« Nipping a Winding Roll Around the Clock | Main | Energy cured inks and coatings »
January 26, 2007
Dancers dancing direction
Q: Which is the best direction for a dancer roller's motion, horizontal or vertical? Also, what is better, a linear or pivot dancer motion?
A: I don’t have a strong preference on horizontal vs. vertical, but I am strongly in favor of pivoting dancers over linear dancers.
I prefer a vertical dancer arm with horizontal motion so that gravity is perpendicular to the tensioning direction, but make sure the dancer arm is hanging (as opposed to standing) with the the pivot point above the roller. Hanging dancers are 'sloped' to run stable; gravity tends to pull the roller back to its null position. Standing dancers, with the pivot underneath the roller are destabilizing with gravity trying to pull the roller away from neutral position.
My preference for pivoting over linear is based on observation of friction and sticking almost always higher in linear systems. If well-engineered, there is no reason a linear system can work great, but too often a linear dancer has more trouble holding its alignment, creating tension variations and wrinkles. A pivoting dancer can also be poorly engineered, but you have a better change to get low friction in a rotary bearing and simple structural design can translate a well-aligned pivot shaft into a well-aligned roller.
-tjw
Posted by Tim Walker at January 26, 2007 09:00 AM
