions if they had enough interest. (We are also available to help guide fellow members.)

Rich and Rick are not one trick ponies. As he adds more information, Rich's Sharpening Handbook is an increasingly valuable reference. Rich has also given me a couple grinding tools of his own design. I think Rick will devise many more drill bit sharpening techniques.

Over the years, I have worked intensively to solve several problems. With me, this has been related to mounting and cutting mats for photographs, understanding and modifying dovetail routing and more recently the kenjig concept. After much frustration, I reached a thought level where answers came easily. That is an exciting state. Rich, Rick and several other forum members have reached that state.

I truly believe that we have only seen the tip of the iceberg with the creative ideas from this forum. The 3X and CBN wheels have expanded our grinding range. The new diamond wheels will continue to expand that range dramatically, especially when coupled with the new Multi Base. Our innovations include Robin Bailey's extended support bar; Herman's platform, several knife jig innovations; and Wootz' clever usb positioning devices.

Rich and I both live in the Columbus, Ohio area. During one of our visits, Rich showed my a stainless steel setting tool Shearig had machined for him. As I recall, Shearig used a design Jan had created. It is essentially an improved kenjig, although comparing the two is like comparing a modern airplane with the Wright Flyer. The original cardboard kenjig is based on Dutchman's solid mathematics. It has been much improved by freely sharing and collaborating on the forum. It has become a truly global project and benefitted from this sharing.

Since first seeing it, I have believed that the DBS-22 is Tormek's most advanced jig (to date). I believe pioneers like Elden, Rich, and Rick have made it even more advanced, with plenty of room to grow.

Ken

[RickKrung]

Rick,

So how well did the newly sharpened, 8-faceted drill work ?

Rich

So, I'm back from the weekend test drilling with the multi-faceted drill with SPAs.  It went about as expected, so a bit anticlimactic.  We only drilled two holes, one with a pilot center-drilled hole and one without. 

The first one, with the pilot center-drilled hole went as expected, peeling off nice chips and not overheating. 




Drilling With Pilot Hole
https://vimeo.com/268613709

Breaking through the back side, one of the advantages of the SPAs was undramatic, which maybe means it worked.  I failed to inspect the back side to see if it left less of a burr, which it should have. 

Breaking Through With Pilot Hole
https://vimeo.com/268613738

Drilling without a pilot hole differed.  Even though the drill had the better centering centerpoint facets, it did wobble, although probably not as much if it didn't have them.  Towards the end, more heat was generated and the center and leading tip (between the primary and secondary facets) burned a bit. 


Drilling Without Pilot Hole
https://vimeo.com/268613771

Both holes cut about 0.005" oversized (0.755"), which surprised me a little and that the second one was the same as the first. 

You can see the damage to the center facets and the burned corner between the primary and secondary facets.


Split-pointing is clearly needed if the drill is to be used without a pilot hole.  We didn't have time then to try split-pointing and I spent much of the drive home thinking of how I might do it on the Tormek.  I believe it can be done, but I'll try it first with the Norton 3x wheels.  Here is a totally cool split-point that would be awesome to do, but I don't think the grinding wheels I have will hold as sharp a corner as this one has. 


Rick