Steel Sphere Which Is Easy to Make With the Help of Some Cement

I saw photos of spheres made out of scrap metal on the internet, but for quite some time I had no idea how I could make one myself.
I needed something in the shape of a sphere to hold all the steel parts in place while I would weld all pieces together. The material had to be strong and it should not melt or burn during welding. Fortunately, cement can do that.

Supplies

Cement - just a small amount
Old towel
Large ball
Scrap metal - at least 150 pieces of 2x2 inch

Step 1: Prepare the Ball

I wanted to make a kind of bowl out of cement, so I could use it to support all my metal pieces during welding.
To get the correct shape, I used a large ball. I wrapped it in some plastic so the cement would not get the ball dirty. Then I used scissors to cut an old towel and get approximately the shape of a circle.

Step 2: Prepare the Cement

I used Portland cement, which is not yet mixed so I had to add sand and mix it. The amounts shown on the photo are the actual amounts that I used. The amount of sand is roughly twice as much as the amount of cement. I added the water from the bottle and mixed cement, sand and water in the bucket. The mixture should be quite wet.

Step 3: Soak the Towel and Place It on the Ball

I put the round piece of towel in the bucket with cement and made sure the towel was completely soaked with cement. Then I placed the towel on the ball so it can take the shape of the ball while it cures.

Step 4: Let the Cement Dry

Portland cement takes quite long to cure. I let it sit on the ball for three days and then I carefully placed the ball upside down so the cement was at the bottom side and I removed the ball. That was easy because the plastic did not stick the the ball. Then I also removed the plastic and let the cement dry further for another 5 days.

If I would have used a quick drying type of cement, this step would have been faster but I was not in a hurry and since I only had the Portland cement I used that.

Step 5: Cut the Steel

I used 3 meters (9 feet) of square tube of 5x5 cm (2x2 inch) and marked it at increments of 2 cm. Then I used an angle grinder to cut the tube into 150 pieces. It took 9 cutting disks to make all these cuts.

Step 6: Cleaning Up

After cutting I had to clean the area from all the debris that was formed during cutting. Then I used a file to clean the inside of each of the 150 steel squares.

Step 7: Prepare for Welding

The cement had cured but it felt a bit brittle, so I made a pile of sand with a dent in the middle and placed the concrete on top. Then I placed the first few steel squares in the concrete bowl. The ground clamp of the welding machine was attached to a loose square part which works well to get a good ground during welding without hindering me.

Step 8: Start Welding

I welded the squares at the point where they touched each other, then added a few more squares, welded them and continued adding squares. When the metal started to become larger than the concrete bowl, I rotated the metal so I always had the support of the concrete for the loose pieces during welding.

Step 9: Continue Welding

I continued to add more and more squares to the sphere until I had used all. I could have cut some more squares to get an entire sphere, but I decided that it is no problem that the sphere has an opening at the bottom side.

Step 10: Check the Concrete

The concrete now has some brown areas which is dirt from the welding. The concrete also has cracked a bit but it still had the right shape and could theoretically be used once more.

Step 11: Enjoy the Result

I experimented a bit with how to place the sphere and took some photos during different moments of the day. I like it best with the open side facing downwards.

Since I did not paint the steel it will turn brown from corrosion very soon, but I like that.