2 axis (azimuth - elevation) motion assembly- best way to fabricate?

[RW]

I want to build an assembly that moves in azimuth and elevation. It will
consist of two subassemblies. Both axis would move
intermittently/infrequently and never faster than 1~2 rpm.

The azimuth axis subassembly must be capable of carrying at least 60 pounds-
the weight of the elevation axis subassembly + the weight of the load, and
must be no larger than 5"~6" dia. at the base. The load will be evenly
divided and balanced at the ends of a 30" long, 1"~1.50" dia. steel shaft
which comprises the main portion of the elevation axis subassembly. The
elevation axis subassembly is in turn centered over and rides on the azimuth
axis subassembly.

In use, both axis must move extremely effortlessly with only a very small,
gentle input (by hand) of the load in any direction.

I have a basic design in mind that should be fairly easy to fabricate from
aluminum but here's where I need some help- what would be the best way to
support the elevation subassembly shaft and the elevation subassembly
itself?

I was thinking of using 2 pressed-in bearings- ball, needle-roller, or ? to
support the elevation subassembly shaft. The elevation subassembly could be
simply placed over a large (1"~2") diameter steel "axle" and rotate on a
thin, 5"`6" dia. Teflon disc/bearing.

But I don't really think this design will be smooth enough so I had a
thought- forget the aluminum and just machine the subassemblies out of steel
to high tolerances and use precision, hardened steel shafts.

Any thoughts out there on either approach? Thanks!

[Mike Swift]

Post by RW
I want to build an assembly that moves in azimuth and elevation. It will
consist of two subassemblies. Both axis would move
intermittently/infrequently and never faster than 1~2 rpm.
The azimuth axis subassembly must be capable of carrying at least 60 pounds-
the weight of the elevation axis subassembly + the weight of the load, and
must be no larger than 5"~6" dia. at the base. The load will be evenly
divided and balanced at the ends of a 30" long, 1"~1.50" dia. steel shaft
which comprises the main portion of the elevation axis subassembly. The
elevation axis subassembly is in turn centered over and rides on the azimuth
axis subassembly.
In use, both axis must move extremely effortlessly with only a very small,
gentle input (by hand) of the load in any direction.
I have a basic design in mind that should be fairly easy to fabricate from
aluminum but here's where I need some help- what would be the best way to
support the elevation subassembly shaft and the elevation subassembly
itself?
I was thinking of using 2 pressed-in bearings- ball, needle-roller, or ? to
support the elevation subassembly shaft. The elevation subassembly could be
simply placed over a large (1"~2") diameter steel "axle" and rotate on a
thin, 5"`6" dia. Teflon disc/bearing.
But I don't really think this design will be smooth enough so I had a
thought- forget the aluminum and just machine the subassemblies out of steel
to high tolerances and use precision, hardened steel shafts.
Any thoughts out there on either approach? Thanks!

You need to give more information on what the limits of the design are.
For instance do both axis rotate a full 360 degrees? does it need room
for slip rings or other mechanical items. If it is a dual tracking solar
collector mount you could just use an automotive universal joint and two
inexpensive linear actuators. Simple, low cost, ten bucks from any
wreaking yard, good for years of service out in the weather. If this is
not what you are looking for please give more information on the load
rather than the design.