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Hi Kevin,

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The original Oldham type coupler is a perfect choice for this application where the misalignment is only axial and is easily reduced.? The other coupler types also may allow for axial misalignment as well as angular misalignment. For the Losmandy mounts we only have to worry about axial misalignment.? So pick the type of coupler that have no or low changes in speed with axial misalignment and that's the best one to use.??

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If you do your research you will find that like the Oldham type each other type of couplers have advantages and disadvantages.? In testing done by many different people none of the alternatives, rigid, various disc types, helical types and bellows types are significantly better performing and often hurt tracking performance.? The reason may be that the Oldham is the best fit for axial misalignment while maintaining low difference in velocity changes due to axial misalignment.?

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So I think that while the Oldham tends to loosen over time, (this is often the problem found that fixes previously good tracking mounts), this is an issue with all of these miniature couplers.? The Oldham type coupler has minimal/no velocity shift and is easily axially aligned in place which helps reduce the already minimal changes in speed.? You can also order the perfect fit from Losmandy.? No need to machine or try to fit couplers with mismatched bores or lengths.??

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My tips for the Oldham couplers are to use a toothpick dab, as little as possible of SuperLube on the plastic coupler parts. Use removable thread adhesive on the grub screws, adjust the gearbox shaft with the Oldham already tight on the worm shaft and hold / float the gearbox side to align the plastic coupler parts with the metal parts of the coupler while snugging down the gearbox fasteners for best shaft alignment.? I also suggest keeping one complete spare Oldham and gearbox in your kit to keep the mount running if you don't want to be waiting for replacement drivetrain parts which sometimes have a long lead time from suppliers.? I'm just saying, you can control your own destiny in this small way.??

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