Questions about torque

[geoffthehammer]

I am trying to devise a magnetic clamp/brake based on the same principles used in magnetic dial indicator bases (and as shown in wikipedia). The magnet would be approx 30mm diameter and 18/20mm across flats by approximately 45mm long. The steel/brass/steel block will be about 40mm square by 50mm deep.
I would envisage using a ferrite magnet and need to clamp the brake shoes to the block.
Questions.
1. If the magnet is supported in (stainless steel) ball bearings, how do I calculate the torqure required to rotate the magnet in order to turn the brake on and off?
2. How do I calulate the clamping force?

Any help would be much appreciated.

 

[MagMike]

There are no simple analytic equations to answer your questions. Trial & error is a possibility, but magnetic modeling with FEA can answer both of your questions.

There are a number of standard magnetic bases available from the catalog houses. Is there some feature or functionality that you need that isn't already available?

 

[geoffthehammer]

Unfortunately the standard bases don't cover what I am trying to do. When I work out how to do it I will post a diagram. It was the feasibility of the calculating the torque I was looking for as operating the clamp will be an automatic operation. It looks as if you have answered my question though, thanks.