ZWO EAF Mounting Bracket for Meade LX90 8inch by TrevOinAus

Last crawled date: 3 years, 3 months ago

This is a remix of the ZWO EAF Holder for Celestron Nexstar 6/8/9 by jamesdedij (February 29, 2020) for the Celstron SCTs and I thank him for sharing the editable design files with me.
I have modified all of the parts in Fusion 360 to fit the geometry of the Meade LX90 8inch SCT and possibly other Meade SCTs depending on the Focus Knob used.
The EAF positioning allows adjustment and removal of the EAF for transport and avoids collision with the LX90 fork arms
It also makes it possible to remove the EAF quickly or to "disengage it" to perform manual focusing.
To improve the gearing between the EAF and the Focus knob, I have added a 32 tooth gear wheel to replace the 16 tooth Alloy gear wheel used initially. To accommodate the new larger gear wheel, a 158mm or 160mm loop belt should be used instead of the 140mm or 142mm belt used with the alloy gear.
I printed all parts in ABS to avoid warping in use, with 70% infill, layer height of 0.15mm. Only the Angled Motor Base may need supports. Recommended 3D print orientation is in the images.
Installation:
After testing for fit and alignment with the Hex Screws, Glue the M4 nuts into the recesses in the Angled Base Bracket
Set the Telescope Tube Horizontal to avoid parts moving when screws are removed.
Wind the Mirror to the rear of the Telescope (Clockwise) and back off half a turn anticlockwise.
Carefully remove the three screws holding the Focus assembly to the telescope rear plate. (Image 1)
Mount the Angled Base Bracket to the telescope rear plate with the new 6-32 UNC 5/8inch screws. (Image 2)
The Focus Collar should be squarely and firmly pressed onto the Focus knob past the knurled finger grip. (It will be tight and it may be necessary to remove any irregularities from the inside of the Focus Collar for it to fit past the Knurled finger grip.)
Carefully rap about 1.5 turns of electrical tape around the base of the Focus Knob to take up the slack and centre to Focus Knob and Focus collar.
The Collar should be located on the focus knob, so that it is close to, but does not rub, on the Angled Base Bracket when the Focus knob is turned.
If the collar is too high on the Focus Knob, the top of it will foul against the chrome faceplate of the EAF during assembly for operation.
Tighten the Headless Screws firmly, so there is no movement between the knob and collar. (Image 3)
Mount the 16 or 32 teeth pulley on the EAF drive shaft so that the centre line of the pully teeth matches the centre line of the Focus collar teeth when assembled. You may need to try this a few times with the EAF not screwed to the Motor base before you tighten the headless screws firmly.
Fasten the EAF to the Angled Motor Base with the 2 CHC M4x12 screws
Glue the Knob-M4s onto the 2 hex screws M4x20. These are used to attach and adjust the Motor Base to the Angled Bracket.
Extra Parts:
GT2 pulley 16 teeth for 5mm axle (to fit on EAF drive shaft)
and
142 (or 140) mm GT2 Loop belt
or
3D Printed 32 teeth pulley for 5mm axle (to fit on EAF drive shaft)
and
158 or 160 mm GT2 Loop belt
3 x Cross Head or Hex 6-32 x 5/8inch) UNC Button Head screws (To secure Angled Base Bracket to LX90)
3 x M4x8 headless screws (From EAF Kit) (To secure Focus Collar to Focus Knob)
2 x CHC M4x12 screws (From EAF Kit) (To secure EAF to Angled Motor Base)
2 Hex M4x20 screws (For use with printed knobs to secure Motor Base to Bracket)
2 M4 nuts (Glued into Angled Base Bracket)