The problem with (spearo) daggers / sharpening daggers

[Mr. X]

I like spearo-dagger dive knives (especially small ones), as the point makes a very good dispatching tool - a more versatile tool (& dispatching implement) than, say, a dedicated iki-jimi spike or fish-stringer spike. However, I've noticed that the points of daggers are:

1. Difficult to sharpen well.
2. The tip is vulnerable to damage.

The tip of my Effesub spearo dagger snapped right off (it seemed to crumble almost) when I press too hard while sharpening its rather thick, pointed blade:

My inexpensive Union spearo dagger on the other hand has proven more robust but maintaining the original point or achieving the more triangular profile (like the Omer Laser knives) I desire, is tricky.

Maintaining sharp edges is problematic because of the traditional "fat-diamond"-profile of daggers. The popular and well regarded Lansky sharpening guide requires a flat area behind the sharpened edge to clamp onto - the Lansky guide simply doesn't work with the United spearo dagger:

I love my new little Omersub USA Mini Laser spearo dagger but worry about that little tip. And wonder if I'll be able to maintain that point & sharp edges. :hmm

[If interested, also see related threads which precede this, such as: http://forums.deeperblue.com/hunting-equipment/77783-effesub-better-knife-uk-spearo-2.html ]

 

[Mr. X]

While looking for information on sharpening daggers, I came across this unusual Canadian dagger blade design on Youtube; I wonder if it might offer some benefits for spear-fishing?

[ame=http://www.youtube.com/watch?v=K8NuAOXPwig]‪Blackhawk XSF1 Dagger‬‏ - YouTube[/ame]

I wonder if the broad 40-degree single-side ground blade edges might not be sharp enough to gut/fillet fish.

Interesting (on the related sharpening video for the above) that the Titanium version is softer than the carbon steel version (stainless steel is often criticized for its softness which often doesn't hold an edge as well as harder carbon steels e.g. 440).

[ame="http://www.youtube.com/watch?v=rW-4oje_Dbc"]‪Blackhawk How To Sharpen the XSF1‬‏ - YouTube[/ame]

 

[Mr. X]

There is much to be said for simplicity. The spike of a fish stringer requires you to carry no extra gear (although a sharp knife is recommended for safety purposes - to cut lines/nets that might otherwise entrap you).

I have now made several iki-jimi spikes, which are surprisingly cheap, simple and effective. Mine so far have used an awl spike and thermo plastic chainsaw-file handle. For the sheath, I use a short section of an old car ariel/antenna for the sheath, with a flattened and drilled tip, v. similar to the sheath on this commercially available iki jimi spike:

I fit a doubled 3mm bungee lanyard through the hole in the sheath and through a hole in the handle. The shot lanyard acts as a wrist lanyard in use, and secures the sheathed spike to my weight belt when not in use. Quite neat.

However, I find the handle bulky and top-heavy (the next version will have the spike extend further to try to remedy that). I wonder if something flatter might be possible - perhaps like something like one of those stainless steel letter-openers sharpened to a point with a flat tape sheath (like narrower version of the RA limpet/Pelaj Pancake sheaths)?!

[The RA Assegai knife looks good and has a good reputation for quality - but I'd prefer a large double guard to protect my hand and to push against while dispatching. And at its rather high UK price, I'm not inclined to compromise on such details .]

Or perhaps even something made out of, say, tubular climbing tape, a bit like a simplified version of this rather spiffy military, sheath designed for the classic WWII Sykes Fairbairn commando dagger:

http://www.sasskit.co.uk/product.php?id=130

 

[Mr. X]

Back on topic. After some experimenting sharpening the spearo daggers, I now mainly try to avoid giving the tip special attention and instead concentrate on maintaining each blade edge along its entire length, from guard to tip. It's by no means perfect but, as long as I am reasonably careful, it doesn't mess the tip up, or snap it.

I've found that a broader angle than normal for the blade edges seems to work better - the United dagger is never going to be a great filleting knife, but it should be sharp enough to gut fish. Some sharpening books recommend forming two flats (double bevel?) on each side of the blade; the first relatively wide and narrow-angled to produce a very sharp blade. But then a much narrower/smaller, broader-angled edge is added at the end. This seemed very counter-intuitive to me at first - why do all that grinding to get a super-sharp narrow edge only to finish if off by blunting it? The answer is that a very sharp edge (especially on relatively soft stainless steel) won't last long. The broad edge will last longer and be easier to sharpen and maintain - the fact that it located at the end of narrow edge ensure that the overall sharpness remains pretty good.

Some articles/video suggest marking the bevel/edge of the blade to be sharpened with felt-tip pen, so you can see where the surface is removed (by lack of ink) during sharpening. I'm toying with the idea of extending this idea to help re-shape the tip of my United dagger, by marking larger areas to grind around the tip, to give it a more accute tip point (more like the Omer USA mini laser shown above).

 

[Mr. X]

More recently, I've noticed that there is Bowie-knife blade variant of the United dagger:

While aesthetically less pleasing to me for spearing, perhaps it offers a good, simple, practical alternative. It is a long proven design for hunting(, combat) and general utility. It has a sharp, presumably easy to maintain tip and blade (notice that it has a flat area, that should allow a Lansky-style sharpening guide to be used).

No doubt a fashionable Japanese-style tanto-blade alternative will eventually be forthcoming.

 

[foxfish]

Great thread Mr X, some very nice looking knifes out there.
I have inherited my brothers titanium knife - that seems to hold a extremely sharp edge.

 

[Mr. X]

Glad to hear you have it and appreciate it Foxfish. I know OMD was very pleased with it. It is, perhaps, the ultimate small spearo dagger - almost identical to the Omer regular (not USA) mini-laser but made with Titanium, rather than stainless steel.