CM25 Engineering 1 4 Nov 2009 DIFFUSER Carousel (~50kg) Driven by air motors – 3 separate ‘actions’ 1.Carousel rotation 2.“30 degree rotation’’ Transfers discs from carousel to carrier 3.Carrier Moves disc in/out of solenoid

CM25 Engineering 2 4 Nov 2009 STATUS – 3 Nov 2009 Mechanics reassembled – Survived basic tests – more required including: Motor speeds Positioning accuracy Bedding-in of gears…. Electronics & Air Crates working LabView controls starting (EPICS can wait) Developing disc transfer operation – critical item – next slides 

CM25 Engineering 3 4 Nov 2009 DISC TRANSFER Disc Holder  Disc  Carrier Carousel rotation D-H Rotation Carrier motion   Discs transferred between Disc Holders and Carrier Each disc has 4 pins on each side to fit 4 holes 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 Pin – hole clearance is +/-- 0.5mm  3 sigma positioning < 0.5mm  Position to < 0.15mm for varying loads on Carousel

CM25 Engineering 4 4 Nov 2009 DISC TRANSFER OPERATION Need to understand this in detail Forces & reactions Potential fouls Friction? Some latches for pins will help Being developed Space is limited

CM25 Engineering 5 4 Nov 2009 Not easy to achieve required accuracy of 0.15mm or better Air motors overrun (but deliberately very slow now) Now use piston to align Carousel arm Measured misalignment is ~ 0.5 mm Depends on load (lead is heavy) Design was not tolerant of any misalignments Have incorporated float + springs in carrier for L – R and U – D misalignment (1mm / 0.3mm) Developing overrun & locking mechanisms for discs Keep pins aligned in disc-holders & absorb overruns More springs…. Building mock-up of Disc-Holder – Carrier arrangement Test various ideas for locking the pins Develop transfer procedure – invisible on real device Allowed 9 weeks in schedule for this (& other tests) May need more inspiration & imagination Transfer operation development on critical path

CM25 Engineering 6 4 Nov 2009 DISC XFER MOCK-UP & PIN-LOCKS

CM25 Engineering 7 4 Nov 2009 STILL TO DO Hardware – Install & commission: – Shaft encoder read heads – Black / gold rings for disc-holder alignment Firmware – Develop FPGA firmware & RS232 interface – Incrementally Software – Develop LabView controls – In parallel with firmware Once LabView controls developed migrate to EPICS – Would be a distraction at present

CM25 Engineering 8 4 Nov 2009 SOME OTHER CONCERNS Compressed air pressure in Oxford is rather low – Would like > 6 bar; can get 4 – 5 bar depending on other users – Need to understand how speeds depend on P – Can possibly improve a bit – Motors run a bit slow Hope overruns are small & do not depend critically on pressure Installation on Spectrometer Solenoid – Flatness of end plate (align to small fraction of mm…) – Awkward; may need shimming Operation in magnetic field – Most – but not all – ferromagnetic components eliminated – esp. v. small bearings in gear boxes on motors – Have spare motors; run with field off ?? Quenches – Potentially large forces – Distortion & loss of critical alignment

CM25 Engineering 9 4 Nov 2009 ASPIRATIONAL SCHEDULE