APA frame inspection

David Payne

24/10/20

Procedure

● Basicly as defined in PSL TN-2016-03

● Some slight alterations● Frame was in wire

winding frame not free● Survey tool was FARO

Vantage laser tracker

Point location tools

● Workshop at Liverpool made us some custom tools to precisely locate reflector at measurement points

Cross corner deviation

● Tolerance: 2.0mm (1mm target)● On table measurement not possible

– Best alternative was using edging tool, constructing edge lines and corner points, taking distance between points:

Measurements and co-ord system

● 6 points along each beam, 5 along head and foot.– P20 unreachable

due to winding frame- moved to next available point

● Co-ord system defined by plane of P1,P6,P12,P17, origin P20

Flatness and twist

(all mm)

● Overall flatness tolerance: 11.0mm

● Overall twist tolerance 1.0 mm/m (?)

● Split into 5 twist zones (same tolerance)

● Zone 5 shows worst twist, but all within tolerance

Comparison to PSL survey

Daresbury PSL

Bowing (beam by beam)

● Deviation from line between head and foot in z (all mm)

● Tolerance 11.0mm

“right”

“left”“middle”

Straightness

● Straightness of board mounting surfaces

● Deviation in y● Tolerance: 1.5 (1.0 target) ● (all mm)

“middle” (no defined tolerance)

“left”Max y dev. -1.5

“right”Max y dev.-1.2

Comparison to PSL: Straightness

Daresbury

PSL

“Right” “Middle” “Left”

Comparison to PSL

Daresbury PSL

Fold

● Displacement in z of side beams relative to centre beam and z of head and foot

● Tolerance 1.2 mm

z

Fold 1.7 mm

Foot tube Rib 1 Rib 2 Rib 3 Rib 4 Head tube

Fold -0.8 mm

Fold -0.1 mm

Fold -0.6 mm

Fold 1.3 mm

Fold 1.3 mm

Where is “folding” coming from?

● Have measurements along edge of head tube (used in slide 3)

● Suggests deviation is not in frame, but in reference points, or in method used to locate them

● Point location tools lift reflector some distance away from frame– Could be picking up and

amplifying surface shape

De v

iatio

n in

z fr

o m s

t ra

i gh t

y

Summary

● APA surveyed in wire winding frame– Not according to original survey

conditions– Twist and bowing within tolerance– Straightness worse than target

but within tolerance– 3 fold measurements outside

tolerance

Fold: rib 3

Fold 1.3 mm

Fold: rib 4

Fold 1.7 mm

Fold: Head tube

Fold 1.3 mm