Bottom Cushion Base

How to make the bottom cushion base for an office chair.

  1. Step 1: Sketch And Extrude

    To begin the model, we first need to sketch the overall shape of the final object. The picture above is done by creating a rectangle and then sketching an arc in the middle.

    After the sketch is done, we can extrude it according to the desired thickness.

  2. Step 2: Creating The Bolt Hole

    After extrusion, the next step would be to mark the holes for the bolt that holds the piece to the bottom seat, when that's done, we can then use the hole function to create it, or alternatively we can use the extrude function to cut out the hole.

  3. Step 3: Creating The Center Part

    The third step is to create the center part, to do this, we first create a sketch of a rectangle on top of the first extrusion as shown in the figure above.

    After the initial sketch, we can then extrude it with the height of 10 mm.

    Next, we can extrude one side of the base with an additional 10 mm.

  4. Step 4: Creating The Mount

    We begin this step by sketching a circle on top of the extrusion with a diameter of 60 mm, this part will be for mounting the vertical stand.

    After the sketch, extrude it by 10 mm.

    And then, sketch another circle with a diameter of 35 mm, and extrude that too.

    Finally, we can create a hole with a diameter of 30 mm and the depth equal to the previous extrusion.

  5. Step 5: Creating The Adjustor

    Step 5, is to create the adjustor for the seat. This is done by first sketching a circle on the other side of the center part with a diameter of 49 mm as shown in the figure above.

    As usual we then extrude the sketch, but this time, we extrude to both direction (up and down) with 40 mm upwards and 10 mm downwards.

    The next step is to thread the extrusion using the Thread function.

    For the thread, I use these settings.

    After the thread is done, we can then proceed into making the top portion of the adjustor. This is done by sketching another circle with a diameter slightly larger than the thread (In my case the diameter will be 51 mm), and then extruding that with a height of about 30 mm.

    To create the shape that we want, I used the chamfer function to create the angle, and then using the fillet function to smooth the top edge.

  6. Step 6: Adding Fillets

    To make the cushion base better, we can add fillets to the edges to make it smoother and to make sure that the edges are not sharp.

    And after that the bottom cushion base is finished.