Linear tracking turntables, whatever happened?


Curious as to the demise and downfall of the seemingly short lived linear tracking TT.
Just from a geometry point of view I would have thought a linear arm should be superior to one with a fixed pivot that sweeps through an arc.
Obviously there is much more to it than that, sort of the reason for this thread.
I am genuinely interested in trying one out for myself as well.
128x128uberwaltz
@bdp24 ,

The ET was on a VPI, will be on my TT project at some point. I'm using a Funk Firm FXR on the Rock 7 The FF arm has X bracing in the arm tube, making it very stiff. Has Max ever released his latest arm?
This has been a pretty informative thread~
For another story, I knew a guy back in Pittsburgh, where I grew up, who mounted a Vestigal arm (remember those, with the wagging headshell attached to a string which tensioned it?) to a Rabco. In theory, I guess it made sense.* In practice, I don’t remember. This was back in the mid-’70s.
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*Or maybe not, given the discussion of vertical inertia here- I don't have the physics knowledge to assess this meaningfully. 
Please tell us what Rabinow did with coat hangers to prevent a toilet from being flushed while the train was in the station. Inquiring minds want to know.
@bdp24 ,

I failed to mention that I have a Moerch DP8 that I'm planning on using with the Rock 7 at some point as well.
@slaw, I know the Moerch arms are another favorite with Rock owners, which is surprising to me given their relatively low mass characteristics. I’ve seen listings for a Townshend Audio Excalibur II arm, but no pics. I have also heard talk of a replacement for the Rock 7, but that was a couple of years ago. The table itself has been in and out of production a LOT of times over the past 30 or so years. For those who are unfamiliar with the Rock, it is intrinsically unusable with linear tracking arms, owing to the arms’ front-end damping trough, which mandates a pivoted arm.