23 Nov
2012
23 Nov
'12
7:57 p.m.
Thanksgiving notes, Saturday November 24th.
Today
-Finished the last of 5 RPS schedules today! So we got all dk angles observed with the RPS
on Keck.
-RX3 and RX4 continue to warm up on the mount, on track to be warm on Monday.
-Took the far field flat off this morning! Yahoo.
-RX0,RX1,RX2 are cooling back down and are all ~4K
-RPS taken down off DSL mast and in Mapo lab now.
-FTS arrived and is in DNF
-The uber chopper stopped spinning two days ago. When we took it apart it was clear that
the gears inside the motor are messed up. The problem feels mechanical not electrical when
you spin the shaft by hand. We have a spare, but
Tomorrow(Sunday)
-Take it easy a bit
-Continue to warm up, remove back side electronics
-Put RPS up for BICEP2 to observe.
Monday
-Take the two cryostats off the mount
-Begin to take cryostats apart
-----Original Message-----
From: keckarray-bounces(a)lists.stanford.edu on behalf of Colin Bischoff
Sent: Fri 11/23/2012 12:28 PM
To: Keck Array; BICEP2 group
Subject: [keckarray] South Pole notes, 2012-11-23
hi all,
We have been progressing well on that schedule that Zak sent around a
couple of days ago. We have been keeping the observation logbook up to
date (and it should be rsyncing to North America) so check it for details:
http://spud.spa.umn.edu/~keckdata/keckdaq_obs_logbook.html
* Last night, we shut off the compressors for rx3 and rx4. This was done
in series, so that we could check them both for He3 using the RGA. Both
tests came out negative, which is good. Rx3 seemed to have a
significantly worse vacuum, but that might have been due to small leaks
in our vacuum hose system.
* We are currently running the last of the five Keck RPS schedules,
expecting to finish Saturday morning. This schedule has rx1 centered at
the back of the mirror, with some mirror coverage for rx0 and rx2.
* Saturday - Take off the Keck ffflat, with help from Jon Kaufman and
Steele. Take down the RPS from the DSL mast and move it to the MAPO mast
for B2 calibrations.
* Sunday - Recover from Thanksgiving. Remove back-end electronics from
rx3, rx4. If necessary, finish setting up the RPS for B2.
* Monday - Take rx3, rx4 out of the mount and start disassembly.
* Tuesday - Finish rx3, rx4 disassembly.
* Wednesday - Grant and Howard remove the one good tile that we plan to
keep at pole for potential installation into the rx1 focal plane.
* Thursday - Zak leaves, hand carrying two FPUs.
-colin
_______________________________________________
KeckArray mailing list
KeckArray(a)lists.stanford.edu
https://mailman.stanford.edu/mailman/listinfo/keckarray
23 Nov
23 Nov
8:16 p.m.
New subject: [keckarray] South Pole notes, 2012-11-24
On 11/23/12 7:57 PM, Staniszewski, Zachary (Guest) wrote:
-The uber chopper stopped spinning two days ago. When
we took it apart it was clear that the gears inside the motor are messed up. The problem
feels mechanical not electrical when you spin the shaft by hand. We have a spare, but
I'm glad we sent a spare motor down. We can buy and send another, but
is it your impression that the motor is undersized? I would suspect
yes. That's my fault--Sam had sourced a larger motor which I rejected
as too heavy for our mass budget. But perhaps we need an extra few
pounds of motor for this beast. Let us know either way what you guys
think, and we can plan a field upgrade of the uber chopper in January.
John
--
___________________________________________________________________
John Kovac jmkovac(a)cfa.harvard.edu
Assistant Professor, Astronomy and Physics, Harvard University
160 Concord Ave rm 310, Cambridge MA 02138, 617-496-0611
9:06 p.m.
New subject: [keckarray] South Pole notes, 2012-11-24
hi John,
I second Zak's comment that the problem is in the motor gearing. We
opened the motor up and could see the smallest gear spinning just fine
when it was powered. It just wasn't engaging with the next gear, which
somehow got pushed out of position. All of the gear teeth still look fine.
I haven't gotten around to reassembling it with the spare motor that
Howard brought down. Installation of the uber chopper has been
surprisingly easy though, so a bigger motor might be an excellent idea.
-colin
On 11/24/2012 02:16 PM, John Kovac wrote:
On 11/23/12 7:57 PM, Staniszewski, Zachary (Guest) wrote:
-The uber chopper stopped spinning two days ago.
When we took it apart it was clear that the gears inside the motor are messed up. The
problem feels mechanical not electrical when you spin the shaft by hand. We have a spare,
but
I'm glad we sent a spare motor down. We can buy and send another, but
is it your impression that the motor is undersized? I would suspect
yes. That's my fault--Sam had sourced a larger motor which I rejected
as too heavy for our mass budget. But perhaps we need an extra few
pounds of motor for this beast. Let us know either way what you guys
think, and we can plan a field upgrade of the uber chopper in January.
John
25 Nov
25 Nov
5:24 p.m.
Colin,
I suspected this might happen. If you want to give it another go with the
small motor make sure the brass collar is tight to the black thrust bearing
and constrains the linear motion of the fan blade shaft. I bet a gust of
wind on the fan blade pulled the motor gears out of place.
In the mean time, I'll draw up some modifications and get the new parts
ready to go down there.
Sam
On Fri, Nov 23, 2012 at 9:06 PM, Colin Bischoff <cbischoff(a)gmail.com> wrote:
hi John,
I second Zak's comment that the problem is in the motor gearing. We opened
the motor up and could see the smallest gear spinning just fine when it was
powered. It just wasn't engaging with the next gear, which somehow got
pushed out of position. All of the gear teeth still look fine.
I haven't gotten around to reassembling it with the spare motor that
Howard brought down. Installation of the uber chopper has been surprisingly
easy though, so a bigger motor might be an excellent idea.
-colin
On 11/24/2012 02:16 PM, John Kovac wrote:
>
>
> On 11/23/12 7:57 PM, Staniszewski, Zachary (Guest) wrote:
>
>> -The uber chopper stopped spinning two days ago. When we took it apart
>> it was clear that the gears inside the motor are messed up. The problem
>> feels mechanical not electrical when you spin the shaft by hand. We have a
>> spare, but
>>
>
>
> I'm glad we sent a spare motor down. We can buy and send another, but
> is it your impression that the motor is undersized? I would suspect
> yes. That's my fault--Sam had sourced a larger motor which I rejected
> as too heavy for our mass budget. But perhaps we need an extra few
> pounds of motor for this beast. Let us know either way what you guys
> think, and we can plan a field upgrade of the uber chopper in January.
>
> John
>
>
--
Samuel A. Harrison
508-982-6276
samuel.a.harrison(a)gmail.com
4192
days inactive
4193
days old
bicep2-list@lists.fas.harvard.edu
3 comments
4 participants
participants (4)
-
Colin Bischoff -
John Kovac -
Samuel Harrison -
Staniszewski, Zachary (Guest)