To find the minimum required shaft diameter and bearing spacing for a unwind
or rewind spindle assembly.
What do I need to know?
The roll and core chuck weight and the dimensions as shown below.
What should I use for the deflection value?
Most materials being unwound or rewound can tolerate greather than 0.0006
x web width of deflection at the end of the shaft.
Example: 24" wide web; 0.0006 x 24" = 0.0144"
The smaller the deflection allowed, the greater the shaft diameter required.
Large deflections create a "baggy edge" on the material being
wound
What is "...Safety Factor" ?
This is a multiplier applied to the maximum expected load (force, torque,
bending moment or a combination) to which a component or assembly will be
subjected.
A safety factor of 1.0 implies that the design meets but does not exceed
the design requirements. A high design factor implies "overengineering"
which results in excessive weight and/or cost.
What if the shaft diameter required is greater than the maximum
bore of the core chuck?
Switch to a larger diameter core chuck e.g. from 3" to 6" inner
diameter cores.
Use a double end supported core chuck
What are the drawings showing?
The top drawing shows a bearing boss assembly with a mounting shaft and
core chuck
The bottom drawing shows the shaft deflecting (exaggerated) from the weight
of the roll
