?
In thinking about the coupler type options out there I remembered a nice chart from Ruland that explains the different types of couplers they offer.? There are other brands of couplers but they all fall into one of the categories on the chart.? I have added a link to the chart below so you can understand the differences and why the folks who tested other coupler types experienced what they did.
?
IME the requirements for the drive coupler based on the mechanical design of the drive system are as follows.
?
Due to the drivetrain design the coupler must be able to accommodate some small amount of axial misalignment while maintaining constant velocity.? Additionally with this drivetrain layout there is no need for the coupler to accommodate any angular misalignment.??
?
The coupler must have zero backlash.
?
The coupler must be very stiff torsionally.?
?
The coupler needs only be capable of moderate torque load.?
?
The coupler doesn't experience significant bearing load so this is not an important factor.?
?
For maximum drivetrain responsivness to changes in speed and direction for example during guiding, the amount of damping and inertia in the coupler should be as low as possible.?
?
Ideally the coupler should not allow axial play in operation or changes in speed or direction. This is important for drivetrain responsivness as when guiding and platesolving centering.?
?
IMO Scott selected the right type for the job based on the most desirable characteristics for the coupler types available.? Check the chart to see how your favorite coupler type stack up.??
?
https://www.ruland.com/coupling-comparison-guide/
?
--
Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric - South Pasadena, CA?
Chip Louie