>>>> bearings
>
>It is not that hard to build hollow tube conical shafts with a relatively
>small bearing at the bottom and a large external bearing at the top. This
>solves the question of shaft bending and shaft harmonics while still
>providing a large bearing separation distance, if desired. My equatorial
>mounts all have these homebuilt conical shafts in the polar axis. Typical
>dimensions for a scope to 10" in size would be bearing separation = 20" and
>conical upper bearing diameter = 20". The upper bearing then only needs to
>be driven by a roller bearing, resulting in a very smooth and accurate drive.
>
>Mel
>
Mel,
How do you build hollow tube conical shafts ("not that hard")?
Do you use steel? Aluminum? What is your material cost?
Do you use two points of contact for your roller bearings? I assume, in my ignorance, that you don't buy a 20" I.D. roller bearing (collar type).
What is the advantage to the 20"L x 20"Dia. ratio? How do you choose that?
Thanks in advance.
Kevin Dowd KSD@vax3.ltec.com