Step 2: Arm Fabrication - Chamberlain LiftMaster Professional BG770 Installation And Maintenance Manual

12
Installation
Arm Fabrication
Step 2:
MODEL BG770 (SINGLE ARM)
If you are making the arm yourself, refer to Figure 5 and its suggestions for the single arm
design.
1 Drill four 1/2" diameter holes using the arm clamp as a template. Tapering the wood as
shown helps reduce the weight and allows you to reduce any warping common with long
lengths of lumber.
2 Finish arm with exterior grade paint and stripe with paint or adhesive backed tape as
required.
MODEL BG790 (WISHBONE ARM)
A twenty-four foot wishbone arm is supplied as standard with every BG790 gate. If a shorter arm
is desired the extension may be shortened. See Figure 6. The maximum arm extension is 8 feet
for a total arm length of 24 feet.
1 Cut to desired length.
2 Finish with an exterior grade paint and stripe with paint or adhesive backed tape as
required.
Doc 01-G0674
Rev D
Length as Needed
up to 12 feet
Material:
6: x 1" Pine or Redwood
5-12"
Figure 5
Material:
4: x 1" Pine or Redwood
Figure 6
3"
01-G0674F7
Up to 8 feet
Arm
Extension
01-G0674F8