CM June 2009 ASPIRATIONAL SCHEDULE Mechanics is reassembled; survived basic tests but more required – including positioning accuracy, bedding-in of gears…. Electronics & Air Crates working; LabView controls starting (EPICS can wait) Developing ‘Disc transfer Mechanism’ – critical item – next slides  Done Ongoing Started Starting Done

CM June 2009 DISC TRANSFER CONCERNS Simplified Disc Holder  Disc  Carrier Carousel rotation D-H Rotation Carrier motion   Discs are transferred between Disc Holders and Carrier Each disc has 4 pins to fit 4 holes on each side Each disc has 2 Sides There are5 Discs Each has (up to)4 Orientations  160 pins & holes to align reliably & reproducibly – or something will bend / break / jam & it’s buggered Pin – hole clearance is +/– 0.5mm  3 sigma positioning < 0.5mm  Position to < 0.15mm for varying loads on Carousel

CM June 2009 Not easy to achieve required accuracy Air motors overrun by several mm, depending.... Now use piston to align Carousel arm Measured misalignments are ~ 0.5 – 1mm Depend on loading (lead is heavy) Design is (was) not forgiving of any misalignments Have incorporated ‘float’ + springs in carrier For L – R and U – D misalignment (1mm / 0.3mm) Designing & developing overrun & locking mechanisms for discs To keep pins aligned in disc-holders & absorb overruns More springs / ‘Terry clips’ …. (? Lead times if custom items?) Shall build mock-up of Disc-Holder – Carrier arrangement To test various ideas for locking the pins & overrun ‘buffers’ To develop transfer procedure – almost invisible on real device Have allowed 9 weeks in schedule for this (+ other tests) May need more inspiration & imagination Transfer operation development on critical path