Longitudinally locked rotating cylinders

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Discussion Overview

The discussion revolves around the design of two close-fitting cylinders that are longitudinally locked but capable of rotating against each other. Participants explore the feasibility of using Teflon rings, the machining of grooves, and alternative materials or designs. The context includes practical applications and constraints related to user interaction with the device.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests machining grooves in the cylinders and using a Teflon ring to secure the inner cylinder while allowing rotation.
  • Another participant requests additional information regarding the limits or constraints, such as speeds and forces, to provide a more informed response.
  • Further details are provided about the dimensions of the cylinders and the forces involved, emphasizing the need for a balance between ease of rotation and resistance to unintended movement.
  • One participant proposes using vinyl tubing as an alternative to Teflon rings for ergonomic benefits, although this suggestion is met with a rejection from the original poster.
  • A participant asks for clarification on the purpose of the device and requests a sketch to better understand the design intent.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the best approach or material for the design. Multiple competing views and suggestions remain, particularly regarding the use of Teflon versus other materials like vinyl tubing.

Contextual Notes

The discussion lacks specific details about the operational environment and potential constraints, such as the exact forces involved and the desired performance characteristics of the device.

Who May Find This Useful

Individuals interested in mechanical design, particularly those working with rotating components and seeking solutions for user interaction and material selection.

KuKu427
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I need to make two close fitting cylinders that are longitudinally locked in position but need to rotate against each other. I want to make this in as few parts as possible.

I was thinking of machining grooves in each cylinder and placing the Teflon ring in the groove of the inner cylinder and pressing the outer cylinder on.

How secure would this arrangement be?
Are there any other alternatives?
Is Teflon the ideal material for the ring?

Thanks in advance for any help.
 
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I would need more information on the overall limits or constraints, i.e. speeds, forces, etc... to begin to answer your question.
 
FredGarvin said:
I would need more information on the overall limits or constraints, i.e. speeds, forces, etc... to begin to answer your question.

The tubes are fairly small.
11.2mm ID, 12mm OD for the inner.
12.05mm ID, 13mm OD for the outer.
approximately 40mm in length for the inner, 10mm for the outer.

Force is what a person will apply to rotate the tubes with his fingers The person should be able to turn this easily, but not so easily that everyday bumps and nudges will turn it on (it's a rotating sleeve used to activate a reed switch). Longitudinal slop or play is a definite no-no.

It has to be able to resist sufficient force that the outer tube will not strip off unless someone puts some effort into it.
 
Sounds like your aim is to either insulate the user ("Teflon rings") or provide some ergonomic benefit by increasing the OD of the control...

In either case, how about using a 10mm length of vinyl tubing over the 10mm OD control?
 
tyroman said:
Sounds like your aim is to either insulate the user ("Teflon rings") or provide some ergonomic benefit by increasing the OD of the control...

In either case, how about using a 10mm length of vinyl tubing over the 10mm OD control?

No that's not what I am doing.
 
What are you doing? Do you have a simple sketch? What is the endgame for this device?

Thanks
Matt
 

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