Connecting Shafts of 2 Very Different Diameters

  • Thread starter Thread starter Steven123456789
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around connecting a motor shaft with a diameter of 4 mm to a steel rod with a diameter of 30 mm. Participants explore various methods for achieving this connection, considering factors such as torque, RPM, and the mechanical setup involved.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant suggests using a machine shop or belt and pulleys for the connection, mentioning the possibility of using bead chain for low torque applications.
  • Another participant expresses concern about the size mismatch and requests more details about the machinery involved.
  • Several questions are raised regarding the support and balance of the 30 mm bar, the maximum operating RPM, and the mounting of the motor.
  • A participant proposes spring-mounting the motor with a rubber wheel against a friction band on the cylinder as a low torque solution.
  • Another suggestion includes machining the end of the bar to a compatible size and using a universal or flexible joint to connect the motor shaft.
  • There is a mention of a method involving a center-tapped bar and a compatible part-threaded bolt for connecting to the motor shaft.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method for connecting the shafts, and multiple competing views and approaches are presented throughout the discussion.

Contextual Notes

Participants highlight the importance of understanding the torque provided by the motor and the specific application of the 30 mm bar, indicating that these factors may influence the choice of coupling method.

Steven123456789
Messages
2
Reaction score
0
I want to ask, if I want to connect a shaft from a motor that only has a diameter of 4 mm to a steel rod with a diameter of 30 mm, what should I do so that the motor can rotate the steel rod?
 
Engineering news on Phys.org
Either a machine shop or belt and pulleys. :wink:
(I suppose if you need very low torque you could use bead chain instead of a belt, but the appropriate pulleys are somewhat scarce.)
 
Steven123456789 said:
a motor that only has a diameter of 4 mm to a steel rod with a diameter of 30 mm
What that enormous size mismatch is telling me, is that likely there are other under- or overdesigns there somewhere. Could you please share more about that ... machinery?
 
Welcome to PF.

How you couple the shafts will depend on how the 30 mm diameter bar is supported, on a frame by one or more bearings, of what type?

Is it balanced?
What is the maximum operating rpm of the motor and bar?

How is the motor mounted to the frame?
Can it self-align with the 30 mm bar?
Or must the coupling be flexible?

How much torque will the motor be providing?
Or what is the 30 mm bar being used for?
 
Baluncore said:
Welcome to PF.

How you couple the shafts will depend on how the 30 mm diameter bar is supported, on a frame by one or more bearings, of what type?

Is it balanced?
What is the maximum operating rpm of the motor and bar?

How is the motor mounted to the frame?
Can it self-align with the 30 mm bar?
Or must the coupling be flexible?

How much torque will the motor be providing?
Or what is the 30 mm bar being used for?
2 bearings, ID 30 mm x OD 37 mm x width 4 mm
Torque the motor providing - 0.4 N cm
the 30 mm bar will be used to rotate the mechanism
 
What is the maximum RPM?
 
If low torque, classic trick is to spring-mount motor with small rubber wheel directly against friction band on cylinder. Like electric-assist bikes did before hub motors....

Plan_B is to machine end of bar down to compatible size, connect motor shaft via 'universal' or flexible joint.

If only needs to rotate in one direction, perhaps centre-tap bar, saw the head off compatible part-threaded bolt and connect that to motor shaft via 'universal' or flexible joint.
 

Similar threads

Ideas welcome on how to attach 2 shafts of different diameters
  • · Replies 17 ·
Replies
17
Views
4K
How to spec a motor for this floor testing system?
  • · Replies 10 ·
Replies
10
Views
2K
Coupling to the shaft of an electric motor (different size shafts)
  • · Replies 1 ·
Replies
1
Views
1K
Can an axle connected to a wheel transmit momentum to the plate to which it is attached?
  • · Replies 11 ·
Replies
11
Views
2K
How Do You Calculate Deflection and Shear Stress in a Tapered Shaft?
  • · Replies 2 ·
Replies
2
Views
3K
How to Measure Torque Required for motor to spin a rotating shaft?
  • · Replies 3 ·
Replies
3
Views
5K
How to couple/connect a shaft to a disk?
  • · Replies 4 ·
Replies
4
Views
3K
Using a motor to spin two discs in opposite directions
  • · Replies 6 ·
Replies
6
Views
2K
Help with Torque and Motor size gearbox requirements
  • · Replies 19 ·
Replies
19
Views
4K
Design a shaft considering torsional failure
  • · Replies 5 ·
Replies
5
Views
3K