Counterweight vibrations

Dan Ward <danlward@...>

Has anyone done analysis on mount vibration from counterweights?  

Assuming one is well within the total weight capacity of a mount/head, would it be better to have two counterweights near the top of the counterweight shaft as opposed to one counterweight near the end of the shaft?  

Intuition suggests a shorter balance column would be less likely to add unwanted vibration, but I am curious as to whether anyone has actually studied this.

Jerry Hubbell - Explore Scientific VP Engineering

On Sat, Sep 21, 2019 at 12:07 PM, Dan Ward wrote:
Intuition suggests a shorter balance column would be less likely to add unwanted vibration,
Hi Dan,

That's a great question. Even though I have not done any real "study" of the issue, as you say it makes sense that the shorter moment arm should reduce the amount of vibration, and that is all because of a problem we call "Flexure" The counterweight shaft of a mount has a bit of "springiness" to it that when hanging a heavy weight at the end will cause more flexure as it is cantilevered out from the mount. Also, when the counterweight shaft is near vertical or if you are "perfectly" balanced in RA then the mass at the end of the shaft acts as a pendulum and any lash in the gears would show an increased level of oscillation or vibration. This gear lash could be considered a form of flexure. So overall it is best probably to push enough weights to the top of the shaft to balance the load.
Jerry Hubbell
Vice President of Engineering

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