Determining Balance Weight Placement Angles
The information provided is for help with Commtest Instruments products:
- vb instrument
QUESTION
How do I determine the correct angle at which to place trial and balancing weights?
ANSWER
There are two options for indicating the position for placing the weights on a rotor object for balancing: With Rotation or Against Rotation.
The choice indicates the way that the phase is to be measured with respect to the rotation of the rotor. The selected option is also stored with any balancing data that is saved for an existing machine, and reused if the data is re-loaded from memory.
Tips for Selecting a Reference Position and Direction of Rotation
1. The Reference Point
It does not matter where on the rotor you make the selection for the position of 0 degrees or blade #1. What is important is that you continue to use the same reference point when you measure out the balance weights as you did with the trial weights.
We suggest that you use an easily accessible point that can be clearly marked as your reference point.
2. Direction of Rotation for Measuring Phase Angles
The following pictures depict the direction of rotation and phase angles that correspond to the options of With Rotation and Against Rotation.
Clockwise Rotation of the Rotor
Measure Phase With Rotation |
Measure Phase Against Rotation |
Anti-Clockwise Rotation of the Rotor
Measure Phase With Rotation |
Measure Phase Against Rotation |
3. Dual Plane Balancing
It is not necessary for both planes in a dual plane balance to have reference points in identical positions on the rotor. The only restriction is that the position selected to be the reference point on each plane must remain the same all the way through the balancing process (see previous heading 1. The Reference Point).
Consider the following example of a screw type fan: When one of the fan blades is selected as the reference point the left-hand plane reference point indicated by the number 1 does not match the angular position of the right-hand plane reference point.
Side view of a screw type fan (Point 1 indicates the selected fan blade and the reference point position in both planes) |
As long as you are consistent in using the same selected reference point in each of the planes for all trial and balance weights, it is irrelevant if the physical locations are different.
FAQ ID: 11687 Last Reviewed: 2 November 2005