Thining out a knife

U

unky_gumbi

Joined
Aug 28, 2009
Messages
7,951
So I took my WIP knife out for a little field testing today and while it worked, I couldn't help thinking that it would work so much better with a thinner blade.
Now I know that I could take me little belt grinder and thin it out a fair amount as long as I kept it cool while doing so, or should I say I think I can.

What I am thinking is that I would like to thin it out by about 1/32-1/16" per side to give it a bit better slicing ability
Can I do this without ruining the HT or should I just chalk it up as a learning experience and leave well enough alone? As it is it batons though wood like a mofo and shaves nicely. It would chop great if it was a couple inches longer, but the slicing is horrible.

Thanks for any advice, the spine is currently right around 1/4"
 
Personally I would keep the knife you have and start a new one. I have found rework can sometimes lead to disasters with nothing to show for effort. Steel and grip material are fairly cheap compared to sweat equity. Besides it is nice to look back a few years down the road and say to yourself "wow I can't believe how much my knives have imporved.

Jim Arbuckle
ABS JS
 
Funny you bring this up! I have decided my little beauty is too thick as well. Yes, it will easily shave hair, but cutting paper, not so good--even with the convexing, the angle is way too steep, I think. I am going to see if I can't work the angle down some with the grinder. As long as it is kept cool, I don't think there is any problem.

If you've seen this tut: http://www.knifedogs.com/showthread.php?t=2303 he does pretty much ALL his grinding AFTER heat treating.
 
If you grind the upper bevel, you will lower the grind line, so you have to raise that too. If it has an upper bevel, make it full flat grind?
 
Mr. Bad Example said:
Funny you bring this up! I have decided my little beauty is too thick as well. Yes, it will easily shave hair, but cutting paper, not so good--even with the convexing, the angle is way too steep, I think. I am going to see if I can't work the angle down some with the grinder. As long as it is kept cool, I don't think there is any problem.

If you've seen this tut: http://www.knifedogs.com/showthread.php?t=2303 he does pretty much ALL his grinding AFTER heat treating.
Click to expand...

he's working CPM 154, grinding after HT is not recommended regardless but you can get away with it more with the air hardening stainless

-Page
 
I think you need to decide what the knife is to be first.
If you had a truck that would haul 1500 pounds of dirt, go up hills, and ford streams, but didn't go from 0 to 60 in 4.4 seconds ...would you think a bigger engine would solve the problem?

Edge geometry is what cutting is all about.
Within normal ranges, blade thickness isn't really an issue if the edge is right. Slicing and chopping are at opposite ends of the spectrum. If you want a chopper, have a high edge angle....a slicer ,a low angle....a utility knife, somewhere in the middle. If the edge is to be a combination use ( utility) expect some trade-off in function. If you make a knife that does one task only ( fillet,chopper,skinner), it should do that extremely well...... if it does all things it will probably do them OK, but not extremely well.
 
Well it was my first knife and started with steel that was too think and I left the edge thick just from inexperience and fear of it cracking in HT. My blade/handle shape, to me is more suited to skinning and slicing then chopping. Its a learning experience for sure, even though the knife is finished I keep learning from it.
I think I will just try and push the edge up a bit more and see how that works for me. After that I will most likely just leave it be. If I ever revisit that design I will make the blade about 1.5" longer and start with thinner steel 3/16" max.
The thing is a little tank though. I hacked and smashed with it, made about 20 fuzz sticks and even did a little digging into a stump with it and it held up. Still reasonably sharp, scales are still solidly attached and everything is still straight. guess that's 5160 for ya.

The other 2 knives I made from 5160 are thinner at the edge and I am working on a scandi grind bushcraft knife in 3/16" O1 right now. then there is the piece of pattern welded steel I am waiting for. That one I have to get in front of me and let it tell me what it wants to be.
 
Last edited:
sunshadow said:
he's working CPM 154, grinding after HT is not recommended regardless but you can get away with it more with the air hardening stainless

-Page
Click to expand...

Ah, so I shouldn't be grinding on my oil quenched 1084 blade? I've been careful to keep my bare fingers on the blade and dip it every pass to avoid over heating.

Perhaps you're right--I should just stop messing with it, fit the handle, and git-r-done. Now that I know not to worry so much about HT issues with .25" stock, I'll thin the next one down considerably more.
 
There is one way to regrind a knife w/o ruining the heat treat... you have to use a Glazier's wet belt grinder. I have one (4x106) my Dad and I made for his shop then he never used it so he gave it me :D and it's the shiznit for stuff like that. you need special wet/dry belts. from C.R. Laurence their silca carbide and LAST FOREVER it seems like. Which is good cause there $70.00 for a box of 5

13853_196593800241_625615241_3887071_6717799_n.jpg


Jason
 
I don't even do 3 passes and dip, I do one pass and dip. I don't really feel heat in my finger tips any more so I would rather be save then sorry. the lack of feeling in my finger tips has gotten me drunk more than once though with the "who can hold the lit end of a cigarette the longest bar bet":D
 
Just to give you a reference to how thick 3/8" is on a knife, I use 3/8" stock for making swords, and it usually gets forged down to nearly half of that. I don't think I ever made a knife from 3/8" stock.
 
I have been buying thinner steel each time, sooner or later I will find the thickness I like. I like thick blades, well thick spines, I also mistyped its actually 3/16 I am using now:o I figure after sanding and finishing I should be around 4 millimeters or .157" at the thickest part.
 
So I just finished backing up the edge grind and resharpened on the water stones, made a world of difference on slicing paper and cardboard. Complete controlled wavy slices in paper with zero snags and will cut under its own weight if drawn on regular cardboard. I will be heading out tomorrow to see how the edge holds up under harder use
 
You must log in or register to reply here.
Back
Top