# Vernier Dial Planetary Reduction Drive



## CoreyB (Nov 27, 2019)

Here's a project I just completed. It's a Vernier dial ball bearing planetary reduction drive. It will be used to
perform fine adjustments of air variable capacitors in amateur radio applications. The end caps and internal
races are done in 12L14 steel and the main body is aluminum. The central shaft is also steel and the carrier
is done in brass. I used a Smithy 1324 with a DRO to create all of the parts and to drill and tap all of the holes.
It took me a bit of time to figure out how to properly create the trough in the center shaft and then a bit more
time to figure out how to make it work smoothly.

--Corey


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## rwm (Nov 27, 2019)

Wow. That looks great and it is a really clever application for such a drive. I confess I don't see exactly how it works though?
Robert


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## brino (Nov 27, 2019)

Is it like most planetary drives except here, instead of gears, the balls are a "rolling friction element" ?

If so, I would think the tolerances would need to be amazing!

-brino


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## CoreyB (Nov 28, 2019)

brino said:


> Is it like most planetary drives except here, instead of gears, the balls are a "rolling friction element" ?
> 
> If so, I would think the tolerances would need to be amazing!
> 
> -brino


Yes, rolling friction but the tolerances are quite easy to achieve. The races are simply 45 degree angles cut
into steel to form a race. This can be done with a high quality counter sink and then polished out to a mirror finish with aluminum clothe and finally a good metal polish.

—Corey


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## eugene13 (Nov 28, 2019)

HAPPY TURKEY DAY, in my back yard at 8:30 this AM


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