This is the third part of eight in this series. Visit the main article here.
PART 3: ADDING a SWIVEL BASE
This cylindrical swivel allows you to keep your mast’s base in place while raising/lowering. It consists of a 2-7/8″ OD metal cylinder attached to a 8″ piece of 4×4 placed at the mast’s base. A right angle metal bracket connects the 8″ piece to the main 4×4. Lowe’s has a good one made by Simpson Strong-Tie, 2x2x3. It comes with 1/4″ holes. I drilled the 1/4″ holes out to 5/16″ and mounted with 5/16″ lag bolts. The Swivel Kit comes with two pre-drilled metal 2×4″ straps and all hardware. See Figure 5.
Step 1. If your winch-it-up mast support is not vertically in place, set it up vertically and attach guys, anchors, rebars (if used), etc. Make sure it’s as vertical as possible.
Step 2. I attached the 8″ piece of 4×4 at the base after the mast was standing at its’ location. It mounts/lays lengthwise and is perpendicular to the main 4×4 support. I used the right angle bracket here with lag bolts. The 8″ piece can be laying directly on the ground, but you might want some scrap material under it for more protection/rigidity. You have flexibility here as long as the swivel and its’ base are secure. See Figure 5.
Step 3. Aligning the Swivel for a vertically square mast. Have a level handy in your pocket. With your mast’s lower and top sections exposed and sitting on the ground without antenna and G-450A (if used) attached, hand raise the mast vertically so you can loosely connect it to the lower standoff. While holding it against the lower standoff, with your other hand place the mast’s base on the 8″ 4×4, adjust it so it is vertically square and tighten the lower standoff. Take your magic marker and mark on the 8″ piece with a circle where the mast sits on it. Now you will be as close to vertical as is reasonably possible. The top section plays no part in this alignment. Note: If you have a straight odd metal pipe that’s easier to use than the mast, for this operation, use it.
Step 4. Placing your Swivel on its’ 8″ base. See Figure 5.
Your swivel has two pre-drilled 4″x2″ straps. Attach the single hole end of the two straps to the cylinder with the provided spacers or washers equally divided between the outer cylinder walls and the straps and then tighten using the 4-1/2″ bolt and nut. Don’t mix up the 4×2 straps. They’re marked A and B. Keep them in the same position all the time as they may not be exact copies of each other. Line up the brackets so the 2-7/8″ cylinder is centered on the circle you marked earlier. Mark and Drill two holes in the sides of the 4x4x8″ and attach with 5/16×1-1/2″ lag bolts. Make sure you have allowed an inch plus clearance from the bottom of the cylinder (when upright) to the top of the 8″ 4×4. I used a 7/32″ drill bit for 5/16″ lag bolt holes though a 3/16″ bit will work fine. Tighten the 4-1/2″ bolt so it has some resistance so you can change the cylinder’s angle as needed, but it stays in place.
Return to Part 2: Instructions to build my 4×4 pressure treated (PT) strap winch-it-up mast support.
Continue to Part 4: Preparing the Mast Support & Mast for Initial Raising.