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Sheath concept drawing, jump-grade Sifu fast-draw rig
- Thread starter Jim March
- Start date
- Joined
- Nov 7, 1999
- Messages
- 6,651
Jim....
What kind of material ??
ttyle Eric...
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On/Scene Tactical
Leading The Way In Quality Synthetic Sheathing
What kind of material ??
ttyle Eric...
------------------
On/Scene Tactical
Leading The Way In Quality Synthetic Sheathing
- Joined
- Nov 7, 1999
- Messages
- 6,651
Hey Jim....
Of course.. LOL
One concern though..
If you are planning on having it form fitting with good definition on the contours,, you may want to add a couple of loops for a pair of Prybars,, cause that may be the only way to get it out ..
ttyle Eric....
------------------
On/Scene Tactical
Leading The Way In Quality Synthetic Sheathing
Of course.. LOL
One concern though..
If you are planning on having it form fitting with good definition on the contours,, you may want to add a couple of loops for a pair of Prybars,, cause that may be the only way to get it out ..
ttyle Eric....
------------------
On/Scene Tactical
Leading The Way In Quality Synthetic Sheathing
Jim March
Knifemaker / Craftsman / Service Provider
- Joined
- Oct 7, 1998
- Messages
- 3,022
LOL!
Two things "wrong" in this picture: first, the angle is too extreme, a realistic version would be closer to straight up and down...maybe halfway between what's shown and pure vertical. I drew it this way because I recycled a pic of the Sifu itself that was already at this angle
.
Second, what's not totally clear is that there's a "snap point" that's not done anywhere near as tight in the "bottom right" corner. That's the corner that's set up for clearance. If necessary, a cut could be made along the bottom seam inwards from that retention point to allow an easier draw.
Errr...in other words, starting at the bottom right corner, a cut of about .5" or so along the bottom edge (as in, the cut would be invisible unless you looked straight up at it) would allow easier "expansion" of the retention snap. The exact length of the cut would have to be arrived at experimentally but as long as it doesn't come inwards enough to hit the lowest part of the knife, retention should still be good. The exact length of that cut, if it's even necessary, would probably vary depending on the kydex grade (.090 versus .125, fr'instance).
Another thing: the fit of the "upper cap" over the pommel would have to be fairly loose, OR the overlap would have to be fairly small, something in the .5" range or so. Too tight up there and it would indeed prevent the lower end from pivoting cleanly outwards.
Last thing, remember that the baseplate would be FLAT, only the folded "endcaps" would be molded around the knife. So the only "tight spots" would be top and bottom, not all along the edge of the blade running 6" or so. With this design, it would fit well only on the side of the person's body it was designed for; southpaws would need a totally different "mirror image" version.
I don't see any real roadblocks, only minor development. You're correct in thinking excess retention would need to be watched carefully.
Jim
Two things "wrong" in this picture: first, the angle is too extreme, a realistic version would be closer to straight up and down...maybe halfway between what's shown and pure vertical. I drew it this way because I recycled a pic of the Sifu itself that was already at this angle
Second, what's not totally clear is that there's a "snap point" that's not done anywhere near as tight in the "bottom right" corner. That's the corner that's set up for clearance. If necessary, a cut could be made along the bottom seam inwards from that retention point to allow an easier draw.
Errr...in other words, starting at the bottom right corner, a cut of about .5" or so along the bottom edge (as in, the cut would be invisible unless you looked straight up at it) would allow easier "expansion" of the retention snap. The exact length of the cut would have to be arrived at experimentally but as long as it doesn't come inwards enough to hit the lowest part of the knife, retention should still be good. The exact length of that cut, if it's even necessary, would probably vary depending on the kydex grade (.090 versus .125, fr'instance).
Another thing: the fit of the "upper cap" over the pommel would have to be fairly loose, OR the overlap would have to be fairly small, something in the .5" range or so. Too tight up there and it would indeed prevent the lower end from pivoting cleanly outwards.
Last thing, remember that the baseplate would be FLAT, only the folded "endcaps" would be molded around the knife. So the only "tight spots" would be top and bottom, not all along the edge of the blade running 6" or so. With this design, it would fit well only on the side of the person's body it was designed for; southpaws would need a totally different "mirror image" version.
I don't see any real roadblocks, only minor development. You're correct in thinking excess retention would need to be watched carefully.
Jim
- Joined
- Oct 4, 1998
- Messages
- 193
Jim,
I love the way your mind works on these things. You now have me wondering about an additional feature. Looking at your drawing I believe you could engineer the design to drag open the blade on the draw. On the Bottom clamp arc up the material to cover the thumb stud. In the area of the stud mold it to a high definition. Thus as you draw the knife the blade will open. You will also need to modify it so as to be able to grab the knife in such a way as to not interfere with the blades travel. Im just thinking out loud here (please forgive my ramble but I get into this stuff
What da ya think?
Another thing that I have found that may or may not be of any help When you fold over the material for your clamps (the side labeled "sealed" in the drawing) mold in a radius along that edge as this will improve the spring action of the retainer. You do this by tapeing a .125 dowel to the knife on that side. When the material is molded the radius created by the dowel creates a flexible hinge that is stronger and more consistent then molding the same edge flat. You can adjust the torque of the flex by changing the size of the radius in your hinge.
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We are the pilgrims masters; we shall go, always, a little farther.
Jim March
Knifemaker / Craftsman / Service Provider
- Joined
- Oct 7, 1998
- Messages
- 3,022
Hi Scott!
First thing, in my experience, every Sifu I've ever handled snaps open so easily that any added "grab the thumbstud in kydex" complexity simply isn't necessary. A better idea is to just position the knife properly for a snapopen after the initial draw.
Maybe in a version done for something shorter, that might make sense?
As to leaving off the "pommel cap"...the whole idea here is that if you're rolling and sliding down the street post-crash, a hard wack to the top or bottom of the sheath won't dislodge the knife. Instead, it'll be driven into the bottom left or top right "locked down" corners of the sheath.
I already have one Sifu sheath that is NOT "crash resistant", see also: http://www.ninehundred.com/~equalccw/blades.html - look for the two pics, bottom of page, plus there's links to the blueprints.
But now that I'm back on two wheels, the "belt slide" rig isn't adequate.
What else...as to that last paragraph, I'm not following you. I had assumed the 3 "locked corners" would be formed with little wings that fold back over the baseplate. Errr...in other words, the "pattern" to cut in the kydex before any folding or heating might look something like this:
(GOD I love Windows Paint
).
Once it's all folded and tabbed, you wouldn't need "extreme outline molding", especially on the pommel area. Although come to think, the tabs are going to need to be longer than shown here because the tab-to-tab horizontal distances will be shorter with the knife actually in there. Make 'em rectangular and about .5" to .75" long versus small triangles as shown, that'll do it.
Jim
[This message has been edited by Jim March (edited 10-24-2000).]
First thing, in my experience, every Sifu I've ever handled snaps open so easily that any added "grab the thumbstud in kydex" complexity simply isn't necessary. A better idea is to just position the knife properly for a snapopen after the initial draw.
Maybe in a version done for something shorter, that might make sense?
As to leaving off the "pommel cap"...the whole idea here is that if you're rolling and sliding down the street post-crash, a hard wack to the top or bottom of the sheath won't dislodge the knife. Instead, it'll be driven into the bottom left or top right "locked down" corners of the sheath.
I already have one Sifu sheath that is NOT "crash resistant", see also: http://www.ninehundred.com/~equalccw/blades.html - look for the two pics, bottom of page, plus there's links to the blueprints.
But now that I'm back on two wheels, the "belt slide" rig isn't adequate.
What else...as to that last paragraph, I'm not following you. I had assumed the 3 "locked corners" would be formed with little wings that fold back over the baseplate. Errr...in other words, the "pattern" to cut in the kydex before any folding or heating might look something like this:
(GOD I love Windows Paint
Once it's all folded and tabbed, you wouldn't need "extreme outline molding", especially on the pommel area. Although come to think, the tabs are going to need to be longer than shown here because the tab-to-tab horizontal distances will be shorter with the knife actually in there. Make 'em rectangular and about .5" to .75" long versus small triangles as shown, that'll do it.
Jim
[This message has been edited by Jim March (edited 10-24-2000).]
Jim March
Knifemaker / Craftsman / Service Provider
- Joined
- Oct 7, 1998
- Messages
- 3,022
Hey, it works pretty good for roughing out ideas.
See, back in '85 I was working at a computer store that sold Macs. We sometimes had time to kill, and I used to have all kinds of fun playing with early versions of MacPaint.
Windows Paint is a direct decendent...so while it may be primitive, I've been using it a LONG time
Now that the Win98/ME/2000 version can write out .GIFs without using an external translator, it's even cooler
Jim