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  10822   Fri Dec 19 19:21:04 2014 diegoUpdateCDSSOS!!! HELP!! EPICS freeze 45min+ so far!

Quote:

[Jenne, Diego]

The EPICS freeze that we had noticed a few weeks ago (and several times since) has happened again, but this time it has not come back on its own.  It has been down for almost an hour so far. 

 So far, we have reset the Martian network's switch that is in the rack by the printer.  We have also power cycled the NAT router.  We have moved the NAT router from the old GC network switch to the new faster switch, and reset the Martian network's switch again after that.

We have reset the network switch that is in 1X6.

We have reset what we think is the DAQ network switch at the very top of 1X7.

So far, nothing is working.  EPICS is still frozen, we can't ping any computers from the control room, and new terminal windows won't give you the prompt (so perhaps we aren't able to mount the nfs, which is required for the bashrc).

We need help please!

[EricQ]

 

EricQ suggested it may be some NFS related issue: if something, maybe some computer in the control room, is asking too much to chiara, then all the other machines accessing chiara will slow down, and this could escalate and lead to the Big Bad Freeze. As a matter of fact, chiara's dmesg pointed out its eth0 interface being brought up constantly, as if something is making it go down repeatedly. Anyhow, after the shutdown of all the computers in the control room, a  reboot of chiara, megatron and the fb was performed.

 

[Diego]

Then I rebooted pianosa, and most of the issues seem gone so far; I had to "mxstream restart" all the frontends from medm and everyone of them but c1scy seems to behave properly. I will now bring the other machines back to life and see what happens next.

  10823   Fri Dec 19 20:32:11 2014 diegoUpdateCDSSOS!!! HELP!! EPICS freeze 45min+ so far!

[Diego, Jenne]

 

Everything seems reasonably back to normal:

Notes:

  • the machines in the control room have been rebooted;
  • the c1iscey frontend now behaves;
  • I saw on nodus, which remained up and running the whole time, a bunch of   nfs: server chiara is not responding, timed out  messages, belonging to the freezing time; it may be that the sync option for the nfs share is too resource demanding, or some other network issue;
  • the FSS was doing strange stuff and the MC couldn't recover the lock; the MCautolocker script wasn't running because of the lock loss of the MC and the lack of communication between the machines; so we did a sudo initctl start MCautolocker on megatron and recovered the MC too.
  12379   Fri Aug 5 09:38:12 2016 SteveUpdateSUSSOS sus wire ordered

0.0017" OD., 500ft steel music wire ordered. Pictures of the existing roll are below. It will be on 8" OD. spool too.

 

Attachment 1: 0.0017.jpg
0.0017.jpg
Attachment 2: 0.0017spec.jpg
0.0017spec.jpg
  12409   Mon Aug 15 14:29:32 2016 SteveUpdateSUSSOS sus wire ordered

The wire will arrive in 1-2 weeks. It is a new production. Brad Snook of Ca Fine Wire was suprised that we are still using the 13 years old wire.  Oxidation is an issue with iron contained steel wire.

He would not give me a shelf life time on it. He recommended to check the strenght of it before usage. It passed with safety factor of 2 just recently.

In the future we'll store the new spool in oxigen free nitrogen environment..

Quote:

0.0017" OD., 500ft steel music wire ordered. Pictures of the existing roll are below. It will on 9" OD. spool too.

 

 

  12410   Mon Aug 15 14:34:33 2016 ericqUpdateSUSSOS sus wire ordered

We have indeed seen numerous tarnished/rusty points along the wires, and just tried to choose lengths free of any of these. I wonder if this can explain the brittleness/ease with which we've been breaking it. My feeling is that we should use the newer wire if feasible.

  12419   Wed Aug 17 22:09:04 2016 ranaUpdateSUSSOS sus wire ordered

Not really true that it passed. That's just an arbitrary margin. Best to throw away all the old wire. We have no quantitative estimate of what the real torque should be. Its just feelings.

Quote:

The wire will arrive in 1-2 weeks. It is a new production. Brad Snook of Ca Fine Wire was suprised that we are still using the 13 years old wire.  Oxidation is an issue with iron contained steel wire.

He would not give me a shelf life time on it. He recommended to check the strenght of it before usage. It passed with safety factor of 2 just recently.

In the future we'll store the new spool in oxigen free nitrogen environment..

 

  12423   Thu Aug 18 15:16:09 2016 SteveUpdateSUSSOS sus wire is in

 

Stress Relieved 0.0017"  Music Wire  CFW P/N: CFW2035025,   Made 08-17-2016                                

    Old  2003    New  2016  
GBL 358.9 240.610 grams
UTS 357,061 229,603 PSI
YTS 343,211 177,371 PSI
ELONG 2.38 0.8 %
HEAT 10622 10622  

GBL (grams breaking load )         

UTS (ultimate tensile strength)                                 

YTS (yield tensile strength) 

ELONG (elongation)  

Quote:

0.0017" OD., 500ft steel music wire ordered. Pictures of the existing roll are below. It will be on 8" OD. spool too.

 

 

Attachment 1: 0.0017new.jpg
0.0017new.jpg
  3581   Fri Sep 17 03:06:06 2010 KojiUpdateSUSSOS sent for baking

Two SOS suspensions for the ETMs were disassembled and packed for cleaning and baking by Bob.

These suspensions have been stored on the X end flow bench long years, and looked quite old.

They have some differences to the modern SOSs.

- The top suspension block is made of aluminum and had dog clamps to fix the wires.
- The side bars are not symmetric: the side OSEM can only be fixed at the right bar (left side in the picture).
- EQ stops were made of Viton.
- One of the tower bases seems to have finger prints (of Mike Zucker?).

I found that the OSEM plates had no play. We know that the arrangement of the OSEMs gets quite difficult
in this situation. Therefore the holes of the screws were drilled with the larger drill.

We decided to replace all of the screws to the new ones as all of the screws are Ag plated and got corroded
by silver sulfide (Ag2S). I checked our stock in the clean room. We have enough screws.

Important note: Use stainless screws in aluminum / Silver-plated screws in stainless
There exists some study about galling: LIGO-G020394-00-D

Attachment 1: IMG_3596.jpg
IMG_3596.jpg
Attachment 2: IMG_3597.jpg
IMG_3597.jpg
  15267   Wed Mar 11 21:03:57 2020 KojiUpdateBHDSOS packages from Syracuse

I opened the packages send from Syracuse.

- The components are not vacuum clean. We need C&B.
- Some large parts are there, but many parts are missing to build complete SOSs.

- No OSEMs.
- Left and right panels for 6 towers
- 3 base blocks
- 1 suspension block
- 8 OSEM plates. (1 SOS needs 2 plates)

- The parts looks like old versions. The side panels needs insert pins to hold the OSEMs in place. We need to check what needs to be inserted there.

- An unrelated tower was also included.

Attachment 1: P_20200311_203449_vHDR_On.jpg
P_20200311_203449_vHDR_On.jpg
  12264   Thu Jul 7 09:13:54 2016 SteveUpdateSUSSOS gluing fixture

Atm 1, It's right arm is perfect.

Atm 3-4, The left one has bended (dropped) end.

Atm 2, Our ruby wire stanoffs will fit the jig. Ruby OD 1.27 mm vs. old Aluminum OD 1.0 mm. Length ruby 6.4 mm vs Al 4.8 mm

Atm 5, The fixture translation stages are a bit loooose. Careful use of the micrometer is needed to be precise

Betsy agreed that the 40m will keep SOS fixtures.

Attachment 1: SOSgluingFixRarmWend.jpg
SOSgluingFixRarmWend.jpg
Attachment 2: SOSgluingFixRarm.jpg
SOSgluingFixRarm.jpg
Attachment 3: SOSgluingFixLarm45.jpg
SOSgluingFixLarm45.jpg
Attachment 4: SOSgluingFixLarm.jpg
SOSgluingFixLarm.jpg
Attachment 5: SOSgluingFixture.jpg
SOSgluingFixture.jpg
  6039   Tue Nov 29 17:10:39 2011 DenUpdatedigital noiseSOS creation

One of the possibilities that we see a large low-frequency digital noise is due to Foton. I've checked the SOS coefficients that saves Foton with a Matlab coefficients. I used a 3 order low-pass cheby1 filter cheby1("LowPass",3,0.1,3) 

In matlab I generated SOS model using 3 approaches 


[A,B,C,D]=cheby1(3,0.1,3/1024) % create SS form

[sos,g]=ss2sos(A,B,C,D)  % convert to SOS form


[z, p, k]=cheby1(3,0.1,3/1024) % create ZPK form

[sos,g]=zp2sos(z,p,k)  % convert to SOS form


[b, a]=cheby1(3,0.1,3/1024) % create TF form

[sos,g]=tf2sos(b,a)  % convert to SOS form


As this is a 3 order filter, in the SOS representation we'll get 2 by 6 SOS - matrix. It is presented below. In each matrix place there 4 numbers - from the Foton file and obtained using these 3 methods.

GAIN

1.582261654653329e-07

1.582261654653329e-07

1.582261654653329e-07

1.582261655030947e-07

SOS-MATRIX

1              1.0000000000000000      #           0                                              #       1      #         -0.9911172660954457     #       0

1              1.0005663179617605      #           0                                              #       1      #         -0.9911172660954457     #       0

1              1.0000000000000000      #           0                                              #       1      #         -0.9911172660954457     #       0

1              0.9999894976396830      #           0                                              #       1      #         -0.9911172660997303     #       0

############################################################################################################

1              2.0000000000000000      #          1.0000000000000000         #       1      #        -1.9909750803252266      #      0.9911175825477769

1              1.9994336820732397      #          0.9994340026283055         #      1       #       -1.9909750803252262       #     0.9911175825477765

1              2.0000000000000000      #          1.0000000000000000         #      1       #       -1.9909750803252262       #     0.9911175825477765

1              2.0000105023603174      #          1.0000105024706190         #      1       #       -1.9909750803209423       #     0.9911175825434912

 

It seems that smth analog to zp2sos is used in Foton. We can see that due to representation error we have derivations in the 4 and 6 digits for SS and TF forms. This means that a pretty big mistake can run due to digital transforms even using double precision as in the Matlab test.

Alex Ivanov said that he'll fix that single precision problem and in the 2.5 release we won't have any FLOAT variables. Though we still do not understand how that variables declared as FLOAT can cause filter calculations. 

  7469   Wed Oct 3 15:58:57 2012 SteveConfigurationIOOSOS coil drivers moved

The SOS coil drivers (Atm2) were moved from 1X1 to 1Y2 location. Is this the best place to locate the  IOO Tip-Tilt steering that will replace the PJ-PZT ?

See 40m wiki T-T

Attachment 1: SOScoildriversTT.jpg
SOScoildriversTT.jpg
Attachment 2: IMG_1680.JPG
IMG_1680.JPG
  7331   Fri Aug 31 17:50:41 2012 SteveUpdateSUSSOS centering target

The SOS centering target is 1.9 mm lower than it should be! 

The hole is 10mm for the  ~6 mm beam

 

 

 

  14032   Thu Jun 28 16:48:27 2018 gautamUpdateSUSSOS cage towers

For the upcoming vent, we'd like to rotate the SOS towers to correct for the large YAW bias voltages used for DC alignment of the ITMs and ETMs. We could then use a larger series resistance in the DC bias path, and hence, reduce the actuation noise on the TMs. 

Today, I used the calibrated Oplev error signals to estimate what angular correction is needed. I disabled the Oplev loops, and drove a ~0.1 Hz sine wave to the EPICS channel for the DC yaw bias. Then I looked at the peak-to-peak Oplev error signal, which should be in urad, and calibrated the slider counts to urad of yaw alignment, since I know the pk-to-pk counts of the sine wave I was driving. With this calibration, I know how much DC Yaw actuation (in mrad) is being supplied by the DC bias. I also know the directions the ETMs need to be rotated, I want to double check the ITMs because of the multiple steering mirrors in vacuum for the Oplev path. I will post a marked up diagram later. 

Steve is going to come up with a strategy to realize this rotation - we would like to rotate the tower through an axis passing through the CoM of the suspended optic in the vertical direction. I want to test out whatever approach we come up with on the spare cage before touching the actual towers.

Here are the numbers. I've not posted any error analysis, but the way I'm thinking about it, we'd do some in air locking so that we have the cavity axis as a reference and we'd use some fine alignment adjust (with the DC bias voltages at 0) until we are happy with the DC alignment. Then hopefully things change by so little during the pumpdown that we only need small corrections with the bias voltages.

SoS tower DC bias correction
Optic

EPICS excitation

[V pk-pk]

Oplev error signal readback

[urad pk-pk]

Calibration [mrad/V] Current DC bias voltage [V] Required correction [mrad]
ETMX 0.06 110 1.83 -5.5305 -10.14
ITMX 0.02 180 9 -1.4500 -13.05
ITMY 0.02 120 6 -0.3546 -2.13
ETMY 0.06 118 1.97 0.5532 1.09

Some remarks:

  1. Why the apparent difference between ITMs and ETMs? I think it's because the bias path resistors are 400 ohms on the ETMs, but 100 ohms on the ITMs
  2. If we want the series resistance for the bias path to be 10 kohm, we'd only have ~800 urad actuation (for +10V DC), so this would be an ambitious level of accuracy. 
  6344   Thu Mar 1 09:26:50 2012 steveUpdateSUSSOS baffle plates are ready

 Green welding glass 7" x 9"   shade #14 with 40 mm hole and mounting fixtures are ready to reduce scatter light on SOS

PEEK 450CA shims and U-shaped clips  will keep these plates damped.

 

Attachment 1: 03011201.PDF
03011201.PDF 03011201.PDF
  16556   Fri Jan 7 17:59:45 2022 YehonathanUpdateBHDSOS assembly -- SR2

{Yehonathan, Paco}

{Paco, Yehonathan}

Today we suspended SR2 (E1800089) which Anchal has loaded into the thick optic adapter. Attachments 1,2 show the height and roll balance adjustments.

I realigned the opLev setup and balanced the suspended mass. Attachment 3 shows the motion spectra on the QPD. There are major peaks at 723 mHz, 832 mHz, and 996 mHz. I inserted OSEMs and tightened them in place. I adjusted the OSEM plates to make sure the magnets are at the center of the OSEMs, then I tightened the OSEM plates to the SOS tower.

The optic was locked keeping the alignment fixed on the center of the QPD.

Again, we should apply some glue to the counterweight to prevent it from spinning on the setscrew. Is there a glue other than EP30 that we can use?

Related: Peek nuts, screws and washers were ordered from Mcmaster.

Attachment 1: SR2_roll_balance.png
SR2_roll_balance.png
Attachment 2: SR2_magnet_height.png
SR2_magnet_height.png
Attachment 3: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
  16557   Fri Jan 7 18:24:25 2022 KojiUpdateBHDSOS assembly -- SR2

Vacseal in the freezer. It could have been expired sooooo many years ago, We need some cure testing.

Can you release the part numbers of the ordered components (and how/where to use them), so that we can incorporate them into the CAD model?

Quote:

Again, we should apply some glue to the counterweight to prevent it from spinning on the setscrew. Is there a glue other than EP30 that we can use?

Related: Peek nuts, screws and washers were ordered from Mcmaster.

  16561   Mon Jan 10 14:00:44 2022 not KojiUpdateBHDSOS assembly -- SR2

Yes,

For the thin optics adapter design, we want Peek 1/4-20 screw (part # 98885A131) to replace the lower back long EQ stop. On it, we will have a Peek washer (part # 93785A600) fastened between two Peek nuts (part #98886A813).

For the thick optics adapter design, we want Peek 1/4-20 screw (part # 98885A131) to replace both the upper and lower back EQ stop. On the upper stop, we need a single Peek nut (part #98886A813).

I will cure-test the Vacseal.

Quote:

Vacseal in the freezer. It could have been expired sooooo many years ago, We need some cure testing.

Can you release the part numbers of the ordered components (and how/where to use them), so that we can incorporate them into the CAD model?

Quote:

Again, we should apply some glue to the counterweight to prevent it from spinning on the setscrew. Is there a glue other than EP30 that we can use?

Related: Peek nuts, screws and washers were ordered from Mcmaster.

 

  16568   Tue Jan 11 09:53:14 2022 not KojiUpdateBHDSOS assembly -- Peek screws and nuts

I handed the Peek parts we got from McMaster to Jordan for C&B.

  16542   Tue Jan 4 18:27:23 2022 PacoUpdateBHDSOS assembly -- PR3

[yehonathan, paco, anchal]

We continue suspending PR3 today. Yehonathan and Paco suspended the thick optic in its adapter. After fixing some nominal height and undoing any residual roll angle (see Attachments 1,2 for pictures), we noticed a problem with the pitch angle, so we insert the counterweights all the way in. Nevertheless, we soon found out that we needed to shift one of the two counterweights to the back of the adapter side (so one on each side) in order to tare the pitch angle. This is a newly experienced maneuver that may apply for further thick optics.

After taring the pitch angle roughly, we noted another issue. The wedge (~ 1 deg) on the optic made it such that the protruding socket heads on the thick side bumped against the lower clamp (not the earthquake stop tip itself). Attachments #4,5 show the before/after situation which was solved provisionally by replacing the socket head screws with lower profile (flat) head screws in situ. Again, this operation was highly delicate and specific to wedged thick optics, so for future SOS we should keep it in mind.

Another issue that we had with the new thick optic adapters is that for some reason there is a recession in the upper backside of the adapter (attachment coming soon). This makes the upper back EQ stop too short to touch the adapter. We replaced it with a longer screw. When inserted it doesn't really hit the back of the adapter. Rather, it touches the corner of the recession, stoping the optic with friction.

While all this was happening, Anchal started mounting AS4 on its adapter. After one of the magnets broke off, he switched to another one and succeeded. This is the next target for suspension. We still need to check the orientation of the wedge. Furthermore, we started a gluing session in the afternoon to prepare as much as possible for further SOS during the week. 3 side magnets were glued to side blocks. 3 magnets were glued to 3 adapters that were missing 1 magnet each.

In the afternoon, Yehonathan and Paco set up the QPD and did all the usual balancing, and then Anchal took the data of which the result is shown in Attachment #3. The major peaks are located at 723mHz, 953mHz, and 1.05Hz. Very similar to the case of the thin optic adapters.

Anchal progressed with OSEM installation, and engraving and yehonathan glued the counterweight setscrew in place. After securing the EQ stops, and wrapping the wires in foil, we declare PR3 is ready to be installed.

Attachment 1: PR3_roll_balance.png
PR3_roll_balance.png
Attachment 2: PR3_magnet_height.png
PR3_magnet_height.png
Attachment 3: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
Attachment 4: PXL_20220104_231742123.jpg
PXL_20220104_231742123.jpg
Attachment 5: PXL_20220104_232809203.jpg
PXL_20220104_232809203.jpg
  16550   Thu Jan 6 17:00:20 2022 YehonathanUpdateBHDSOS assembly -- LO2

{Paco, Yehonathan}

Today we suspended LO2 (E1800089) which Anchal has loaded into the thick optic adapter. Attachments 1,2 show the height and roll balance adjustments.

I realigned the opLev setup and balanced the suspended mass. We figured that if we use 2 counterweights we will be 1 short. We decided to use 1 mass at the back of the adapter. This has the additional advantage that the Viton tip on lower back EQ stop can touch it and act normally. The optic was successfully balanced in this way. Attachment 3 shows the motion spectra on the QPD. There are major peaks at 712 mHz, 854 mHz, 876 mHz, and 996 mHz. As expected using only 1 counterweight raised the center of mass and lowered the pitch resonance frequency. The optic was locked keeping the alignment fixed on the center of the QPD, OSEMs were inserted and the SOS tower was engraved.

We should apply some glue to the counterweight to prevent it from spinning on the setscrew.

Attachment 1: LO2_roll_balance.png
LO2_roll_balance.png
Attachment 2: LO2_magnet_height.png
LO2_magnet_height.png
Attachment 3: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
  16544   Wed Jan 5 19:18:06 2022 YehonathanUpdateBHDSOS assembly -- AS4

{Paco, Yehonathan, Anchal}

Today we suspended AS4 (E2000226-B). Anchal mounted Lambda Optic mirror with an RoC closest to AS4 in a thin optic mount. He noted that this optic as well as AS1 don't have a wedge angle. The specs claim that the wedge angle is 2 degrees what should have been clearly seen by inspecting the optic with a naked eye. All the ghost beam deflections probably come from the curvature of the mirror.

We did all the height and roll balancing using a camera (Attachment 1,2). We balanced that pitch of the adapter using a QPD not before we realigned the OpLev setup.

We measured the motion spectra (attachment 3). Major peaks are found at 755 mHz, 964 mHz, and 1.062Hz. I locked the counterweights setscrew and observed that the pitch balance doesn't change. I locked the EQ stops such that the alignment of the mirror remained the same by monitoring the QPD signals. I clamped the suspensions wires to the suspension block.

The only thing remaining is inserting the OSEMs.

 

Attachment 1: AS4_roll_balance.png
AS4_roll_balance.png
Attachment 2: AS_4_magnet_height.png
AS_4_magnet_height.png
Attachment 3: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
  15788   Tue Feb 2 17:09:17 2021 yehonathanUpdateBHDSOS assembly

I set up a working area on the table next to the south flow bench (see attachment). I also brought in a rolling table for some extra space.

I covered all the working surfaces with a foil from the big roll between 1x3 and 1x4.

I took the SOSs, SOS parts and the OSEMS from the MC2 table to the working area.

I cleaned some LN Allen keys with isopropanol and put them on the working table, please don't take them.

Attachment 1: 20210202_165501.jpg
20210202_165501.jpg
Attachment 2: 20210202_162452.jpg
20210202_162452.jpg
  15790   Tue Feb 2 18:24:54 2021 KojiUpdateBHDSOS assembly

You can remove the components of the optical table enclosure (black ones) and use the optical table as your working area too.

 

  15796   Thu Feb 4 15:14:55 2021 YehonathanUpdateBHDSOS assembly

I gathered all the components I could find from the SOS towers and the cleanroom and put it all on the table next to the flow bench (See attachment).

I combed through the cleanroom cabinet for SOS parts but didn't find all the parts listed in the procurement spreadsheet. I did find some extra items that were not listed.

This table compares the quantities in the spreadsheet to the quantities collected on the table. Green rows are items I found more than in the procurement spreedsheet while red rows are items I found less.

ITEM DCC # Qty required Qty in procurement spreadsheet How much I found
SENSOR/ACTUATOR PLATE D960002 14 21 21
SUSPENSION BLOCK D960003 7 9 9
TOWER BASE D960004 7 10 11
RIGHT SIDE PLATE D960005 7 12 13
LEFT SIDE PLATE D960006 7 12 13
UPPER MIRROR CLAMP D960007 7 8
7+1 teflon
LOWER CLAMP D960008-1 7 8 8
LOWER CLAMP, OPPOSITE D960008-2 7 8 8
WIRE CLAMP 1205308-1 10 17 9
CLAMP, SUSPENSION BLOCK D960134 14 19 21
STIFFENER PLATE D960009 7 9 9
DUMBBELL STANDOFF D970075 50 10 7
SAFETY STOP, LONG D970313 14 2 10
OSEM assy D960011 35 2 13 wire wound osem housings (gold)
WIRE STANDOFF D970187 20 7 0
GUIDE ROD D970188 10 9 0
MAGNET D960501 50 54 51 rusted + 37 slightly rusted. Didn't put on table
SAFETY STOP, SMALL D970312 28 0 4
SAFETY STOP D970311 28 0
16+9 stained w/o spring
SS Spring Plunger 8498A999 35 4 27
Attachment 1: 20210204_144007.jpg
20210204_144007.jpg
  15808   Tue Feb 16 13:13:39 2021 YehonathanUpdateBHDSOS assembly

Gautam pointed out that there are extra Sm-Co magnets stored in the clean optics cabinet.

I took the magnet box out and put it on the rolling table next to south flow bench. The box contains 3 envelopes with magnets.

They are labelled as following:

FLUX 94 - 50 parts

FLUX 93 - 10 parts

FLUX 95 - 40 parts

(What is FLUX??)

The box also contains some procurement documents.

The clean and bake dcc says :

1. Ultrasonic clean in methanol for 10 minutes

2. Bake in vacuum at 177 C° for 96 hours

Should we go ahead with the C&B?

  15810   Tue Feb 16 15:29:01 2021 KojiUpdateBHDSOS assembly

The curie temp of SmCo seems about x2 (in K) of the one for NdFeB. i.e. 600K vs 1000K. So I believe 177degC = 450K is not an issue. Just make sure the curie temp, referring the specific property for the magnets from this company. (You already know the company from the procurement doc). It'd be great if you upload the doc on the 40m wiki.

  15811   Tue Feb 16 22:59:36 2021 YehonathanUpdateBHDSOS assembly

Done.

Also, the magnets are nickel-plated. I guess that doesn't matter for the baking (Curie temp of 355 °C)?

Quote:

The curie temp of SmCo seems about x2 (in K) of the one for NdFeB. i.e. 600K vs 1000K. So I believe 177degC = 450K is not an issue. Just make sure the curie temp, referring the specific property for the magnets from this company. (You already know the company from the procurement doc). It'd be great if you upload the doc on the 40m wiki.

 

  15821   Fri Feb 19 12:21:04 2021 YehonathanUpdateBHDSOS assembly

A summary of things that need to be fabricated/purchased/done:

Part What needs to be done How much more needed
SUSPENSION BLOCK Fabricate SS dowel pins for 1 suspension block. 2X(diameter 0.094"+-0.002, length 0.38"+-0.01)+2X(diameter 0.188"+-0.002, length 0.5"+-0.01)
WIRE CLAMP If using the opposite side is acceptable, we have enough.  
DUMBBELL STANDOFF Fabricate. Schematics. Need to check the size is compatible with the magnets we have. 40 + 10 for double stacking of side dumbbells. With the existing dumbbells, we'll have 18 spares.
SAFETY STOP, LONG Fabricate or buy. Schematics 4
OSEM assy Check if we have 35. Schematics  
SAFETY STOP, SMALL Fabricate or buy. Schematics 24
SAFETY STOP Fabricate or buy. Schematics 12
SS Spring Plunger Buy from McMaster. Find and check custom plungers around the X arm. 8
4-40 3/8" Ag SHCS Buy from uccomponents.com 30
4-40 1/2 Ag SHCS Buy from uccomponents.com 60
1/4-20 3/4 Ag SHCS Buy from uccomponents.com 150
1/4-20 5/4 Ag SHCS Buy from uccomponents.com 30
1/4 SS Lock Washer Buy from McMaster 30
1/4 SS Lock Wassher (Reduced OD) Buy from McMaster 30
Viton Tips Need to find stock Not sure. Existing eq stops have phosphor bronze springs. Should all of them be replaced with Viton?
Steel Music Wire There are 500ft of wire (enough for many SOSs) in a desiccator somewhere according to this elog  

 

  15969   Fri Mar 26 10:25:37 2021 YehonathanUpdateBHDSOS assembly

I measure some of the dowel pins we got from Mcmaster with a caliper.

One small pin is 0.093" in diameter and 0.376" in length. The other sampled small pin has the same dimensions.

One big pin is 0.187" in diameter and 0.505" in length. The other is 0.187" in diameter and 0.506" in length.

The dowels meet our requirements.

  15999   Tue Apr 6 15:42:57 2021 YehonathanUpdateBHDSOS assembly

We got some dumbells from Re-Source Manufacturing (see attached). I picked 3 in random and measured their dimensions:

1. 0.0760" in diameter, 0.0860" in length

2. 0.0760" in diameter, 0.0860" in length

3. 0.0760" in diameter, 0.0865" in length

In accordance with the Schematics.

Attachment 1: 20210406_150724.png
20210406_150724.png
  16011   Fri Apr 9 20:54:54 2021 YehonathanUpdateBHDSOS assembly

Today I assembled the skeleton of 6 towers, without clamps and sensor assembly (attachment 1).

Some of the side plates have this weird hole that doesn't fit any of the suspension blocks (attachment 2). I didn't notice when I counted the parts and now there are exactly enough side plates to assemble 7 towers.

Also found that one of the stiffener plates has a broken threading.

We will need more parts to go beyond the necessary 7 SOSs. I will do the recounting later.

Things to do next:

1. Find the capped spring plungers and send them to C&B.

2. Assemble the clamps onto the suspension blocks.

3. Push some Viton tips into the vented screws we got to make safety stops.

4. more C&B: Magnets, dumbells, dowel pins, OSEMs.

5. Push clean dowel pins into the last suspension block.

6. Assemble 7th Tower.

7. Assemble safety stops and clamps.

8. Glue magnets to dumbells.

 

 

Attachment 1: 20210409_202717.jpg
20210409_202717.jpg
Attachment 2: 20210409_202755.jpg
20210409_202755.jpg
  16018   Mon Apr 12 17:30:11 2021 YehonathanUpdateBHDSOS assembly

Today, I screwed the plungers on the sensor plates and installed them on the Towers. I also installed the wire clamps on the suspension blocks (attachment).

I ran into problems in 2 separate suspension blocks: one had a dowel pin that was slightly too fat for the wire clamp. In another, the tapped holes were too short so that the 4-40 screws couldn't be screwed all the way.

 

Attachment 1: 20210412_170913.jpg
20210412_170913.jpg
  16111   Mon May 3 16:49:04 2021 YehonathanUpdateBHDSOS assembly

I found a "vice" in the cleanroom (attachment 1). I used it to push dowel pins into the last suspension block using some alcohol as a lubricant.

I then assembled the 7th and last suspension tower (attachment 2).

Things that need to be done:

1. Push Viton tips into vented screws and assemble the earthquake stops.

2. Glue magnets to dumbells.

Attachment 1: 20210503_161422.png
20210503_161422.png
Attachment 2: 20210503_161456.jpg
20210503_161456.jpg
  16170   Tue Jun 1 16:17:06 2021 YehonathanUpdateBHDSOS assembly

I tried to push the clean Viton tips into the vented screws just to find out that the vented holes are too small. We need to drill 0.1" diameter holes about 0.1" deep into these screws and clean them again.

 

  16172   Wed Jun 2 01:03:19 2021 KojiUpdateBHDSOS assembly

Can you just cut the viton tips smaller? If you cut it to have some wedge (or say, taper), it can get stuck with the vent hole.

 

  16215   Fri Jun 18 19:02:00 2021 YehonathanUpdateBHDSOS assembly

Today I glued some magnets to dumbells.

First, I took 6 magnets (the maximum I can glue in one go) and divided them into 3 north and 3 south. Each triplet on a different razor (attachment 1).

I put the gluing fixture I found on top of these magnets so that each of the magnets sits in a hole in the fixture. I close the fixture but not all the way so that the dumbells get in easily (attachment 2).

I prepared EP-30 glue according to this dcc. I tested the mixture by putting some of it in the small toaster oven in the cleanroom for 15min at 200 degrees F.

The first two batches came out sticky and soft. I discarded the glue cartridge and opened a new one. The oven test results with the new cartridge were much better: smooth and hard surface. I picked up some glue with a needle and applied it to the surface of 6 dumbells I prepared in advance. I dropped the dumbells with the glue facing down into the magnet holes in the fixtures (attachment 3). I tightened the fixture and put some weight on it. I let it cure over the weekend.

I also pushed cut Viton tips that Jordan cleaned into the vented screws. While screwing small EQ stops into the lower clamps I found some problems. 4 of the lower clamps need rethreading. This is quite urgent because without those 4 clamps we don't have enough SOS towers. Moreover, I found that the screws that we bought from UC components to hold the lower clamps on the SOS towers were silver plated. This is a mistake in the SOS schematics (part 23) - they should be SS.

Attachment 1: 20210618_115017.jpg
20210618_115017.jpg
Attachment 2: Untitled_2.png
Untitled_2.png
Attachment 3: 20210618_160041_HDR.jpg
20210618_160041_HDR.jpg
  16216   Fri Jun 18 23:53:08 2021 KojiUpdateBHDSOS assembly

Then, can we replace the four small EQ stops at the bottom (barrel surface) with two 1/4-20 EQ stops? This will require drilling the bottom EQ stop holders (two per SOS).

 

  16221   Tue Jun 22 17:05:26 2021 YehonathanUpdateBHDSOS assembly

According to the schematics, the distance between the original EQ tap holes is 0.5". Given that the original tap holes' diameter is 0.13" there is enough room for a 1/4" drill.

Quote:

Then, can we replace the four small EQ stops at the bottom (barrel surface) with two 1/4-20 EQ stops? This will require drilling the bottom EQ stop holders (two per SOS).

 

 

  16227   Mon Jun 28 12:35:19 2021 YehonathanUpdateBHDSOS assembly

On Thursday, I glued another set of 6 dumbells+magnets using the same method as before. I made sure that dumbells are pressed onto the magnets.

I came in today to check the gluing situation. The situation looks much better than before. It seems like the glue is stable against small forces (magnetic etc.). I checked the assemblies under a microscope.

It seems like I used excessive amounts of glue (attachment 1,2). The surfaces of the dumbells were also contaminated (attachment 3). I cleaned the dumbells' surfaces using acetone and IPO (attachment 4) and scratched some of the glue residues from the sides of the assemblies.

Next time, I will make a shallow bath of glue to obtain precise amounts using a needle.

I glued a sample assembly on a metal bracket using epoxy. Once it cures I will hang a weight on the dumbell to test the gluing strength.

Attachment 1: toomuchglue1.png
toomuchglue1.png
Attachment 2: toomuchglue2.png
toomuchglue2.png
Attachment 3: dirtydumbell.png
dirtydumbell.png
Attachment 4: cleandumbell.png
cleandumbell.png
Attachment 5: assembly_on_metalbracket.png
assembly_on_metalbracket.png
  16229   Tue Jun 29 20:45:52 2021 YehonathanUpdateBHDSOS assembly

I glued another batch of 6 magnet+dumbell assemblies. I will take a look at them under the microscope once they are cured.

I also hanged a weight of ~150g from a sample dumbell made in the previous batch (attachments) to test the magnet+dumbell bonding strength.

Attachment 1: 20210629_135736.jpg
20210629_135736.jpg
Attachment 2: 20210629_135746.jpg
20210629_135746.jpg
  16235   Thu Jul 1 16:45:25 2021 YehonathanUpdateBHDSOS assembly

The bonding test passed - the weight still hangs from the dumbell. Unfortunately, I broke the bond trying to release the assembly from the bracket. I made another batch of 6 dumbell+magnet.

I used some of the leftover epoxy to bond an assembly from the previous batch to a bracket so I can test it.

  16259   Tue Jul 27 17:14:18 2021 YehonathanUpdateBHDSOS assembly

Jordan has made 1/4" tap holes in the lower EQ stop holders (attachment). The 1/4" stops (schematics) fit nicely in them. Also, they are about the same length as the small EQ stops, so they can be used.

However, counting all the 1/4"-3/4" vented screws we have shows that we are missing 2 screws to cover all the 7 SOSs. We can either:

1. Order new vented screws.

2. Use 2 old (stained but clean) EQ stops.

3. Screw holes into existing 1/4"-3/4" screws and clean them.

4. Use small EQ stops for one SOS.

etc.

Also, I found a mistake in the schematics of the SOS tower. The 4-40 screws used to hold the lower EQ stop holders should be SS and not silver plated as noted. I'll have to find some (28) spares in the cleanroom or order new ones.

 

Attachment 1: 20210727_154506.png
20210727_154506.png
  16260   Tue Jul 27 20:12:53 2021 KojiUpdateBHDSOS assembly

1 or 2. The stained ones are just fine. If you find the vented 1/4-20 screws in the clean room, you can use them.

For the 28 screws, yeah find some spares in the clean room (faster), otherwise just order.

  16262   Wed Jul 28 12:00:35 2021 YehonathanUpdateBHDSOS assembly

After receiving two new tubes of EP-30 I resumed the gluing activities. I made a spreadsheet to track the assemblies that have been made, their position on the metal sheet in the cleanroom, their magnetic field, and the batch number.

I made another batch of 6 magnets yesterday (4th batch), the assembly from the 2nd batch is currently being tested for bonding strength.

One thing that we overlooked in calculating the amount of glue needed is that in addition to the minimum 8gr of EP-30 needed for every gluing session, there is also 4gr of EP-30 wasted on the mixing tube. So that means 12gr of EP-30 are used in every gluing session. We need 5 more batches so at least 60gr of EP-30 is needed. Luckily, we bought two tubes of 50gr each.

  16359   Thu Sep 23 18:18:07 2021 YehonathanUpdateBHDSOS assembly

I have noticed that the dumbells coming back from C&B had glue residues on them. An example is shown in attachment 1: it can be seen that half of the dumbell's surface is covered with glue.

Jordan gave me a P800 sandpaper to remove the glue. I picked the dumbells with the dirty face down and slid them over the sandpaper in 8 figures several times to try and keep the surface untilted. Attachment 2 shows the surface from attachment 1 after this process.

Next, the dumbells will be sent to another C&B.

Attachment 1: dumbell_before.png
dumbell_before.png
Attachment 2: dumbell_after.png
dumbell_after.png
  16426   Tue Oct 26 10:17:14 2021 YehonathanUpdateBHDSOS assembly

Things that I need to start suspending optics:

1. Winch adapter plate (D970314). Might need to make one.

2. Quad photodetector

3. Camera and camera mount

4. Beam height target

5. Height gauge

  16439   Thu Oct 28 23:13:19 2021 YehonathanUpdateBHDSOS assembly

{Tega, Yehonathan, Koji}

Suspension of a Dummy Optic

We gathered the components needed for suspending a 2" optic housed in a 3" ring adapter:

1. SOS Tower

2. Winches+Winch adapter plate (Attachment 3)

2. HeNe Laser + Power supply

3. A steering mirror

4. QPD + ND2 Filter + Electronic amplifier

5. Oscilloscope

6. Dummy optic housed in a ring adapter (Attachment 2)

An OpLev was built using the HeNe laser, steering mirror, suspended optic, QPD (Attachment 1).

The beam height was set with a ruler. The QPD was placed in front of the laser and its height was adjusted until the Y signal vanished.

The beam was made parallel to the table. First, roughly by using an iris. Then, more accurately, by measuring the beam directed at the suspended optic with the QPD and zeroing the Y signal by adjusting the steering mirror.

We suspended the dummy optic using a music wire we found in the cleanroom cabinet.

All the wire clamps on the ring adapter, SOS, and winches were loosened.

About 0.5m of music wire was cut. Then, the wire was threaded through the wire clamp on the adapter side block, around the ring adapter, and through the wire clamp on the other side block, keeping the wire untwisted. The optic was put on the safety stop and the height was roughly adjusted using the lower EQ stops.

The wire pair was then threaded through the wire clamp on the suspension block and held near the winches. The wire was made to go through the groves at the side blocks. The wire was clamped to the side blocks. The wires were clamped on the winches. The wires were pulled by the winches until the magnet marking on the side blocks was centered on the OSEMs' holes on the side plates of the SOS (attachment 4).

Once the heights were set, the wire was clamped at the suspension block.

We balanced the dummy optic using a counterweight.

We placed the QPD at the laser reflection from the optic. We adjusted the screw set going through the counterweights to adjust the balance. The pitch imbalance was monitored by observing the Y signal on the oscilloscope.

Comments:

1. Turns out that for a 1/4" thick optic, the rear counterweight needs to be removed for achieving balance.

2. To fix the counterweight on the setscrew we will use some epoxy.

3. Seems like the left optical table in the cleanroom is slightly tilted. We need to fix it.

4. The bottom long EQ stop is not touching the adapter due to the balancing mass socket. We might want to put a nut on it.

5. Still need to glue 3 more side magnet+dumbell assemblies to rods and then glue them before gluing them to the side blocks which will take at least 2 more days until we can start suspending a real optic.

Attachment 1: OpLev_Setup.jpg
OpLev_Setup.jpg
Attachment 2: suspended_optic.png
suspended_optic.png
Attachment 3: 20211029_113011.jpg
20211029_113011.jpg
Attachment 4: 20211029_113052.jpg
20211029_113052.jpg
  16443   Tue Nov 2 15:02:03 2021 YehonathanUpdateBHDSOS assembly

{Yehonathan, Tega}

We took the free-swinging spectra of the OpLev in the X and Y direction.

To make the motion of the optic quiet we turned off the airflow on the optical bench and moved the QPD close to the SOS so that the laser beam stays more or less within the QPD sensitive area.

In the process, we realized that the cleanroom HeNe went bad. It turned off after a few minutes after turning it on. The behavior repeated with another power supply. We replaced the HeNe and realigned it coarsely.

The data was taken using an oscilloscope while the optic was swinging freely. The PSD was calculated afterward (attachment 1).

Surprisingly, the pitch has a resonance frequency of ~ 2.5 Hz. And this is after we removed the back counterweight.

Additionally, we aligned the tilt of the optical table. Using a spirit bubble we adjusted the tilt by using a wrench on the table legs. As we suspected, the table was slightly tilted in the north-south direction.

Attachment 1: FreeSwingingSpectra.pdf
FreeSwingingSpectra.pdf
  16446   Tue Nov 2 22:50:30 2021 KojiUpdateBHDSOS assembly

2.5Hz is surprising. Can you move it down to sub 1Hz by adding a socket cap screw at the top instead of the set screw for the Teflon piece? How much mass do you need to add?

ELOG V3.1.3-