General Rule for applying the correction weight

[dynaman]

Hi guys,

I was reading an article recently regarding the application of the correction weight when performing a single plane balance. The article stated a rule of thumb, "Always shift the trial weight in the direction opposite the observed shift of the reference mark from the original vibration position to the trial weight vibration position."

Does anyone have any views on whether this rule applies to all cases?

cheers

M.

Article reference (p157):

http://xa.yimg.com/kq/groups/3862917/1088457995/name/DYNAMIC+BALANCING.pdf

 

[Tmoose]

I do what the vectors tells me.

What would that rule of thumb have you do if the phase stayed the same? (vectors correctly provide different answers if amplitude increased or decreased)
I'm guessing there are a few more rules of thumb for those no phase shift cases

 

[electricpete]

I didn't see exactly that statement. I saw a different statement on pdf page 8/34, labeled 157, where it states:

ALWAYS SHIF THE TRIAL WEIGHT IN THE DIRECTION OPPOSITE THE OBSERVED SHIFT OF THE REFERENCE MARK FROM "O" TO "O+T"

In the old days, strobes were used for balancing. The analyser monitored vibration and provided a pulse to trigger the strobe to flash. Then you looked for an identifiable position on the shaft (like keyway), measured it's movement compared to stationary reference (for example top dead center) to determine phase.

Most people with modern digital analysers do it differently. The analyser calculates a phase by comparing vibration against a signal generated by a strobotach which monitors shaft keyway and generates once per pulse shaft.

While the vector diagram might look the same in both cases, there are important differences in approaches (some call them conventions) on how you convert phase to vectors and/or convert vector solutions to balance weight placement.

Before wasting any energy to determine whether either of these statements is correct, we have to ask: are you balancing using strobe (the old way) or using the modern method?

If not using a strobe, I would find a different reference to learn your conventions from.


=====================================
(2B)+(2B)' ?

 

[electricpete]

"generates once per pulse shaft"[/]
should've obviously (?) been
"generates once per shaft rev pulse"[/]

=====================================
(2B)+(2B)' ?

 

[dynaman]

Hi electripete,

Thanks for your reply. Yes I'm using the old strobe method. It took me a while to realise what you stated and yes the vector diagram is different. As it turns out the method in the article works well for my strobe method.

cheers

Mark.