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Raka 15th April 2004 05:21 PM

Balancing
 
Is there any diy way of balancing a platter?

DRC 15th April 2004 05:52 PM

What about turning it on to it's side and let gravity do its thing (the bearing needs to have very low friction) ? The heavy part will stop at the bottom. This works well balancing wheels ...

Dave

Raka 15th April 2004 06:14 PM

Thanks for the comment. Yes, I knew that, but this can be a destructive test, since the spindle is horizontal and will rest onto the bearing. I'll try this with a cheap table, tough.

ingvar ahlberg 15th April 2004 08:31 PM

This is pretty hard as unbalance in a decent quality platter is very small so You would ned to balance dynamicaly.
You can try to put the platter in a lathe, if central shaft is part of platter attach a bit of shrink tubing to shaft to avoid dents in shaft.
If platter is free from shaft then use a simple shaft from a scraped tt and thread the tip so You can lock platter to shaft with a nut.
Now You can check static balance with lathe unengaged from drive, and also find any geometrical unbalance turning it at slow speed. If lathe is of good precisison and shaft integral with platter You can adjust smaller errors.

sigmapower 15th April 2004 08:43 PM

No, the simplest way to balance a platter need a tools used for balancing the wheel of a grinding machine.

sreten 16th April 2004 04:25 PM

A large flat platter can be statically balanced by using a larger ball
bearing in the centre hole and noting where the edge comes to rest.

If you get consistent results usually just proves the
centre hole has been drilled in the wrong place ;) .

Dynamic balancing I presume is much harder.

For a thorens :

If you attach the whole platter sub platter mat etc to
a carefully levelled motor via a flexible drive - rubber
tube from shaft to the bearing spindle and spin it at
speed you will get an edge float to to the inherent
precision of the edge with any dynamic imbalance
superimposed.

You could probably just do this with the normal bearing
and investigate if their is an ideal position for the platter
on the subplatter in terms of edge float.

You only need a slight tilt of the main bearing to show
the static imbalance, if you use thin oil in the bearing.

A tilted platter oscillating to its final position is not a good sign ;).

:) sreten.

thanh 18th April 2004 07:04 AM

I think balance technique can't cancel the distortion absolute.I think it can only cancel even harmonics


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