please help--just made a blade that wont sharpen---never seen anything like this==please advise

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timfish

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Im sick to my stomach---spent several days bangin out a leaf spring into a really cook looking knife---i wish i could post a picture of it but dont know how---anyways, I went through the heat treat, got it past magnetic putit back in for a bit longer--quenched in canola, then tempered it twice at 350--2 hours---
put a handle on it --tried to sharpen it==on a 1x30 then 2x42 ---the blade is shaped like a kukri--which is why i used my 1x30
still no edge---banged on my anvil (mad by this point),,,handle broke off but no damage to steel--holy cow--
figured it was too hard, ground the handle off===threw ir back in the oven at 350---tried sharpening again===banged it again on anvil---the knife put adivot into my farriers anvil---my GOODNESS
IDEAS please
 
As far as pics go, you have to host them on something like Imgur or flikr or some other hosting site.

As far as edges go, what do you mean by "no edge"?
Do you mean you can't establish a sharp edge, or do you mean it won't stay sharp once you get it there?
 
Sounds like you didn't get it hot enough for long enough when you tempered it.
 
First thing is I would re-temper at 400°F. 350° is too low.

Second,
Get a new 220 grit belt and reshape the bevels at 15° per side. Once they meet and form a burr, repeat with a new 400 grit belt. Then strop the blade on both sides on a charged leather strop until the burr seems gone. Then slice up a cardboard box to remove the unseen burr remaining. I bet it will be sharp as heck now.
 
great questions and thank you==
I can get the edge up to a DECENT sharpness (convex grind)---it stays the same--even after 2 slams on the anvil---NO DAMAGE to the blade--NONE==crazy---PLEASE advise
Im using the paper slice method to determine sharpness--heck it dont even grab my fingers---but it does grab my fingernail---please help---THANKS!!!!
 
Stacy E. Apelt - Bladesmith said:
First thing is I would re-temper at 400°F. 350° is too low.

Second,
Get a new 220 grit belt and reshape the bevels at 15° per side. Once they meet and form a burr, repeat with a new 400 grit belt. Then strop the blade on both sides on a charged leather strop until the burr seems gone. Then slice up a cardboard box to remove the unseen burr remaining. I bet it will be sharp as heck now.
Click to expand...
thank you---thank you!!!!!!!
 
timfish said:
great questions and thank you==
I can get the edge up to a DECENT sharpness (convex grind)---it stays the same--even after 2 slams on the anvil---NO DAMAGE to the blade--NONE==crazy---PLEASE advise
Im using the paper slice method to determine sharpness--heck it dont even grab my fingers---but it does grab my fingernail---please help---THANKS!!!!
Click to expand...

I suspect that your blade is very thick and it forms very wide angle that's why it grabs your fingernail and it doesn't get damaged when you hit the anvil, but it doesn't cut paper.
 
Daniel Fairly Knives said:
An edge can get sharp if its hard or soft, you are probably not reaching an apex on the blade. Look at the blade edge up, does the edge reflect light?
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i thank you for your help--my blade is hammered down to ABOUT an 1/8"--please continue advice---i REALLY wanted this knife to work----
 
Ok so your edge, right behind where you are sharpening is 1/8th inch?

That's why you can't get an edge. You're WAY too thick. You need to grind bevels till you are "dime"- ish thick before you start sharpening...

At the very least. If you leave it too thick you're gonna end up with an axe, not a knife.
 
timfish said:
Im sick to my stomach---spent several days bangin out a leaf spring into a really cook looking knife---i wish i could post a picture of it but dont know how---anyways, I went through the heat treat, got it past magnetic putit back in for a bit longer--quenched in canola, then tempered it twice at 350--2 hours---
put a handle on it --tried to sharpen it==on a 1x30 then 2x42 ---the blade is shaped like a kukri--which is why i used my 1x30
still no edge---banged on my anvil (mad by this point),,,handle broke off but no damage to steel--holy cow--
figured it was too hard, ground the handle off===threw ir back in the oven at 350---tried sharpening again===banged it again on anvil---the knife put adivot into my farriers anvil---my GOODNESS
IDEAS please
Click to expand...
Learn to sharpen knife on that grinders or use other way to sharpen that knife . The problem is you, not too hard steel :) Probably you rounding edge over and over , or you not reach apex . And you MUST remove burs after you finish on grinder . Too hard steel is more easy to sharpen then soft steel !
 
Thickness definitely sounds like a big part of the problem here. It's much harder to get a blade that thick to slice paper. Even if you manage to get it to shave, (not super easy with something that thick either). Its going to tend to rip the paper.

Compound on top of that, the steel is probably much softer than you think it is. Especially with it not chipping after hitting an anvil. And what N Natlek said is true. It's generally a lot easier to get a sharp edge on harder steel. It debuts much cleaner (ime), and it doesn't round over as easily.

and potential problems like remaining burr from sharpening, or rounding it over, and you've got a dull blade.
 
A.McPherson said:
Ok so your edge, right behind where you are sharpening is 1/8th inch?

That's why you can't get an edge. You're WAY too thick. You need to grind bevels till you are "dime"- ish thick before you start sharpening...

At the very least. If you leave it too thick you're gonna end up with an axe, not a knife.
Click to expand...
The spine is bout an 1/8,,,I believed the edge down,,,any help is appreciated
Thanks
 
While you can post images by creating an account with Flick, etc, you can post a couple without the need to create an account by using https://imgbb.com/. Just upload, choose how long you want the image to be active, and copy/paste the BBcode link to the forum post.

how thick is the blade 1/8” up from the cutting edge?

If the blade is hard enough to cut the anvil, and tough enough not to break during all this banging, it sounds like it is good enough to get sharp. Might be too hard, but that is best determined once you have a sharp edge.

Does sound like the edge is too steep at the apex, but…are you trying to get to final sharpness straight from the grinder? My experience has been that my grinder gives a good burr, but best sharpnes always requires a final dressing of the edge by hand to remove burrs and polish. A burr might catch a finger nail, but won’t cut paper.

Do you really know what the steel is? Not all springs are 5160.

best of luck

Chris
 
Pictures would definitely help. There are a few unknown variables here. What angle did you sharpen to? What grit belt are you sharpening with? Are you raising a burr? Thickness and hardness of the steel is somewhat irrelevant. You can shave with a 1 inch thick piece of mild steel bar if you sharpen it correctly.
 
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