Rounding the Spine

A

Augus7us

Joined
Oct 9, 2014
Messages
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Hey All,

I like to round the spine on my kitchen knives. Currently I use the slack belt and rotate the spine back and forth to round it out. I don't like this technique because it is difficult to control and error prone.

I'm looking for something more precise and repeatable.

So for those that round the spine and have a system that works well how are you doing it?

Thanks

-Clint
 
I round the spine on mine with strips of sandpaper. I just go back and forth and up the grits until I'm happy with where it's at.
 
Are you doing this pre heat treat? I'm not sure if just sandpaper would cut it on a hardened blank and thus far all my kitchen knives have been AEBL ground post heat treat.

On one I did knock the edge off on the grinder then used the "shoe shine" method with sandpaper and it turned out ok.

-Clint
 
Yes, hardened steel. 62 Rockwell AEB-L
I use Rhynowet sandpaper, but i doubt the brand makes a difference.
I do the same around the heel and finger groove or where my index finger makes contact.
 
I break the corners of my spine on a worn 120 grit belt on the flat platen and do my choil on a 1/4" small wheel (very carefully). Then I cut tiny strips of rynowet and polish them from 400 to anywhere from 800 to 2k. Sometimes a mirror'd spine and choil are neat. After the corners are broken on the flat platen for the spine I take it off and slack belt them much like you mentioned with a 120grit or A100 belt then put it in a vise and "shoe shine" them with the rynowet just like the choil. Here is a bunka I just made with spine and choil at 800 to match the finish on the blade. I do all my grinding after HT, this is 52100 @ 62 Rockwell. Any inconsistency on the spine from the slack belt can be fixed with sandpaper by hand, as you see in my choil it is rounded nice and consistent after breaking corners on a small wheel. Good 120grit silicon carbide sandpaper strips will smooth it pretty easily. I round my spine right before I handsand because I like the hard corners to rest my finger on when I grind.
choilreleif_zpsrmi2zrz2.jpg

-Trey/Comet
 
Similarly to Trey, I'd do the majority of material removal with the flat platen, where you can have more control. Knock the corners off, even cut a couple of facets, and then finish up with a slow slack belt and/or shoe shine method.
 
Try it lengthwise on the platen.
 
Last edited:
Very interesting, I have rounded the spine on a few knife blades and always use flat platen and follow with slack belt.
 
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