I’ve already recovered the rxblog server. I hope every things will be okay.
24 degree levation
From: Patrick Michel Koch
To: mchen
Subject: For archive: AMiBA 24 degrees elevation
Dear MingTang,
attached 2 images when we ran into the 24 degrees elevation
problem – just for your archive.
Hopefully not to be seen again in future.
Cheers,
Patrick
Platform Measurement /Ring
From: raffin@asiaa.sinica.edu.tw
Subject: Re: measurement platform/ring
Date: June 4, 2005 3:41:38 PM HST
To: mchen@asiaa.sinica.edu.tw, ydhuang@asiaa.sinica.edu.tw, koconnell@sma.hawaii.edu
Hi all,
Yesterday, Joshua and I measured the distance between the platform pins
with a better accuracy than the first one Ted and I did with a regular
measuring tape.
The setup can be seen on the pictures:
– 2 slotted aluminum cylinders nicely sliding on the pins allowing
the rigid measuring scales to go through. i had Dayton-Jackson make
those. screws to lock in place during setup and reading
– 2 continuous reading stainless scales
– scales supported along their length by a 2 meter channel
– channel supported on the ground to avoid sag
I think that the error on the measurement is less than 1 mm. (reading
error better than 1/4 mm)
We reproduced the measurements twice, with a new setup each time, and
we got very consistent results.
The results are of the same order of magnitude that the measurements we
did together, but not at the same location. i probably misread the
tape last time, not having my right glasses!
the resulting values are=
A1A2 2410.6 mm ( 1.4 mm)
A2A3 2412.15 mm ( 3.0 mm)
A3A1 2413.1 mm ( 3.8 mm)
According to drawing the distance should be: 2409.15 mm.
This, actually is not too surprising when thinking about it, given the
platform assembly tolerances. I don’t think we can do any better.
This leads however to a quite tricky problem for the interface ring. I
can think of 2 ways of proceeding:
***** Solution A
– Give these measured values to Moo, and ask him to drill only the big
holes for the interface pins, so 6 holes total.
– dismount, paint and ship the ring to mlo
– at mlo, assemble the ring, position the platform precisely on top of
the interface ring, and mark the holes for the M20 bolts (need a crane
or boom truck?)
– bring down to hilo the 3 A-sections and have Dayton Jackson drill the
6×12 holes.
– ship the 3 pieces back to mlo, and proceed with re-assembly of the
ring and integration of platform/ring to hexapod.
***** Solution B
– align the 3 interface plates as precisely as we can under the platform
– connect the 3 interface plates (with tbd adjustable, and dis-mountable
templates) to locate them in the plane. It can be tubes, or a device
connecting the 6 pins with threaded rods and nuts as suggested by Kevin
– write down the lengths, dismount and ship to Moo.
– setup these templates with our 3 flat plates on the ring
– have Moo drill the holes.
Other solutions exist, but the first one is the safest, I think,
slightly more expansive as we have to ask Dayton to drill holes (not a
big cost I would think) and rent a crane for one more day/trip. My
concerns with the second solution is the reproducibility of the mlo setup.
Please let me know your comments,
thanks,
regards, philippe
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