Garnier Limb Installation




Garnier Limb® Treehouse Attachment Bolt Installation Instructions
by Michael Garnier
drill hole illustration
Illustration is of finished bolt ready hole with 3 stage bit and discontinued powder coated GL.
For a downloadable document copy of text: click here (you may have to right click and 'save file')

Directions for 1 Step 3 Stage GL Drill Bit:

Ensure drill is level or beam will not sit nicely on the GL (some drills have a small bubble level, otherwise sit a short level on top of the drill while starting to drill). It is best to aim for the center of the tree whenever possible (having a second person to sight from the ground is useful). The 1” auger bit should drill fairly smoothly until you hit the toothed inner bit. The toothed inner bit clogs easily, which will require pulling back and clearing several times per GL (the tip of a screw works well, clean just so that the teeth are exposed, completely clearing the bit causes it to clog faster). The 3” Milwaukee bit often has trouble with the thick, stringy bark of some softwoods; it tends to grind rather than cut. The best technique is applying multiple shoves on the drill, rather than steady pressure, to get through the bark. Again, you will have to pullout several times per GL to let the 3” Milwaukee bit clear (when you feel the drill bog down). Keep drilling until the 3” Milwaukee bit cuts through the cambium layer into the sapwood. This ensures that you get maximum bearing capacity from the inside surface of the 3” boss. The further into the tree you go past the cambium, up to 1” for a 1” thick boss the greater you increase the bearing capacity of the outside circumference of the 3” boss. This will decrease the amount of room you leave for growth. Once to depth, pull the drill out while running it forward to clear all chips from the hole (reversing out leaves all chips in the hole). Measure depth of 3’’ cut so you can tell when the 3’’ boss on the GL is close to seating.

If drilling in really hard wood you may need to drill the 1” hole first with a ship’s auger. The 1 step has 3 different size holes it drills all at once as it get to the end.

Directions for 2 Step 2 Stage GL Drill Bit:

This bit you need to drill the 1” hole with a separate 1” ship’s auger, some models use an auger to guide the 3” Milwaukee but are not strong enough to cut the 1” hole while being used as a guide.

Be sure to drill the 1” hole deep enough. At least 6”. The rest of the drilling instructions generally apply. This bit set does not have the 3rd stage which is a 1 1/8” counter bore that allows the treads to start easier and gives more room for the portion of the GL that does not have threads. In soft wood use a pocket knife to wallow out the end of the 1” hole to help the treads start. The wood should be able to compress enough to allow the larger diameter part of the GL to seat. In harder woods you need to wallow out the hole more or use a 3rd stage bit.

Directions for Installing GL:

GL should be clean before installation to reduce chance of infection. Screw GL as far as possible by hand (ensuring it’s going in straight). Use a large pipe wrench (at least 24” handle) on the shank of the GL just past the collar. It’s easiest to tie a rope to the end of the pipe wrench handle and have someone on the ground pull down while the person in the tree resets the wrench. You can tell when the GL is in all the way because it will become very hard to keep turning and the GL will squeak loudly with each turn. Do not over-tighten. When mounting bracket on beam, make sure it is as close to the tree as is possible while still supporting the beam. The beam should be 2’’ from the boss to allow for growth.
The wrench is not on the recommended side of the collar for finish tightening in this shot, but it cab help just getting it started in the hole.

Independant GL installation article by John Carberry: click here