Recommendation? Advice on wavy edge...

C

Chris Horner

Joined
Aug 14, 2018
Messages
11
I've been grinding away on my first stock removal knife, using 1095 steel, and having a very good time working on the blade. Y'all have been a great resource in learning the tips and tricks of the trade so far, but I find myself at the point of needing direct advice as opposed to just reading the archives.

After I got the blade into the shape I was envisioning and the surface finish I thought appropriate, I had allowed the edge to thin too much. Understanding that this makes blade warpage a risk during heat treating, I gave the blade a run of normalization (3 slow runs up to about 1425F w/ air cool) as some have described here and then heat treated it (slow run up to non-magnetic plus a little time, then quenched in canola).

Well, in any project something must go awry, and in my case it was the edge. You can see in the photo that the overly thin blade edge went wavy. The blade itself didn't warp or twist, just the edge, and only about 0.25 mm from the blade centerline, with the distortions rising from the edge only about 0.5 mm towards the spine.



What opinions do y'all have about how to approach this problem? The way this newbie thinks, there are two approaches:

- File the distortions out, i.e. shortening the blade height, and then putting in the planned secondary bevel.
- Filing/stoning in a tall secondary bevel to remove the distortions.

Regardless, being my first attempt, I'm going to finish this blade even if it's such a bag of crap that I keep it remind myself of the learning process.

Thanks,

Chris Horner
 
Depending on how thick you left it at the edge, option 2 may not be possible? If the waves of bacon go through the centerline of the blade, you won't be able to grind a bevel without a "hole" in the edge.

I personally just shorten it, i.e. grind the edge back past the bacon which results in less distance between the spine and edge.

Good lesson to learn tho. And looks good so far for a first knife too!
 
i would go 1/2 and 1/2. grind 1/2 of the distortions out, and the other half should disappear when you do the secondary bevel if the distortions are only only 1mm tall. i leave my edges about as thick as a dime before heat treat. if i go below about .020" i get the wavy bacon edge in the quench. .025" seems optimal, never had a warp at that thickness.
 
john april said:
i would go 1/2 and 1/2. grind 1/2 of the distortions out, and the other half should disappear when you do the secondary bevel if the distortions are only only 1mm tall.
Click to expand...

Sounds like this would save me some grunting over the file, too.

john april said:
i leave my edges about as thick as a dime before heat treat.
Click to expand...

That's my #1 lesson learned on this attempt: I need to leave more meat on the bone before I toss it in the barbecue.
 
First of all thats a great first blade. I think there has been some great advice so far. I would grind the bevels flat. If you expose a hole shorten your grind height and thin the edge to your desired thickness. Especially with carbon steel its best to leave a fatter edge before heat treat. The more symmetrical your grinds are, the thinner you can go. I would also try to grind post heat treat and see how you like that. I do it sometimes and its not too bad. Some people hate it but its worth a try, at least once. Glad to here you are finishing it no matter what, thats a great attitude to have.
 
Thanks for the compliment and encouragement.

Stang Bladeworks said:
...I would grind the bevels flat...
Click to expand...

By this, do you mean basically blunting the blade to remove the wavy portion? I just want to make sure I understand, because the bevels themselves are flat ground. It's a little more apparent in the pic below, before I heat treated the blade.

45979716331_7700452831_c.jpg


Stang Bladeworks said:
I would also try to grind post heat treat and see how you like that. I do it sometimes and its not too bad. Some people hate it but its worth a try, at least once.
Click to expand...

Is there some advantage to shaping the bevel after heat treatment as opposed to before? I am, as my kids say, a total noob here, so I'm open to new ideas. The post-heat-treat grinding isn't terribly difficult or rough on my tools? Remember, I'm working this with a drawer full of files and sandpaper.
 
Last edited:
Oh to be sailing the waves of bacon....

So if you grind the bevels after heat treating(HT), you have very little chance of the blade warping.
The downside is that the blade has to be kept cool while grinding so you don’t get too much heat build up and ruin your HT.
This actually isn’t a huge deal, just dip the blade in water after every pass and it’ll work out just fine.
 
A.McPherson said:
So if you grind the bevels after heat treating(HT), you have very little chance of the blade warping.
Click to expand...
That makes good sense.

A.McPherson said:
The downside is that the blade has to be kept cool while grinding so you don’t get too much heat build up and ruin your HT.
This actually isn’t a huge deal, just dip the blade in water after every pass and it’ll work out just fine.
Click to expand...

Ah, grinding and cooling. I'll keep that in mind for later knives..this one is going all "manual" just two arms and the files, 'cause that's all I've got right now.
 
Oh yeah, if you only have files, you really can’t shape post HT unless you’ve got a LOT of time and sand paper on your hands. And you really hate yourself.
 
So a few minutes with a flat bastard and I've removed 0.06" from the blade height and almost entirely lost the sharpening notch. Lesson learned: filing a flat edge, you spend 80% of your time making sure the edge is true, not removing stock.

32108891648_55256f70e7_z.jpg


All but two or three of the bacon edges are gone, and those remaining I can't see but only feel with my fingertips. When the kids trot off to bed, I'll cut another 0.03" - 0.05" to guarantee the bacon is gone. I'll need to shorten the height of the ricasso at the heel, or it'll look like some ridiculous spike.

Thanks to y'all, I think this can be called a recoverable learning opportunity.

...and I have a name for the knife: The Bacon Blade.
 
Haha, also before you take much more off the edge, sand the flats again to flatten them back up. May see that you might not have to take back the edge much more.
 
...and, thanks to you all, the blade is flat and straight again.

45991101581_50662397ce_c.jpg


I took a bit of everyone's advice. I worked a steel block with sandpaper to flatten the bevels as much as possible, then a wheel grinder to blunt the edge, removing 0.05", dipping in water after every pass. Spent a fair bit of time squaring/truing the edge with a file and left the edge thickness at 0.03" wide, a bit less than a dime thickness

I sandpapered the cheeks, ricasso, and bevel up to 220 grit and it looks much better. Because I had to blunt so much on the edge (0.1" total), I lost the sharpening choil. The little round detail file I used for that cut before hardening the blade just ain't up to the job now...it wasn't even polishing the edge when I tried to cut with it. Not the end of the world, I suppose.

Secondary bevel next, then the handle. Might actually get it done by Friday.

Thanks again, to all y'all!
 
Last edited:
Awesome save - it looks great!

If you have a dremel tool, you can chuck up a small stone (like a chainsaw sharpening stone) and put that sharpening choil right back in.
 
onespdfrk said:
If you have a dremel tool, you can chuck up a small stone...
Click to expand...

Thanks for the compliment!

I have a dremel, but all my stones are 1/4" or bigger diameter. Next time at the local wallet vacuum, I'll pick up one of the 1/8" or 5/32" stones. Good idea, thanks.
 
This thread has been interesting and informative.

What sort of wood is that?

Can you tell us a bit about the blade design? What sort of work do you have in mind for this knife?
 
You must log in or register to reply here.
Back
Top