Re: stacking variacs

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: David Speck <dave-at-davidspeckmd-dot-org> 

Dave,
Yep, a flexible coupling is the simplest way to go.

Look for a "Lovejoy coupling" -- there are lots of them up on eBay.
They accommodate all sorts of misalignments, and have very little 
backlash.  Just look for a set that matches your shaft diameter.  You'll 
need two metal coupler elements and a rubber connecting spider.  They are 
typically sold individually to allow you to connect shafts of different 
diameters.

Examples:

http://cgi.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&category=43016&item=3810811738&rd=1

http://cgi.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&category=43016&item=3810810688&rd=1

http://cgi.ebay-dot-com/ws/eBayISAPI.dll?ViewItem&category=43016&item=3810812671&rd=1

Dave Speck

>Another approach that will accommodate ALL angular misalignments form ALL
>sources is to cut the drive shaft in half and place a flexible shaft
>coupling between the variacs. The rubber-biscuit type shaft coupling will
>easily accommodate the misalignment that is causing your binding, and is
>relatively inexpensive. See McMaster-Carr's website for many different types
>of shaft couplings.