Reserve closing loop length: measure from where to where?

[nigel99 143]

pchapman

For JAVELINS:

So that jpg, presumably current, shows 2 1/8" (53mm) to 2 1/4" (56mm) unstretched.

Funny, because the manual current in 2012 ("rev 3") says:
"Suggested reserve closing loop after setting and pre
stretching to be 54mm to 57mm. (2 1/8 +/- ¼”)"

The numbers differ, the measurement techniques differ, and the metric conversions are inconsistent and can't all be correct. But who knows, maybe it was all a deliberate change.

(And does everyone really get the loops that short in practice??)

Yes the current manual. The previous loop in my rig was 7cm (stretched) and I shortened it to 6.5cm on last repack. I only just got my rating though and the 6.5cm is first pack job of my gear. 6.5 is stretched though.

Experienced jumper - someone who has made mistakes more often than I have and lived.

[mxk 1]

riggerrob

For decades, the Vector factory installed perfectly flat, aluminum pack tray stiffeners (aka. anchor plate).
I have never seen one bent along the vertical axis (parallel to the spine). Maybe this is something new from the Vector factory??????

I've attached three photos of how the plate looks now. I also took hundreds of photos just after receiving the rig so that I know what various pieces looked like when they were brand new. One of these original photos happens to capture just a bit of the anchor plate. To my eye, it looks like the plate came bent at the sides from the factory.

I can't understand how such a bend could be created from too much force applied at the grommet. The middle part is perfectly flat, only the sides are bent. On the other hand, this is exactly the type of bend I would use to give the plate additional strength.

[riggerrob 558]

Those longitudinal bends look like they were made at the factory. That is the simplest way to stiffener the anchor plate.

[pchapman 261]

mxk

The current manual says 4 1/2 ±1/4" on page 16 and 4 1/2 ±1/2" on pages 30 & 38. I didn't even notice originally that the range is 1/4" in one place and 1/2" in the other .

Going back to this older conversation, I just packed a brand new Vector III with an Optimum 143 reserve that's supposed to be middle of the range for the rig size.

(Fairly cool and dry conditions, 64 F, 40% relative humidity.)

With a loop of about 4 3/4" I needed to let the rig sit a day to even close it with my leverage tool. I knew it would be too tight: it pull tested about 40 lbs.

Started again with a loop just a tad under 5" long, also after stretching it with a leverage tool. (With hand stretching, one has to allow for more tightening of the loop over time and thus 'stretch' in the loop. The classic reason for a loop to be 1/8" longer after the repack cycle than when you packed it.)

Anyway, this time it closed fairly 'normally' with the leverage device and tested to around 22lb, just barely ok. That's at about the top end of one of their stated closing loop sizes, and above another.

They don't even say "should be" but say "will be", like it is mandatory.

I try to follow what 'the book' says about shaping a reserve but don't go crazy on the 'secret stuff'. Maybe it is the humid Florida air that they ignore as a factor, or maybe I still suck at packing after 1300+ reserves, but I remain pretty skeptical about what manufacturers say in their manuals....

[mxk 1]

For pre-stretching, do you mean that you use the leverage tool before installing the loop in the container? What do you use as an anchor?

I also noticed that pre-stretching by hand (and I put about as much force into it as I can) doesn't seem to be enough for a stable loop length. For my last repack, I measured the force for pulling the temporary pin out after closing flaps 4 & 5, which was 18 lbs - higher than the manual recommends (8 to 12 lbs, page 37). I had to use the leverage tool to close the container and the pull force at the pin was ~28 lbs, if I remember correctly. Tested it again 24 hours later and got 14 lbs. Verified this again just now. Had I followed the suggestion for 12 lbs after flaps 4 & 5, my loop would have been too long. So much conflicting information...

Kenneth Gajda is giving a Vector 3 packing demo at PIA next week. Anyone care to record a video for those of us who can't attend?

[mcordell 2]

put the handle of a positive leverage tool through the loop and the washer in the groove of a knee plate. Make sure it's anchored well so you don't pop yourself in the face. Kneel on the plate and pull with both hands.

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[pchapman 261]

Quote

I also noticed that pre-stretching by hand (and I put about as much force into it as I can) doesn't seem to be enough for a stable loop length.

Yeah I use my leverage tool. Mines a little different than standard, with the axle / crank mounted on supports on top of a plate, but in any case the dimensions often allow it to be used with the washer in the groove as mcordell says. (I might make an additional plate with a smaller gap in it so there's less bending force on the washer as with the larger gap.)

Sounds like his 'two hand pull with an anchor' way also gets a good effect, compared to the old Cypres manual 'one arm pulling in each direction'

One can hand pull a loop good and tight, but putting it on the tensioner one easily gets another 1/8" without much effort. Some of that 'stretch' probably would happen during the pack job itself (especially when packing a tight rig with a leverage tool), or maybe some might happen over time while it is packed, I don't know. But it is nice to be able to plan loop sizes with less variation between the plan and the final result.

I think I got into the super-stretching after seeing somewhere that one can make the marks on a Cypres loops just 3/8" apart, between the zero point and the knot point. But that was way too little... IF trying to hand stretch once the loop was already threaded around the Cypres washer and creating friction.

[gowlerk 1,911]

I've always found that the trick is not to pull on them hard at all. But rather to jerk them several times stretching them a small amount at a time. I wrap one end around a T bar and slip the loop end into another then sit at my desk and give it about 10 to 20 sharp tugs. Works for me.

Always remember the brave children who died defending your right to bear arms. Freedom is not free.

[nigel99 143]

gowlerk

I've always found that the trick is not to pull on them hard at all. But rather to jerk them several times stretching them a small amount at a time. I wrap one end around a T bar and slip the loop end into another then sit at my desk and give it about 10 to 20 sharp tugs. Works for me.

I was taught to use the closing plate and stand on it with the washer underneath, and to use the pullup cord wrapped around the aluminum paddle. Works well.

Experienced jumper - someone who has made mistakes more often than I have and lived.