Re: Secondary Tweaking
Bob Luffel (bobl@gr.hp.com)
Mon, 3 Apr 95 11:28:24 MDT
>
> Recent posts regarding "tuning up" Novak secondary components have been
> very helpful. I implimented the cap/socket screws in place of the
> Phillips head - with a ball driver, it is much easier to adjust! I
> wrapped the threaded secondary mounting shaft with about two layers of
> teflon plumber's tape - nice snug fit, smooth to turn. One more
> embellishment I am considering is to machine a slot down the length of the
> mounting shaft and buy or make one of those special washers with a small
> "tang" on it which will locate in the slot (you see this construction on
> the shafts of toggle switches). The result is that any torque from
> tightening the main nut on the shaft is not transfered to the spider. I
> also replaced the main nut with a wing nut which allows for easy finger
> tightening. Next, impliment the loading spring idea, possibly with a
> teflon washer for the final touch. My goal (other than to play with
> neat stuff from the hardware store) is to make collimation easy enough
> that I will not dread doing it.
>
> Any one "souped up" the primary mount?
>
Some comments on weak points of the Novak primary mount. The 3 angle
brackets than surround the mirror edge and to which mount the angled
mirror clips are held in place by a single screw. I have heard horror
stories of these loosening permitting the mirror to fall out! When
transporting a tube horizontally, all of the mirrors mass can be supported
by a single bracket. I recomend adding a second screw/bolt and/or
gluing this join also.
Adding a set of 'push' screws (rather than relying just on the springs)
as others have mentioned is a good idea, too. Finally, the pads that
contact the mirror (heads of some nylon screws) are pretty small.
I would consider going to some larger diameter cork or teflon pads, especially
on the larger (12.5" or larger) or thinner mirror sizes.
Bob