TS-Optics 2" MONORAIL M90 Focuser
The TS Monorail focuser for 6" and 8" RC telescopes from TS-Optics, GSO and AstroTec and for several refractors from Sky-Watcher is an improvement of the time-tested Crayford focusers. Our goal was to offer a focuser for highest loads, like heavy CCD cameras, with very high precision at the same time. We exactly succeeded in this with the Monorail focusers.
At the telescope side, the MonorailM90 has an M90x1 thread with 7.5 mm depth and 360° rotation. This allows a connection to various telescopes and is ideal for hobbyists. But Teleskop-Service also offers an individual adapter solution for all people who do not have access to a lathe. The suitable item has the number Sonder-M90.
The advantages of the TS Monorail focusers at a glance:
♦ higher load capacity than with normal Crayford focusers - instead of small ball bearings, a massive stainless steel rail, which is laterally clamped, is used.
♦ more precise guiding of the draw tube and no more tilting when locking
♦ smooth motion and finest adjustment even at loads of up to 4 kg
♦ 1:10 dual speed for accurate focusing
♦ Motor focus can be retrofitted
Operating principle of the Monorail focuser and the advantage compared with Crayford focusers:
Instead of small ball bearings, like in Crayford focusers, a massive stainless steel rail handles bearing and also lateral fixing.
The disadvantage of Crayford focusers with ball bearings: The small ball bearings of the Crayford focuser are loaded if locked. As the locking screw is not placed exactly between the ball bearings, one pair of the bearings is more heavily loaded. This results in tilting and unsharp stars in one corner.
The advantage of the MONORAIL principle: The function of the ball bearings is taken over by the stainless steel bar which is firmly connected to the draw tube. Nothing can bend anymore. Only lateral guidance is taken over by ball bearings. These bearings only fix the lateral position and do not need to take on load anymore.
The drawtube is fixed with a locking screw which is exactly centered at the upper side, so the entire construction is evenly loaded. Tilting is definitively avoided, the draw tube stays exactly at the given position.
With the middle screw of the "quincunx", only the friction is adjusted - see image at left.
