Re: ATM ...on homebuilt EQ mounts

[Brad Davy <bdavy@fred.net>]

Jim Piunti wrote:
> construct a mount using threaded plumbing pipe that the fittings are >almost

I built my GEM with threaded plumbing pipe for the Declination axis. 
Rather than try to turn the mount on the threads, I made journal
bearings for the pipe using plumbers epoxy around the pipe.  I then used
a lazy susan swivel bearing (from my local hardware store, $3.50) for
the thrust bearing.  End result turns very smoothly when the assembly is
properly balanced.  Since the Declination axis does not have to move
when tracking, the makeshift journal bearing accuracy is not an issue. 
The threaded joints make for easy assembly/disassembly of the mount. 
For the RA axix, I used a small axle from a military surplus store, two
journal bearings that fit the axle, and then another swivel bearing from
the hardware store.  I'm still waiting for the skies to clear to check
accuracy, but I am encouraged by preliminary results.

Bottom line, looseness of the threads doesn't matter as long as you're
not expecting them to turn.



-- 
Brad
bdavy@fred.net               http://www.fred.net/bdavy/home.html
bdavy@nox.cs.du.edu