Thank you for posting!!
Inspired by God, Forged by Fire, Tempered by Water, Grounded by Earth, Guided by the spirit.. Randy Haas
I agree with the intent of the post. That is, that grinding asymmetry into your edges isn't as simple as it might seem but as far as how much wiggle room you actually have to work with, I'd say you have a lot more than this thread makes it seem. Whatever is done to one side if the bevel just has to be balanced in one way or another on the other side to avoid steering. I see steering as more of a trade-off than something to be avoided at all costs. It just depends on the knife, the material being cut and the user. There's a lot of room for wiggle and don't tell me the fool that sharpened my A-type had any sort of geometry in mind when he ground that haphazard POS bevel.
I completely agree with you on all points.
Just to explain a bit more though, the reason why I mention steering as an unwanted by-product of improper asymmetrical sharpening is because of how many knives (literally hundreds upon hundreds) I've had to fix for people who caused themselves problems through either trying to do something special that read about on the internet (experimenting), simple lopsided sharpening over time, or from sharpening services that offer single sided sharpening only. The results are all the same regardless of what caused the condition, the knife owner wants to turn back the clock and fix the knife to steer straight again, sometimes this is simple (as is often the case fortunately) and sometimes not so simple. So while I agree that steering is a trade off of sorts (and maybe something even desirable to some) it's something best avoided by most. My post is meant to help the majority of people avoid the pitfalls of misinformed advice found across the interwebs.
Thank you Dave .
and yet this forum is still thriving .
A clever cook can make good meat of a whetstone. Erasmus
Interesting post. I do not know if this Q belongs in this thread or not, so if not, mods, please separate!
I am a lefty (I know challenged...)
How do i best approach this assymetry that comes from the original blade grind?
How do you other leftys do?
It's been my experience (with double beveled knives like gyutos) that most lefties buy righty knives and find grinding more on the left side than the right helps make the knife feel better to them. I think a good place to go for lefties is to get a thinner 60/40 gyuto as a starting point since this is much less likely to cause problems.
Now when you're talking about double beveled knives such as the honesuki & garasuki that are 90/10 ground as well as single beveled knives you'll either have to learn to use the right handed versions or pay the premium for the lefty versions, no way around this.
Assuming the following assumptions are true (gathered from this thread, but may have wrongly interpreted)
1. Sharpening the edge on both sides at the same angle can create asymmetry and put the edge where you want it to be relative to the spine
2. Sharpening the edge on both sides with a different angle on each side can create asymmetry and put the edge where you want it relative to the spine
3. Both methods can put the edge in the same spot
4. The key difference between the two is ONE angle (left or right side depending on what he blade wants)
5. This angle will either either widen (steeper angle) or narrow (shallower angle) the bevel.
Example: I sharpen one side at 15*, the bevel may end up being 0.3mm wide. I now sharpen this to be 7.5* instead and end up with a bevel 0.6mm wide.
Again using either method (same angles vs. different angles) will put the edge in the same spot relative to spine. One method achieves this by grinding more vs. less. The other method uses different angles.
Assuming the above is true the only difference in the end result is the width of the bevel on one side. Using 15* vs. 7.5* this difference may be 0.3 per above example.
Question (finally): Does this 0.3mm difference in bevel width really make all the difference in whether a knife steers or not (or at least less)?
Based on the posts here the answer should be yes. Personally I can see this being the case with very thick blades (that should maybe be thinned) or single bevel knives, but with lasers that have a barely perceptible edge I see this not so much. If someone could elaborate on this more that would be great. Still wrapping my head around all this.
Hi Clayton, I'm not sure that I can agree with all your extrapolations but assuming that your math is correct I'll answer about the issue of whether or not such a small amount (you mentioned 0.3mm) difference between the angles on the right and left side being a factor in a thin laser knife steering or not - I say probably not. It's unlikely that mistakes made on a really thin 60/40 ground knife will make that much of a difference but it is likely that some effect will occur over time. The thicker knives will be less forgiving earlier on.
Thanks Dave. When you say "but it is likely that some effect will occur over time" - Do you assume that the user is not thinning the blade?
Assuming they are thinning the blade over time, would the impact or "non-impact" of same angle vs. different angle not remain steady?