I aim to build a system of a steel flat bar rotating around a pivot point with the help of a couple of dc motors mounted on the edges of the bar. After doing some search I decided to build it using a steel punched bar, a steel axle hollow shaft as the rotational axis and a couple of rotating gears to mount a potentiometer in order to take measurements. My issue is how to connect the flat bar with the hollow shaft in order to enable the bar to rotate around this point. What component should I consider ? I suppose that the hollow shaft should go through this component and then this component should be connected to the flat bar using some screws perhaps.

  • $\begingroup$ You asked for ideas not a list of skills or tools. $\endgroup$
    – Solar Mike
    Commented Nov 23, 2020 at 6:01
  • $\begingroup$ I know. Why are you telling that ? I didn’t ask a list of tools or skills from anyone. $\endgroup$ Commented Nov 23, 2020 at 11:10
  • $\begingroup$ Since you didn’t get the simple instructions given in the answer, I was eliciting your skill level - seems clear enough now. $\endgroup$
    – Solar Mike
    Commented Nov 23, 2020 at 11:23
  • 1
    $\begingroup$ a shaft going through [Component X] and [Component X] mounted with screws -> [Component X] may be described as a bearing block $\endgroup$
    – Abel
    Commented Nov 24, 2020 at 0:15
  • $\begingroup$ @Abel this is maybe what I was looking for. Thanks! $\endgroup$ Commented Nov 24, 2020 at 1:45

1 Answer 1


If you have an old bicycle take the crank pedal assembly out and used it. I would even keep the whole shaft and bearing and sprocket. just torch cut the part from the frame and grind it smooth.

Otherwise, one trip to the junkyard will reveal many potential candidates.

  • $\begingroup$ “just cut torch the part from the frame and grind it smooth”. I didn’t quite get it. This is gonna be my first assembly so I kinda need a bit of more advice, if you could ! $\endgroup$ Commented Nov 22, 2020 at 23:51
  • $\begingroup$ I meant if you don't have a Sawsall or even a hacksaw you can cut it off the frame with a small propane torch. you will have to cut off the lower center part of the bike frame. $\endgroup$
    – kamran
    Commented Nov 23, 2020 at 0:50

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