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Any hints to correct an over-shot plunge grind?


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I am making three identical knives for a commission. On one side of one of the blades, I have allowed the plunge grind to cross the spine of the blade... very, very slightly... you can barley catch it with your fingernail, but it's there and it won't do.

 

Any hints or work-arounds to fix this? All the others come up slightly short of the spine, and they look good.

 

I know the key to prevention is practice, but I'd really like to save this one.

 

 

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do a very careful grind on the whole face of the tang on that side till it comes down to the intersection of the plunge. If the over grind on the plunge is as light as you say, no-one will pick the slight difference in tang thickness.

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Yep, a gentle hand, slow grind speed and frequent checks are the key. Don't rush yourself and it'll be fine. If its as slight as you say, you only have to take around two thousands of an inch or so off.

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Sounds good. I'll give that a try.

 

I might just take it down with a sheet of abrasive on a flat surface. My current grinder is a Grizzly and without speed control those surgical maneuvers are quite nerve-racking. 

 

Appreciate the help. I'll keep you posted.

 

 

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Got the same grinder and you are right lol. It isn't built with uber precision in mind. I would suggest getting a nice piece of glass or flat granite, tape some sandpaper to it, wet it down and start sanding. Make sure your pressure is even across the blade or you'll grind one end more than the other. Switch it end for end often and keep the paper wet. You'll get it in no time.

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I would do it on the grinder, get it perfect, then give it one last tiny tickle, somehow let go of it, and get it stuck between the belt and platen at 6000 sfpm :D

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Been there, done that, fixed it too.

I would put it in the hand sanding station and do the flat sand by hand with the abrasive on a hard flat stick.

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On 9/30/2020 at 4:28 PM, John N said:

I would do it on the grinder, get it perfect, then give it one last tiny tickle, somehow let go of it, and get it stuck between the belt and platen at 6000 sfpm :D

 

Welcome to my world!

 

Again, thanks for the encouragement. I put some 120 grit paper on my marble slab and it seems like a save.

 

I appreciate it.

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I have a Grizzly as well, and have had that issue more then once. 

The way I fix those, is I take off the tool rest, grab my trusty welding magnet ( the triangle ones ) and lightly hit the tang area flat against the platen using a worn belt ( like a 100-120g ) and then as suggested do final cleanup on a flat surface with fresh sandpaper. 

 

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