Infinity Cube

Having purchased a 2-meter length of 10-mm steel bar and only using 6-cm of it to stop a BBQ grill from collapsing, I was on the lookout for a project to use the remaining bar during my final welding class. Creating a small cube sculpture was chosen.

2-meter length of 10 mm steel bar

Inspiration for the 'infinity cube' came from this web page. Studying the image allowed me to work out how to cut and assemble the cube.

The calculation for the bar lengths was made by working out the ratio of the lengths given in the web image and calculating steel lengths to fit from a 2-meter length of square bar.

The ratio of small to larger bars was 88.6%, it worked out to 12 x 11cm and 6 x 9.75cm could be cut from the bar. This required 19 labourous hacksaw cuts to be made.

To help cut the 18 steel bars, I made a miter box from a couple of pieces of scrap 4 by 2s. This assisted cutting the 45-degree miters. (Tip: buy a cheap mitre box to ensure better accuracy)

12 bars were cut, each 11 cm long, with a 45-degree miter at each end. This was achieved by sliding the bar along and rotating it 180 degrees after the first bar had been cut.

After cutting 12 bars, practice how they will be welded together. The plan is to weld the 12 longer ones into pairs, using a magnetic clamp to assist while a tack weld is placed on each corner. Welding them into pairs should also assist in assemble and reduce confusion in working out which bar goes where.

Six shorter (9.75 cm length) bars are cut. Notice the miter on these are at 90 degrees angle to each other. 3 one way and 3 the other. This is achieved by rotating the bar 90 degrees in the miter box.

Three hacksaw blades with different number of teeth were purchased to cut the steel bars. As I didn't know which would work best, I timed how long they took. The first time a new blade was used gave its' fastest cutting time. The 18 teeth blade was faster than the 24 or 32 teeth blade and could cut a miter in the bar in just under 3 minutes of toil.

For assemble I figured some small wedges might assist in aligning the bars, so I cut some as shown above. (As it happened, these weren't used during welding and assembly, mainly due to time pressure, but were used when painted)

The welding occurred during the final welding class and so it was assembled quickly and this showed in the quality of welding. The plan was to tack weld first and once the cube was assembled to go over and weld the diagonal cuts. A printout of the cube was nearby for assembly guidance and some notes made on the order to weld. This was of assistance when you are working 'under the pump' time wise. Six pairs of the longer piece were first tack welded 90 degrees to each other. A TIG welder was used, set to 100 amps.

To form the base of the cube, a couple of the shorter pieces were added to a longer pair. Similarly to form the top. A calk line was drawn on a square metal assembly plate to add in welding at 90 degrees and to make the base and top flat. This proved easier than using the magnets for this stage.

Sides were welded flat and then welded to the base. The angle magnets were used for support. The top was the final assembly and connected with the previously welded pieces.

After checking things were 'square enough', diagonal welds were made on the outside miter cuts and the corners fully welded. The main consideration being to complete the cube before the end of the welding class.

Using a grinder the welds were leveled out and then a flapper disk used in preparation for painting.

A couple of coats of hammered-finish spray paint were applied to give the sculpture a subtle blue sheen.