Putting an initial edge on a freshly heat treated knife

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DantheDJ

Joined
Oct 19, 2016
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48
Hello everyone,

I asked about this some time ago, but I didnt get quite a satisfying answer :D

The thing is, how do I put the initial edge on a knife, how to get from that 0.5-1mm after HT edge thickness, to something that I can then sharp on a stone, then polish...

Im interested in a secondary micro bevel, I recon thats easier both to make and to sharp later on :)

Ive searched the web for some videos on this topic, and even youtube knife makers seem to always either finish their knives with belt grinders, or if it is titled in the video "no power tools", then they just skip over it and show the finished product and thus leaving me in the dark bout how its done :eek:

So, if you have a video tutorial for this, or there is just some dead simple way to do it that I am not aware of, pray tell, it would mean a lot for me knives.

Thank you for your time, cheers!
 
After HT, the whole blade need to be re0sanded. You sand the blade down until the bevels have all decarb removed and the edge is around .2mm. You should be at 400 grit or higher by the time you get there. Once the blade is sanded to its final finish, the edge is left unsharpened until final assembly is done. After all the handle work is finished, put the edge on at your desired secondary bevel.

If you don't have a grinder with a flat platen, sandpaper and a hard backing block will work fine. It takes more time to sand down the hard steel, but the process is the same as how you made the blade before HT.
 
Don't make the mistake I did when I fist started out. I was all focused on preserving that thickness for heat treat and then it would stay pretty close to that .030" after finishing. Then I would throw a micro bevel on there and expect it to cut. Nick Wheeler posted something quite a while ago but it's easy to see on social media. A lot of knifemakers leave their knives fat and then throw a huge secondary bevel to get it to cut. That's not good geometry. We're making knives, not axes. The micro bevel should be a micro bevel.
 
seems to me your edge is way too thick
I'm at .005"-.010" when I'm all done grinding (less than .3 mm)

easy to sharpen then and customers love the way it cuts.
 
0.3mm is 0.012" . That is OK for a field use knife. Since I mostly make kitchen blades, I like to take them down to 0.2mm (0.007") at the most. Normally, I take it down to a near zero edge ( about 0.1mm/0.004" but you really can't measure it without a comparator scope)
 
Anyways, I made a little gizmo following all your advices and that got the job done, its not sharpend in any way, but it will cut paper with ease. Im waiting for my glue to come so I can finish it up and then imma sharpen it for reals.

Here are some pictures:
https://www.flickr.com/photos/144377406@N08/albums/72157679285868373

I left the knife with its tempering colors, it was wrapped in foil, so it gave it a nice dark, black finish. Its prettier in person :D

Ive got here two types of handles, one is plastic pvc pipe, and the other is black locust wood. What is your opinion, which one should I choose?
 
DantheDJ said:
Anyways, I made a little gizmo following all your advices and that got the job done, its not sharpend in any way, but it will cut paper with ease. Im waiting for my glue to come so I can finish it up and then imma sharpen it for reals.

Here are some pictures:
https://www.flickr.com/photos/144377406@N08/albums/72157679285868373

I left the knife with its tempering colors, it was wrapped in foil, so it gave it a nice dark, black finish. Its prettier in person :D

Ive got here two types of handles, one is plastic pvc pipe, and the other is black locust wood. What is your opinion, which one should I choose?
Click to expand...

No , you don t follow advice you get here :) That is not edge for knive , it is for adze :D
 
Don Hanson III said:
You don't have a belt grinder? ;)
Click to expand...

I can say that I have , but I am making wheels two years and not yet finished .And I think that I see one scratch in corner on blade ............so back to 120 grit ;) Kidding of course ......Stacy is right ,I think 0.3 is enough . Steel is 5mm 1.2519 and can hold thinner edge but next one maybe :thumbup:
 
Natlek said:
No , you don t follow advice you get here :) That is not edge for knive , it is for adze :D
Click to expand...

Howdya figure that, what did I do wrong?
Lets recap, 4mm spine, full flat to 0.5-0.6mm at the edge, and then I did the secondary bevel on top of that...
Aaaand I made it shave, just for you :*
 
You have to remove several thousandths of an inch from the surfaces to remove all decarb and get to the fully hardened steel. Shininess isn't an indicator of anything relater to that. There are no hard rules on the decarb thickness, but if you take off about 0.2mm on each side, the final bevels should be in the 0.2mm thickness range.

0.5 to 0.6mm at the edge is too thick for the final edge thickness pre-sharpening.

0.3mm is the thickest you want. As I said, I do 0.1 to 0.2mm on most of mine, then sharpen at the desired angle.

.05 to 0.6mm is what I do pre-HT.

Your photo shows an edge that looks far too thick when it was sharpened. It may shave, but it will cut a lot worse than a thinner edge will. I would leave this one as-is, and plan the next one to end with a thinner edge. My rule of thumb is to sand until it starts to get sharp, dull it back a few strokes with 120 grit paper, and sharpen from there.
Be careful when sanding the bevels, as it may become sharp in some places. The spot where the blade curves up toward the tip usually gets sharp fastest.
 
Not a problem, this mistake is fixable, given I left it too thick, I can always sand it down again without ruining it :)

I dont know how it looks on the pictures, but its a really small blade, It can be done in a yify.

Thank you all for your help :D


Let the sanding commence!!
 
On my kitchen knives, I like grinding down until I can bend the edge slightly by running the edge on the back of my finger nail. I'm pretty sure that it usually gets to that point around at around .005" or so. My non-kitchen knives are left a little thicker so that the edges are a little tougher in case people use them on something that could cause chipping.
 
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