This mount comprises a heavy machined C-casting which pivots in a shoe to form the adjustable polar mount block, a cast DEC axle mount and two pairs of PTFE-lined bearings for the RA and DEC blocks. The axles are 1.5" Stainless steel and the clutches for the worms on each axle are friction driven using springs for constant pressure, with thrust bearings between the spring and the pillow block to provide the rotating pressure surface. The RA worm wheel is cast bronze with spokes, 10" in diameter with 360 teeth. The DEC worm is solid bronze 6" in diameter by 1/4" thick, again in bronze with 180 teeth. Both axles have worm mounts using bronze busings to hold the shaft which carries the worm. The worm is spaced using spacers at either end and uses PTFE washers to maingtain accurate spacing and take up any play. The worms are 3/4" diameter steel which are locked on to the the shaft using two grub screws.

The jobs I need to do on this mount include :

• De-rust and re-spray all parts - done
• Polish and paint the DEC and RA setting circles - done
• Clean and wear-in the RA and DEC worm wheels - done
• Build a RA and DEC drive to replace the original synchronous and DC motors to allow GoTo control - underway ( See PIC Microstepper driver & PIC GoTo drive board) - underway
• Fabricate a worm wheel cover for the RA and DEC Worm wheels. - beginning
• Install a digital encoder on the RA and DEC axles to measure 'absolute' periodic error. (The pointing position is already handled using incremental encoders on the worm drives). This will allow me to measure and correct for Periodic Error on the worms without guiding.

This is what it looked like before I started and while dis-assembling the parts.

So far the mount is largely re-built in the garage with new springs and a stepper motor drive in RA.