1. CM24 1 1 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

2. CM24 2 1 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

3. CM24 3 1 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