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Author Topic: Sharpening tri-cut tips?  (Read 1386 times)

Offline NateP

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Re: Sharpening tri-cut tips?
« Reply #15 on: September 07, 2019, 11:34:34 AM »
Maybe I'm not using the term "quench" properly.  The point of the ice water is to keep the the steel from overheating to a temperature at which the strength will be significantly affected.  If you keep the spear on the grinder for too long then the tip will certainly become discolored and brittle.  I've found that by minimizing grinder time and cooling the tip frequently this can be avoided. This works for me.  The very fine point won't last just because of it's structure.  This is true even with a brand new spear.

Offline Rob102

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Re: Sharpening tri-cut tips?
« Reply #16 on: September 07, 2019, 04:21:20 PM »
Maybe I'm not using the term "quench" properly.  The point of the ice water is to keep the the steel from overheating to a temperature at which the strength will be significantly affected.  If you keep the spear on the grinder for too long then the tip will certainly become discolored and brittle.  I've found that by minimizing grinder time and cooling the tip frequently this can be avoided. This works for me.  The very fine point won't last just because of it's structure.  This is true even with a brand new spear.

If you overheat the tip you will anneal it. If you quench carbon steel in ice water it will harden if you do it to 17ph it will make it brittle

Offline Kshang

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Re: Sharpening tri-cut tips?
« Reply #17 on: September 07, 2019, 10:57:16 PM »
I got myself a hand file and spent like 5-8 minutes on the RA tri-cut tip, and am pretty happy with the result.  I was recently watching YouTube videos and trying sharpening my knifes on a whetstone, and this speartip filing process is much easier in comparison. 

One thing I did was, other than following the angle of the original cut, I also created a steeper (less acute) angle close to the very tip, because I badly chipped the tip from my last dive, so I would otherwise have to grind off quite a bit of metal if I were to keep the original angle throughout.  I would think the idea would be similar to the (slight) difference between a rock-point tip and a strictly pencil-point tip, with the former having a second, less acute angle, cut at the very end of the tip.  This should make my ongoing maintenance a bit easier, and what I really need are the sharp edges between the three faces anyway and less a perfectly pointy tip. 

Echoing what another user said earlier in the string, I think this also enables you to sharpen the tip on the road (e.g., multi-day trip, liveaboard) when you don't have access to power tools in the shop (not to slight power tools such as a bench grinder though, which I would use if I had one handy). 
« Last Edit: September 07, 2019, 11:01:26 PM by Kshang »

Offline Diver Dan

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Re: Sharpening tri-cut tips?
« Reply #18 on: September 08, 2019, 11:33:36 PM »
Maybe I'm not using the term "quench" properly.  The point of the ice water is to keep the the steel from overheating to a temperature at which the strength will be significantly affected.  If you keep the spear on the grinder for too long then the tip will certainly become discolored and brittle.  I've found that by minimizing grinder time and cooling the tip frequently this can be avoided. This works for me.  The very fine point won't last just because of it's structure.  This is true even with a brand new spear.

If you overheat the tip you will anneal it. If you quench carbon steel in ice water it will harden if you do it to 17ph it will make it brittle

It doesn't really matter if you use ice water or motor oil or 17ph unless you are actually trying to achieve a specific temper. Quenching hot steel in anything will not make it brittle unless the metal is at least glowing at a cherry red. Basically making a spear is similar to making a knife or an axe. you want the tip, or edge to be able to keep a sharp point but not break under normal use, and the rest of the steel should be a bit softer to absorb flex and impact. When forging metal, it is glowing hot. If left to air cool, the forged metal will be relatively pliable and won't break if bent when cold. It is "soft". If you "quench" steel when it is glowing red hot, the molecules will "crystalize" into a very hard, but very brittle state. This is "hardened" steel. But for most applications you do not want hardened steel because it will break before it bends and it will probably be harder than a typical file so trying to sharpen it with a file would be pointless (no pun intended) So tempering is the process of heating the metal carefully, finding the right balance between brittle, hard and soft for whatever application you need. But if you overheat your spear tip while sharpening it, you have softened it. If you over heat it to the point that it is glowing red and you quench it in any liquid while it is still glowing red, you will harden that part of the spear and it will be brittle. So ya, if you don't know how to not over heat it on a bench grinder or belt sander just get a high quality file and do it by hand.

Offline TheKeeneroo

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Re: Sharpening tri-cut tips?
« Reply #19 on: September 09, 2019, 08:54:56 AM »
I heard of a guy that once epoxied a golf ball at the end of his spear and shot fish in the face to "knock them out." I've also hunted with guys that literally never sharpen their spear. It's more like a #2 pencil before it has ever been sharpened. He chalked it up to laziness... Just makes me wonder how important razor sharp spears are for us NorCal hunters. I'm sure symmetry plays into long shots for accuracy, but when you're shooting ~3 feet or less, makes me wonder. I've only ever once had a spear not go through the full fish and flopper not deploy, and that's because I was single banded, "long" shot a pathos 60 against a 15# sheephead (which I shot just forward of the upper gill plate edge - a very thick part of the fish).
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Offline Diver Dan

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Re: Sharpening tri-cut tips?
« Reply #20 on: September 09, 2019, 09:57:17 PM »
Funny timing for this topic. Last weekend I took a solid, straight  head shot to a 8 pound size cabezon. It was sitting on a rock and the spear went through the head and hit the rock. The fish went ballistic. I tried to grab it and shove the spear the rest the way through the head, but the fish took off. Pulling my spear back to reload, I saw the spear had snapped about 1" below the flopper. I also noticed that where the break was, half the metal looked like a clean break, half was obviously rusty. So there was definitely previous damage to the spear I did not notice.  *Inspect your spears often*

So then I grabbed my back-up gun out of my kayak. Found another cabezon about 6 pounds. Decided to line up my shot from behind the gill plate so the spear would go through the body and out the head to avoid hitting the rock. I took my time to get the right shot and hopefully not break the spear on my back-ip gun. The friggin' spear hit the fish hard but bounced off! Looking at he tip, it definitely was not very sharp. It also wasn't totally blunt, but I'm sure if it had a sharper tip it would have sliced through the cab's skin rater than glanced off of it.

Just my 2 cents



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Re: Sharpening tri-cut tips?
« Reply #21 on: September 10, 2019, 01:04:26 PM »
wow !!! this many replies and most action in a thread in a long time in a post about sharping spear tips hahahahahahahahaha

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Offline Rob102

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Re: Sharpening tri-cut tips?
« Reply #22 on: September 10, 2019, 02:49:58 PM »
Funny timing for this topic. Last weekend I took a solid, straight  head shot to a 8 pound size cabezon. It was sitting on a rock and the spear went through the head and hit the rock. The fish went ballistic. I tried to grab it and shove the spear the rest the way through the head, but the fish took off. Pulling my spear back to reload, I saw the spear had snapped about 1" below the flopper. I also noticed that where the break was, half the metal looked like a clean break, half was obviously rusty. So there was definitely previous damage to the spear I did not notice.  *Inspect your spears often*

So then I grabbed my back-up gun out of my kayak. Found another cabezon about 6 pounds. Decided to line up my shot from behind the gill plate so the spear would go through the body and out the head to avoid hitting the rock. I took my time to get the right shot and hopefully not break the spear on my back-ip gun. The friggin' spear hit the fish hard but bounced off! Looking at he tip, it definitely was not very sharp. It also wasn't totally blunt, but I'm sure if it had a sharper tip it would have sliced through the cab's skin rater than glanced off of it.

Just my 2 cents

If your spear broke when you shot a rock, do you know what causes that?  Brittleness.
When you inspected it and found rust, do you why? It had a stress fracture because it was brittle. Rapid quenching is PRECISELY what causes brittleness, and it doesn't have to be red hot. Temperature to aneal depends on the final hardening temperature. And if a shaft is only case hardened, when you grind the tip yuhave removed the hardened steel.

Offline Diver Dan

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Re: Sharpening tri-cut tips?
« Reply #23 on: September 10, 2019, 11:02:03 PM »
Funny timing for this topic. Last weekend I took a solid, straight  head shot to a 8 pound size cabezon. It was sitting on a rock and the spear went through the head and hit the rock. The fish went ballistic. I tried to grab it and shove the spear the rest the way through the head, but the fish took off. Pulling my spear back to reload, I saw the spear had snapped about 1" below the flopper. I also noticed that where the break was, half the metal looked like a clean break, half was obviously rusty. So there was definitely previous damage to the spear I did not notice.  *Inspect your spears often*

So then I grabbed my back-up gun out of my kayak. Found another cabezon about 6 pounds. Decided to line up my shot from behind the gill plate so the spear would go through the body and out the head to avoid hitting the rock. I took my time to get the right shot and hopefully not break the spear on my back-ip gun. The friggin' spear hit the fish hard but bounced off! Looking at he tip, it definitely was not very sharp. It also wasn't totally blunt, but I'm sure if it had a sharper tip it would have sliced through the cab's skin rater than glanced off of it.

Just my 2 cents

If your spear broke when you shot a rock, do you know what causes that?  Brittleness.
When you inspected it and found rust, do you why? It had a stress fracture because it was brittle. Rapid quenching is PRECISELY what causes brittleness, and it doesn't have to be red hot. Temperature to aneal depends on the final hardening temperature. And if a shaft is only case hardened, when you grind the tip yuhave removed the hardened steel.

Rob, I love you brother. But I Know how to weld, forge blades, heat treat and anneal blades. I know about brittleness  and I know how to determine where a stress fracture may have started. The "stress fracture" was caused by hitting several rocks through ling and cabezon heads. With all due respect, your above comments are not accurate.

Offline Diver Dan

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Re: Sharpening tri-cut tips?
« Reply #24 on: September 10, 2019, 11:06:25 PM »
 :D

Offline Rob102

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Re: Sharpening tri-cut tips?
« Reply #25 on: September 11, 2019, 07:40:22 AM »
:D

Maybe I’m wrong. I’m just a dumb millwright.

Well, off to the machine shop.

:)

Offline Diver Dan

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Re: Sharpening tri-cut tips?
« Reply #26 on: September 11, 2019, 08:50:58 PM »
And my spear broke about 2" from the tip, so that part of the spear never got hot from sharpening. It probably got "work hardened" by hitting rocks. But no part of the spear was hardened from quenching under heat.

Offline charlierobinton

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Re: Sharpening tri-cut tips?
« Reply #27 on: September 11, 2019, 09:01:58 PM »
Fancy steel working lingo aside, I find my spear tips stay sharper when I hand file them to a point rather than using the bench grinder. I think I have a habit of going for "razor sharp" with the bench grinder, but when I'm sharpening by hand I usually get bored and stop when it is just "sharp enough" lol. I feel like the "sharp enough" point holds up better when I shoot the shit out of rocks, which I love to do.

Offline Sea-Monkey

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Re: Sharpening tri-cut tips?
« Reply #28 on: September 11, 2019, 09:10:15 PM »
At the risk of needlessly perpetuating this thread, has anyone heard of hardfacing a spear tip? May be too small to do, but if possible it should seriously extend tip life and reduce the need to sharpen so often.

Offline Rob102

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Re: Sharpening tri-cut tips?
« Reply #29 on: September 12, 2019, 03:55:22 AM »
At the risk of needlessly perpetuating this thread, has anyone heard of hardfacing a spear tip? May be too small to do, but if possible it should seriously extend tip life and reduce the need to sharpen so often.

I’ve only hardfaced things with a lot of base material. Aqua-chisels for farming operations, rock crushers in a quarry, asphalt drums, things with a lot of parent metal. I’ve only used stick, but you can flux core or tig it on.  Only tig would be precise enough to build up something as small as a spear tip and not heat a large are or blow the tip off.  Then you would have to use a grinder to put a point or edge back on it.

It sounds good in theory but with such a small amount of parent metal and high amount of heat transfer in stainless, who knows. I wouldn't do it.  It's easier to run a file across it once a year.

Personally, I make it a habit not to shoot rocks.

 

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