Friday, April 27, 2012

Understand the Spindle! Part IV

I seem to have made a mistake in my calculations.

A rim weighted whorl does tend to slow the copp/ spindle system after the copp has gotten large enough to act as a good whorl.  This was my basis of analysis for suggesting that whorls be removable so that they do not slow the spindle as the copp is finished.

Center weighted whorls on the other hand, can be fixed because they do not tend to slow the spindle as much.


Karen said...

The increase in moment of inertia will be the same for the same sized (mass and diameter)copp. So is it it that you build the copp differently, or that the relative increase in I is different?

Aaron said...

I looked around and everybody had rim weighted whorls, so I thought every spindle had to have rim weighted whorls as a necessary evil. OK, so I thought, take that necessary evil off as soon as it is no longer necessary.

However, I do not see center weighted whorls as a problem. They just help the spindle spin fast. If they are not a problem - I do not have to take them off, I can just leave them on.

However, that is just me. I try to balance speed with simplicity. The wood whorls glued onto the spindle are easier to make.

Spindle design moves forward.

The fastest spindle is the one with a brass cap nut as a whorl. It also turns out to be easy to make. And the nut is removable. I like it best.