Making a Sinking Foundation is fairly straight forward.
Please make sure you wear appropriate safety gear while working with cement/concrete!
Materials
- 4 pcs 4" Nipples (1" Diameter Black Pipe)
- 2 pcs 6" Nipples (1" Diameter Black Pipe)
- 1 pc 10" Nipple (1" Diameter Black Pipe)
- 3 T Connectors (1" Diameter Black Pipe)
- 4 bags 50lb Ready Mix Concrete
- 1 pc End of a barrel with a 10" skirt.
- 1 pc 2x4, about 18" long (to be cut into 4 1/2" lengths)
- Gorilla Tape
- 20ft roll of 1/4" x 1" self-adhesive foam weather stripping
Tools
- Water, Shovel, Mixing Bucket etc
- Respirator, Gloves, Eye Protection, other safety gear.
- Spirit Level
- Pipe/Monkey Wrench
- Chop Saw
Preparation.
Cut the skirt on a barrel to 10 inches and place it on the floor with the open side up. You can also use the mid-section of a barrel and screw a 3/4" plywood circle into the bottom. In the photos here, I used a plywood base.
Make an H-frame with a vertical post, using the 1" diameter black pipe. This could be welded together, but its a lot easier to just use nipples and T fittings. Make sure you crank the nipples into the fittings using a pipe wrench.
Screw four 4" nipples into the opposing ends of two T-connectors. Now screw two 6" nipples into the T's on those assembled pieces. The other end of the 6" nipples are screwed into the opposing ends of a third T connector. This should give you a frame that looks like an "H". Make sure everything is tight - use a monkey wrench and bench vise. Check that it lays flat on the floor.
Screw a 10" nipple into the central T connector, and check that it is truly vertical when the H-Frame is on the floor.
CHECK THIS WITH A LEVEL, don't just eyeball it. And check it on more than just one face!
Note - this photo shows the H Frame already mounted in the drum.
Mounting the H Frame
Cut a 2x4 or 2x2 into four blocks 4 1/2" long. The exact measurement is not critical, but THEY NEED TO BE THE SAME LENGTH.
Place these on the surface of the barrel so that the 4 1/2" dimension runs vertically. Screw them in place from the undersite. They're acting as spacers to keep the H frame positioned half way up the skirt of the barrel. Place the legs of the H frame onto these.
Tape or screw everything in place so that the vertical post is exactly centered in the middle of the barrel. Measure this very carefully, and double check that the post is indeed vertical. Use fender washers or something similar as shims on the legs of the H Frame to adjust it as needed.
Mixing and Pouring the Concrete
WEAR A REAL RESPIRATOR with fresh filters during this next step. A simple cloth or surgical mask is not going to do the job. Work outside. Cement dust is not heathy.
Mix up a 50lb bag of concrete with some water in a bucket. You'll need about a gallon of water per bag. Slowly add the water to the mixture rather than adding the mixture to the water. Keep churning it up with a shovel until there are no more dry spots. You're trying to make a mixture that has the consistency of heavy mud.
Pour this into the drum, spread it evenly, and then repeat with another bag. I used 3 1/2 bags to make this foundation. The drum I used had a diameter of 24 1/2", so if youre using a standard sized drum you'll probably only need 3 bags. Buy 4 and take one back, this is not an operation that you can pause mid way through to go and buy an extra bag,
When the drum starts to fill up to the brim, add the concrete mix slowly.
Use a piece of wood to pat it down and smooth off the top. Only the top 6" or so of the 10" nipple should stand up above the cement. Make sure the top of the cement is really level and leave it to dry for a couple of days.
Sealing and Preparing
Once the concrete has set up, cover the exposed surface with 3 or 4 layers of Gorilla Tape. The idea is to seal this up so that any cement dust cannot escape into the air while you're hammering. Run a few layers around the rim of the barrel to lock it down.
I find it useful to use the extra wide tape. I also run the different layers at different angles to cross-hatch it.
Finally, on top of the Gorilla Tape, stick down a roll of 1/4" x 1" foam weather stripping. This is to make a squishy surface that the Lazy Susan will mate to and settle on.
Basically you can cover 75% or more of the Gorilla Tape with the weather stripping. Make sure you go all the way out to the edge with the weather stripping. The pattern you use is not critical, you can make a giant spiral starting at the edge and going inwards if it helps your OCD 🙂
Final Thoughts....
You may look at this and think it's overly complicated, especially the H frame. You're probably right. It may be perfectly possible to just stick a single vertical post into a drum full of concrete. If you try it and it works, please let me know!