Sharpening factory edge

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Gradyw

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Jan 23, 2017
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When you sharpen a factory edge for the first time which are normally toothy does it seem like the middle of the edge is the last thing that gets hit like it's almost a hollow ground edge? I've noticed even with consistent angles right at the edge and the shoulder the grind lines go away first but it takes a minute or two to get rid of the middle... is this normal?
 
Gradyw said:
When you sharpen a factory edge for the first time which are normally toothy does it seem like the middle of the edge is the last thing that gets hit like it's almost a hollow ground edge? I've noticed even with consistent angles right at the edge and the shoulder the grind lines go away first but it takes a minute or two to get rid of the middle... is this normal?
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Yes. Some are sharpened on a wheel and this creates a micro hollow grind.
 
Ahh ok spyderco was the one that just did it to me and I was lazy and didn't get them out but got it sharp.. had some chips after cutting and slashing at a dirty ratchet strap. Wasn't expecting that lol
 
I think what you are describing is an over-under grind. Meaning the over ground one part and under ground the next. This puts a "wave" in the edge and when you put the edge on a flat stone the over ground low spots of the edge don't make complete contact.
 
Yea that could also be the issue.. it didn't take long to fix and I was sharpening S30v which wasn't bad but it def takes longer to sharpen then some steels I'm use to practicing on. I have a mirrored edge now after spending a little more time today. Also I get a little nervous sharpening my more expensive knives haha
 
This is a macro view from a Tramontina machete I picked up a while back. The swept file lines show where its overgrinding the previous hollow grind on the edge. I have only come across this a few times on smaller cutlery, and when regrinding edges I've sharpened on my wet wheel grinder.

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That's exactly how my pm2 was I was talking about.. seems like my spyderco centofante did the same thing too
 
^ That's very surprising. I thought Spyderco ground edges in on belt sanders and then knocked off the burr with a buffing wheel. I wouldn't think that process would produce any kind of "micro hollow ground edge".

I've been wrong a bunch of times, and this could be one of those times. :)

Brian.
 
Well the buffing wheel (keyword) could've done it.. I know it's not removing much material but could've been just enough to do it
 
If I could send pictures I could show u right by the tip I still have an area right in the center of the edge I didn't remove when I sharpened it again
 
Gradyw said:
When you sharpen a factory edge for the first time which are normally toothy does it seem like the middle of the edge is the last thing that gets hit like it's almost a hollow ground edge? I've noticed even with consistent angles right at the edge and the shoulder the grind lines go away first but it takes a minute or two to get rid of the middle... is this normal?
Click to expand...

Your example is one of the reasons why, when I sharpen a factory knife for the first time... I now tend to use a more coarse stone and just reprofile/"grind in" a new edge. Too many factory knives seem to come with "issues" (not necessarily bad, just different than what you or I may do)... that it's better, in my view anyway, to just start fresh.
 
cbwx34 said:
Your example is one of the reasons why, when I sharpen a factory knife for the first time... I now tend to use a more coarse stone and just reprofile/"grind in" a new edge. Too many factory knives seem to come with "issues" (not necessarily bad, just different than what you or I may do)... that it's better, in my view anyway, to just start fresh.
Click to expand...

This is what I do, to many variables in a factory edge to try and follow it.
 
Well that spyderco edge makes me want to have a coarse edge for all my knives... i normally mirror or close to it all my edges.: after playing with that knife I stropped some of my knives on an aroma 140 just to get a clean coarse edge and it definitely has a way more aggressive cut. Didn't understand what ppl meant by that until I got a good coarse edge in my hand
 
I'm also curious now what steels give the coarsest edge.. I understand now the make up of the steel has a big difference in how clean an edge can be or how aggressive it can be.. slowly putting all the parts together
 
My two recent ZT blades have had some over/under grind. One of them took a while to grind out, such a pain in the ass.
 
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