I have installed several static cable and brace arrangements in large ponderosa pines, Douglas-firs, and a big leaf maple in situations where there was included bark and co-dominant stems; I also cabled a large oak limb to the main trunk of a tree recently just before we had a major ice storm. That limb (40 ft. long and a foot in diameter) would have most likely snapped and landed in the street if I had not cabled it! The homeowner said that the tips were just a few feet off the street (instead of 15 ft.).
The big Doug fir I cabled and braced had a subordinate trunk with chronic resin flow at the union; even though I thought it's failure potential was moderate, the target had extremely heavy traffic. The upper main trunk had several old and new ring shake cracks; maybe it wasn't by the book, but I installed three through bolted braces spaced along around 15 ft. of trunk (at different angles) there as well. This was a 120 ft. tree that had been topped, was huge (4 ft. dbh) and next to a golf course club-house. We first thinned and dead-wooded the crown, and shortened some limbs over the roof.
For braces in all big trees, I use 7/8 galvanized threaded rod and galvanized nuts and washers, and round off the thread on the stub of the rod; I sometimes have stacked two washers and two nuts on each end as well. Bomber is better in my book. After burning up lots of saw-saw blades, I bought a very expensive (and heavy!) EHS cable by-pass snipper with 3 ft. handles as well as grinder to cut the rod.
For cabling, I solely use 3/8 EHS cable, dead end grips, thimbles, and either eyed through bolts or sections of rod, also through bolted and with Amon eye nuts for anchors. I have yet to use a lag for an anchor.
I DO NOT cable and brace trees with significant decay anywhere near where I am drilling -- I believe that this is asking for trouble.
It is about time I go back and inspect all my jobs; whether or not that was in the original contract, I believe that an inspection behooves the arborist -- if the tree fails AFTER you "improved it", look out. :help:
How many of you have seen "systems" made up of soft cable bent directly around an eye, instead of at least going through a thimble? I have some samples of "cabling" in a black locust that failed two different ways in the same tree: at one point, the lag pulled out -- a loop of cable was present hanging in the air, and there was a hole in the trunk where the lag had been; in another spot, the cable had worn through and broken (and almost broke at the the end -- no thimble). :bang:
I got a call on that tree because it was making "weird noises" ---two large trunks were rubbing and creaking across an active basal crack in a slight breeze; the driveway, car, and home as the targets! :msp_ohmy: I went home, and came back and climbed up and installed truck strap tie-downs and chains at three levels along the two trunks as it was getting dark, and referred the take-down to a guy with a lift truck the next day. The guy just undid my rigging as he chunked the tree down.
The crack looked fresh, but the cabling looked like it had failed some time earlier, which made the situation even more spooky :msp_scared:. There had not been a storm, and it was mid-summer; had the extra growth since the cable failure (there were two) and summer winds done it, had the decay been a factor, or what? The home=owners didn't even know tat the tree had been cabled or was in active failure, just "making weird noises". Ever hear Click and Clack on the radio? She made the noises for me on the phone :msp_tongue:
I did not attempt to install a cable and brace system on the tree because there was decay in the butt as well as the active failure, and I had not done many installations up to that point. Possibly the tree could have been saved (three trunks, 18 in. to 24 in. each, and around 90 ft. tall), but it sure made a big pile of nice firewood!