PDA

View Full Version : How to remove scratches and polish knifes after thinning?



jgraeff
11-26-2011, 03:49 PM
I thinned and convexed my kino HD but it is all scratched up now. The performance is awesome however I hate the look of it now. I like things to look nice.

Any ideas on how to fix this? Tried to polish it up on my natural it removes some but it just looks uneven will try to post some pics.

Eamon Burke
11-26-2011, 04:03 PM
sandpaper. 3m wet/dry, in assorted grits. lubricant will help to create a haze if scratch marks are bothering you.

Benuser
11-26-2011, 04:10 PM
Just meant as an addition: experiment with sandpaper + mud from your stones.

jgraeff
11-26-2011, 04:29 PM
Lubricant as in water? Also do I need to go in one direction only?

Andrew H
11-26-2011, 05:11 PM
One direction only will make the finish more even, and lubricant as in water + a drop or two of Dawn detergent.

Eamon Burke
11-26-2011, 05:23 PM
I use mineral oil, but anything that suspends swarf works.

I think unidirectional strokes makes an even finish

Marko Tsourkan
11-26-2011, 05:37 PM
A complete scratches removal would require refinishing the whole blade. It can be done on a grinder (machine finish) or by hand (hand-rubbed finish).

To do it by hand, you would need to remove a handle (it is fairly easy to knock off a handle), and if you don't have a vise, but have some old work bench, you can screw a piece of wood to it (got to sink the screws deep), with at least a couple of inches hanging over the edge of the bench. You will clamp your knife's tang with a C-Clamp to overhanging section of the wood. Some guys line the wood with leather or some other cushion, to make sure the blade lays flat while you apply pressure on it. I cover the wood section with a plastic tape, so I can clean it up easily from sanding slurry (removed metal and Windex lubricant)

You will need a sanding stick or sorts. It should be about 12" long, or long enough that you can hold it with two hands. Pad the bottom of the stick (3 inch section or so) with a piece of leather or cork gasket material. This will create a cushion to "hug" a shape of your knife.

Cut a strip of sandpaper as wide as your cushioned area, wrap it around, and sand your knife with back-and-forth motion. As you use up the paper, move it up, so you have a fresh area to sand with. You can pick an assorted pack from your local automotive supply shop. I use 3M Emperial.

You need to spray the knife and paper periodically to reduce loading. I prefer Windex over water or WD40.

If you thinned your knife with DMT XXC, start with 220 or 320 and then move to 400 and finish your blade with 600 grit removing scratches of the previous grit, before moving onto next. Up to the last finishing grit, you can sand with a back-and-forth motion. Once you get to your last few passes on your finishing grit, sand in one direction only, tang to a tip, one pass per new exposed area of your paper. This will put down finishing scratches.

Paper should cost your around $5 and you need only one sheet of each grit.

M

stevenStefano
11-26-2011, 05:38 PM
It can be very tricky. Sometimes you get scratches in weird places from low grit that you missed that are a PITA. I use a 4000 grit micromesh paid with 5k stone slurry which works quite well

jgraeff
11-26-2011, 09:44 PM
I'm a little nervous about taking the handle off gonna try without removing it.

Gonna go to Walmart tonight what grits shall I use? I started my thinning with a 400 gesshin, then 1k, 6k, and takashima.

If I can't get it anyone willing to do it if I ship it out? Should be getting another knife soon anyways.

ThEoRy
11-26-2011, 10:22 PM
My question is why did you want to thin a kono hd? Mine's pretty freaking thin to begin with.

jgraeff
11-26-2011, 10:48 PM
It wasn't so much for thinning but I was trying to get more of a convex grind on it because I was getting a lot of sticking. I should have used a higher grit stone to start guess I know from now on though

jgraeff
11-27-2011, 01:32 AM
Alright guys i gave it a go tonight just finished its no bad.. could have spent more time on the 320 grit i think, although looks much better than it did before hard to tell from pictures but its a lot better.

I may go over it again another day when i can i have plenty of sandpaper left over. Id like to get it to polish up more though. If any of you have any tips that would be cool.

Here is the pictures i took during it in case anyone is interested.

https://picasaweb.google.com/114802200883644205776/November272011

I can definitely tolerate the look of it now, however i don't think i will be doing any more convex grinding on my own. If i need it done i will send it out unless i can have someone show me the proper way.

Marko Tsourkan
11-27-2011, 08:06 AM
Removing handle is not a big deal and you will also be able to check that you tang is not rusting. When putting a handle back on, you can melt beeswax on the tang giving it some protection.

Looks better, but it can look even better than factory finish (machine finish) if you put in time and do it properly.

Kanji on your knife are stamped fairly deep, so they will stay.

jgraeff
11-27-2011, 09:06 AM
Id love to see a video of how to do it that way id feel more comfortable overall.

To knock the handle off i put it in a vice and just tap it with a piece of would or something?

I understand the rest of it and i will try to do it but i will need a replacement knife until then.

Marko Tsourkan
11-27-2011, 09:51 AM
To knock a handle off. Don't have a video but here are the instructions.

- Put blue masking tape over the edge, so you won't cut yourself. Very Important!
- Find a piece of wood (that you can hold with one hand) that is longer than your blade by 4-6" so you have plenty clearance for the tang
- You need some soft of a mallet or a hammer. A wooden mallet works best.
- Place the wood piece against a handle, and while holding a knife and block with one hand (left in my case), hit on the other end of the wood block with a hammer. You might have to hit a few times before you start seeing a movement in the handle.
- To install it back, you stick the handle in and tap on the bottom of the handle until tang sinks in fully. I usually melt some wax on the tang while it is half way, so the tang gets coated and wax seals off the cavity. Then I melt some wax around the tang while it is seated, for a final coat.

The advantage of friction hold over epoxy is for reason like this - refinishing (or sometimes regrinding) a blade.

2657

I will take pics of my setup for hand finishing and post in this thread later.

tk59
11-28-2011, 12:42 AM
I'm a little confused. Which side of the knife were you trying to convex? I am right-handed. The left side of my knife has the stock finish on it still...

jgraeff
11-28-2011, 09:00 AM
I only did the right left the back normal but while I was thinning on the back I did get some scratches on it, most of the damage was on the front.

wsfarrell
11-28-2011, 10:57 AM
To knock a handle off. Don't have a video but here are the instructions. [...]


Thanks, that will go in my notebook. Do you see a lot of blades that are epoxied in, or not many?

Marko Tsourkan
11-28-2011, 12:34 PM
Thanks, that will go in my notebook. Do you see a lot of blades that are epoxied in, or not many?

The only one I have seen was Carter's. Even on Takeda knives, epoxy around a tang hole is applied after the tang was burned in, so those handles can also be removed undamaged.

Why do Japanese knives burn in the tang hole? Because it makes sense. Shaping 4-4.5" deep hole is not easy by other means, a hold is very strong and a handle can be easily replaced down the road. The times you might see epoxied handles would be on oily hardwoods, as those tend to crack often when burning in, so it would make sense to shape a tang hole by other means and glue a handle in. Plus, those handles should expect to last during a knife's lifetime without a need of replacement.

M

jgraeff
11-28-2011, 01:16 PM
ok well i went over it again it looks good except right down by the edge its a little hazy, any ideas on how to correct that?

https://picasaweb.google.com/114802200883644205776/November282011

Marko Tsourkan
11-28-2011, 01:36 PM
Dead link

karloevaristo
11-28-2011, 01:53 PM
low to high grit progression of sandpaper and micron films work great! and are very cheap... just a buck or so... http://www.amazon.com/3M-Lapping-263X-Micron-Sheet/dp/B0002FT3O2/ref=sr_1_1?ie=UTF8&qid=1322507081&sr=8-1

Marko Tsourkan
11-28-2011, 01:58 PM
Does $9.24/sheet (w/shipping) seem cheap to you? :)

I find automotive wet/dry paper work better, as abrasives (silicone carbide) break down nicely, leaving a nicer finish (than using a lapping film). Plus lapping film has stiffer backing, so not easy to wrap around your finishing stick or whatever you finish with (some use rubber blocks)

M

karloevaristo
11-28-2011, 02:15 PM
just trying to show the picture... you can get those in stores that sell 3m products... :D

jgraeff
11-28-2011, 10:36 PM
ok try this https://picasaweb.google.com/114802200883644205776/November282011

slowtyper
11-28-2011, 10:46 PM
You can get a whole range of micro mesh pads for about $10 seems like a good deal also.
http://www.leevalley.com/en/wood/page.aspx?p=62127&cat=1,42500