Wood Base (v2) for Bowflex 552 Dumbbells

This is a simple plywood base for a pair of Bowflex SelectTech 552 dumbbells. The cradles are strapped onto the plywood. The main purpose of this is to keep the cradle from lifting up with the dumbbell when it is set to the 52.5 lb (max) setting. That happens because the empty cradle is quite light, and even with the dial set properly, the notched ring can catch on the hook in the cradle enough to lift it up. This is described and demonstrated in my YouTube video: Why Bowflex Dumbbells Get "Stuck". The added weight of the plywood and the other cradle prevent this problem from occurring. A secondary benefit is that it keeps the two cradles nicely aligned with each other, and they stay in one place on the floor.

This version (v2) is much simpler to build than the first version (v1), which uses screws to fasten the cradles to the plywood. That version may void the warranty and is susceptible to damaging the cradles in certain cases. The only advantages of v1 are that it is cleaner looking and a bit less expensive to build without the straps.

Materials

• 3/4" (or 23/32") plywood large enough to cut a 15" x 16" piece

e.g. :

Home Depot: Handprint 300950

Lowes: Model 199340

• 2" mending plates (2 needed)

e.g.:

Home Depot: Everbilt 15299

Lowes: Reliabilt 22519ZCXLG 

• #10, 1-1/4" wood screws (4 needed)

e.g.:

Home Depot: Everbilt 807521

Lowes: Hillman 35062

• 48" long x 3/4" wide lashing straps (2 needed)

e.g.

Amazon: 48-inch lashing straps 

• Screw-in rubber feet (4 needed for hard floor usage only)

e.g.:

Home Depot: Everbilt 49072

• Spray paint or brush paint (optional)

Tools

• Carpenter's square
• Pencil
• Saw:
• Table saw (preferred), or
• Circular saw, or
• Hand saw
• Drill and 1/8" drill bit
• Phillips screwdriver (or bit)
• Sandpaper or finishing sander

NOTE: the plywood is nearly square, but not quite. From front to back (in line with the cradles), it is 15". From side to side, it is 16".

• Mark a 15" long x 16" wide rectangle on the plywood using the carpenter's square
• Use a table saw, circular saw, or hand saw to cut the 15" x 16" piece

• Make marks 2" on both sides of each corner
• Mark each corner with a diagonal line connecting the two points
• Cut the corners as marked
• Use sandpaper or a finishing sander to sand the cut corners (and the other sides, if necessary)

NOTE: If you want to paint the mending plates, you can defer this step until after the next

• Use spray paint or brush paint to paint the top and sides of the plywood. I used flat black. The cut corner pieces can be used to raise the plywood so you can get good coverage on the sides
• No need to paint the bottom

The 2" mending plates hold the straps down between the cradles so that each cradle is held down on both sides. A "footman loop" would be more elegant, but they are more expensive, harder to find, and they don't show anyway.

• Use the square to measure and mark a line down the middle (between the position of the two cradles). It should be 8" from each side. The line only needs to be about 7" long in the middle of the board.
• Mark the center point on the line (7-1/2" from the front or back)
• Make marks on the line 7/8" and 2-7/8" from the center point in both directions (4 marks total)
• Place the mending plates on the line between the two pairs of marks and check that the distance between the centers of the plates is 3-3/4"
• Mark the screw holes through the mending plates
• Use the 1/8" drill bit and drill 4 pilot holes for the #10 1-1/4" screws
• Drive the screws in through the mending plates until just before they would poke through the other side of the plywood (top of head just over 1/2" above plywood)
• (Optional) Paint the mending plates and screws

For carpeted floors, do not install the feet; they will just put divots in your carpet. For hard floor usage:

• Flip the plywood over
• Mark the positions of the four feet (your choice of how close to the corners)
• Drill a pilot hole for each (1/8" for the suggested feet)
• Screw the feet on

• Thread the straps under the mending plates and then under the base
• Insert the ends into the buckles, but just pull a little bit through
• Insert the cradles under the straps
• Lightly tighten the straps
• Align the straps
• Fully tighten the straps
• (Optional) Use a paperclip (preferably black) to hold the strap ends down