To begin beveling the borosilicate needle after preparing the grinding assembly, insert the needle into the needle holder and tighten the retaining ring to secure the needle in place. Open the regulator and increase the pressure to 24 pounds per square inch. Rotate the course adjustment knob enough to raise the needle holder till the needle is raised higher than the surface of the rotating abrasive plate.
Rotate the entire manipulator so the needle swings into place above the rotating plate. Position the needle on the plate such that the rotation of the plate moves it away from the needle tip. Watching from the side, use the coarse adjustment knob to lower the needle toward the abrasive plate surface and stop when the needle is almost touching the surface of the liquid.
Adjust the needle position so that it is in the center of the field of view. Once in the center, slowly increase the magnification, making slight adjustments to keep the needle tip in the center of view. At maximum magnification, stop the grinding plate and focus the microscope on the surface of the abrasive plate.
Once the surface is in focus, immediately restart the plate rotation. Using the manipulator course adjustment knob, lower the needle toward the abrasive plate. In the field of view, observe the needle and the shadow of the needle.
When the two are close to touching, switch to the fine adjustment knob. Continue lowering the needle until it touches its shadow. At this point, read the caliper and note the reading.
This reading indicates the abrasive plate surface is at or below this caliper measurement. Allow the needle to remain at this caliper reading for five to 10 seconds. Using the manipulator fine adjustment knob, raise the needle, while ensuring it stays underneath the surface of the wetting agent.
Stop the rotation of the abrasive plate briefly to observe whether bubbles escape from the needle tip. If bubbles are not present, move the needle back to the previous caliper reading. Lower it slightly.
Take a new caliper reading and repeat the steps as demonstrated previously. If bubbles are seen, restart the abrasive plate to observe if bubble formation occurs while the plate is rotating. Once bubbles are observed with the abrasive plate not rotating, slowly decrease the air pressure by rotating the regulator adjustment knob.
When the bubbles stop flowing from the tip of the needle, note the pressure. Then, increase the air pressure until bubbles start flowing again from the needle tip. Once the beveling is over, raise the needle above the abrasive plate, ensuring it is high enough not to hit anything as the entire manipulator is rotated away from the plate and microscope.
Once the needle is in a position where it can be safely removed, lower the air pressure to zero. Remove the needle and place it in a needle storage box like a Petri dish until it is used.
