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View Full Version : Sharpening problems recently...?? Need some advice



jgraeff
09-10-2012, 03:13 AM
Ok so i have been having horrible luck with sharpening lately.

To start there is an old yangi laying around here( masamoto i think) that is really dull i figured id sharpen it up for the chef as if gotten pretty decent as sharpening my deba. I used the sharpie to make sure i was hitting all the right spots and evenly. I got a nice full burr along the entire edge and removed it all completely. Only the first 1/3 of the edge has any bite to it, the rest seems like its completely dull, could i have used too much pressure doing uroshi?


Also the owner here has a vintage sab chefs knife and its also dull as hell. I tried to sharpen it with existing bevels around 22 degrees or so pretty high, i took it to the 400 to get some new metal, got a nice burr, and removed it and took it up to 2k, thinking it was sharp. It felt like it had a nice edge on it, however it won't cut. I thought i rolled the edge possibly by too much pressure so i tried to steel it, no use, so i repeated the 1k and 2k stones being very careful and still no cutting what so ever. Im really confused on this one??

Its weird because on my knives i can take them from not cutting to extremely sharp in no time, im pretty sure my technique is good or i wouldnt be able to get any knife sharp right? I have sharpened tons of other knives with no issues as well.

JBroida
09-10-2012, 03:19 AM
pictures?

Benuser
09-10-2012, 04:19 AM
On the vintage Sab: abrade the existing edge at 90 degree, build a relief bevel of 10-12 degree, and finally end at some 15 degree per side if it's a carbon. Often, these blades have been steeled a lot, and feel like butter. You want to make sure you removed all the fatigued steel. Sandpaper may help a lot.

jgraeff
09-10-2012, 11:00 AM
Jon here is a few sorry only have my iphone to take pictures with.

http://i941.photobucket.com/albums/ad259/jgraeff/IMG_1038.jpg

http://i941.photobucket.com/albums/ad259/jgraeff/IMG_1037.jpg

http://i941.photobucket.com/albums/ad259/jgraeff/IMG_1036.jpg

http://i941.photobucket.com/albums/ad259/jgraeff/IMG_1035.jpg

http://i941.photobucket.com/albums/ad259/jgraeff/IMG_1034.jpg

http://i941.photobucket.com/albums/ad259/jgraeff/IMG_1039.jpg

thats all the yangi, as you can see the tip has been broken off somehow i touched it a little bit but wanted to get it sharp first, No pics of the sab thats at work.

Benuser- so basically just put the knife on the stones as if im trying to cut the stone? and follow the rest?

Benuser
09-10-2012, 02:53 PM
I prefer to remove the steel at 90 degree to make sure it's all gone, and verify the profile. And it's very fast. Use coarse sandpaper for these few strokes and for building up your relief bevel (=thinning behind the edge). Put a strip of sandpaper on your stone, and perform edge trailing strokes as you where stropping. Probably you will have to partially remove the finger guard to make possible a flat relief bevel.

jgraeff
09-10-2012, 03:24 PM
ok so worked on the yangi again today and got it sharp! here are the end results i also fixed the tip. Will polish the second bevel later on my fingers are pretty sore, im beginning to think that the knife is bent a slight bit, and that the shinogi wasnt perfectly straight.

http://i941.photobucket.com/albums/ad259/jgraeff/IMG_1043.jpg

http://i941.photobucket.com/albums/ad259/jgraeff/IMG_1045.jpg

pictures are not the best but all i have.

bieniek
09-10-2012, 04:28 PM
You use strop?

jgraeff
09-10-2012, 07:54 PM
i do on my double bevels but not on this one why do you ask?

bieniek
09-11-2012, 02:49 AM
I thought it might have been too high of an angle when stropping, could cause "slipperiness" of the edge. And the feeling of dullness.

I remember when this was happening to me some time ago. The way i fixed the problem, is when i raised a burr and flipped it from other side, i would, on the same stone, just exchange 15 passes one by one changing sides every stroke. After that on a 1k stone if you check for bite with you fingernail, it should bit right in.
Stropped after, checked again, after 1k stone it should be smooth, but have plenty aggression.

To be super careful i would only do one by one strokes [flipping the knife] and repeat 10 times or so, paying carefull attention to angle and pressure applied [first 3 strokes same pressure as on 1k, next 3 half pressure out, last 4 no pressure]

If at that point the edge ist there, I would just repeat over and over again.

I also noticed its easier to sharpen properly a knife that is thin above edge. If the sab is thick, that might e part of the problem.

bieniek
09-11-2012, 02:52 AM
but that is not the case with yanagi, best guess is that the bevels hasnt met yet, or they did but are not honed properly