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Author Topic: Sharpening tri-cut tips?  (Read 1195 times)

Offline Kshang

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Sharpening tri-cut tips?
« on: September 04, 2019, 04:58:26 PM »
I've been using shafts with rock-point tips, the sharpening of which is fairly easy by rotating them on my angle grinder. 

I recently got a gun with a tri-cut tip (Rob Allen).  After a couple of days in the water, the tip starts to wear off.  I know lots of folks on this board use Rob Allen and Pathos guns, which I understand come with tri-cut tips.  Do you have a simple way of sharpening these tri-cut tips, or do you grind them into rock-point tips?  Seems to me that, to get decent sharpening of tri-cut tips, I will at least need to get myself a bench grinder, or better yet, belt sander, but I would rather not have another piece of equipment take up my garage space if there's a good alternative.  I thought about grinding it into a rock-point, but I do like the penetration of a tri-cut tip, so wanted to quickly check. 

Thanks in advance,

Offline Zzz

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Re: Sharpening tri-cut tips?
« Reply #1 on: September 04, 2019, 05:38:32 PM »
I clamp my angle grinder down to a plastic folding table and create a bench grinder! A legit bench grinder or belt sander would be more precise, but an angle grinder works with a little finesse. Tips don't need to be perfect for what we do

Offline TimBekk

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Re: Sharpening tri-cut tips?
« Reply #2 on: September 04, 2019, 05:59:18 PM »
I file or grind to a pencil tip. Once it is a pencil tip I can keep sharp with a file between dives.

Offline Kshang

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Re: Sharpening tri-cut tips?
« Reply #3 on: September 04, 2019, 08:03:13 PM »
Thanks.  I'll probably give it a try, though the idea of a fast spinning angle grinder slipping off my sawhorse makes me a bit uneasy. 

I clamp my angle grinder down to a plastic folding table and create a bench grinder! A legit bench grinder or belt sander would be more precise, but an angle grinder works with a little finesse. Tips don't need to be perfect for what we do

Offline Kshang

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Re: Sharpening tri-cut tips?
« Reply #4 on: September 04, 2019, 08:04:09 PM »
That's my backup plan, if I cannot keep the tri-cut in reasonably good shape. 

I file or grind to a pencil tip. Once it is a pencil tip I can keep sharp with a file between dives.

Offline Rob102

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Re: Sharpening tri-cut tips?
« Reply #5 on: September 04, 2019, 10:23:47 PM »
Clamp it in a vise and use a bastard file. Sharpens like a razor.

Offline TheKeeneroo

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Re: Sharpening tri-cut tips?
« Reply #6 on: September 05, 2019, 07:15:53 AM »
I use a hand file on both pencil and tri cut tips. It's a bit more elbow grease and skinned knuckles, but it's easier than setting up my grinder on a folding table with clamps and such and I can do it on the side of the road before a dive.

One thing to keep in mind with grinders (from what I've read in the past) is how hot the shaft can get which alters the strength of the metal. You might keep a damp towel nearby and cool the metal down every few seconds. I'm sure someone that works with metal more than I do can chime in on the truth of this.
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Offline Amsmosh

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Re: Sharpening tri-cut tips?
« Reply #7 on: September 05, 2019, 07:43:15 AM »
I’m lazy I just use a bench grinder.
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Offline pclark

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Re: Sharpening tri-cut tips?
« Reply #8 on: September 05, 2019, 09:33:46 AM »
I just use an handheld angle grinder and it works great, but a bench grinder would be better.  Just dont grind past the tri-cut as it will rust out anywhere you hit.   If its going to be more than a day until I use it I'll hit it with some spray paint to prevent the rust.

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Re: Sharpening tri-cut tips?
« Reply #9 on: September 05, 2019, 02:30:09 PM »
all I will say is do not over think it and and keep it "KIS"  keep it simple  like others have said bench grinder, angle grinder or hand file
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Offline Diver Dan

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Re: Sharpening tri-cut tips?
« Reply #10 on: September 05, 2019, 10:22:38 PM »
I use a hand file on both pencil and tri cut tips. It's a bit more elbow grease and skinned knuckles, but it's easier than setting up my grinder on a folding table with clamps and such and I can do it on the side of the road before a dive.

One thing to keep in mind with grinders (from what I've read in the past) is how hot the shaft can get which alters the strength of the metal. You might keep a damp towel nearby and cool the metal down every few seconds. I'm sure someone that works with metal more than I do can chime in on the truth of this.

If using a grinder or belt sander or anything that can generate heat on that level, have at least a cup of water on hand to dip the tip into about every 2 seconds. A good spear shaft should be hardened and tempered so that it does not mushroom when it hits a rock, and does not shatter when it hits a rock. If you get it too hot while sharpening it you will anneal (soften) it to the point that it will mushroom or bend if you hit a rock. As bare steel heats up you will see that rainbow color develop. Yellow, Orange, purple, blue.. Any of those colors mean you got it too hot. Well, a little yellow might not be too hot, but best to avoid it as your spear should already be tempered to the perfect hardness. Also as the tip gets finer, it heats up A LOT faster so one second on a belt sander without quenching can over heat it. If you ever see a glowing dull red, Cut off the tip, quench it and start over.

Offline TheKeeneroo

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Re: Sharpening tri-cut tips?
« Reply #11 on: September 06, 2019, 07:58:51 AM »
I use a hand file on both pencil and tri cut tips. It's a bit more elbow grease and skinned knuckles, but it's easier than setting up my grinder on a folding table with clamps and such and I can do it on the side of the road before a dive.

One thing to keep in mind with grinders (from what I've read in the past) is how hot the shaft can get which alters the strength of the metal. You might keep a damp towel nearby and cool the metal down every few seconds. I'm sure someone that works with metal more than I do can chime in on the truth of this.

If using a grinder or belt sander or anything that can generate heat on that level, have at least a cup of water on hand to dip the tip into about every 2 seconds. A good spear shaft should be hardened and tempered so that it does not mushroom when it hits a rock, and does not shatter when it hits a rock. If you get it too hot while sharpening it you will anneal (soften) it to the point that it will mushroom or bend if you hit a rock. As bare steel heats up you will see that rainbow color develop. Yellow, Orange, purple, blue.. Any of those colors mean you got it too hot. Well, a little yellow might not be too hot, but best to avoid it as your spear should already be tempered to the perfect hardness. Also as the tip gets finer, it heats up A LOT faster so one second on a belt sander without quenching can over heat it. If you ever see a glowing dull red, Cut off the tip, quench it and start over.

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Offline Rob102

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Re: Sharpening tri-cut tips?
« Reply #12 on: September 06, 2019, 08:23:32 PM »
I use a hand file on both pencil and tri cut tips. It's a bit more elbow grease and skinned knuckles, but it's easier than setting up my grinder on a folding table with clamps and such and I can do it on the side of the road before a dive.

One thing to keep in mind with grinders (from what I've read in the past) is how hot the shaft can get which alters the strength of the metal. You might keep a damp towel nearby and cool the metal down every few seconds. I'm sure someone that works with metal more than I do can chime in on the truth of this.

If using a grinder or belt sander or anything that can generate heat on that level, have at least a cup of water on hand to dip the tip into about every 2 seconds. A good spear shaft should be hardened and tempered so that it does not mushroom when it hits a rock, and does not shatter when it hits a rock. If you get it too hot while sharpening it you will anneal (soften) it to the point that it will mushroom or bend if you hit a rock. As bare steel heats up you will see that rainbow color develop. Yellow, Orange, purple, blue.. Any of those colors mean you got it too hot. Well, a little yellow might not be too hot, but best to avoid it as your spear should already be tempered to the perfect hardness. Also as the tip gets finer, it heats up A LOT faster so one second on a belt sander without quenching can over heat it. If you ever see a glowing dull red, Cut off the tip, quench it and start over.

Which is exactly why I use a file.

Offline NateP

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Re: Sharpening tri-cut tips?
« Reply #13 on: September 07, 2019, 08:58:44 AM »
I don't have a bench grinder, but I do have a drill press.  I found this cheap grinder attachment on amazon (see pic) and it works pretty well.  I just brace the spear shaft on the drill press table and press one side of the tri-cut against the bottom of the grinder wheel, then rotate to sharpen the next face.  As Diver Dan mentioned, you have to quench frequently, I use ice water.  I also found that getting a very fine point is a waste of time, as it will disappear as soon as you get anywhere near a rock.  If you have a power tool, (especially one that is stationary), you may want to consider this as an alternative to buying a separate grinder.  I tried hand sharpening and maybe I didn't have the ideal file but it took forever.  This setup works for me.


Offline Rob102

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Re: Sharpening tri-cut tips?
« Reply #14 on: September 07, 2019, 10:31:34 AM »
I don't have a bench grinder, but I do have a drill press.  I found this cheap grinder attachment on amazon (see pic) and it works pretty well.  I just brace the spear shaft on the drill press table and press one side of the tri-cut against the bottom of the grinder wheel, then rotate to sharpen the next face.  As Diver Dan mentioned, you have to quench frequently, I use ice water.  I also found that getting a very fine point is a waste of time, as it will disappear as soon as you get anywhere near a rock.  If you have a power tool, (especially one that is stationary), you may want to consider this as an alternative to buying a separate grinder.  I tried hand sharpening and maybe I didn't have the ideal file but it took forever.  This setup works for me.


If you are getting the shaft hot and quenching with ice water you are more than likely changing the temper of the steel. Depending on the material, carbon steel, spring steel, etc. you will either harden the tip or make it brittle so that will never hold an edge if it hits a rock. RA shafts are carbon if I remember correctly and pathos are precipitation hardened spring steel and they should be quenched differently.

 

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