Rounding choils

Brock Cutlery

Brock Cutlery

Joined
Jan 10, 2015
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I just wanted to ask if anyone has figured out a fast easy consistent way to round choils on say a 240 Gyuto?
Typically I'll use my small wheel after grinding the choil and swing the blade from side to side more or less to rough it out, then hand sand with small strips of paper. Is there an easier way?
 
Brock Cutlery said:
I just wanted to ask if anyone has figured out a fast easy consistent way to round choils on say a 240 Gyuto?
Typically I'll use my small wheel after grinding the choil and swing the blade from side to side more or less to rough it out, then hand sand with small strips of paper. Is there an easier way?
Click to expand...

The best way i've found is to do it all by hand, with ducktape / masking tape backed rhynowet (even after heat treating). Take about 20 minutes but it's 100% consistent all the way around the knife. I find when i try to start it on my machine with a jflex slack belt, i grind more facets in it (even CONSTANTLY moving it) and it takes extra time and can be more rounded on one side. Curious to see what others say here.
 
Nick Wheeler used a rotary tool disk with a groove to round over sharp edges in one of his handle videos, see below. I think that might work for the choil on a kitchen knife if the radius is not too small.

Edit: Looks like BF strips the time information from the link, look at around 12:20.

 
I use a 1" wide scalloped aluminum oxide belt running at moderate speed. I use the slack portion between my tracking wheel and platen wheel and swing the knife back and forth. I've found it to work really well on my AEB-L knives with a 320 grit belt. It cuts slow enough that I'm not in danger of overdoing it anywhere but fast enough that it only takes 30 seconds start to finish.
 
CallumRD1 said:
I use a 1" wide scalloped aluminum oxide belt running at moderate speed. I use the slack portion between my tracking wheel and platen wheel and swing the knife back and forth. I've found it to work really well on my AEB-L knives with a 320 grit belt. It cuts slow enough that I'm not in danger of overdoing it anywhere but fast enough that it only takes 30 seconds start to finish.
Click to expand...

That sounds pretty good. I'll try that, thanks! Still interested in other options if anyone has any.
 
I use a convolute deburring Scotch bright wheel. I think it is a medium grit -320, medium hardness felt like wheel, not the soft non-woven kind.

I put a very rough, fairly even 45’ bevel on the choil, then smooth it out with the deburring wheel. Takes less than two minutes. Requires just a little practice and a good eye.

I bevel the wheel to one edge about 40’ so that it will reach in the corner easy. I’m using an 8” wheel on a 1750 rpm buffer, I wouldn’t use a faster moving machine. You will have to buy the flanges to hold the wheel also. I’ve used 3m and Norton wheels, both last really good.

Easy-peasy.

Hoss
 
On hidden tang knives, do you guys cut the shoulders before or after rounding the choil and spine? First four or five knives I made, I cut them at the beginning and only cleaned up a little after HT, less than half a millimeter. I had issues washing out the corner when rounding spine and choil. I now grind the shoulders with a file jig after rounding and get much cleaner results.
 
DevinT said:
I use a convolute deburring Scotch bright wheel. I think it is a medium grit -320, medium hardness felt like wheel, not the soft non-woven kind.

I put a very rough, fairly even 45’ bevel on the choil, then smooth it out with the deburring wheel. Takes less than two minutes. Requires just a little practice and a good eye.

I bevel the wheel to one edge about 40’ so that it will reach in the corner easy. I’m using an 8” wheel on a 1750 rpm buffer, I wouldn’t use a faster moving machine. You will have to buy the flanges to hold the wheel also. I’ve used 3m and Norton wheels, both last really good.

Easy-peasy.

Hoss
Click to expand...


That sounds very interesting Hoss. Does it want to grab?
 
Brock Cutlery said:
That sounds very interesting Hoss. Does it want to grab?
Click to expand...
That’s why I sharpen the wheel to one edge. Yeah, just make sure the heel doesn’t get too close. I move the knife to a safe angle while finishing.

Hoss

edit: I do put electrical tape on the edge to make it “less” dangerous
 
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3m micro finishing film with the 5 mil backing. Cut it into lengthwise strips, then shoeshine method

if you plan out your work and your profile you can do it pre heat treat. Then it’s a simple clean up with finer grit abrasive

same for the spine
 
i also use the 1" wide scalloped belts, using the slack portion above the platen, i stand off the side and run at low (very low) speed. I like a full round radius not a chamfer . I haven't gotten it to come out perfect yet though, it does the job. I do it before the final belt finishing of the bevels as the scalloped belt can leave marks on the bevels.
 
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