|
|
(Your shopping cart is empty)
What are the differences between Treehouse Attachment Bolts and Garnier Limbs?
Similar in Theory, Slight Variations in Specs.
Specs for TABs vs. GLs
Both Treehouse Attachment Bolts (TABs) and Garnier Limbs (GLs) are made from 1.25" 4140 steel rod. The wood threading is then turned onto the inner end, a 3" diameter collar is pressed onto the center, and a nut threaded onto the outer side. Predrilling a 3" hole in the tree is required, so the gamble was that the fastener would be dramatically stronger than a 1.25" lag bolt. It worked! These treehouse fasteners are a derivative of the 150 year old timber washer / lag screw design, or a "collared lag stud," and it found a new use for supporting loads in live trees in the late 1990's.
The original fastener that has now been trademarked as the garnier limb was a huge step forward in treehouse attachment methodology in its time. Treehouse "pioneer," Michael Garnier, Arborist Jonathan Fairoaks, and Engineer Charlie Greenwood all had some amount of input into the original prototype that came to be known commonly known as the garnier limb and newer/better variations that go by other names. The garnier limb was a fantastic accomplishment and a step in the right direction. The major shortcoming of the garnier limb was the weak point behind the collar. This issue was subsequently addressed by Greenwood Engineering by pushing the threading to start back 2 inches behind the collar, and creating a conical stress transition point. Greenwood further specified heat treating and other details on his well known STF (Stud Tree Fastener) diagram (he chose not to use garnier limb as the name at that time). Treehouse builder Dan Wright (Tree Top Builders) has modified the thread specs from the STF design to make them faster to install and do less damage to the wood on the way in. These are the current specs preferred by Treehouse Supplies and we sell them as Treehouse Attachment Bolts.
Most Treehouse Attachment Bolts on this website are heat treated, but not all of them are - check to see if they are marked "HP" for heat treated and powder coated. You'll notice that the small TAB 1x6 is also offered in a non-HP version which is the lower cost option for small, low weight treehouses.
To read more, check out the following articles:
|
|
