Topics

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

Explore Scientific, LLC.
jrh at explorescientific.com

www.explorescientificusa.com
1010 S. 48th Street
Springdale, AR 72762
1-866-252-3811

Author: Scientific Astrophotography: How Amateurs Can Generate and Use Professional Imaging Data
             Remote Observatories for Amateur Astronomers: Using High-Powered Telescopes From Home


Mark Slade Remote Observatory (MSRO) IAU MPC W54 Equipment
Wilderness, VA
Mounts
: ES PMC-Eight G11 + Telescope Drive Master (TDM)
Scopes: ES 165 FPL-53 ED APO CF, ES 102 FCD100 ED APO CF
Cameras:  QHY174M-GPS + FW, QHY163C
Misc: 3-inch 0.7x Focal Reducer Field Flattener, Filters: Luminance,
Red, V-band Photometric, Diffuser, 200 lpmm Spectral Grating

Software: MaxIm DL 6, Cartes du Ciel, Astrometrica, AstroImageJ, AutoStakkert!