Locked Brummell

[nu2hike]

I just finished making some dynaglide whoopies. The buries on my locked Brummells were only about 4"! Is this going to be a problem? Would stitching them make them safer? Or is there a way to take them out & redo them?
Sorry for the multitude of questions!
Thanks

[MAD777]

The buries should be 3.31" plus another 1.65" taper.
Stitching it doesn't add any significant strength. It just keeps the bury from falling out when unloaded.
Yes, you can take them out and re-do them. But you have to gingerly remove the bury without putting any load on it.

Or you could leave them as is if you are never going to get anywhere near the rated load for a "proper" bury.

[Bubba]

I've made buries shorter than the manufacturers' recommendation with no issues but I'm willing to take the chance. If you are not then redo them.

[nu2hike]

Thanks for your help! I decided to just redo them using the appropriate length buries! Better safe than sorry

[GaryBunk]

The buries should be 3.31" plus another 1.65" taper.
Stitching it doesn't add any significant strength. It just keeps the bury from falling out when unloaded.
Yes, you can take them out and re-do them. But you have to gingerly remove the bury without putting any load on it.

Or you could leave them as is if you are never going to get anywhere near the rated load for a "proper" bury.

I saw this post the other day and was curious as to how you come to the long or additional length on the bury? I looked at Sampson and several other tables and can't find anything to that? Can you tell me where you got it?

[MAD777]

Somewhere in this forum there is a thread on this topic, but my iPhone search capabilities are weak. However, here is the table that I copied from that thread.

ImageUploadedByTapatalk1344886945.925252.jpg

[GaryBunk]

[QUOTE=MAD777;786951]Somewhere in this forum there is a thread on this topic, but my iPhone search capabilities are weak. However, here is the table that I copied from that thread.

ImageUploadedByTapatalk1344886945.925252.jpg[/QUOTE

That is sort of my question, I talked to Sampson and there doesn't seem to be a reason to add the taper as the force is carried by the locked brummel and other end of the whoopie sling would be the failure point. Basically the taper is a waste as far as adding strength, that is why they say 2 fids and cut on an angle.
3 fids would be the length required for a straight bury.

[MAD777]

Let me warn you that I am no expert on splicing so take this with a grain of salt. It is my understanding that a sudden reduction in size of the cord (no taper) creates a weak point.

While that may or may no be true, I know it's much easier to splice with some kind of taper.

Perhaps someone that really know this stuff can help us both out

[GaryBunk]

Let me warn you that I am no expert on splicing so take this with a grain of salt. It is my understanding that a sudden reduction in size of the cord (no taper) creates a weak point.

While that may or may no be true, I know it's much easier to splice with some kind of taper.

Perhaps someone that really know this stuff can help us both out

No I understand completely, I am waiting for several orders of dynaglide and ran across this post, I spoke to the techs at Sampson and they said for a whoopie 2 fids was enough and the cut at an angle (or I assume remove the normal strands). I asked why no additional for taper and their responce was that nothing was added by increasing the burry length. I looked at New England rope and they only suggest 1 1/4 fids on a locked brummel. So you can imagine my surprise and wanting to try and find the answer before making new whoopie slings.

Thanks,

[DemostiX]

1. Guidelines from decades of field experience is a bury of 70- 72 diameters. This is longer than for polyester and nylon ropes. No need to know what a fid is.
2. Diameters are part of a guideline for the field, necessarily with a safety margin.
3. The guideline was developed over cordage ALL OF WHICH is larger than what we are talking about. It may be that a better empirical rule fit over all cordage is 80 X (diameter**.95), or that different rules fit line of different constructions.
4. Sizes of cordage to which the guideline is applied are nominal. All the dyneema cordage has the same density after use. So cordage of the same weight per length cannot really have different diameters. They must be the same. Which further shows you that you are dealing in approximations.
5. You taper so that the incidence of breakage at the end of the bury at tensions lower than full breaking strength are reduced. You also taper so that stress over time is not concentrated at an abrupt internal termination, because that will prematurely wear the rope.
6. You will never see breakage at all unless the cord is stressed severely.
7. The locked brummel carries some load, but it is not meant to carry anything approaching the full load which is properly carried in the bury.
8. The splice without brummel and with taper can carry the largest load.
9. A splice with locked brummel and short bury will fail at far below breaking strength of the line itself.
10. If you are committed to not bothering with a taper, and wish always to show it is of no benefit, create splices with a locked brummel, a short bury, and no taper, say 15-30 diameters. There will never be a failure at the blunt termination because the splice will fail first in the brummel or in raveling.