Subject: Re: [sloan-25mlog 3756] 2.5m obslog 20171112 (SJD 58070)
From: John Downey
Date: Mon, 13 Nov 2017 08:33:06 -0700
Yes, Nick always handled this. =20
I do not know who is now coordinating fiber work.  As far as I can =
remember, ferrules and anchor blocks are made by the UW machine shop, =
and the parts (including fiber) would be shipped to C-Tech for assembly. =
 I don't know where Nick got the fiber, but I do recall that he said it =
was a bit difficult to source a coherent bundle product at the required =
diameter.  The last time we had acquisition fibers made I believe there =
was fiber on hand already at UW.  If there is some there still this gets =
a bit easier.
> On Nov 13, 2017, at 8:13 AM, mark klaene  wrote:
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> sounds like we definitely need to order some and at this point , can a =
different design , really be that much worse?  doesnt sound like it.=20
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> I assuem Nick has done this ordering in the past , who will now?
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> mark=20
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> On Nov 13, 2017, at 8:00 AM, John Downey wrote:
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>>=20
>>>=20
>>> * Cart 4 has NO Acquisition fibers!
>>=20
>> I'll replace them the first day it is to be unplugged.
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>> Last week I took an inventory of dead & failing fibers.  We have 12 =
dead between all cartridges and 13 in various states of decay.  I =
usually wait until both are dead to replace them, but I don't need to do =
it that way if it causes problems during observing - please let me know =
if it would be better to replace them individually instead.
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>> On hand we have 34 new acquisition fibers, in ~6 months I'll have =
probably used the bulk of them, so we will then need another significant =
batch of them.  A batch of forty seem to be good for 1 year to 18 =
months.
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>> At this point, before we're in a mad hurry to get them made, we =
should discuss whether or not a redesign is necessary.  Dan Long found =
that this generation of fiber tends to fail a bit earlier, and right at =
it's anchor block.  We currently add some vinyl tubing in an attempt to =
reduce bending stress there, but it only buys us a few months.  Dan's =
theory is that the practice of fixing the furcation tubing and both ends =
of the assembly tended to add stress to the plastic fiber, and that we =
should try two pieces of tubing that telescope and can slide to better =
accommodate bending.  I believe he said the earlier fibers were made =
that way, but I will look around for some of them this morning to =
confirm that.
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