What do you think about letting the tip get blue?

blgoode

blgoode

Knifemaker / Craftsman / Service Provider
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Oct 3, 2003
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Dont be dirty guys.....he he

Okay, I was reading another sites tips on high performance blades and it was suggested to let the tip get a little blue after the final tempering. I had this same thought but not to this degree. The intention is to not have a snapped tip under hard usage. Having the tip be around 50 rc but still able to hold a decent edge???

Seems like on a hard usage blade it would be ground with such a profile that there isnt any tiny needle like tip to snap off. Guess this would need to be done on tactical stabbing type blades or some bird and trout types.

Any thoughts?
 
That's a good question, and I suppose it really comes down to personal preference and the intended use of the knife. In a hunter, utility knife or kitchen knife I'd much rather have a tip that would hold an edge as long as possible so I don't think I'd want a softer tip on that kind of knife. There is nothing more frustrating to me than a blunted tip on a knife. In a camp knife or survival knife a less brittle tip might be an advantage in digging or prying situations.

I think overall I'd rather address the problem with the grind and blade geometry rather than tempering the tip softer. My two cents for what it's worth, I hope some others add their opinions.
 
I remember reading that Greg Covington lightly torches the tips of his fighters to keep them from chipping off. Maybe he'll pipe in with some info on the subject.
 
That's a good question, and I suppose it really comes down to personal preference and the intended use of the knife. In a hunter, utility knife or kitchen knife I'd much rather have a tip that would hold an edge as long as possible so I don't think I'd want a softer tip on that kind of knife. There is nothing more frustrating to me than a blunted tip on a knife. In a camp knife or survival knife a less brittle tip might be an advantage in digging or prying situations.
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I completely agree with this, it depends on the intended purpose. Besides Guy's examples, if I was making a whittling knife where I'd want to cut with the tip, I'd leave it the full hardness of the rest of the blade.

Right now I'm making a combat knife for a friend who's likely going to Iraq for a second time, and he requested a strong thrusting tip. So I partially took care of this with blade geometry and profile (full convex for a thicker center and a clip point so it's pointy enough with out being a needle), but I also tempered the last 1/4" blue. He won't likely be trying to detail work with the tip, more likely stabbing it into boxes to open them with a very very slim chance of needing to stab an enemy, edge holding is less important then tip strength for this case.
 
Burchtree said:
I remember reading that Greg Covington lightly torches the tips of his fighters to keep them from chipping off. Maybe he'll pipe in with some info on the subject.
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Yep...this is exactly what I do. In fact, I just did the tip on a cable damascus Bowie today.

A couple weeks ago I had a ladder pattern Bowie blade laying on my kitchen table and one of the Maine Coon cats knocked it to the floor, of course, straight on the tip. The tip was curled over so I took i tot he shop and tapped it around a bit on the anvil with a small ball peen hammer. If the blade would have been the same hardness at the tip as the edge, it would have been a catastophic failure.

Keep in mind though that these are fighting knife tips rather that camp knives or spear points.....and it is not really necessary on those type of blades with proper heat treatment
 
BL,

You're working in O1 tool steel. Torch it lightly if you like but I advise not taking it up to blue or purple. Blue, I believe, is too high for that steel and may make it even more brittle. Take it up to a dark golden and stop. My 2 cents worth.

RL
 
Advice taken RL. If I were making fighting knives...I'd surley blue the tip.

I'll stick to straw for now. I have a good HT in the oven as we speek :D :D

Hope my last knife destruction has tought me a little.....I think it did :cool:
 
Greg, are you sure the tip would have snapped if fully hard? Are you sure it would have been damaged at all?

I used to agree with this philosophy, but no longer do, or at least not to that extent. In some very specific situations, I may want to take the tip a point or two softer than the rest of the blade, but not that soft. I have used both fully hard and soft tips on some of my bigger knives, and the hard tips simply resist damage better all around.

With most of the common steels, there is a certain hardness range where the steel has the greatest impact strength and bending strength. That fact does not change whether the steel happens to lie at the tip or rearmost portion of the edge. Think about this for a minute- if the tip (which several of you have even reinforced through geometry) needs to be that soft to resist breaking, then wouldn't the harder portions of the edge shatter the first time you chop something fairly solid? Now, don't just spout off an answer that would be popular in the magazines. Really think about this for minute.
 
I work mainly with 5160, 1084 and damascus (usually 1084, L-6, 15N20 and such mixes) and I only let the blade go to a bronze color. A bit past dark straw but, just before it starts to go light violet. Just from testing, and customer feedback, I haven't had a tip chip/break yet......and I throw test blades. ;)

I haven't worked with O1 so I can't say there. I bow to those with the experience with that one.
 
I haven't worked with O1 so I can't say there. I bow to those with the experience with that one.

What did you mean by tha J? 0-1 is the only steel I have used... TRy it out, you may dig it.
 
J.,

Mete could better advise here. In simple high carbon steels I understand it is recommended not to temper in the 500 to 700 F degree range because it causes brittleness (blue brittle). It is probably dangerous in high speed applications but may also help cause blade breakage.

RL
 
I stay the same all the way
I use all of it ( the edge) and don't want any bending.
right tool for the right job..
if it's beefy just right it should be ok even when dropped.
have faith in your work, I've taken 1/4 divots out of my floor with the tips :eek:

RL not sure about the blue thing being more brittle? I sometimes take the spine
all the way back to steel color way past blue and water tube the edge to keep it cool.
 
I may have to try it B. Just haven't gotten there yet. :rolleyes: Actually, I do want to try it out. I've heard great things about O1.

Roger, I don't temper my blades any more than 400. Usually 390-400 for 1084 and 375-385 for 5160. I would think blue would bend not break. Of course, I only edge quench unless it's damascus but, I still go back and blue (torch) my tangs and spineson both. This is to avoid possible breaking. I know it's redundent but, safe is safe. ;) I'm a firm believer in CYA.
 
When quality 52100 and 5160 are forged and heat treated to best advantage you can work up a tip that will scratch a 62 RC steel and still flex without chipping. That is with 52100, 5160 can also be worked with little danger of chipping maybe not quite as hard, but plenty tough.

Test those tips for the qualities you want and you will know if a safety net is needed.
 
It is only that range between about 500 and 700 F (blue, purple). Below and above poses no problem.

Mete can advise all us better on this.

RL
 
I've drawn to a dark straw on a couple of bowies, but if there's any dout I do the "concreat floor test", just drop the blade point first from about 5 feet and if everything is good the blade should take a chunck out of the concreat with only a little dulling/damage to the edge of the point. I've found that unless it's got a real thin needle like point I don't need to draw it back.
 
Way to go Will, I am proud of your honest concern and you have developed a test that sounds valid and most significantly, readilly available with immediate results.
 
This turned into a good thread. Ize Likes it!
 
There are many alloys that are best not tempered in the 500-600F range since there is a drop in toughness, O-1 included. Pay close attention to the tip shape. The WWII Sykes -Fairbairn commando knife is a good example .It is sometimes listed as a "light duty combat knife !![That's an oxy-moron]. It's thin tip had a reputation for breaking off when you stabbed the enemy if you hit web belt or other gear.
 
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