Hot Water Fiber Bending Procedure

Overview

The light guide is offset soon after the SciFi section in an S-bend to reduce the amount of fiber exposed to the electrons' trajectory. Fibers are placed within a water tank, heated with the water, then bent and cooled within the tank. The process takes many hours.

Preparation Procedures

Measurement

Before beginning the bending procedure, you will first need to determine the most appropriate position for the fibers in the particular bundle you are constructing. The cross-sectional width of the fuse sites vary from fiber to fiber. To avoid having a row or column in the bundle that is larger or smaller than another, fuse site measurements are made and fiber position is optimized. The orientation of the fibers are noted in the Bundle Names Google document and labeled so that orientation can be controlled for the bending process, effectively choosing the final position of the fiber in the bundle.

Orientation

• First ensure that each part of the bending unit is clean and don a pair of powder-free gloves.

• Be sure that the chimneys and the bottom halves of the collars are attached to their appropriate plates.

• Open the intermediate storage box and remove the fibers you will be bending. Place these fibers on a flat surface, always being cautious with the fuse site.
• Use the bundling tool to place the fibers in the correct orientation and position as defined by the Bundle Names Google Document.
  • Note: Because the bundling tool is 5 fibers wide and 6 fibers high, and the collars are 6 fibers wide and 5 fibers high, the bundling tool must be rotated when placing fibers in the collars. Therefore when the bundling tool is used, the fibers should be put in columns first with the orientation opposite of what is stated in the Google Doc, and their order rotated 90 degrees. For example if the final position and (orientation) of the fibers is:

OB(a) - OH(a) - ON(a) - OE(a) - OJ(a) - OO(a)
O4(a) - O9(a) - O14(a)- OD(a) - OI(a) - O15(a)
O3(a) - O8(a) - O13(a)- OC(a) - O10(a)- OM(a)
O2(a) - O7(a) - O12(a)- O5(a) - OG(a) - OL(a)
O1(a) - O6(a) - O11(a)- OA(a) - OF(a) - OK(a)

Then they should be placed in the bundling tool as:

OO(b) - O15(b)- OM(b) - OL(b) - OK(b)
OJ(b) - OI(b) - O10(b)- OG(b) - OF(b)
OE(b) - OD(b) - OC(b) - O5(b) - OA(b)
ON(b) - O14(b)- 013(b)- 012(b)- 011(b)
OH(b) - O9(b) - O8(b) - O7(b) - O6(b)
OB(b) - O4(b) - O3(b) - O2(b) - O1(b)

• Put a collar around the bundle so that it is secure around the fibers but does not cause damage. The fibers should not be able to slide through, rotate, or change orientation.
  • Note: While working with one end of the bundle, always be cautious of the other end. Any bends may cause damage to the fiber.

Bending Procedure

Placement into Collars

Securing the Orientation

It's important for bending to make sure the scintillating end of the fibers are square and flush. This process usually requires 2 technicians.

• Start by placing a flat block in front of the bundle and secure the collar onto the bending unit. Have one technician hold the flat block in place (or clamp the block to the table.)
  • Loosen the collar around the bundle enough to the fibers to slide but not change orientation.
• Gently take each fiber and push it through the collar so that it butts up against the flat block. If you have a second technician with you, have them watch the fuse sites and you'll be able to see when all the fibers are flush.
  • Note: Be sure not to strain any of the fibers during this process!
  • When you are certain that the fibers are flush against the block, carefully tighten the chimney around the bundle so that the fibers neither slide nor change orientation. If you see that any fibers are offset by more than ~.5mm, repeat this process.

Offsetting the Fibers

The next step involves offsetting the SciFi end past the bending unit. This will compensate for the length of fiber required to produce the S-bend.

• Cautious of the fiber orientation of the bundle, secure the second collar around the bundle.
• Make sure the first collar (the collar closest to the popsicle stick) is tight enough to hold the fibers in place without slipping. Detach the first collar from the bending plate.
• Loosen the second collar so that the fibers may slide through it without damage or change in orientation.
• Slide the first collar so that the fibers are flush against the edge of the bending plate.
• Tighten the second collar so that the fibers do not slide.
• Loose the first collar so it may slide along the fibers. Move it to the "start" position as labelled on the bending plate and then tighten it again so the fibers do not slide or change orientation.
• Loosen the second collar and move the first collar to the "finish position". This moves the fibers one inch past the bending unit plate to compensate for the length of fiber needed to produce the S-bend. This is also the final horizontal position of the fibers for the entirety of the bending process.
• Tighten the second collar and all collars after (third through seventh). Loosen the first collar, and re-attach it to the bending unit plate and then tighten it.
  • At this point, all seven collars should be tight around the bundle, and attached to the bending unit.

Placement into Chimneys

• Using a clamp, secure Bending Plate #2 to the bending bar so that the fibers ends are flush with the edge of the farthest chimney.
  • From this point onward, be wary of the fibers and the chimneys. The chimneys are sharp may cause damage to the fibers if they are caught in a chimney slot and strained.
• Using a straight zip-tie (or any other straight, thin piece of plastic), separate the fibers (which should be in a 6x5 matrix) into 6 columns of 5 fibers each. Place a strip of paper in between each column in the meantime.
• As viewed looking at the SciFi end, take the right-most column and place it in the chimneys. The bottom fiber goes in the right-most spot on the chimney, and you move left as you progress. Take the next right-most column and repeat.
  • Only 3 columns of 5 fiber each will be placed into Bending Plate #2.
  • Do not push or force any fiber into a chimney slot as this will cause damage to the fiber!
    • If a fiber does not fit into a chimney slot, use a small file to widen the slot. Make sure it is large enough that the fiber seeds into the chimney slot with no resistance.
• Make sure that the lightguide fibers reach to the very end of the chimney on plate #2. If they do not, move the plates and the bar until the lightguides reach the end of the chimney AND the bar (and its blocks) are able to fit between the metal tubes on the plates.
  • This step is important as it sets the distance the plates will remain from each other as well as the bend in the fibers.
• Place a chimney clamp on top of the first chimney (closest to the collars/popsicle stick) and secure it in place with 3 screws.
  • The chimney clamp holes are dependent on orientation. Both the chimneys and chimney clamps are marked on one side. Lining up marks gives the orientation that the chimney plate should be attached.
    • If any of the screws resist while the chimney clamps are being installed back the screw out and try a different screw. If the screw still resists, try moving the chimney clamp to better line up the holes on the chimney and chimney clamp. Forcing a screw will lead to cross threading and ruin the chimney!
• Record the orientation and fiber name of each slot in the chimney in the Bundle Names Google doc. Here you may check that you have not altered the orientation of the fiber matrix.
• With extreme care, cut off the main portion of the fiber tag with scissors. Afterwards, remove the rest of the fiber tag with your hands and remove the remaining adhesive glue with a dry lint-free cloth.
• Secure the rest of the chimney clamps on the rest of the chimneys of Bundle Plate #2. Do not screw them down so tight that they damage the fibers, but do secure them enough so that no fibers can slide out of their slots.

• Place Bending Plate #1 on top of Bending Plate #2 and the bending bar.
  • Be sure to align the chimneys on plate #1 directly above the chimneys on plate #2.
• Secure both plates to the bar with clamps.
• Repeat the process for placing fibers in the chimney slots. Again starting with the right-most column, and the bottom fiber going into the right-most slot. Repeat the chimney and tag-removing process.

Placement into Popsicle Stick

This step requires two technicians.

• Remove the collar tops of the first and second collars nearest the popsicle stick.
• Secure a chimney clamp onto the bending plate and rest the SciFi ends of the fibers against it so you may attach the popsicle stick to the bending plate without having to hold the fibers.
• Have one technician tilt the entire bending unit (bending bar, bending plate, and chimney plates) with both hands so that a second technician can attach the popsicle stick to the bending plate. Place a large washer between the popsicle stick and the bending plate. This is so the fibers do not have to bend.
• While holding the fibers in the proper oriented matrix, place the fibers gently into the popsicle stick. They will jut out of the end because of the extra length.
• Gently place the popsicle stick top onto the fibers without stressing them, and put the two rods through the popsicle stick. The rods are different, so if they are not properly aligning with the threaded rods, switch their positions. Secure the bolts onto the threaded rods a few turns so that the popsicle stick top doesn't move.

Filling and Siphoning the Tank

Make sure that the pumps and heaters are off for this step!

• It is important that the water be clean each time a new bundle is put into the water. As the pieces of the bending unit rust, the water needs to be changed and the tank cleaned each time a new bundle is to be bent.
• Once the tank has been drained and cleaned, open all of the valves near the right exclusion area including the inlet valve from the faucet.
• Turn on the cold water and let the tank fill.
• It will take about 30 minutes for the tank to fill high enough to immerse the fibers and bending unit. Fill the tank until the water reached the top of the highest horizontal 2x4.
• Once the tank is full you should wait for thirty minutes to allow any air bubbles to coalesce into bigger bubbles so they may be siphoned out.
  • Put the siphon completely underwater in the tank and pump it until no more air bubbles come out.
  • Keeping the siphon underwater put the hose into the inlet of the left exclusion area and pump the siphon until no air comes out of the outlet of the left exclusion area.
• After the water systems have been siphoned and there are no air bubbles, have two technicians place the bending unit and fibers into the room temperature water.

Running the LabView Program

• Plug in both netbooters. They are located on either side of the tank.
• Open the "2 Heaters 1.2" Labview program.
• Click on the dials for "Heater and Pump 1" and "Heater and Pump 2" to turn on all water heaters and pump.
  • There are three temperatures listed on the interface. There is the water temperature, and the two surface temperatures of each heater. Watch for a bit to make sure neither heater gets more than 3-5 degrees Fahrenheit hotter than the water temperature.
• The temperature should reach 160-162 degrees Fahrenheit before bending starts.

Bending

Three lab technicians will be needed for this procedure. Be sure all technicians have read the procedure before bending. This section should be completely in approximately 3-3.5 minutes and is extremely important. Fibers are very delicate in this stage and may easily break.

• Place the four stools upside down on the ground in the spots designated by tape.
• Wear thick rubber gloves to protect your hands from the hot water.
• Two technicians should remove the bending unit from the tank and place it upside down on the stools.
• All clamps should be removed from the bending unit. Be careful taking them off as now the chimney plates are no longer attached to the bending plate.
• With one technician holding the bending plate, and one technician bracing the chimney plates and bar, have the third technician take hold of the top bending plate and secure it on the first two threaded rods.
  • Repeat this step for the other bending plate.
    • This is the most important part. Do not drop the bending plate as it will break many fibers.
• With one technician still securing the bending plate, place the second two threaded rods in their positions and screw them into the bending plate.
• Cover the hot water tank.
• Lift the now bent fibers and bending unit on its side on top of the tank cover.
• Gently and evenly tighten the bolts on the popsicle stick. There are four- make sure none is too much tighter than any other. This will create an even and smooth S-bend.
• Once the S-bend is created uncover the tank, and gently place the bending unit into the hot water.
• In the LabView program, turn off heaters 1 and 2. Make sure the pumps are still running.
• Prop open the cover slightly and wait until the water cools to room temperature.

Post-Bending Procedure and Cleaning

• Once the water returns to room temperature, have two technicians remove the bending unit from the water.
• Place tag stickers on the fiber bends. The outer 15 fibers will be labeled A-O and the inner 15 fibers will be labeled 1-15.
• Remove all collar tops and the last 4 chimney tops.
• Carefully remove the last collar top and support each fiber end as you remove the fibers from each chimney slot.
• Have a second technician remove the bolts of the popsicle stick and then the popsicle stick top.
• Remove these 15 fibers from the popsicle stick and then replace the rods and bolts to the popsicle stick so the other 15 fibers don't fall out.
• Supporting the S-bend and the large bend, transport these fibers to a dry, flat area where they can not be cleaned.
• Have one technician support the chimney plates and the bending plates while a second technician removes the threaded rods from the bending unit.
  • Remove the outer bending plate and replace the rods.
• Repeat the previous steps: remove the 4 chimney tops and then the last. Remove the fibers from the chimney slots. Free the fibers from the popsicle stick. Move the fibers to a new location.
• Repeat the step of removing the second bending plate and place the bending unit flat on the table with the threaded rods hanging off. Clamp the bending plate to the table so it doesn't fall off.

Cleaning

Because of the metals reacting with the water in the tank, the resulting bending unit and fibers have deposits of rust and hard water stains. Everything must be cleaned before the next step or before reuse.

For cleaning the fibers: Wet half of a lint-free cloth. Gently clean each individual fiber from end to end using the wet cloth. Once all or most deposits are removed, go over the entire fiber again with the dry side of the cloth. Be sure the fiber is clean and dry before moving onto the next fiber. All 30 fibers must be cleaned before storage.

For cleaning the bending unit: To minimize the amount of deposits on each bundle, the bending unit is cleaned between each use. The metal chimneys, collars, threaded rods, and popsicle stick must be cleaned with a wire brush. The glass plates are wiped with a damp cloth.