Info about this Onglette graver Geometry.

[mrthe]

Hi , i have see in a Alexandre Sidorov promo video that he sharp the Onglette in this way.
Anyone can explain me why he make this sort of "V" negative mark on the face of the Onglette and what are his benefits or for what type of work is indicated?
Thank you

 

[monk]

my guess-- the groove in the face may allow a slightly better view of the tool point when he is cutting. certainly less metal there when touching up the graver face.

 

[JAT]

I have played around with that a little, and the one thing it definitely does is cut down on sharpening time! It also helps keep the chip, or curl of metal, out of your way so you can see what your doing. I am still playing around with it but that is what i have discovered so far. I am curious as well, to see what others have to say!!

Josh

 

[Ron Spokovich]

After almost 40 years of sharpening tools, the nick he's put into the face seems to have no real purpose except for identification. The geometry isn't right for a 'chipbreaker' type of grind, and time saved regrinding the face would be miniscule. It's possible that he's ground, or polished, his onglette in a certain manner, and wanted a witness mark of some kind to save time searching on his bench. He may have gravers made out of carbon steel and HSS, and wanted to differentiate between the two. Years ago, in an early machine shop, we'd send out tubular inside micrometers to Starrett to be 'stretched', a process where they made them a little longer before recalibration so as to provide material for regrinding the hardened ends. . .they were returned with a small nick on them to indicate that the process was done. Only two or three 'stretch' sessions could be done before the mikes were completely worn out. As shown, at least to me, the nick has no real cutting purpose.

 

[sam]

I have one of those gravers, Paolo. I've not used it and don't know much about it.

 

[mrthe]

Just curious, time ago i was reading about negative face or negative heels and i was curious to know if was something like that, for the lenguage sometimes is hard to me understand some technic word and i think is interesting learn more about this type of sharpening

 

[Marrinan]

Could it have anything to do with making the cut which eventually becomes the ball for hold stones in place. Perhaps to keep it centered or keep it from braking off. Just a thought. Fred

 

[LVVP]

When I cut a long line (especially silver) it helps to make nice right curl

 

[Beladran]

i just watch a stonesetter video on youtube that had that exact shaping to it.

 

[Beladran]

might be a stonesetter thing... just watched another video where they cut that into what looks like a 90degree

 

[Keirkof]

The v-notch in itself has no purpose. It's just a way to grind away metal from the back of the graver so the face can be ground down faster. The notch and face are ground with a coarse diamond-ceramic wheel on the flexshaft. For the notch, use one corner of the diamond wheel. For the face, use the wheel's flat disc. Then polish the face and the sides with a fine diamond-silicone disc.

The business end of the graver ends up as any 'regular' onglette, it's just a way to remove excess at the back...

 

[Keirkof]

I've noticed that GRS are now stocking the yellow diamond wheel that Alexander Sidorov uses for polishing gravers. He has also made this video showing his onglette sharpening technique to go with that.

 

[BLW]

I believe the V grove is meant to act like a positive rake angle on a cutter tool and is supposed to relieve the force of the chip on the tool making a smoother cut and allows the chip to peel away from the cutting tip

 

[monk]

i have way too much time on my hands, i'm going to take 2 identical gravers, i'll notch 1, leave the other one plain. will report back with whatever happens.

 

[ETHELBERT]

Looks like it could be used as a ramp of some type to put the stone on and then let it slide into place. Just a wild guess.

 

[monk]

see my recent post, "mythbuster". the curl or chip is totally unaffected by a notch or groove.

 

[Andrew Biggs]

I've just been talking to Alexander in Basel and asked him about this.
He gave a great explanation.

Cheers
Andrew

 

[mrthe]

Andrew please share it!!! This year was impossible for me assist to the Basel World but next year i want to go , for all the Forum members that yes will assist...have a great time!

 

[bdext002]

I attended his GrandMasters class at GRS a couple years ago and don't remember seeing this type of graver. He did show us a few other variations for stonesetting applications. Pending Andrew's explanation, I'd say that it may be something as simple as reducing the amount of metal on the face will reduce the time it takes to sharpen and re-polish the graver face while allowing the entire side of the onglette to still be used.


Bryce

 

[Andrew Biggs]

Sorry it's taken so long to get back to you. I've been busy at the BaselWorld show and just got back home. Its a bit hard keeping up with things using a phone.

Bryce is correct. Because Alexander uses a yellow wheel for sharpening he found that it took too long and was too hard on the yellow wheel to sharpen the full metal face. So by placing the groove in the face it the reduced time it took to sharpen the onglette.

Cheers
Andrew