sling sizing

[woodgas631]

I picked up a couple stainless cmi tailboard blocks in 5/8 and now I need slings, but the sherrill catalog says, "Generally our blocks have capacity to support a sling 1/8 inch larger than its designated running line capacity." Does that mean I can step up to 3/4 tenex whoopies and loopies and exploit the safe wwl of 5/8 stable braid? Or are they just simply pointing out that the block itself is not the weakest link, and I have to use 5/8 slings, which is rated just under the wwl of the 9/16 db I have? Im going on double capacity for anchor slings and blocks numbers. 5/8 slings fit nice in my opinion. Does anybody actually cram 3/4 into the top sheave of there blocks? I'll consider it a sin unless you pros say otherwise. I often here mention to the slings being the weakest link here on this board so im just wondering. It just seams odd to me that the manufacturerererer would have addressed it after all these years. If you run 5/8 db to lower bigger wood through this block than your defying the wll by like 1000 lbs or so on the tenex slings right? Do they assume your reaving it through multiple blocks and it will just spread out and be within the margin or what? Id hate to shell out the lumber on amsteel if thats the solution. Id rather just cycle through slings more often. Who in there right mind would postpone a job because they didnt want to exceed the wll of there sling within reason? What do you guys do? How many questions can I ask in one single post? Huh?.................................................................?...............................................................................Im just trying to save paper. Thanks.

 

[Panama]

Woodgas, I'll bite. First, you don't have to be an expert to get on here and reply, though there are many here that do. Most of us do things a particular way based on our personal experiences, so we usually do not agree on one "correct" way of doing things. This often leads to argument or even heated jousting, as we each believe so strongly in our hard earned opinions.
I would recommend you never try to "exploit the safe wwl of 5/8 stable braid". Most who have been doing this work for a while have learned that "stuff occurs", so we stay well below safe working load limits.
I personally use 5/8" cmi stainless blocks with 5/8" tenex, 1/2" tenex, or even 3/8" tenex (out at the tip) with 5/8" stable braid bull rope, but my loads stay well below the recommended wl of the slings, blocks and bull rope. When things get heavy, I use 3/4" cmi ssl blocks with 3/4" tenex slings and 3/4" stable braid. If I was going to work close to it's recommended wl, I would move up to 1". I haven't tried the amsteel slings yet.
My top block is normally used to give me the best landing-zone, so it is usually out towards the end of a branch, but always backed up on the trunk, near the branch base with a stronger block and sling. Again, just my opinion, so I recommend you form your opinion of what the "correct" way of rigging is, very slowly and safely.

 

[John Paul Sanborn]

Does anybody actually cram 3/4 into the top sheave of there blocks? I'll consider it a sin unless you pros say otherwise.

If it closes; yes I do. Especially 2/4 in Tenex eye slings.

IMO the anchor sling should be the highest rating in the system, because it will take a lot of heavy cycling. Unless you melt the line, it will be cycles to failure that gets you.

I use the ICS spring blocks for everything, and 1/2 in stable braid for most rigging, with a 9/16 for bigger stuff. Rarely do I use anything bigger.

 

[woodgas631]

whoops!

My mistake... I was factoring a 10 to 1 on the running line, not 5 to 1 like the samson site reads. Sorry. In that case, it seems like a recipe for disaster if you were to creep up to the wll with these small blocks with my 9/16 db. I know your probably all rolling your eyes around like "listen to this little school boy, were gonna read about him in the obituary section one day". I'm just trying to figure out where the edge of the cliff is so I can keep a far distance from it. Don't worry. I won't be dumping honda civic size wood on my rigs thinkin its o.k. cause the #'s work out. Call me a puss, but i'll be takin stuff one little branch at a time for a while and slowly progress until I develope a "feel" and a good sense of things. If it takes me all day to do what you guys can do before lunch, oh well than. I have time, a big back yard with plenty of trees that need removal and a brother who knows how to be a decent groundie. It's a perfect opportunity for learnin for both of us.

 

[John Paul Sanborn]

but i'll be takin stuff one little branch at a time for a while and slowly progress until I develope a "feel" and a good sense of things. If it takes me all day to do what you guys can do before lunch, oh well than.

I think we all started like that, so shame.

I think many people underestimate the rope, and fail to respect the tree enough. The tree is often the weakest link in the system. One thing I do is push the loads on limbs in safe areas, so that I can see how they react. I have never broke a rigging line, or pulley, but I have had a few rigging points fail on me. Most of them were, not intentional, but "let's see what happens". One was with a redirect i was uncomfortable with, but my client insisted I rig it so that the load would come down in a convenient location.