Freehand vs guided, which results in a better edge?

• 
  Support BladeForums!
  Paid memberships don't see ads!

I don't think I really "got" sharpening until I used a guided system (KME). Having the constant angle took my lack of skill (not maintaining a constant sharpening angle) out of the equation and allowed me to actually do the things that people talk about here (create a burr, remove the burr, refine the edge, etc). Without the guided system, I would not have been able to do any of these things.

Maintaining a constant sharpening angle is hard... REALLY HARD. IME, it takes a lot of time to develop that skill and without it you are not going to be able to get a knife really sharp freehand. With that in mind, I think that starting with a guided system is the way to go. Guided systems are far from foolproof; you really have to know what you are doing or the guided system is just a wast of $s.

I am not sure if freehand or guided produces the "best" edge, but I think that a skilled sharpener with a guided system could produce the best edge. However, I think that the difference between a guided and freehand edge when done by a really skilled sharpener would be negligible.

I am now diligently working on my freehand technique. It is slowly improving. I guess that I could have skipped learning how to sharpen with the KME. But now, when I work freehand I KNOW what I need to do and how the process works. I just need to develop the skills that will allow me to do it without a guide.

 

That's a great point, I remember learning, heck I'm still learning.

I'd say that a guided system is superior in consistently but your so limited with what you can sharpen its ridiculous.

It's already expensive enough for quality abrasives let alone needing the appropriate jig or device for different tools( axes, swords, razors, machetes, scissors)

 

In truth they didn't specifically mention freehand, rather they found convex geometry increased longevity by a notable % IIRC in the >20% range (I sent an email, hopefully they'll clarify). This used to be listed on their website but I couldn't find it when I went back for the link.

This led to them developing and offering in their sharpening machines, grinding wheels that can make the "gothic arch edge" - 32° at the apex and 31° 1mm back from the edge. To me that sounds like a good freehand edge...

I do not know what it does further back, what the total contact area is on their wheels out past 1mm - presumably it grinds more than 1mm of steel.

Will update this if they get back to me.

 

Interesting. Any link to their original findings? A one degree change sounds perfectly reasonable for the angle play in a freehand edge.

 

For the life of me I cannot find the link that described their reasoning behind adopting the 'gothic arch', am left with what I can recall which I'd swear stated a longevity increase of approx 20% in some of their testing.

This is about all their FAQ page mentions currently:

For myself, I don't own a guided system so presumably all but my woodworking tools are going to be convexed, and even those to a small extent. I've got nothing to compare them to as most factory edges are belt and wheel so also not flat.

Edit to add:
my 10" wet wheel edges don't seem to last any longer or shorter than any other edge either, hard to believe a (near) perfectly flat bevel will pull the results in an obvious way relative to convex or hollow. I suspect one would really need to torture test to see a difference, and then you might as well factor in ease of touch-ups etc. CATRA seems to feel a certain way or they wouldn't bother with the added engineering.

 

I'll dig around and see if I can find it. You'll forgive my skepticism, but 20% is a lot.

 

I agree. I took it with a grain of salt when I first saw it, and the fact I can't find any current reference means I either dreamed it up or maybe they've backpedaled a bit.

 

A coarser & faster-cutting oil stone, in a similar vein to the Norton India stone, would be Norton's Crystolon line in silicon carbide. Just one example, but a versatile one.

Jason B. posted this vid in reply to essentially the same question (re: scrubbing stroke?) in another thread. It's as good an example of the scrubbing stroke as any I've seen.

David

 

Also look up "Jon Broida" from Japanese knife imports and "Korin" videos also Murray Carter.

 

Its like washing dishes one handed scrubbing stroke. Careful with the other hand
[video=youtube;OPGGo3W15HQ]https://www.youtube.com/watch?v=OPGGo3W15HQ[/video]


Regarding faster cutting, speed is relative, , even the "slow" stones are fast enough
- a loaded stone is slow, solution is clean it, like in the dishwasher
- a worn/slick stone is also slow, solution is condition it, a short rub 20seconds, on slightly coarser abrasive , either sandpaper on tile/glass, or another stone (crystolon) , on tile/glass/stone with a pinch of loose grit , some loosened form stone with a nail (if it works)
- not using oil will also slow things down , stone will load/wear more
- as will using low pressures, its a hard bond stone wont hardly dish, so if its not cutting fast enough, press harder
- stone collector stefanwolf88 calls it fast
[video=youtube;Jk1zhaRRzRc]https://www.youtube.com/watch?v=Jk1zhaRRzRc[/video]

 

A rule of thumb whatever method is used; Every pass made across a diamond plate or stone where the angle is maintained at the chosen angle will move the edge towards the sharpened condition.
Every pass made across a diamond plate or stone where the original chosen angle is not maintained whittles away at the edge, lessening the life of the knife and increasing the time needed to produce the desired edge. You are working against yourself and the off angle needs to be produced on both sides of the blade in order to maintain a "balanced" edge.

Enjoy the experience, Fred

 

Amazing video. That's eerily similar to the way I sharpen. But I don't de-stress the edge. Does it really help? It seems wasteful by directly grinding away the steel at the edge.

 

Hi,
Like with everything it depends.

First part behind the idea of cutting off the edge,
is to remove the steel damaged from use,
to remove the stressed steel,
to "destress" the edge.

Second part is to make a shiny reflective surface to gauge your progress.
With some practice with same knife its possible to stop before raising a visible burr,
and you can sharpen with least amount of metal removed.

So does this help?
Well, I don't use my knives a lot, or hard, just basic kitchen duty, cutting paper when sharpening as a hobby
So, there is not a lot of damaged steel to remove,
so I don't really need to cut it off, but I still do.

Seeing the reflection could be tricky, it was for me , before I figured out wipe blade on wet rag, place on dark towel and use strong flashlight

Most of the time I raise a burr, a big one, as its faster for me than checking for reflection... still manage to whittle beard. Whittling head hair is a tougher challenge (rarely get that sharp) and raising big burrs doesn't help there, but it takes hair to notice that difference.

If you raise a burr on purpose you'll remove more steel, for me, ~100 sharpenings about ~5mm of blade width removed ... in my kitchen use that is sharpen every 3 months, or 25 years of use, with another ~2cm blade width left.

In Sharpening and Knife Lifetime me2 says: With care and practice (both very important), I can sharpen the knife in question, including destressing the edge, and remove as little as 0.0005" of width per sharpening (0.0127mm or 12.7 microns). This is with forming a detectable, but small, burr. That translates to 0.05" lost over 100 sharpenings (1.27mm/300). That translates to 0.15 inches lost over 300 sharpenings (3.81mm/300). If sharpened monthly, that is 25 years.
Cliff says ideally ~1.5mm / 100 sharpenings, or 15microns per sharpening

There is always room for improvement, just keep it fun

 

I got the dmt alignment jig but don't use it anymore better results freehand. Their diafold stones are good but I think I'll upgrade to their bench stones. I finish with green on balsa.

 

Martin,

Today I rebevelled my ZDP and using DMT cards. I found myself using the 'lifting the handle ' method. Apparently with narrow stone such as Spyderco triangle and small 4"x1" DMT, rotating blade is better. With a wider stone, lifting handle is easier.
I also learned to 'listen' to the flat of the bevel through the finger/hand. It is really helpful to keep as flat as possible an edge, free hand.

:thumbup:

 

• 
  Support BladeForums!
  Paid memberships don't see ads!

Chris - good to listen through fingertips, even if only a fraction of the total inputs its a huge asset, and one of those that make dealing with a wide range of tools absolutely essential.

If you imagine the edge/abrasive contact point being digitized so it can be rotated 360 on any axis, the contact angle will look the same no matter the strategy. It all depends on the orientation.

Viewing it as raising the handle really applies to bench stone work where the abrasive is sitting flat on something. also the feeling thru fingertips works best on Japanese tradition two hands strategy.