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Nails – Part Deux

Galibier Design - Savoie Idler Pulleys
(click to enlarge)

The first post in this series (For Want of a Nail) was inspired by lessons learned – both in the manufacturing as well as final assembly of our 2019 drive system update.

So, we’re back on the trail, finalizing the design of our Savoie (idler drive – formerly named the Eiger), and it’s no surprise that the same challenges presented themselves.

Precision, precision …

If you’re subscribed to our mailing list, you know that release of our 2019 drive update was delayed by production challenges – specifically, developing a process to machine our drive pulleys to our required .0004″ tolerance (that’s four ten-thousandths).

The closer our belt drive turntables approach the immediacy of idler drive (and they’re very close), the greater the demands grow on precision of manufacture.  Purveyors of rubber belt driven turntables don’t face these challenges, but no one ever accused us of taking the easy way out 😉

Who says idlers have to be noisy?

Flash forward to the Savoie.  The key challenge with this design was to bring the noise floor down to approach that of a belt driven turntable.  We expected this to be an unrealistic goal, but we knew we could get closer, and we refused to target it for release until we had the Garrard and SP10 crowd not only lining up, but beating down our doors.

Well … we’ve done it!  We’ve exceeded our expectations. Anyone who tells you that idlers are noisier than belt drives should prepare to be surprised.

We mention the SP10 (direct drive) above, because we’re of the opinion that both idler and belt drive (when done right) are superior solutions to direct drive – in all the ways that are attributed as being direct drives’ strengths.  That’s a story for another day.

Some Background

The root cause we were working on with the Savoie is the chatter resulting from a less than perfect idler pulley.  The same tolerances that work with a belt drive, result in the idler literally “bouncing” against the driven surface (the platter) – 565 times per second at 33-1/3 rpm in our design.

This idler chatter is one of the reasons your Garrard has a prominent upper-bass coloration.  Their idler wheels are larger, and therefore turn more slowly, and bias the noise floor closer to these upper bass frequencies.

So, we’ve once again learned that the effort to bring a turntable design home is inversely proportional to the size of the part.

We learned that machining stainless steel is a walk in the park, compared with achieving precision with friction bearing materials like the rubber and polyurethane surfaces in the above photograph.

What’s next?

We’re on to finalizing the physical layout of the drive module and the base.

Stay tuned for updates.  We’re on our way!

08-June update:  we’ve started reaching out to fabricators for bids.  Click here for that story.