What would be the best steel to make a diving knife from. One that will be used in the ocean a lot.
My nephews son is a diver and works in the salt water every day. Can someone with a little knowledge on this help me out.
Funny enough, I have a brother in law that likes diving and I was thinking about this recently. What I decided is that titanium with a carbonized edge would be the best for corrosion resistants and weight.(Id love to hear others thoughts)
I think titanium would hands down out perform any carbon steel as a dive knife material. The only drawback may be material cost- especially if you figure in the cost of a carbidizer. I could build one that may not outperform Ti out of S90V or 440C but could do it for a 1/3 to 1/4 the cost and it would get the job done.
440C with a mirror finish is hard to beat for a dive knife. Divers are compulsive about washing their gear in fresh water when the dive is over. It's the first thing you learn.
Why not something exotic? Because it's not necessary. Keep in mind what a dive knife is really all about. A dive knife is the very definition of a sharpened pry bar. It's a beater that can cut things if need be. Cutting things is the least of what you use it for. 90% of the time you are prying, digging, scraping, or banging on something. You just don't do a lot of cutting while diving. Sure, you want that ability. God forbid you get tangled in something, but unless you are wreck diving or purposely going around netting or rigging gear, divers avoid snags like the plague.
I've had a lot of dive knives over the years. Some good, and some junk. But there are some things to consider in your design.
-Large, grippy handle. Dexterity underwater sucks. Especially if you are wearing gloves and even more especially in cold water.
-Somewhat rectangular handle profile so that you can index the edge without looking at it.
-Exposed tang. You beat on things a lot with your knife.... because it's the only thing you have to beat on something with. A little bit of tang extending out of your grip is nice to have.
-Square tip. You use your knife to pry quite a bit. Whether oysters, barnacles, rocks, whatever.
-Sharp point. Go into a dark closet with gloves on and imagine retrieving a knife. All of a sudden you are very scared of anything with a sharp point.
-anything that snags. You'd think a lanyard would be a great idea. In reality, lanyards tend to wave around like long, wet hair. They wrap around everything and knot themselves. Maybe make a lanyard hole, but leave it up to the user to actually affix a lanyard if they want to.
Again, just my opinions. Obviously it's your design. This is just based on my experience over the years. The vast majority of my diving is ocean diving, with foot entry through heavy surf and surge. If your nephew is a working diver, you really need to ask him what he wants out of the knife. He may have some specific needs he wants addressed.
John has covered most of the good points - salwater corrison is NOT an issue with dive gear, simply because any diver worth his/her salt (pun intended) will be washing ALL gear in fresh water after dives.
I have an old Army buddy that owns a large maritime salvage company in New Orleans. He wanted to help me out when I first started getting into making knives and was looking into buying a large quantity of custom dive knives from me. He said his divers were well paid and loved spending money on stuff like that. After actually asking the divers what they wanted in a knife, titanium and cheap were the top two requirements. I didn't make any dive knives.
i thought id make a dive knife but then after asking divers and doing some research i found that dive knives are frequently lost, dropped, and not exactly well cared for. why? because you can buy em for around 10 bucks. i didn't see where anyone would want a dive knife from me costing 10X the price of what their used too. but if your making it for a gift or whatnot go for it! i will defiantly make my self a dive knife one day. Maybe try that Newer stuff "Zi-Finit nitrogen steel"... alpha has it and its not really supposed to rust from what i've read.
EDIT: John above covered everything, do what he said! haha
we all know what dive knives are really for though? sharks! to protect yourself from sharks you have to cut your dive buddy and swim away! ;D
If it's a working knife, then sharpened pry bar is the name of the game. Heavy is better because if he uses it to chisel, beat, scrape, and bang then the knife needs to be slightly heavy to generate any momentum underwater. He'll be wearing a buoyancy compensator so it's not like the weight of the knife matters at all for fatigue. Heavy in the hand is very desirable. Bright color for the handle is VERY desirable, especially if he's a hard hat diver. He'll be working in seriously crappy visibility with very poor field of view. Anything that helps him see the knife is a good thing, especially if drops it in the muck. Everything is black underwater. The deeper you go, the less light and the faster colors shift. Blue colors turn black quickly, followed by yellows, reds, and even white turns to dark gray. Shiny and bright are a Godsend. That's the reason I suggested a mirror finish.
So, from the little work I've done with Ti, I'm under the impression that when it bends, it stays bent. (liner lock?) Stainless at least has the spring to return to true (when properly heat treated). 154CM is more rust resistant than 440C and CPM154 is twice as tough for the same hardness. Seems like an awesome choice for something that could pry and cut. It's magnetic though. He isn't one of those divers is he? :what!: