Acquisition Camera: TaskList to check Flexure

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Acquisition Camera Task-List to check Flexure

• Date first created 02/05/04
• Date last modified02/06/04

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Task1 (Repeat Georges Measurements)

• To Do
• Remove Cover on Acquisition CameraAC and check
  to make sure all of the guts are bolted down
  adequately. Also check bolts holding structure
  together
• Replace covers, making sure all bolts are torqued
  down adequately
• Also, check George Mount bolts
• Check bolts that secure the XY stage from inside
  AC
• Question Is this possible without removing the
  AC from the Telescope? George?

Georges Measurements 10-29-03
(Phone) a)Attached indicator to George Mount
measured flexure on XY stage saw from .004 to
.006 movement. b)Measured flexure at location of
POM saw .013 movement George for b) where did
you attach the magnetic base to? AO-Spool?
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Task2 (XY Stage)

• To Do
• Check XY stage for proper functioning.
• Check anti-backlash feature.
• Does stage repeat!
• Is the holding torque of brakes adequate to
  prevent movement of AC assembly?

NOTE Weights AC 79 lbs Stage 50 lbs George
Mount 30 lbs POM 3 lbs
To check for backlash Can unit supported by XY
stage be moved when brakes are on?
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Specs forXYR Stage XYR-1212-P-5TPI-150SM

• Features
• X-rolled ways
• Hall Limit Switch
• Anti-backlash nut
• Precisions grade

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Task3-1(Deflection Tests)

• To Do
• Check the stiffness of the interface shown at
  right
• Use Push-Pull scale and indicator (Strain Gauge)
• Do this with Telescope at Zenith. Push with 5 lbs
  and measure deflection at same location. See next
  slide.

Weak side
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Task3-2
Top covers must be on for this measurement
Dial Gauge
F
See also FEA analysis of the support structure at
the end of .ppt
Dial Gage Attached to AO-Spool with Magnetic Base
Use F5 lbs, same as in FEA Analysis
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Task4 (POM Assembly Integrity)

• To Do
• a) Is POM Assembly accessible while on Telescope?
  George? If so.
• b) Check if POM itself is moving in its housing
• c) Are Springs working properly?
• d) Are Springs made from Spring Material?
• e) Are Bendix Pivots clamped tight?
• f) Is anything touching the top of the AO
  Structural Assembly

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FEA on George Mount Results

This FEA was done 10-29-03 From e-mail to
George. Hi, To get an idea for the structural
stiffness of the George Mount a simulation was
done. A jpg showing the results of the FEA is
attached. (georgefea01.jpg) FEA Model Setup 1)
The Load was taken to be 160 lbs and is acting in
the z-direction.(see triad in jpg.) The load is
due to the Acquisition Camera and its
contents, in addition to the large X-Y Stage.
This is a worst case scenario,the case where the
telescope would be horizontal. 2) The mounting
surface that in practice bolts the George Mount
to the AO Spool, is held fixed in the Simulation
Model. FEA Results The maximum displacement seen
in the FEA Model is .0021 inch with a top stress
of 1540 lbs/in2 I recall a number .013 inch that
George measured. It appears that the George Mount
is not wholly responsible for the flexure. Where
does the rest of the flexure come from? The 
stiffness of the Structure that holds the POM was
analyzed when the Acquisition Camera was built.
Deformations were found to less than .001 inch.In
this case, a 10 lbs load was assumed for the
POM. Further Comments The structures were
analyzed not using any bolted joints. If the
bolts in the real structures are not fully
tightened, flexures are the result. A further
area to check is the POM and its mounting. Did
anything change? Has this flexure been seen when
the Acquisition Camera was in place? Has it been
measured the same way? Vern     For an analysis
of the Acquisition Camera see end of .ppt
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Acquisition Camera FEA-1
POM simulated with a 5 lbs load Gravity included
in Analysis, both acting in y direction. Max
deflection is 0.00094 inch
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Acquisition Camera FEA-2
Summary No deflection greater than .001 inch
observed in analysis with a simulated POM load of
5 lbs and Gravity included Length of Finger is
19.75 inch
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Summary

• The .004 to .006 inch movements that George
  measured between the George Mount and the XY
  stage tells us that we need to take a closer at
  this stage. If memory serves me correctly, the
  stage was once driven to its ends and had to be
  forced out of this position.
• Adding the maximum deflections that were obtained
  in the FEA analysis of the George Mount and the
  Acquisition Camera we should observe a relative
  movement from the George Mount to the location of
  the POM of about .003 to .005 inch.This is
  nowhere near the .013 inch that George reported
  seeing.
• Since the Acquisition Camera, when either mounted
  on the George Mount or on the AO Structural
  Assembly, is directly coupled to the AO Spool,
  there should be no differential movement between
  them.
• George and Doug Can you please review this
  document. Give me whatever feedback you can think
  of. George, there are also some questions for you
  on some of the slides.