Removing thinning scratches

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jgraeff

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Hey,

i have a friend that sharpened his knife, he thinned it and both whole sides look pretty bad was wondering if there is a way to fix this without sandpaper or a beltgrinder?

i was wondering if the mud from stones would help smooth out the finish?
 
Using actual stones to refinish an entire blade isn't fun and I've never gotten a nice, even finish that way. Applying mud to some sort of substrate like cork has worked for me to an extent.
 
Good topic, I wondered about this too. Wonder if anyone has pics of a knife thinned on a stone.
I'm assuming it's part of the learning process. (Not to thin using too rough of a grit)
 
wet/dry sandpaper is the way to go, in my opinion. i've gotten good results using a King 800, as well. refinishing goes along with thinning, so a small investment in sandpaper is a good idea.
 
A friend, huh? :D
I've never done a great job polishing a knife with stones only. Mud could work but it would take awhile. Is there any reason you don't want to use micro mesh pads or sandpaper?
 
Mud on cork is pretty limited in terms of the depth of scratches it will fix.

Putting a satin finish on using wet/dry sandpaper on a hard foam sanding block is not all that difficult. Lubricate with water/Dawn, sand in one direction only, start with 220 and finish around 400 or so, and you you can mimic a Shigefusa kasumi finish surprisingly well.
 
These are two knives I've thinned and blended on stones. You don't have to blend that far up the blade.
P1070138 (1024x768).jpghamaguri-front.jpg
 
You know sandpaper is available at any auto body shop, or even Auto Zone for like $5, right? It's a rare solution--fast, cheap AND good.
 
Andrew H said:
A friend, huh? :D
I've never done a great job polishing a knife with stones only. Mud could work but it would take awhile. Is there any reason you don't want to use micro mesh pads or sandpaper?
Click to expand...

ya actually a guy a work that didn't want me to do it ;)

will try to get a picture tonight. Also if anyone has any videos of how to do it with sandpaper that would be awesome i did it about a year ago with my Kono HD it came out ok but not as good as id like you can always see the scratch marks
 
The problem is you have to start with almost the grit that caused the deepest scratches; otherwise all further effort will be in vain.
 
You can do it with stone.

But it will train you patience.
 
Quality automotive sandpaper is your answer. The reason sandpaper is better than stones is that with a flexible backing (like rubber), your sanding block will conform to a blade's shape, particularly to that of a convex.

Here are some tips that would make your work easier.

You want to remove the handle (if you have a wa) if possible. You want to fix your knife on a block of wood so it is stationary. You want to have a sanding stick that you can hold with two hands. Typically 12" long, 2" wide board with a glued piece of thick rubber gasket or leather in the middle would do. All this is going to give you a fairly good finishing result.

You will have to remove all scratches, not just sharpening scratches, to have a good finish. Many knives are finished with vertical scratches and Scotch-Brited over, so there might be deep scratches hidden under finish. Start with 220 and sand until you get rid of all scratches. Then move on 320, 400, 600, 800. I don't see any practical reason to go above 800 grit. Use Windex as lubricant.

Use back and forth sanding motion. When you get to the 800, your motion should be in one direction only. That will apply even final finishing scratches. Finally, go to the stones and put a thin bevel on your knife.

M
 
The "Marko method" is certainly the most uncompromising and through way to do it (big surprise).

But Ive also had very good results with a cheap neoprene&cloth mousepad.

-put mouse pad on table or countertop (work surface) with one side touching or slightly overhanging the edge of the work surface.

-put sandpaper over top of mousepad.

-put blade ontop of sandpaper so that handle is hanging out over the edge of work surface

- apply glentle downward pressure to blade (BUT DO NOT PRESS ON THE HANDLE UNLESS YOU WANT TO BEND/BREAK IT OFF)

-move blade "in and out" from tip to heel; heel to tip
 
Not done knives but have done with numerous other tools and another vote for wet and dry.
 
I think most knives will have to be thinned sooner or later, so refinishing process has to be thought out as well.

I use a drill wise ($20) with a 2x2x18" or so block of wood in it. You can bolt your wise to a table top, so it is stationary. I use another block of wood on top of the one in the vise. I clamp in a top one to the bottom one as well as a knife's tang with a C-clamp. You can also us a bracket and a little wedge, similar to how Maxim secures his knives. For that matter, you can skip a vise all together.

Why two blocks? I like the height and I like the fact that I can rotate the top block slightly to the left or right (while the bottom is stationary) to change angle of scratch lines.

If a handle is fixed on a knife, you can carve a recess in the top block to 'sink' the handle in and to clamp it.

Simple, but very effective setup. It has worked for me very well.
M
 
You all don't know how glad I am that this topic was brought up. I thinned or tried to thin or maybe just wasted a whole lot of my time on my A-type a year ago. After I was finished I decided to polish the blade face. I ended up with a shiny blade with a few blemishes I couldn't get out without starting over. I just stuck the knife back into its saya and stuck in in the bottom of my knife drawer. I think this is a good a time as any to get that knife back out and have another go at it.
 
Thanks for the step by step Marko. Will be stopping by the auto parts store for some sand paper after work.
 
jgraeff said:
ya actually a guy a work that didn't want me to do it ;)

will try to get a picture tonight. Also if anyone has any videos of how to do it with sandpaper that would be awesome i did it about a year ago with my Kono HD it came out ok but not as good as id like you can always see the scratch marks
Click to expand...

99Limited said:
You all don't know how glad I am that this topic was brought up. I thinned or tried to thin or maybe just wasted a whole lot of my time on my A-type a year ago. After I was finished I decided to polish the blade face. I ended up with a shiny blade with a few blemishes I couldn't get out without starting over. I just stuck the knife back into its saya and stuck in in the bottom of my knife drawer. I think this is a good a time as any to get that knife back out and have another go at it.
Click to expand...
im glad i read this post as well. ive been Starting with 800 grit auto sand paper! haha no wonder all my scratches remain
 
Marko Tsourkan said:
I think most knives will have to be thinned sooner or later, so refinishing process has to be thought out as well.

I use a drill wise ($20) with a 2x2x18" or so block of wood in it. You can bolt your wise to a table top, so it is stationary. I use another block of wood on top of the one in the vise. I clamp in a top one to the bottom one as well as a knife's tang with a C-clamp. You can also us a bracket and a little wedge, similar to how Maxim secures his knives. For that matter, you can skip a vise all together.

Why two blocks? I like the height and I like the fact that I can rotate the top block slightly to the left or right (while the bottom is stationary) to change angle of scratch lines.

If a handle is fixed on a knife, you can carve a recess in the top block to 'sink' the handle in and to clamp it.

Simple, but very effective setup. It has worked for me very well.
M
Click to expand...

Pictures please.

PZ
 
Benuser said:
The problem is you have to start with almost the grit that caused the deepest scratches; otherwise all further effort will be in vain.
Click to expand...

You can take out 60 grit scratch with 220 grip paper, but you will have to put some time (and paper) into it.

Pabloz, will take some next time I have my camera in the shop.

M
 
Justin0505 said:
The "Marko method" is certainly the most uncompromising and through way to do it (big surprise).

But Ive also had very good results with a cheap neoprene&cloth mousepad.

-put mouse pad on table or countertop (work surface) with one side touching or slightly overhanging the edge of the work surface.

-put sandpaper over top of mousepad.

-put blade ontop of sandpaper so that handle is hanging out over the edge of work surface

- apply glentle downward pressure to blade (BUT DO NOT PRESS ON THE HANDLE UNLESS YOU WANT TO BEND/BREAK IT OFF)

-move blade "in and out" from tip to heel; heel to tip
Click to expand...

thats how i do it, though i only move the knife from heel to tip. the results are pretty good, in my opinion.
 
I have a 12 inch square piece of rubber that I got from McMaster-Carr that sits on the bench top, and the sandpaper sits on that after a sprit with water. I can then work to blade on that surface as needed to achieve my desired effect. A little water under and over the paper does the trick!
 
SpikeC said:
I have a 12 inch square piece of rubber that I got from McMaster-Carr that sits on the bench top, and the sandpaper sits on that after a sprit with water. I can then work to blade on that surface as needed to achieve my desired effect. A little water under and over the paper does the trick!
Click to expand...
The drops of water are very clear to me, the squared inches
though required some thinking.
 
I am so glad this topic is here. I don't have a problem with my blades having scratches, but when I did my bosses I was a little ashamed of them. He liked the over all look and feel but I was mad it wasn't perfect/like new.

Now to go and do some more learning.
 
Marko Tsourkan said:
You will have to remove all scratches, not just sharpening scratches, to have a good finish. Many knives are finished with vertical scratches and Scotch-Brited over, so there might be deep scratches hidden under finish. Start with 220 and sand until you get rid of all scratches. Then move on 320, 400, 600, 800. I don't see any practical reason to go above 800 grit. Use Windex as lubricant.

Use back and forth sanding motion. When you get to the 800, your motion should be in one direction only. That will apply even final finishing scratches. Finally, go to the stones and put a thin bevel on your knife.

M
Click to expand...

Is 800 grit high enough for a mirror polish?

Thanks
 
chinacats said:
Is 800 grit high enough for a mirror polish?

Thanks
Click to expand...

What finish is left largely depends on what sandpaper brand you use. Some leave much finer finishes than others, but I don't think any 800 grit paper will leave a mirror finish.
 
chinacats said:
Is 800 grit high enough for a mirror polish?

Thanks
Click to expand...

Not in a true sense (like a mirror), but you can see your reflection, particularly if you oil your knife.

800 you will get fine satin finish, provided you put down a nice foundation with preceding grits.

M
 
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