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This is a capstan for a stringbender for an acoustic guitar. When actuated, the String Wheel turns about 15-18 degrees. It does NOT spin, but simply turns, then is pulled back to "zero" when released.

My problem is that when I tighten the nut (bottom) the entire shaft binds and sticks. I assume that the 2 washers in the center are the problem, but am not sure how else to assemble it. Without those washers, the entire bearing rubs against the surface of the Housing and sticks. The small washers are the diameter of the bearing's center shaft, and so I thought they would release it from sticking to the Housing.

It's a simple setup (I want to keep it that way), but I would like to be able to tighten the shaft properly. I've attached sketches of the parts, and a photo of a finished piece on a guitar. Thanks.

--john

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  • $\begingroup$ When you loosen the nut just a little, does the wheel spin freely? In between the two bearings should be a tube, not two washers. This is adding friction. $\endgroup$
    – GisMofx
    Commented May 2, 2022 at 2:05
  • $\begingroup$ either don't tighten as much or find a new method of assembly $\endgroup$
    – Tiger Guy
    Commented May 2, 2022 at 4:25

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You need a collar around the shaft in the middle hole of the housing.

At the moment you are clamping the rotating assembly to the housing between the two middle washers. Fit a collar so the washers are held clear of the housing at that point.

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  • $\begingroup$ Solar Mike: Thanks for that. The shaft is M5. I could enlarge the hole in the housing and insert a collar or bushing that would accept the M5 and push the two washers away from the housing just slightly. I assume that's what you mean. I appreciate it. Thanks again. ---john $\endgroup$
    – jegenes
    Commented May 2, 2022 at 5:34
  • $\begingroup$ @jegenes you may have the same issue with the top plate… $\endgroup$
    – Solar Mike
    Commented May 2, 2022 at 5:35
  • $\begingroup$ the drawing is incorrect. Actually, the bearing doesn't touch the top part. The opening is larger than the bearing (not shown) $\endgroup$
    – jegenes
    Commented May 2, 2022 at 14:13
  • $\begingroup$ @jegenes well, any analysis is difficult if the drawing is incorrect. $\endgroup$
    – Solar Mike
    Commented May 2, 2022 at 14:15
  • $\begingroup$ yes... sorry. just did a very quick drawing. The bearings are actually about the same diameter as the string wheel. I screwed up and drew the string wheel too small in the picture. As you can see in the photo, the top plate's opening allows for free movement of the string wheel and the top bearing beneath it. $\endgroup$
    – jegenes
    Commented May 2, 2022 at 15:01

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