Steve Bedair's
Telescope Site
Longview , Texas
Updated 3-2003

Joe Bauer's Celestron 9.25  Fine Adjust Focuser


Here's a fine adjust focuser idea that Joe Bauer came up with. Joe provided me the vernier speed
reducer along with a set of detailed drawings and I provided the machine work. Great idea Joe !
The focuser uses a very small Vernier speed reducer that has a  6 to 1 reduction.
The large focuser knob ( coarse adjust )  turns the focuser shaft at a 1 to 1 ratio.
The smaller knob ( fine adjust ) turns the focuser shaft at the 6 to 1 ratio.

Parts Breakdown

Fine adjust focus knob, coarse adjust knob, vernier, adapter ring , shaft adapter

Parts Description

    Fine adjust knob:  Radio Shack part # 274-424A  (1" OD aluminum knurled knob x 1/4" ID)

    Coarse adjust knob:   2-1/4" od x 3/4" & 1-3/4" id  . Turned and knurled on a metal lathe. The id
                                    recess was formed  using a boring bar with the od held in the lathe chuck.

    Vernier speed reducer:  The vernier units are $9.95(US) each; item VD61, from the bottom of
                                        this page:  Click here
                                        The manufacturer's page is here: Oren Elliott Products
                                       Note: the vernier needs to have the dial flange to work for the focuser unit.

    Adapter ring:      1-5/8" od x 5/8" & 1-1/8" id aluminum turned on metal lathe.

    Shaft adapter:   Turned from 3/4" od stainless steel on metal lathe. ( aluminum would work also )
                            Reduces from  1/2"  id  to 1/4" od.
                            large portion: 3/4" od x 3/4" & 1/2" id
                            small portion: 1/4" od x ???" one edge flattened

 The Vernier speed reducer is very stiff "out of the box". A lot of this is due to the grease used.
Six small tabs around the od of the vernier can be bent to adjust the pressure. I also went ahead
 and disassembled , cleaned and re greased. After this movement was very smooth.

Fine adjust focus knob, coarse adjust knob, vernier, adapter ring , shaft adapter

Fine adjust focus knob, coarse adjust knob, vernier, adapter ring , shaft adapter

The adapter ring is notched to allow for access to the shaft adapter
mounting screw.

Back view.
The two mounting holes in the adapter ring are threaded.

Vernier mounted to adapter ring.
The threaded mounting holes will allow the mounting screws to
be marked from the top side.

Coarse adjust focus knob

Rear view

Completed Focuser

Front view.

Contact Steve

Contact Joe Bauer

 The information provided can hopefully help with building your own focuser or having one built.
I would really like to build one for everyone who ask but at this time I just have too
many projects going on at once.
Thanks & good luck,

Steve's Telescope Site
Steve's Metal Working Site