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View Full Version : If my knife veers to the left or right what should i do?



andygraybeal
12-16-2012, 12:26 PM
I've been sharpening for a while now and I know I'm still missing important information. I would like to take the time out of my life to spend another round with Dave himself, but I've not the time or the money. Maybe when October rolls around again.

For now though, I assume there is a good tutorial that explains what happens when my knife wants to head, let's say for now, to the right. i'm right handed. it has gone to the left many times.. but for now it is heading to the right when i cut straight down. maybe i'm not cutting straight or something.. so there is still room that my perception is off. the movement to the right isn't that much. but it's annoying and i feel like i'm doing a better job than i've done in the past. but it's something that i don't understand and i find it annoying. i can easily compensate with adjusting my arm/wrist.

thanks to the forum i just learned about the wixey angle finder.. and eventualy i'd like to get my hands on a usb microscope for the funs of it all.

please, understand that i know in general every part of my technique needs improved.

but without knowing the exact angle, but understanding 90 half, 45, half, 22, and right below that is about 15. so my guess is i'm hitting 15degrees or below on either side of the knife, i build the burr, as evenly as i can.

how do i arrive at the center of the blade to make it not veer left or right? is it a dance that i just end up getting a feeling for or is it hit or miss for the rest of my life?

Salty dog
12-16-2012, 01:11 PM
What kind of knife are you using?

andygraybeal
12-16-2012, 01:31 PM
Ah.. you can't read my mind?

Hiramoto AS Gyuto 300mm that everyone here loves. I bought it from a recommendation when I asked in the knifeforum.com a couple of years ago.

Salty dog
12-16-2012, 01:48 PM
I don't think it's the sharpening unless someone flattened the back of the knife. I use a 70/30 and don't have steering issues.

When using a long knife and you are cutting towards the tip it's more likely to steer. Because of the length the nuances are amplified and you have less control. Also check your grip.
Do you find steering issues when you are cutting closer to the heel?

andygraybeal
12-16-2012, 01:55 PM
ah, maybe someone did flatten the back of the knife a little :) (not much!!) ... but also the front of the knife too. i was trying to do what i saw jmbroida doing on his website. maybe i don't understand.

I think I need to understand 70/30 better... can you explain? I've even read An Edge in the Kithen.. I give myself an F.

I do use a pinch grip. thanks for saying what you did about cutting towards the tip.

and... yes, i think the steering issue is closer to the heel.

btw, I've read your website :) i like it.

JBroida
12-16-2012, 02:55 PM
huh? There is a chance you may have confunsed my single bevel and double bevel videos if you are flattening the back of your suji

andygraybeal
12-16-2012, 03:00 PM
huh? There is a chance you may have confunsed my single bevel and double bevel videos if you are flattening the back of your suji

Not Suji, Gyuto

andygraybeal
12-16-2012, 03:03 PM
JBroida, and yes, i probably misunderstood your videos in the first place! I hope you don't think I'm saying anything wrong with your videos! I love your videos and I'm sure it's my own misunderstanding. I do have that clear :)

JBroida
12-16-2012, 04:30 PM
whops...thats what i get for responding from my phone this morning. Do the double bevel geared videos we made make sense though?

andygraybeal
12-16-2012, 06:16 PM
i think your videos are a good resource and as far as i assume your video is right on. i'm confused a bit about what Salty just said about the flattening of the back side a bit.

Benuser
12-16-2012, 08:21 PM
What kind of edge have you applied?

JBroida
12-16-2012, 08:22 PM
i believe he is wondering if you or someone sharpened the back almost flat or flat as one might do on a single bevel knife

chinacats
12-16-2012, 10:56 PM
How about some pics?

The Edge
12-16-2012, 11:44 PM
A shot of the choil would help here. My guess is that even though you are sharpening each side at the same angle, you are starting off on the right hand side of the knife (in relation if the edge is pointing down). If you sharpen both sides equally, you can end up with a larger bevel on the left side, since that is where you finish your sharpening. This will affect the geometry, and cause it to steer. There are ways to combat this.

a. Start your sharpening on the left side, and do what you normally do.
b. Use a smaller angle on the left side of the knife, using the same exact steps you use now.
c. Only debur the knife on the left side, and don't try and grind away too much steel.

I could be wrong with this, so pictures could really help out, but remember that the forces exerted on the knife while cutting cause steering. While there are many small nuances that can affect this, the usual culprit is the bevel, the angle it is set at, and how large it is. Someone please correct me if I'm off base here.

Cadillac J
12-17-2012, 12:39 PM
^^
we need pics!

Do you have a camera that you can put the macro setting to focus on the blade's cross section like this?
http://i48.tinypic.com/14warm.jpg

andygraybeal
12-18-2012, 09:49 AM
Okay I got pics.

http://imgur.com/a/eFbM2

here's the best one of the choil:
http://imgur.com/sqzZa

Tell me if these are helpul. I need to improve my photo taking skills to.

I appreciate all the input so far. I'm trying to learn. I guess where i fell off the boat was when i ground the side of the knife with the angle to acute?
i didn't grind much, and we can stop pretending that another person touched my knife :) I've been the only one in contact with it.

Thank you.

The hekler
12-18-2012, 12:35 PM
Pictures a little rough but it does look flatter on the left side which I assume is where you get the steering from. I'll let someone more experienced post on what to do to fix it as I'm rather new to this sharpening thing.

eaglerock
12-18-2012, 01:43 PM
The knife looks a bit think behind the edge, maybe it just need some thinning ?

Benuser
12-18-2012, 05:27 PM
Hard to see, not because of the pix, but due to my crappy screen.
Could it be the left bevel has disappeared, and the right side may use some thinning right behind the edge?

Crothcipt
12-19-2012, 01:54 AM
It looks like you have a slight bend to the right too. Not sure if it's just the pic., or if I am just seeing stuff.

andygraybeal
12-20-2012, 07:51 AM
Hah, thanks everyone.. i'm sorry for the crappy pictures. maybe i'll figure out a carriage for both the knife and the camera to take better pictures on my workbench.

echerub
12-20-2012, 02:46 PM
Could it be the left bevel has disappeared, and the right side may use some thinning right behind the edge?

That's what it looks like to me as well.

allumirati
12-20-2012, 06:42 PM
Yes that knife is VERY thick behind the edge. Also the left side looks almost flat and the front a rather obtuse bevel. The thickness magnifies the effect of the asymetry. The knife also looks to be cladded. IF that indeed is the case it would be best to keep it symetrical. To turn an asymetrical knife into symetrical is hard though. For now I would mostly sharpen on the back until the knife is somewhat symetrical and then thin both sides evenly. You COULD do that all at once that that's a lot of work at one time.

allumirati
12-20-2012, 06:45 PM
Another option if you're not up to the task. It might be a good idea to save time and energy and spend the money to have it professionally ground.

andygraybeal
12-21-2012, 06:15 AM
Another option if you're not up to the task. It might be a good idea to save time and energy and spend the money to have it professionally ground.

Awesome. thank you. i feel like a failure :)

Benuser
12-21-2012, 07:42 AM
I wouldn't go so far as to suggest to turn a Hiro into a symmetric blade, as other issues will then arise. The aim should be to restore common proportions though.
I would put a small 15 degree bevel on the left side. Something like .5mm. On the right side, for the time beeing, strop at some 12 degree. From this point on you have a working blade again.
Then, go thinning the right side only. There is a lot to be abraded, at least twice as much as you removed from the left side.
It isn't that hard, but it's a lot of work.

Benuser
12-21-2012, 11:08 AM
Perhaps it's good to explain the sense of what I proposed. I mean to rebalance the friction on both sides, enhancing it on the left by reintroducing a relatively obtuse bevel, and reducing it on the right side by thinning and thus convexing.

andygraybeal
12-21-2012, 09:49 PM
I wouldn't go so far as to suggest to turn a Hiro into a symmetric blade, as other issues will then arise. The aim should be to restore common proportions though.
I would put a small 15 degree bevel on the left side. Something like .5mm. On the right side, for the time beeing, strop at some 12 degree. From this point on you have a working blade again.
Then, go thinning the right side only. There is a lot to be abraded, at least twice as much as you removed from the left side.
It isn't that hard, but it's a lot of work.

hm just to be clear ... the right side is the side that as i'm holding it to cut as a right hander, correct? or the right side in the pictures? the knife is upside down in the picture, so the right side in the pictures is the left side of the knife.

as far as i'm holding the knife, the left side.. i swear i didn't go at it too much. and today.. for whatever reason... i was thinking i should work on thinning the left bevel (as i'm holding it, left). but now i come home and read what you wrote and i'm overwhelmed.

The Edge
12-21-2012, 10:59 PM
Before getting carried away with thinning the knife anymore. Let's get back to the original problem. It originally steered to the left, which a knife ground for a right hand user should do to some degree. Now it is veering to the right. Try sharpening the left hand side (edge pointing down) at around a 7-10 degree bevel, and the right side at a 16-20 degree bevel. The forces that interact with the bevels on a knife are the main factors that cause steering. Don't get me wrong, the rest of the blade geometry will greatly affect cutting performance, but just do me a favor and do this simple little thing before trying to reinvent the wheel. I can't imagine you doing so much damage to the knife by sharpening it a few times, that it needs a complete overhaul.

andygraybeal
12-21-2012, 11:34 PM
The forces that interact with the bevels on a knife are the main factors that cause steering.

This is the epiphany i saw today while i was using it... i know.. epiphany is not the right word... but for me it might as well be. thanks for th response. this makes me feel like i do understand, reassurance.

allumirati
12-22-2012, 03:06 AM
Awesome. thank you. i feel like a failure :)

Just saying. I do it myself and it turns out ok but nowehere near professional. I also have a belt grinder. So if your willing to spend the money and risk in ruining your knife. Go for it. If I had money I'd get my knives professionally done too.