# MAG-1000 Balancer VERSUS the Nail in the Wall

Discussion in 'Magna-Matic' started by Magna-Matic, Sep 18, 2013.

2. ### Magna-MaticSponsorfrom Waldo, WisconsinPosts: 827

Hello All,

Here is a part of the bulletin which defines UNBALANCE.

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Unbalance, what is it?
Only rotors in motion (bodies that are connected to a shaft) have the unique physical property called unbalance.
There are three types of unbalance known today they are as follows:

Static Unbalance is when the center of mass and the center of rotation do not coincide. (not in the same location)

Couple Unbalance is when there are two unbalance conditions that may have the same magnitude, but their direction may be offset by 180ยบ relative to each other. This can create a wobble in a rotor.

Dynamic Unbalance is the same as couple unbalance except for the rotor may have infinite unbalances and may be distributed at random along the axis of its rotation.

How is Unbalance detected or measured?
Static unbalance detection is a measure of gravitational force.
This detection method is commonly referred to as static balancing.

Couple and Dynamic unbalance detection is a measure of centrifugal force and requires the rotor to be power rotated (spun).
This detection method is commonly referred to as dynamic balancing.

What are some examples of rotors that would use static balancing?
The method of static balancing is typically used for single plane rotors that are thin, such as a lawnmower blades, circular saw blades, abrasive cut-off wheels, narrow pulleys, flywheels, impellers, clutches, fan blades, etc.

What are some examples of rotors that would use dynamic balancing?
The method of dynamic balancing is typically used for multiple plane rotors or rotors that are very deep, such as motor armatures, drums, turbines, multiple rotors on the same shaft, complex asymmetrical parts, wide car wheels etc.

Why use static balancing for lawnmower blades?
Static unbalance detection is the most economical for servicing and manufacturing lawnmower blades and discs.
Dynamic balancing is not commonly used for servicing or manufacturing lawnmower blades because dynamic balancing
instruments are very expensive and not required for single plane rotors such as the lawnmower blade.
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The excerpt above comes from the Magna-Matic EDUCATIONAL BULLETIN SERIES "Understanding Balance, and why a nail in the wall is not a useful measure of balance"

3. ### CQ_DXLawnSite Memberfrom MAPosts: 67

We have a wall with numerous blades hanging all over it. (Show & Tell) My favorite is a blade that is hanging on a nail. The left end of the blade always dips down (heavier) while the right end with the blade numbering is always up (lighter).

New customers are asked which is the heavier end? Most say the end dipping down. (Sad some cannot figure this out - - until they are given a see-saw analogy). This blade is then taken off of the nail and put on the Magna-Matic 1000 balancer. Imagine their surprise as they watch the numbered end of the blade slowly dip down.

At this point they come face-to-face with reality - and the precision of the MAG-1000.