Paullus
02-06-2020, 09:36 PM
Hi all,
I recently purchased a JMI EV focuser to replace the standard unit on my Skywatcher 8" reflector. The existing bolt spacing is about 86x76mm and the JMI unit is 70mm square. As the Skywatcher unit has a large diameter (92mm) locating ring on the bottom of the focuser plate, there is a large hole in the scope tube which doesn't leave much material left to safely drill 4 new holes.
So rather risking drilling 4 holes close to the edge (and the anxiety that comes with drilling into a telescope), I designed an adapter plate to utilise the existing bolt holes that I can bolt the new focuser to. The existing bolts that held the Skywatcher focuser are reused, and I had to purchase 4/ M5x0.8mm 20mm long countersunk bolts with hex nuts to mount the JMI unit. These bolts were cut down to approximately 17-18mm long. However the adapter comes at a cost of 5mm of backfocus, if that's critical.
I have attached photos of the design, the printed item, and the STL files in case anyone else needs to print their own. Details of the print are:
0.4 nozzle
0.2 layers
25% infill
PLA
Hope this helps someone out :)
Cheers
I recently purchased a JMI EV focuser to replace the standard unit on my Skywatcher 8" reflector. The existing bolt spacing is about 86x76mm and the JMI unit is 70mm square. As the Skywatcher unit has a large diameter (92mm) locating ring on the bottom of the focuser plate, there is a large hole in the scope tube which doesn't leave much material left to safely drill 4 new holes.
So rather risking drilling 4 holes close to the edge (and the anxiety that comes with drilling into a telescope), I designed an adapter plate to utilise the existing bolt holes that I can bolt the new focuser to. The existing bolts that held the Skywatcher focuser are reused, and I had to purchase 4/ M5x0.8mm 20mm long countersunk bolts with hex nuts to mount the JMI unit. These bolts were cut down to approximately 17-18mm long. However the adapter comes at a cost of 5mm of backfocus, if that's critical.
I have attached photos of the design, the printed item, and the STL files in case anyone else needs to print their own. Details of the print are:
0.4 nozzle
0.2 layers
25% infill
PLA
Hope this helps someone out :)
Cheers