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| The Meade LX200 was used as the design basis for
the general SCT RoboFocus application. The concept
was to use the primary focus knob on the back plane
of the scope, and driving the focus movement with a
set of timing sprockets and a timing belt. The motor
support bracket sits directly on the rear scope
cover and is held into place with a double-sided
Very High Bond, (VHB), tape designed for powder coat
finished surfaces. The sprocket (two different sizes, as the
GPS model has a slightly larger diameter knob),
simply slides over the existing knob, is adjusted
for the proper height, and tightened into place with
three set screws. The bracket is positioned in a
manner to allow the 8 inch timing belt to be secured
between the motor and the focus knob. The motor can
slide approximately one half inch to adjust tension
on the belt. A special bracket has been designed
for mounting the RoboFocus system onto the Meade 8
inch GPS model. With the mirror lock knob and handle
both mounted on the rear plate, there is not
available surface space next to the focus knob to
directly mount the motor bracket. This special
bracket supports the motor above the rear handle and
attaches to the timing sprocket mounted on the upper
portion of the focus knob.
RoboFocus has been successfully attached directly
to the Meade Microfocuser on the GPS models. This
allows the mirror to be locked while focusing.
Contact us for complete plans/instructions
Many people question the use of the primary focus
knob over using the mirror lock and adding a
secondary third party focuser. The stability and
precision of the RoboFocus system provides
extraordinary results with this setup. In fact, a
study conducted with RoboFocus units mounted first
directly to the primary focus knob on the LX200,
then onto a JMI NGF-S focuser added to the same
scope, resulted in nearly identical results. This
LX200 Study
can be downloaded and viewed or printed.
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| The most common Takahashi RoboFocus install is
the Rack & Pinion setup, mounted directly onto the
focus shaft, after removing one wheel knob.
Takahashi has standardized with an 8mm diameter
shaft on both the 2.7 inch and 4 inch focuser. A
small brass coupler (with a built in "clutch" on the
motor side), attaches the motor directly to this
shaft, and is held into place with two set screws on
each end. The system comes with a set of "generic"
motor support brackets, as well as a new optional
finished "Takahashi Bracket", (see Products,
Category 2).
There are some Takahashi models, (probably the most
common being the Sky90), with short tapered focus
shafts. For these models we make a special, shorter,
coupler with the set screws very close to the end.
Many users of these scope have found this solution
workable with all features and functions of the
RoboFocus then available.
Takahashi also makes a line of Newtonian/Cassegrain
telescopes, (the CN-212 a common RoboFocus install).
The RoboFocus solution for these scopes is built
around the SCT motor bracket and a timing
sprocket/timing belt.
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| The Celestron line of SCT telescopes typically
utilize the standard SCT motor mounting brackets and
timing sprockets/timing belts. There are several
attachment approaches based upon scope model and
focus knob assembly. The "classic" line of Celestron
scopes (C8 and C11 for example) have either a 1/2 or
3/4 focus knob (after removal of the rubber finger
grip). A couple of models have gnarled metal focus
knobs that cannot be easily removed. We have a
larger timing sprocket that slides over this knob
The Nexstar GPS models, CGE1100 and CGE1400 have a
unique install. Once the grip is lifted off, what
remains is a short, stepped tube assembly on a
raised housing. We include both a special timing
sprocket and an elevation block attached to the
motor bracket. The CGE1400 elevation block includes
a cut-out to straddle the ribs that radiate out.
The C9.25 uses a sprocket directly over the existing
focus knob (0.87 inches in diameter), without
removal.
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| The NGF-S has a small tear-drop motor that is
removed by loosening the set screws applying
pressure on the shaft, and removing the single screw
that holds the motor onto the housing. The RoboFocus
NGF-S motor has an identical shaft and motor
mounting hole. This allows the RoboFocus motor to
simply slide into the housing and attach exactly the
same as the JMI motor. We also supply an additional
sleeve bearing for the inside slot to provide
smoother and more stable operation. This motor
also works for the NGF-SE (model without the JMI
motor). In 2005, the NGF-S was replaced with the
NGF-C model. This focuser is small and operates with
a small gear motor under a center housing plate.
This motor is removed, along with the Crayford style
shaft, and the RoboFocus motor mounted nearly the
same as the NGF-S. The housing on the NGF-C does not
have a motor mounting screw hole, so a special
mounting plate is provide. This plate uses our
double sided VHB (Very High Bond) tape to adhere
motor to the flat surface on the side of the
housing.
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| A standard Rack & Pinion RoboFocus setup is used
on the DX1 and DX2, with the motor mounted directly
onto the 1/8 inch diameter shaft under one of the
focus knob wheels. The motor can be supported with
the "generic" brackets that come with the system, or
an optional mounting bracket, (see Products
Category 2), can be
purchased. The optional bracket does require the
drilling and taping of two mounting holes on one of
the side flanges. We will drill and mount the
RoboFocus motor at no additional cost if focuser is
sent in to Technical Innovations.
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| All Astro-Physics focusers are Rack & Pinion
style and have a standard 1/4 inch diameter shaft.
Installation is very straight-forward, with the
motor attached to the shaft via a small brass
coupler with a clutch piece next to the motor shaft.
The motor can be supported with the "generic"
brackets that come with the system, or an optional
mounting bracket, (see Products
Category 2), can be
purchased. These brackets attach to the bottom of
the housing, using existing screws/holes.
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| The Feathertouch focuser from Starlight
Instruments comes in both Rack & Pinion and
SCT models, both of which can be fitted with the
RoboFocus System. Discussions with Starlight and
tests run by current users, show that extremely good
results are obtained with he RoboFocus motor mounted
on either the "coarse" or 10:1 "fine" focus knob. As
a result, most owners tend to mount on the coarse.
With the Rack & Pinion model, the motor is mounted
directly onto the shaft (1/4 inch on coarse and 3/32
inch on fine) under focus knob. The motor is
supported with generic brackets provided with the
system.
The SCT model rises 2.5 inches above the back
plane of the Telescope. The RoboFocus attachment is
standard "SCT", with timing sprockets and belts
connecting to either the fine knob (0.928 inches in
diameter) or coarse focus (1.238 inches in diameter.
Because of the height, an adjustable mounting
bracket is included in the package. This bracket
allows the positioning of the motor at either focus
knob level.
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The Orion 80ED has a Crayford type focuser
with a unique attachment design. The knob wheel
itself has an attached shaft that slides over
another shaft and under a sleeve before being held
into place with a set screw. The shaft attached to
the focus knob wheel actually screws into the wheel,
which allows the wheel to be removed (a set crew
hold shaft firm), leaving the rest of the assembly
in place. The motor coupler can then match up with
the treads at the end of the in-place shaft.
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| All TeleVue focusers are Rack & Pinion style and
most have a standard 9mm diameter shaft.
Installation is very straight-forward, with the
motor attached to the shaft via a small brass
coupler with a clutch piece next to the motor shaft.
The motor can be supported with the "generic"
brackets that come with the system The exceptions
identified are the Pronto and Genesis, (0.43 inch) ,
and the Stellarvue with a shaft diameter of 0.338.
The RoboFocus system has been installed on all of
these.
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| The timing sprocket/timing belt approach can be
adapted to nearly any SCT telescope with a primary
mirror focus attachment. You will need to check for
available surface mounting area near the focus knob,
(approximately 1.5 inches wide by 3 inches long),
and get a diameter measurement of the focus knob, or
shaft under knob. If you do not have a caliper, the
"paper method" can be used. Wrap a small piece of
paper around the knob, mark and measure the
circumference, then divide by 3.1416 to calculate
diameter.
The Clement focuser uses a timing sprocket/belt
setup. Either have Clement attach motor priro to
shipment of focuser, or obtain the proper mounting
bracket directly from them.
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| Below are listed several focusers that we have
successfully mounted the Rack & Pinion style
RoboFocus units onto. For these units, we have all
the information needed to provide the proper setup
directly to the buyer: Meade LXD55 - Shaft
size 1/4 inch.
Vixen Models - Shafts of either 6mm or
9mm, please confirm prior to order
Williams Optical - Shaft size 7mm
TEC140 - Uses Feathertouch focuser - shaft
size 1/4 inch
MAK 67 - Shaft size 5/32 inch
Megrez 80 - Shaft size 4mm. Special
coupler due to tube design and shaft length
Nearly any Rack & Pinion or Crayford style
focuser can be equipped with RoboFocus. We will need
information, such as shaft diameter, available
mounting options and other characteristics (for
example protruding parts), that may cause special
installation concerns. Email or call to discuss your
equipment.
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| RoboFocus can be adapted to nearly any device
requiring precise and repeatable focus movements. We
are happy to work with you and your application to
assure success. RoboFocus has been used on
electronic research microscopes, radar tracking and
response devises and range sights. For
additional ideas or input into your application
design email jerrysmith@robofocus.com
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