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Wed Dec 31 15:59:59 1969
Little PMC Assembly
I collected the following things to assemble one unit of little PMC (attachment 1)
Piezoelectric Transducer (PZT)
Epoxy 30 CL
1. Start by assembling the plane mirror to the clamp. First, put an O ring inside the clamp envelope(attachment 2) and then gently place the flat mirror on that(attachment 3). Rotate it 45 degrees and bolt this setup with the metal spacer using screws and Allen Key, Follow the same procedure for another plane mirror as well. The plane mirror is 99% reflecting on one side and transmitting on the other. The reflecting surface should be placed facing inside the clamp. An easy method to find the coating of the mirror is to hold it from the sides (never touch the middle part) and then checking if the bottom surface of the mirror is visible. If the bottom part is visible, then the side facing you transmits light and hence should be towards the outside. After this stage of assembly, it will look similar to attachment 4. Note: 3/8'' screw was used for this step.
2. Next, proceed to assemble the endcap unit. The PZT should be glued centered on the endcap and the curved mirror should be glued centered on the PZT. As is it very difficult to align them properly, a jig can be used for gluing purpose. The external space has the same diameter of the PZT, the internal one has the same diameter of the curved mirror. The slots on the edges are used for the wires of the PZT. Epoxy 30 CL can be used for this purpose. A necessary support system can be assembled as per need.
I was assembling two units of the little PMC yesterday night. I followed step 1 of the procedure. It went uneventful. While assembling the 2nd unit, an unfortunate incident happened.
I was working on attaching the plane mirror between the spacer and the clamp(with O-ring). I bolted all the 3 bolts then observed a small crack in the mirror. To investigate further I opened the bolts. Then I observed that one of the bolts broke inside. The exact cause of the breaking of the bolt is not known. One possibility could be that it was a bit misaligned as it was the first bolt to be bolted and in the process got stuck to something. Not knowing what to do further, I wrapped up everything, kept all the things at their appropriate places, locked the lab and left.
Attachment 5 shows the broken screw on the left and a normal screw on the right. Attachment 6 shows a cracked mirror. Attachment 7 shows the broken screw fixed inside the spacer.
Today morning, Anchal and I went back to investigate the situation. It is quite unlucky to have a bolt broken from very near to the edge and getting it stuck in the spacer. Further investigation is required on how to take the broken screw out.
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