Feathered Edge and Hand sanding?

Brian Avila

Brian Avila

Joined
Jan 2, 2011
Messages
1,286
To start out what is the difference between posting in the Shop Talk and the Hammer & Tongs section?

The real reason for the post is the talk about the feathered edge and hand sanding techniques.

So I have been taking my flat grind to .01". Then from there, do this little "scandi" kind of grind to get the edge thinner and almost sharp and still have some meat behind the edge, trying to do what Nick Wheeler was talking about on his custom knife making video he posted. I do this between the 120 and 240 grits on my grinder. Then I go to hand sanding.

The problem I come to is the blending of the edge. I can semi blend it with hand sanding, but I am not really happy with the results. It doesn't look like a flat grind like all the other knife makers, when it is all finished and sanded and has an edge but you don't see the sharpening marks.

I can't get a picture to show it. It looks flat in the pictures I take, but when you shift the light over the blade you can see the little convex at the edge towards the tip.

I am guessing that I should just flat grind to just below .01" thick and then sharpen the sucker and then hand sand and be careful?
 
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I'm not quite sure what you are asking about. But, maybe this is it. When you sharpen the edge will often go to a "pumpkin" shape. This edge has a "support" to it and for me is hat I want to get on my blades. Perhaps if you aim for say .005 on the edge before sharpening it will provide you with a much better cutting edge. Frank
 
Let me see if I can explain a little better. I am looking to make better knives in the edge geometry department. I saw Nick Wheeler post a video on one of his threads show how custom made knives are better than a factory knife.

It showed how he would thin the edge, like a extra "scandi" grind on the edge, and then feather it so that it looked blended.

So I tried that and was hoping to feather/blend while hand sanding. It didn't come out very great. So my question is:

How do I feather the edges so they look nice, like a sharp JS test knife where you don't see any sharpening marks ( at least from what I can tell from the pictures )? Or do I just need to go total flat and not worry about this method?
 
If I understand what you're asking, you do it as part of the lenthwise hand sanding to make
a convex edge as part of the blade finish. Work wet.
 
I think you might be getting a couple of my posts mixed up a little... just enough that your description/wording is throwing folks off.


The "Scandi grind" reference I made was regarding the clip grinds on some of my fighters.

Typical Finnish and Scandinavian knives have a narrow bevel that is ground down to zero--- meaning it's ground right down to sharp, NO secondary bevels. To sharpen that type of bevel, the most common approach is to lay the entire bevel on a sharpening stone.

So mentioning a Scandi grind when talking about a main bevel that is fully flat ground with some convex geometry added... is a bit confusing.

Not picking on 'ya or arguing semantics...! Just try'n to help. :)




Now back to your question---

It would help me out if you had some photos of how you're doing this, as well as what you're not happy with in the results. I think I get it, but a couple pics would clear it up.


You can hand sand a convex blade with only a hard backed sanding stick/block... but if you're having trouble blending, then you probably need to make a sanding stick/block with a soft surface. Keep in mind! It's just for blending/feathering--- if you do ALL of your sanding with a cushy sanding block, you'll wash out crisp transitions!!! Some guys want to do that. I spent many years getting to where I could grind/file/sand crisp transitions, so I personally do not want to wash them out.



I'm pretty sure you were thinking of this video.... ??? Somewhere around 5:30 is where I started adding the convex geometry.

[video=youtube;RhijW7L9Cm4]https://www.youtube.com/watch?v=RhijW7L9Cm4[/video]


It's harder for me, to get a really nice looking, clean finish on a machine finished blade because I don't make the blades absolutely FLAT. I can... but that isn't what I consider an optimal blade grind. Hand finishing is the easiest way for me to blend everything together for a super uniform/clean look.

The rotary platen is a great way to get things feathered together on a machine finished blade. On my typical custom knives, I do the convex feathering on the 2X72 belt and rigid platen just a little (no rotary platen work), then clean it up on the 9" disc, then hand sanding everything.
 
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Nick - your right I think I am not saying the right words. You are correct, that is the video I saw and want to try that geometry with my knives.

Later tonight I will be able to get some pictures for you so you can see the different things I am having problems with. The pics I was trying to take last night wouldn't show what I needed. I have one knife at 500 grit ( length wise ) and then I have another knife that I worked on the grinder that I haven't hand sanded yet. That might help.

I don't like washed out lines either, so I have been using a metal sanding stick and my fingers to blend. I might try some leather on a piece of metal to blend.

What I don't like on the knife I am working on is at the tip it really does look convex and not flat, if I am doing this right it should have a flat look with the convex edge geometry right?
 
Ok so I have some pics. what I did was ground to just under .01", then tried the convex edge shape and got this. The grinding was done up to 220 grit.

8B26E976-7A6C-420B-86F5-C40667DEF59F_zpsajlxxhyr.jpg


Then I started the hand sanding and got this...

AF0FFE42-B14E-47E1-86A2-D122D4F82C6F_zpsk2tvsy2b.jpg


The hand sanding is up to a dirty 500 grit, length wise.
 
No the edge is not .010" still. Its "sharp", I cut myself hand sanding, but probably not as sharp as I want it to be. But it isn't final sharp and I am not done hand sanding yet.

It was really hard to get the "wave" of the convex to show up in the pictures, sorry this is the best I could do.
 
I forgot to say what I was unhappy with on the pictures. If you look at the hand sanded blade in the tip area, you can see that there is a convex to it compared to the rest of the blade which I got to blend in nicely. I am not sure if that is a function of my grinding and trying to get the geometry or if it is bad hand sanding.
 
Grrr--- I've tried to reply to this thread about 7 times, and BF keeps kicking it out... :grumpy:

It might just be your expectations... A

tip that is ground thin, but with enough

meat behind it to be really strong, is

going to be convex... Take a look at some

close-up shots of knives from guys like

John White, Mike Quesenberry, Samuel

Lurquin... there are many others, but I

know for sure those 3 have close-up pics

of blades floating around the net that

show what I'm talking about.

I used to grind mine VERY VERY flat and

thin, but even with something like 3V and

professional heat treat, that leaves the

tip vulnerable. On a kitchen knife, or

something like a leather cutting utility

knife, I don't think that's an issue, but

just about any other type of knife will

benefit from having the tip "drop in"

somewhat abruptly.

From what I can see in your pics, it looks

pretty darn good to me. :) It could

probably be blended/feathered in together

a little more, but I'd say you are already

ahead of most with what you're showing

there. :thumbup:


Just to keep from inviting a flame-up

here, I am NOT saying I think a knife

should have the tip of a screwdriver or

cold chisel! ;) I'm just saying a tip

that's got a little meat behind it can

still have a needle point feel, and still

be very strong. :)
 
Well, my text is all screwed up, but I'm about out of patience with BF, so I'm not messing with it! :foot: ;)
 
Thanks Nick, that is a lot of help. I tend to agree with your thought process and how you go about things.
 
I have several different sanding blocks for hand-finishing blades. My favorite block to use when blending/feathering a convexed edge into a flat bevel is a G10 scale with a piece of 50A-durometer rubber glued to it. McMaster-Carr carries a ton of different rubber materials in different durometers. Try a few different types and see what works best for you.
 
Shawn Hatcher said:
I have several different sanding blocks for hand-finishing blades. My favorite block to use when blending/feathering a convexed edge into a flat bevel is a G10 scale with a piece of 50A-durometer rubber glued to it. McMaster-Carr carries a ton of different rubber materials in different durometers. Try a few different types and see what works best for you.
Click to expand...

I would have probably made some like that as some point, but I don't want to spend like $20-$30 on more rubber than I would need. I would only need like 3" long strip that is like 1.5" wide, and I would want different durometers
 
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