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Purchased some rigging stuff

Discussion in 'Commercial Tree Care and Climbing' started by mikecross23, Apr 4, 2003.

  1. mikecross23

    mikecross23 ArboristSite Guru

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    I broke down today and bought two 5/8" tenex eye slings, a 5/8" block, and a porty III. I bought the eye slings locally for the same price as Sherrill offers and ordered the block and porty from Sherrill. That should give me time to get confident w/ my sling attachment. I don't have time right now to read past threads about attaching slings, but for now I'm expecting to use the timber hitch and maybe the cow hitch (don't know how to tie yet.) If anyone has any good tips for sling attachment please speak up.

    I couldn't afford the samson stable braid 5/8" x 200' rope yet. But Bailey's is having a sale until I think it is May 1st. Until I get a good bull rope I will use what I have, 1/2" three strand w/ a 7,000 some odd pound tensile rating. I will stay small, but I want to hear what you all think about using 1/2" rope on a 5/8" block. If I remember correct, somewhere I have read that it is bad to use different rope and pulley sheave diameters. Is this true?

    Thanks,
    -Mike-
    :)
     
  2. tjk

    tjk ArboristSite Operative

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    Hey Mike, which block did you get. I have a couple of CMI 5/8 blocks and love them. One is 7 or 8 years old and is still is perfect working order. You can use a 5/8 block for any rope 5/8 or smaller. The cow hitch is the best for attacthment.
     
  3. mikecross23

    mikecross23 ArboristSite Guru

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    tjk,
    I bought the one in the Sherrill catalog on pg. 22, letter C. I couldn't find a brand listed anywhere for it.

    I remeber reading about the cow hitch being a good one to use. I just don't know how to tie it. Tonight I will search my books and this site and figure it out.

    -Mike-
    :D
     
  4. Kneejerk Bombas

    Kneejerk Bombas ArboristSite King

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    The ideal sheave is 1/8" larger than the rope.

    The ideal attachment is the clock hitch.
     
  5. tjk

    tjk ArboristSite Operative

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    I;m not familial with the clock hitch what are its advantages over the cow. I've been using the cow hitch for many years with great results. Mikecross. The cmi blocks are stainless steel. The painted ones are aluminum. The both have the same working load limit. I just perfer the cmis because of the history I have with them, plus the have less moveing parts.I cant spell 2-day
     
  6. BigJohn

    BigJohn ArboristSite Guru

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    It is said that you should maintain a 4:1 ratio. With a half inch rope you should have a 2 inch pulley. As far as attaching this block I like the cow hitch but sometimes we don't have enough sling to tie all that so a 5 twist timber hitch works well. I wouldn't concern yourself with the 5/8 bull rope. I personsally taken down alot of large poplar tree on a half inch line. I could but out 12 foot pieces at 18 to 24 inch diameter on a half inch line.

    Do you know you shouldn't run 5/8 bull rope with a 5/8 sling? Your sling should be bigger than your rope. Your sling has to take twice the rope does. So if you lower a 500 pound log the sling is holding 1000# and that does include the initial shock load.

    So that being said what does everyone think about the two ring fritcion savers from Buckingham? Do they maintain a 4:1 bend ratio? I don't think so. The rings are at best 1/2 inch each, a total of an inch. This is not acceptable according to the "rules".
     
  7. treeclimber165

    treeclimber165 Member A.K.A Skwerl

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    Y'all are confusing sheave diameter with sheave width. Let's not confuse everyone else any more than necessary.

    Mike (and anyone else who cares)-
    The CMI pulley you bought is fine for ropes up to 5/8" diameter. It has a 4000# WLL which would make a tensile strength of 16,000# or more. The tree you are attached to and/or the rope will break long before the pulley fails. The sheave diameter is 2¾" which is plenty large enough for 5/8" rope.

    The diagram for the cow hitch is in your 2002 Sherrill catalog on the bottom of page 38.
     
  8. seanlarkin

    seanlarkin ArboristSite Guru

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    Mike,
    If you ever have any questions about any of our products, or how to use them, please call us (1-800-525-8873) and ask for Johnny (ext 231). That is part of our extended customer service - post purchase support. Also, we'll match that sale price you mentioned. Just bring it up next time you order, provided it's before May 1st, or whenever that sale ends.

    All,
    We put a good deal of effort to break down tensile strength vs working load limit ratings in the new catalog. We also switched our rating system to WLL, instead of tensile, because it's just the safer number to use. This thread give me an idea for next catalog: discussing sheave width, sheave diameter and the appropriate rope sizes...

    _Sean
     
  9. mikecross23

    mikecross23 ArboristSite Guru

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    Sean,
    Thanks for the customer service!!! That's why I like dealing w/ Sherrill. I like the way you guys break down the SWL limit vs. the tensile strenght. I've noticed other companies don't do that and today I had to teach my local dealer about the climbing goods they offer b/c they don't know, they just sell it.:rolleyes:

    tjk,
    by your description I ordered a cmi stainless steel block.

    Brian,
    Thanks for the cow hitch diagram. I like the cow hitch b/c most of the trees I do will be small enought to use the extra line and it just looks more secure than a timber hitch. Now I need to practice it before I need it.;)

    Big John,
    Thanks for the reasurance on the 1/2" line. I will however get a 5/8" stable braid for the simple comfort of cheap insurance. Over rated will save me the stress of wondering.:confused: I will use the 1/2" line for limb lowering and small sticks, but when I have to lower a large spar I will go ahead and get a larger bull rope.

    I gave a bid today for 12 removals on a very tight lot. 5 of them were w/ in 6" off the roof line and have an 8' wide lowering zone btwn house and privacy fence. One of the trees (12" -14" dbh pine) had actually grown into the roof line about 2". Lots of light branch rigging for the rest. I gave a good competative bid and hopefully will get the job. My parents have some low risk pine removals for me "when I get a chance." Will be great practice for some practical situations.:D

    Thanks for the tips, keep 'em coming!
    -Mike-
     
  10. treeman82

    treeman82 Addicted to ArboristSite

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    Mike, sounds like a fun job :) I find that stuff within a couple inches of the building provides a nice challenge for me, which sometimes requires a bunch of rigging, or sometimes just a pull rope and a truck.
     
  11. ORclimber

    ORclimber ArboristSite Guru

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    Those blocks, eyeslings, and ropes come in handy for all kinds of things. I used some today to upright my 1000 lb. stump grinder solo, with a pull from the chip truck.
     
  12. mikecross23

    mikecross23 ArboristSite Guru

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    I figured they'd also be handy in skidding logs from back yards when there is not a direct path to the front. I see lots of options and can't wait to put this stuff to use!!!:blob2:

    -Mike-
     
  13. Stumper

    Stumper One Man Band

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    "Best" is a very subjective thing. My preferred method for slinging a block was arrived at back when I did a lot of pine removals that involved blocking and lowering spars in tight quarters. I made up spliced rope slings with a small eye on one end and a large eye prussiked onto the line for an adjustable eyed sling(an adjustable buckstrap without snaps -see Sherrill catalog page 16). Pulley,'biner and strap allowed quick repositioning without re tying knots. There are stronger set ups. There are setups that can suck a couple of inches of slack out of the rig relatively speaking. This set up is very handy so long as you aren't going beyond proper rope WLL.
     
  14. mikecross23

    mikecross23 ArboristSite Guru

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    I'm gettin' all jittery waiting on my block and porta wrap!:D
     
  15. TheTreeSpyder

    TheTreeSpyder Addicted to ArboristSite

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    The sling on the pulley takes the 2x load (in parallel lines ie. support and control legs to pulley).

    If having to choose, the pulley should actually get more sling strength than porty, in standaard setup.

    i think of the cow hitch as a larks/girth hitch with an overhand knot. As all lacings, the loaded line coming into the primary haalf hitch should immediately choke close upon loading. ie. if putting on porty on trunk, the first turn around the trunk should come over porty then down, for an immediate consstricting lock against the immediate restriction imposed by the half hitch coming over the proposed load pulling up on the porty.

    i think all knots should be so examined, and purposely laced pre-tightened and to immediately pull tighter on loading.

    If you have to skid refuse out of a 200' yard with a 100' of truck run; you can even pull it off by cutting the power in half/ doubling distance by rigging with the pulley on the truck pulling. Also good for liting logs into dump with truck, especially if you collect another pulley (doesn't have to be impact block) and make a 2/1 lift powered by a 1ton+.

    BigJohn, i have tossed out the idea of the sharper bend in line from friction saaver/ friction hitch friction increaser. None of the rope companies i called would specifically name the device, but in general commeented that 1/2" line should run with 2"bend minimum, Samson was pretty specific about this. The general feeling i got around here is that with just body weight loads we weren't pushing the rope that hard, to worry about. i've personally trained my eye to scan and say would i put a load many times my weight on that system and impactwith a safety factor? Nope? Well then i shouldn't put my lil'butt on it. Maybe too much overkill, it is the way i've coached myself and read this strategy in most everything else we do.

    i'd check into some kind of simple pretightening jig to play with, and bone up on high impact swetaing in, then compound the 2! Sometimes lifing up like a fixed crane.
     
  16. treeclimber165

    treeclimber165 Member A.K.A Skwerl

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    Hey Mike,
    They didn't tell you? I told them that you wanted it sent to my house, and they believed me! Thanks for the PW, buddy! :D
     
  17. mikecross23

    mikecross23 ArboristSite Guru

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    Glad they didn't listen to your squirely self Brian!!

    My stuff arrived today and while fidgeting w/ it wondered if it is easier to lace the eye sling w/ the block attached or not. Do most of ya'll tie and then connect the block, or is it already attached and then tied?

    I've got the perfect small pine removal (maybe 10" dbh) w/ nothing around to start practicing. I need to practice my cow hitch some more 'cause that thing is kinda wicked at first!

    I got an email today from member and Sherrill employee Sean Larkin about some new items for 2003. One of them was a throw line cube. Looks nice, but the price even nicer! I think it was $12 -$14 for a 12" or 14" cube. Now I've got to place another order!:rolleyes: Thanks Sean

    -Mike-
     
  18. TheTreeSpyder

    TheTreeSpyder Addicted to ArboristSite

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    For best tightening, i lace my cow hitch, whoopie sling etc. the same on any device pulley, porty etc.

    i lace the attatchment line tight around the neck of the porty, not the base, this makes a smaller amount of line in the binding, then i take the porty and yank it around leveraging the line to slide down the base, tightening it even further in the process. i work the hardware attatchment outside of the choke too. This can be done with most of the heavier blocks, depending on the taper.

    Always making sure that on the porty if the pull is coming from above, that the first turn of the hitch on the attatchment comes over the tail to the porty, to immediately on loading choke shut. Usually the pulley will incur 2x load pulling down, so first turn on it's attatchment comes under the tail to the pulley to immediately choke close upon loading. Same in rigging limbs to go to the side, always schedule the pretightened choke to pull immediately tighter closed on loading.

    Another good thing to remember is that a a length of line or a sling has a base strength of X, stretched out and loaded; in a choke the strength is 80%X, but in any basket formation (with just 2 legs), strength is calculated at 200%X generally. At that scale a basket is 2.5x stronger than a choke. On a block with 2xload impacting and a 10,000 sling that is the difference between 8,000# strength and 20,000#strength. Sometimes a basket can slide so a double/round turn/or choke basket can give both grip and strenght at a cost of just more line. This is how you can use an attatching line the same size as the rigging line, in some situations. Every time you turn the line around the support and through the pulley (make round turn basket and bring both ends and the belly of the roundturn around the block's bolt) it gives more legs of support to the block's 2ximpact loads, at a loss of some grip.

    What Big John says is a good rule of thumb, and the way i learned it (eventually); but when up there, even trying to screech more confidence out of a bigger sling, these strategies can be employed. These strategies can really help tweak a lot out of those lil'CMI looprunners, especcially for 'the fold flat as a handkerchief' and unroll to all this strength.



    :alien:
     

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