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In the Shop => General Tormek Questions => Topic started by: Sharpco on November 19, 2019, 06:07:34 am

Title: The chip SG stone made
Post by: Sharpco on November 19, 2019, 06:07:34 am
I used SG-250. The dressing is done by diamond plate(#80 >>> #400). After that, I did honing on leather wheel.

But I could find chip on the edge. Could you tell me what's wrong?  ???
Title: Re: The chip SG stone made
Post by: jeffs55 on November 19, 2019, 10:43:57 am
I am going to say that the angle is too sharp, so the blade is so thin it chipped from a faulty inclusion.
Title: Re: The chip SG stone made
Post by: Sharpco on November 19, 2019, 11:26:01 am
I am going to say that the angle is too sharp, so the blade is so thin it chipped from a faulty inclusion.

It's about 17 dps. I think it was not too low.
Title: Re: The chip SG stone made
Post by: cbwx34 on November 19, 2019, 03:14:11 pm
I used SG-250. The dressing is done by diamond plate(#80 >>> #400). After that, I did honing on leather wheel.

But I could find chip on the edge. Could you tell me what's wrong?  ???

If grading the stone with an 80g diamond plate really leaves it that coarse, try not to grind all the way to the edge... you'll end up with large chips in the edge that you have to grind out with a finer finish.  Stop before the coarse grind reaches all the way to the edge.

That's what the picture looks like... a large 'groove' in the bevel, that leads to the chip.
Title: Re: The chip SG stone made
Post by: john.jcb on November 19, 2019, 04:19:33 pm
The main bevel adjacent to the edge appears to be extremely coarsely ground. I think that this may be leading to your problem. I see very deep grooves at 90° to the edge and I think when you sharpen the edge you end up with areas that are extremely thin and fragile.

Another possibility is if the knife has been improperly used it may have developed micro cracks which are not visible to the naked eye. These cracks can propagate during sharpening and result in the nicks you see.

I only use the 80 grit when I need rapid material removal for an already damaged knife or one where I am changing the angle.
Title: Re: The chip SG stone made
Post by: Sharpco on November 20, 2019, 01:52:44 am
Thank you all. I'll try to stay longer on the #1000 SG wheel(dressed by #400 diamond plate).
Title: Re: The chip SG stone made
Post by: Stickan on November 22, 2019, 08:36:04 pm
Hi all,
I was reading john.jcg's answer about micro craks which I am certain is the main reason.

"Another possibility is if the knife has been improperly used it may have developed micro-cracks which are not visible to the naked eye. These cracks can propagate during sharpening and result in the nicks you see."

Knives with powder steel tend to have this kind of breakout more than knives with stainless steel.

The main reason I checked the forum today was to wish all a great and sharp weekend!

Sincerely,
Stig