The picture at
right shows my starting point. I use the Losmandy dovetail
system on my telescopes and mount. This system allows me
to interchange telescopes with minimal effort and allows me to
fine tune declination balance by moving the plate to which the
telescope is mounted forward or backward in the mount's saddle
plate. In the picture at the right, SocalAstro rings are mounted to the dovetail plate and the telescope
fits snugly in the rings. The telescope is mounted to the
rear of the plate such that the focuser with Robo-Focus™
installed has plenty of clearance for focuser rotation. The problem with this
mounting scheme is that declination balance is very poor.
To obtain balance with my CCD camera, I had to add 15 lbs to the front of the mount's
saddle plate. While my mount can easily
handle the weight, I prefer to not have that much dead weight in
the system.
The first step
was to move the telescope and mounting rings forward on the plate as shown in the
picture at the right. This moved the balance point forward
and allowed declination balance without the 15 lb weight.
The problem
with this mounting scheme is that the focuser cannot rotate 360
degrees. Rotation is limited by the Robo-Focus™
motor on one side of the focuser and by the 10:1 focus knob on
the other side.
To allow free
rotation, the telescope needed to be elevated a bit higher from
the mounting plate. Taking a cue from the SocalAstro rings, I
fabricated two spacers from 6061 aluminum rectangle
stock. I cut the length of the spacers to width of the
bottom of the rings. I drilled three holes in the stock
which lined up with the holes in the rings. I counter
bored the middle hole to allow a cap screw to fasten the spacers
to the rings. Cap screws would go through the outside
holes to fasten the ring/spacer assemblies to the mounting
plate.
After I drilled
and counter bored four holes in the mounting plate to accept the
new ring mounting scheme, I fastened the ring/spacer assembly to
the mounting plate.
Now I can
rotate the focuser 360 degrees and have declination balance.