Sharpening counter sinks

[Serge Nelissen]

Jan... shapen by hand? No jig availale?

[Jan]

Serge, you are correct, without special sharpening device, the described procedure is only an attempt to prolong the life of the countersink not its real sharpening.   

I do not have the Tormek Drill Bit Sharpening Attachment so I cannot tell you if this could be used for countersink sharpening or not. Do not hesitate to answer the Tormek support.

Jan

[Ken S]

I once watched a knowledgeable Tormek sharpener fumble with trying to sharpen a very dull small parting tool. He was trying to follow the standard Tormek practice of using the multi jig. That procedure works well with standard parting tools. This smaller parting tool did not stay secure in the jig.
I was the junior member, so I did not speak up. I would have just rested the parting tool on the support bar and sharpened it freehand. It would have been sharp "in no time".

I like jig sharpening. However, sometimes it is more efficient to carefully freehand sharpen something. With thought, care, a fine graded wheel and a light touch, the job is usually quickly done.

Do not sell handheld sharpening short.

Ken

[Serge Nelissen]

I'm going to make my own jig...
When it's finished I'll show pictures 

[Ken S]

Great idea, Serge. Several of us have made and shared jigs. We all benefit from this!

Ken

[Elden]

   Here is one person's approach to sharpening a single fluted countersink. While not a rock solid approach as the machines that can be seen from doing a search for "sharpening a counteracting", he achieved good cutting results.

https://m.youtube.com/watch?v=26DSNBclJKk

[Jan]

Thank you Elden for posting the link to this video. I like the fence used to guide the chuck with the countersink at the desired angle. Clever and inspiring solution. 

Jan

[RichColvin]

Do not sell handheld sharpening short.

Ken,

I am a HUGE fan of repeatability.   With the cutting edge consistently the same, I get consistent results when turning.  So I'm not a fan of freehand sharpening. 

The Tormek jigs make repeatability possible.  I have great luck when using them.

Kind regards,
Rich

[Ken S]

Rich,

I totally agree, however, at this point, and the foreseeable future, there is no Tormek jig for countersinks. For a one off, or rarely needed sharpening job, I have no problems with skillful handheld sharpening. In my pre Tormek, pre Veritas sharpening jig days, I did a lot of handheld shsrpening. Like you, I prefer the precision of a well designed jig.

Ken

[RichColvin]

Ken,

Sounds like an opportunity for the KenJig developer...

Rich

[Ken S]

Good idea, Rich. Unfortunately, unlike Thomas Edison, I don't have the luxury of making simple drawings and turning them over to John Kruesi (Edison's chief machinist). Edison also had almost thirty machinists on his staff at Menlo Park. Edison's phonograph was one of those sketches given to Kruesi.

And, unlike some of our members, I don't have the luxury of having a machinist in the family.......

Ken

[Herman Trivilino]

I bought a set of these three-fluted countersinks and I find that they do not produce a very smooth bore. Are these intended only for use on a drill press?

[Herman Trivilino]

Once Herman wrote, "I find it hard to think in three dimensions". Most certain for me is to hold the 3D object in my hand.

Just so you know, Jan, I stole that from Stephen Hawking. In his book, A Brief History of Time, he talks about the difficulty of thinking in four dimensions, stating that he already has a hard enough time thinking in three.

[Jan]

Explanation appreciated, Herman! 

I bought a set of these three-fluted countersinks and I find that they do not produce a very smooth bore. Are these intended only for use on a drill press?

Based on my experience countersinks require firm pressure and perfect perpendicular alignment what is tough to do by hand. For smooth bore the countersinks should be run very slowly and a cutting fluid should be used. 

Similarly to drill bit, countersink cutting edge must have a relief angle also (typically 5 to 8°). Relief behind the cutting edge has even to be slightly larger and must continue around the conical surface segment of the countersink's tip.

Jan

[Jan]

Serge, I was inspired by the videos mentioned in this topic and prepared very simple jig for countersink sharpening on Tormek.

The most important is that the jig enables to set the relief angle of the cutting edge. I have used 7°. 

The first picture shows that the jig consists of short Al rod attached to the tool rest.

The second picture shows that the countersink really cuts with the cutting edge and the relief behind the edge is sufficient. After test countersinking the marker was removed only along the cutting edge and not from the conical surface behind it.   

Jan