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MOFOD MkII Fork Friction Mount
Gemini MOFOD MkII Fork Mount is the ideal solution for demanding astronomy applications (public, school, society or professional observatories). The Modular Fork Design allows changing the OTA by sliding the fork arms in or out. MOFOD Fork Mount is the most stable observatory class mount with remote control. Join the Gemini Friction Fork Revolution!
Gemini MOFOD MkII Fork Mounts have the following advantages over German Equatorial mounts:
- No counterweight needed – smaller inertia can be rotated faster.
- No meridian flips needed – no lost time.
- No guider recalibration or field rotation needed.
- No collision with the pier is possible – more safety in remote mode.
Disadvantage? Forks were not as flexible to changing OTA as German Equatorial mounts. But the Modular Fork Design allows changing the OTA by simply sliding the fork arms out or in. Any compact telescope from 340-mm to 540-mm wide can ride this fork.
What is Modular Fork Design (MoFoD)? The MOFOD Fork Mounts are easily separated into 4 main parts: the RA base, the horizontal arm (tube) and the two fork arms. The orthogonality of the main axis is adjustable, ensuring maximum pointing precision. Two persons can do the setup in 1 hour with a set of Hex keys.
Technical parameters: The mount rests on a robust RA head that sits in an aluminium casting, holding two large tapered roller bearings. The shaft upper (larger) diameter is 140-mm . To drive the mount we choose friction drives for their very low PE and rock solid operation. The slight backlash present in large worm gears or the trend to vibrate if unbalanced is absent and the slewing speeds are very high with low power consumption. Safety clutches are mounted in both axes to prevent damage to the drive system or the OTA. In case of a collision the drive system will stop the motors within 5 seconds.
To ensure precision in pointing and reliability in remote mode high resolution encoders are mounted on each axis. The encoders have an absolute reference point that enables the driver to find the home position after a blackout or crash of the control PC. The stepper motors have 0,1″ resolution.
The optional 1kg sliding weight inside the horizontal fork arm allows fine balancing the OTA for best operation. Coarse balancing is achieved by sliding both fork arms with the OTA in the correct direction.
Specifications:
- Materials: Zink plated steel, powder coated (base), cast aluminium, 6082 aluminium (RA housing and shaft), stainless steel, (fork arms), tapered roller bearings, stepper motors, high resolution optical encoders.
- PE: ca 5” ptv in 30 minutes
- Weight: RA base ca 55 kg, Horizontal arm ca 13 kg, Fork arms with drive ca 27kg.
- Payload: 70 kg
- Pier interface: D360-mm circular
- Accepted OTAs: from 25 cm up to 45 (optics diam.) cm or multiple smaller instruments. The typical OTA for a fork is any Cassegrain derivant (RC, DK, SC, MC) or a fast Newtonian. The fork has 600mm free swing for the eyepiece end of the OTA.
- OTA interface: 3” Losmandy female (400mm male rails supplied upon request) or flat plate for tube rings.
- Price includes Pulsar ASCOM GoTo Control.
