Recommendation? Sharpening large knives on a bench stone

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maximus83

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Nov 7, 2011
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What is the largest knife size that you can realistically freehand sharpen on a typical bench stone (say something 8" to 12" in length, and 2" to 3" wide)? And, when sharpening large knives on a bench stone, do folks have any basic tips to make this process go more smoothly?

I'm starting to learn and getting pretty good results on DMT and basic water stones with smaller folders and fixed blades up to 5" or so. Actually really fast progress thanks to folks in this forum. I'm also learning how to profile blades that have a large belly area and getting more consistent bevels across the entire belly to the point. But still struggling with how to get consistency across the entire edge bevel when shaping a really large blade on a bench stone. I put a sharpie on a big 8" carbon steel blade last night and tried to reprofile it, the results were, shall we say, depressingly inconsistent. :rolleyes: Areas I seemed to struggle the most: back near the heel (just cannot get that part to come out even with the rest of the straight portion of the edge, this is the second large practice blade I've had this issue), and right before the belly starts (trouble blending the bevel from the straight area into the belly evenly).
 
I'd say about 24" depending on how rigid the blade is. After that your hands will be spaced pretty far apart for control and the weight of the blade is going to flex it near the grip. You could do larger but will have to change how you support the blade.

Scrub in overlapping sections - you're only sharpening the region that's in direct contact with the edge. Do not attempt full sweeps on a large knife.

Work at a 45° angle to your rake path - this will give you max resistance to shifting at the start of each pass. Go slow at the start of each pass as well, again to minimize shifting with the initial drag.

If the tool is really large you can always brace it and take the stone to the tool.

Demo'd with Washboard but benchstone is the same principle.


 
Nice, thanks! On the 2nd video, interesting to see the approach of using your knee to stabilize for field sharpening. Would it also work in the field to do something like: rest the spine of the machete on something (knee, rock, branch, etc) with edge straight up at 90 degrees. This would be one way of minimize machete blade flex as a factor, and for me, would simplify the process a bit as I'd only have to worry about one angle--the sharpening tool in my hand. Then use a 2-grit puck type sharpener in circular motions. For me at least, this keeps it super simple, and also reduces risk of cuts which I think I'd have if I used a rectangular stone as you were doing in the 2nd video. I guess a folding DMT XC/C sharpener would give the same level of safety with the handle. The only downside of my approach to field sharpening I've noticed is the whole circular motions process with a puck makes it tricky to get a clean, consistent edge. It's very rough, mainly for chopping and hacking types of tools only: truly "field sharpening" at its finest. :-)

On the 1st video, yep that's what I was wondering about doing large ones on bench stones. The scrubbing in overlapping sections made sense all along, I've been doing that. What was interesting and new was that you only did a relatively few "backhoning passes" I assume to remove the burr, otherwise everything you did was scrubbing directly on the edge bevel. So unlike an ordinary sized blade where you scrub mainly to profile the bevel, and then you do slices to apex it, here you never really do slices at all. Is that just because of the practical issue of the huge size of the blade, it wouldn't really prove anything trying to do either continuous full-blade slices, or overlapping slices in sections? It looks like it's just scrub to set the edge bevel, and backhone to eliminate the burr.
 
maximus83 said:
Nice, thanks! On the 2nd video, interesting to see the approach of using your knee to stabilize for field sharpening. Would it also work in the field to do something like: rest the spine of the machete on something (knee, rock, branch, etc) with edge straight up at 90 degrees. This would be one way of minimize machete blade flex as a factor, and for me, would simplify the process a bit as I'd only have to worry about one angle--the sharpening tool in my hand. Then use a 2-grit puck type sharpener in circular motions. For me at least, this keeps it super simple, and also reduces risk of cuts which I think I'd have if I used a rectangular stone as you were doing in the 2nd video. I guess a folding DMT XC/C sharpener would give the same level of safety with the handle. The only downside of my approach to field sharpening I've noticed is the whole circular motions process with a puck makes it tricky to get a clean, consistent edge. It's very rough, mainly for chopping and hacking types of tools only: truly "field sharpening" at its finest. :)
Click to expand...

You can certainly use something like a stump etc to stabilize. My experience is that I get a better outcome off my knee but I have no doubt others do fine using whatever method. When doing my hatchet I sometimes just hold the puck in my hand palm up, and bring the tool to it. On a machete I bring the puck to the tool.

The smaller the circle the better the outcome in my experience. It also helps if your big choppers are convexed a bit, as it becomes even easier to do a good job. The deluxe finish is some firepit ash on a smooth piece of wood with a few drops of water, strop a few times, shave armhair.

maximus83 said:
On the 1st video, yep that's what I was wondering about doing large ones on bench stones. The scrubbing in overlapping sections made sense all along, I've been doing that. What was interesting and new was that you only did a relatively few "backhoning passes" I assume to remove the burr, otherwise everything you did was scrubbing directly on the edge bevel. So unlike an ordinary sized blade where you scrub mainly to profile the bevel, and then you do slices to apex it, here you never really do slices at all. Is that just because of the practical issue of the huge size of the blade, it wouldn't really prove anything trying to do either continuous full-blade slices, or overlapping slices in sections? It looks like it's just scrub to set the edge bevel, and backhone to eliminate the burr.
Click to expand...

If I understand you correctly there are a couple of things going on.

With wet/dry you don't want to finish with leading passes, edge leading slices actually hamper the outcome. The same principle is at work with softer waterstones as well.
The best practices go:
-Scrub or limit yourself to backhone passes - raise a burr or three finger sticky.
-Remove burr with a few super light, leading passes.
-Refine with a few backhone passes. A new burr will not form immediately, so a couple of passes and good to go.

Once I get to the paper the burr is already gone, so I'm either burnishing a little or refining it further with compound.

If that had been a diamond plate or other hard fixed abrasive I'd have finished with some very light leading passes and then (or not) refined further with the compound/strop. Wet/dry is a little different of an animal, so while many of the mechanics are the same, application is not.

The product demo on my website has a lot of good general tips for freehand and some very good ones for wet/dry, is worth a watch. Skip to about 7 minutes if you want to jump over the product specific material, tho it does explain the how and why of the Washboard.

 
I used a 2X8" IB8 (same stone) to sharpen a 14" pizza or cheese cutting two handled knife. It can be done. Yes, I just worked in sections, not sweeping. DM
 
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