Above is the Standard 'GL' with 5-1/4" throw into tree (heavy thread left end), 6" pirch for attachments (right end finer thread). Available on Parts & Plans page.
The way I remember it- It all started with the first World Treehouse Conference in 1997. Peter Nelson got together with myself, Michael Garnier, and convinced me to put on a Treehouse conference. The purpose of which was to study, share and promote safe and better Treehouse building. In October 1997 at the first World Treehouse Conference we (the main participants were myself, my Engineer Charley Greenwood and arborist Jonathan Fairoaks) tested all kinds of tree fasteners and found them all to be wanting in one manner or another. Metal brackets bolted to the tree held the most weight. My first treehouses were built by lag bolting metal brackets to the trees then bolting the beams to the metal. This in my view by itself was an advance in Treehouse technology over just nailing or bolting a beam directly to the tree.
(of early prototypes, these were disappointing) (discontinued powder coated GL, hole & bit illustrated)
(illustrated need for a better fastener over time, flat bracket & lag bolts is not good for the tree or the metal)
I built my first Treehouse in 1990 to last 20 years and it has passed that 20 this May, 2010. The tree naturally reacted to the new load and grew extra wood below the bracket (bolster blocked it). The beam has fared well because there was no wood to wood contact for the first 18 years (no place for moisture and bugs to hide out). The problem with this method is that each year this bracket eventually becomes more intrusive to the tree. Trees grow a new ring of wood every year. The bolted metal brackets do not allow this. This helps the Treehouse by bolster blocking, but ends up hurting the tree by not allowing the bark and cambium to expand. J-lag hooks and straight lags did not even hold their recommended working load limits.
After the discouraging results were in from the testing we did, the idea of simulating the design in a limb of a tree was entertained. I thought this was a great idea being that trees hold massive loads out away from their trunks on the branches. The search for a better Treehouse fastener was on.
Later that year I met and befriended Scott Baker, a consulting arborist. It was his opinion, and it became mine, that it would be best to allow the tree more room to grow. This meant that the attachment point needed to be larger and or stronger to account for leverage. It is also our opinion that it is better to make one larger clean wound than numerous smaller ones.
(all these were all disappointing as well, but we learned a lot)
There were three basic designs presented at the 1998 World Treehouse Conference, Fairoaks (who did a lot of cabling of treehouses) brought a 12'' long 2'' diameter stainless steel mammoth with a channel on the end for a cable, Garnier had collared bolts and Greenwood's inserted pipe (picture of pipe prototype in the above built by Garnier, not Greenwood).
The Fairoaks’ Limb won hands down and was so massive that at 10,000 pounds test weight, it started lifting the tree out of the ground. The problem with it was the difficulty of actually putting it in the tree, its size and therefore impact on the tree.
Greenwood’s design proved disappointing to say the least. Theoretically it had enough diameter of 1 ½", and depth at 2-3" to allow enough surface area for weight bearing.
I brought my 1 ½” bolt with a collar welded onto 1 ¼" and 1 ½” (grade 2) machine bolts by my welder Kevin Coopee (pic above). The 1 ½” bolt held 3000 pounds applying the force at the 2” away from the tree mark. The 1 ¼” bolt with the a 2 ½” collar welded on held 6500 pounds tested at the same mark. From these results and consulting with others in the Treehouse community, I decided to increase the grade of the bolt and diameter of the collar to 3”.
I worked out the first schematics on this new design with a machinist by the name of Michael Birmingham. The first batch of product I originally called artificial limbs was produced in Medford, Oregon in December of 1998. The first test of these units showed that they held up to 8000 pounds.
An added benefit to the new GL’s superior weight bearing capacity, it proves to be far less intrusive to the tree overtime.
(showing tree adapting over time, this installation is over 15 yrs. old, early versions have been finer tuned, older install shows purchase into tree.)
In 2002 Greenwood developed the first HL or heavy limb. Greenwood and others have continued to make modifications to the Original Garnier Limb®. I never tried to patent the Garnier Limb® and welcome all and any improvements, and certainly thank all that I asked and received help from, paid for or not. The one thing that I ask is that you do not sell a Garnier Limb® . I developed (invented) the artificial limb known as Garnier Limb®. I spent a lot of time and money on developing the original. I continue to develop better ways to produce and implement the product. I don’t mind open sourcing, but do not expect me to give away my registered trade mark rights or trade secrets. There are a few other sources where you can pay more now, but get less quality than you will with the original improved Garnier Limb® I produce.
To the very best of my extensive knowledge, I was the sole developer and manufacturer until 2002. In late 1999 Jake Jacob started calling my Artificial Limb a 'Garnier Limb' or 'GL' and it stuck.