I have this assembly of a cylinder and a block, where the cylinder can rotate inside the block. enter image description here

How can I connect the cylinder and the block in a way that is detachable, so that while the connection is close, the cylinder can not be moved, and while it is open, it can be moved? The cylinder is supposed to be able to be set in every rotary position.

One suggestion that I had was to connect them using a screw, as shown in the picture. enter image description here

However, in this way, the area where they make contact is very small, so I thought maybe there was a better solution? Are there maybe any ressources where you can read about problems like this?

Thanks for any replies and ideas!

  • 1
    $\begingroup$ Have a look at machining indexers used for setting and holding parts. $\endgroup$
    – Solar Mike
    Jul 31, 2022 at 12:49
  • 2
    $\begingroup$ The suggestion you've drawn out is actually fairly common. If you want to prevent the piece from being able to turn while mounted, make a small part of the cylinder flat. $\endgroup$
    – Mast
    Jul 31, 2022 at 17:28
  • 1
    $\begingroup$ The small contact area won't be an issue for holding force - people use set screws for massive loads. It might be an issue if you're worried about damaging the shaft material. $\endgroup$
    – Emily Conn
    Aug 1, 2022 at 14:33

1 Answer 1


enter image description here

Figure 1. A slot and clamp screw provide an even clamping friction around the surface of the mating surfaces and doesn't leave grub-screw marks.

enter image description here

If forced to use a grub screw then a groove can be cut in the cylinder to allow the grub screw to bite on an area that isn't a mating surface between the block and cylinder. This will prevent problems with burrs binding on the mating surfaces.


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