Four-sided ricasso shoulders?

T

Tenebr0s

Joined
Jun 3, 2012
Messages
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I've heard of some makers cutting shoulders on all 4 sides of the tang to allow for easier fit up with guards, and covering up any minor gaps that would otherwise show. I'm interesting in trying it, but am concerned that this would create an excessively weak tang/blade junction. When I ordinarily grind in my shoulders, I cut a small radius at the corner with a chainsaw file. If I were to do steps on the flats of the tang, however, it would be pretty hard to get a radius without grinding fairly deep in. Cutting them in with a flat file seems like it might make too sharp an angle...

Curious to hear if others have experience with this!
 
I usually do chainsaw file on front and back... blade and spine edges to radius and remove any stress risers to reduce the risk of breaking when chopping or batonning, and then just file/sand the sides of the tang slightly narrower the whole length of the handle so the largest part widens out just where the guard will be pressed into place and voila.
 
Yes, I place the file guide on the place where the shoulders will be, then file with a chain saw file or grind the shoulders in ... making sure the transition is curved, not a 90° angle. Then I lightly file or grind the sides to relieve the tang about ten thousandths of an inch on each side. From there, I taper the tang a bit to make sure there is no bind when the guard slips on. This makes a shoulder that goes all the way around, and makes the guard sit flush easier. It also makes soldering neater and simpler. With careful filing of the guard slot, it will tap on just snug.

This system is very useful when the ricasso is a trapezoid, not a rectangle. On some big blades, like a Bowie, the spine side is wider than the edge side. It is also that way on most Japanese blades. By making the tang have a shoulder all the way around, the guard slot is much simpler to fit without gaps.
 
I know that MS Lin Rhea does it fairly often. Here is a quote from last years "Blade 2015 - Show us what you got" thread regarding the strength of this type of construction. Somebody was asking why he created such a weak spot/stress riser after he showed a few pics of the unfinished knife shown below.

lwrhea said:
I may agree with you in the technical aspects of the naked blade, but I believe the addition of properly fit hardware will change the dynamics considerably from torsion and side to side/up to down shock into tensile. In a nutshell, this is what make the hidden tang construction able to stand up beside Full Tang construction. It is no longer a blade. It is then a completed knife.
Click to expand...







Just thought that you might find this informative and interesting. :)

~Paul
My YT Channel Lsubslimed
... (It's been a few years since my last upload)
 
BTW, you could still add a radius to the sides of the ricasso/tang area, you could probably use a small round needle file to get the side transitions started and then just grind or file away the excess steel on the tang starting directly behind the radius you made. I'm pretty sure that it doesn't matter too much about the size of the radius in that area, but just as long as it's not a straight, harsh 90 degree cut angle I think it would work fine. This is just the way that "I" envision it, as I've never made any in this type of construction.

Just don't forget the above quote by Lin about all the hardware fitting properly being the thing that gives this type of knife construction it's strength. ;)

~Paul
My YT Channel Lsubslimed
... (It's been a few years since my last upload)
 
I did not know there was another way of doing this. Of the 2000 I've made with all four sides ground, none have failed. If you use sound heat treatments through this area there is no reason an 1/8 inch tang or narrower should not suffice, with shoulders ground on the bevel sides as well.
No matter how the blade is heat treated, full immersion in the quench, or partial submersion, treating the area around the ricasso/shoulders area as separate, never fails to produce a sound structure.
I do this by setting the finished blade in wet sand, using a butane torch to relieve the tang and ricasso/spine areas.
Fred
 
Thanks for all the replies. I feel more confident trying this now that I know it's not so unusual after all. Fred, do you like to draw the shoulders all the way back to soft, or do you leave them at a spring temper?
 
Spring temper.

Have you tried drawing a blade back sitting it in wet sand. I use a cookie sheet filled with play sand; just enough water to keep it wet. The blade will sit upright; cover everything you don't want heated. Use a small torch, butane works.

Fred
 
I also draw the tang and ricasso area after treatment and use sand also just as Fred does and have never had a problem.
 
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