I messed up grinding tang fullers

Joseph Bandeko

Joseph Bandeko

Knifemaker / Craftsman / Service Provider
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Dec 9, 2021
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So I was grind in the fullers on a hunter in 52100 I’m working on and accidental ground to far and had to cut out the spot that was really thin,
so what I need your advice on is that now there’s not a whole lot of material there and am wondering if there’s enough steel there or do I need to start over. So the narrowest spot (where the arrows are pointing) is about 0.2” and the thickness in that spot is about 0.135”
The knife will not be intended for super hard use but I still want it to be beefy enough to do some harder use tasks.
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Any input would be very appreciated.
 
If it were me, I would start over and make a new one. But I would definitely heat treat that one as well and keep it as a shop knife.
 
You might be able to solder on a steel bolster, that would stop the area flexing?
But it would still bug me.
 
If you have 5 mm here ,and you use say micarta and peen pins maybe would work .But if ever break it would be there.............
bolster with two small pins would also add strength that point.
Edit - anyway I don t think that i will ask money for that knife
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are you using a 2" wheel? i have never seen anyone grind through the other side. . a larger wheel will keep that from happening. is it a tapered tang? if not, i would grind more from the butt end than the front where the leverage point is.
 
Yes it’s a 2” wheel. Yes tapered tang.

Part of why I messed up is because I do all my grinding freehand, and I was at the second I ground to far, focusing on getting the fullers somewhat straight and even.
(Stupid mistake)
 
well you can/should just start over.. 5160 is cheap steel to buy..
but you might be able to build up the weakened area with some welding .. just enough to bring its strength up ..
like where it is the widest. match close to the tang thickness... this is assuming you have not heat treated it yet.
you can also only heat treat the business part of the blade, leaving the handle soft /more flexible..
 
Also I didn’t grind through, I just ground it papery thin


Pinoy Knife said:
well you can/should just start over.. 5160 is cheap steel to buy..
but you might be able to build up the weakened area with some welding .. just enough to bring its strength up ..
like where it is the widest. match close to the tang thickness... this is assuming you have not heat treated it yet.
you can also only heat treat the business part of the blade, leaving the handle soft /more flexible..
Click to expand...
If I do use it I would HT it then torch temper that spot back.
I don’t think welding is a very high quality idea.
 
If I start over I’ll probably use cru forgeV
(that was the last of the 52100 I had, so I’ll have to order more)
 
I was thinking about doing micarta bolsters, do you think that would be enough?

Here’s the thing, I’ve seen hidden tang knives with just as much material (on the tang) but with this the two pieces are a about an inch apart, so I want to say it would be good (especially since it won’t be intended for super hard use)
 
Bunker Hill Blades said:
I was thinking about doing micarta bolsters, do you think that would be enough?

Here’s the thing, I’ve seen hidden tang knives with just as much material (on the tang) but with this the two pieces are a about an inch apart, so I want to say it would be good (especially since it won’t be intended for super hard use)
Click to expand...
I think it is not really comparable to hidden tang knives strengthwise. I think it should be plenty strong for a edc but I wouldn't give it to someone else. Maybe ht and temper and see if it survives some bending in the vice. Reality is it will probably not have to survive similiar stresses in real life unless someone decides that is a perfect tool for batoning wood or prying stuff open.
 
Bunker Hill Blades said:
Also I didn’t grind through, I just ground it papery thin



If I do use it I would HT it then torch temper that spot back.
I don’t think welding is a very high quality idea.
Click to expand...
like i said to start over..
but IF you wanted to try to save it.. you can get high carbon arc welding rods to build it back up.
that way you don't really hurt it too much.. it won't be 52100 unless you tig weld it with a piece of scrap for filler
then you would have to thermal cycle before heat treating it.
 
Bunker Hill Blades said:
I was thinking about doing micarta bolsters, do you think that would be enough?

Here’s the thing, I’ve seen hidden tang knives with just as much material (on the tang) but with this the two pieces are a about an inch apart, so I want to say it would be good (especially since it won’t be intended for super hard use)
Click to expand...
Why not full scale from Micarta ? Micarta can handle heavy peening .......
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Hey would if I finished it up (not to the usual quality, like belt finish and a cheap wood) and then did a pass around to see what y’all think of this model? (It would be a bit before I could have the time to finish it)
 
If you aren't comfortable selling this because of fears of failure, why would you want to give this to somebody else to use and possibly injure themselves when/if it fails???
 
weo said:
If you aren't comfortable selling this because of fears of failure, why would you want to give this to somebody else to use and possibly injure themselves when/if it fails???
Click to expand...
I’ll do some testing of my own to make sure it’s not going to fail and hurt someone. Also I think the only reason it would break is if someone was “abusing“ it.
I was thinking the pass around wouldn’t be so much of a use it hard situation but just more of a handle it, make some cuts with it, tell me what you think and send it to the next person.
 
If each of those sides are .2 thick, you've got nearly a half inch of material there... That's gonna be pretty strong.

Since you've decided to scrap it anyway, clamp it in your vice and hang on it, see if it bends. Clip a carabineer with a rope on it, hang now and more weight till it breaks or bends. Then you'll know what kind of stress that amount of metal can take!
 
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Bunker Hill Blades said:
I’ll do some testing of my own to make sure it’s not going to fail and hurt someone. Also I think the only reason it would break is if someone was “abusing“ it.
I was thinking the pass around wouldn’t be so much of a use it hard situation but just more of a handle it, make some cuts with it, tell me what you think and send it to the next person.
Click to expand...
I can see some uses for that handle, actually. Wrap it with paracord and sharpen those inner edges. They'd shave feather sticks, cut cord, be a little storage area for matches, etc.
I've seen skeleton framed knives with about that much handle.
 
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