On Rowe-Ackermann Schmidt-Astrographs RASA 11" or RASA 36cm systems it can happen that the respective RASA UFC adapter ( Baader UFC S70 11" RASA Telescope-Adapter (optical height: 3 mm) (#2459126, € 95,-) or Baader UFC S70 RASA 36cm Telescope-Adapter (optical height: 3 mm) (#2459135, € 225,-) ) slips laterally to the Schmidt plate, when the telescope moves from east to west. Since the RASA systems do not have a lateral centering collar, the adapter can slip a few tenths of a millimeter. This problem can only be solved by friction.
Therefore it is very important to strongly tighten the union nut first.
In addition, since April 2020 we have slightly roughened the flange surfaces of the adapters to increase friction at this point and prevent slipping.
For all adapters delivered previously, we therefore recommend doing this procedure afterwards. For this purpose we recommend a normal sandpaper with approx. 180 grit.
We also recommend cross sanding as in the video below to prevent slippage in both the X- and Y-axis.