This tool consists of a pole with a diameter slightly less than that of the spinner. On the end of the pole is a tapered prong with a diameter of 4 mm at the tip and 6 mm at the base. This tool is inserted in the top of the magnet and gently lowered until the prong gets wedged into the empty spinner. The spinner is removed with the tool. The entire operation takes less than 10 seconds and no reshimming is required.
Wednesday, May 26, 2010
Retrieving Empty Spinners From Magnets
Despite my best efforts in teaching students how to properly use NMR spectrometers, invariably a new user will, on occasion, drop a sample spinner into a magnet without a sample. This is usually done in our undergraduate laboratory by inexperienced students who have finished collecting their data and feel a need to return the empty spinner to the magnet. The problem is that ejecting the empty spinner with the eject air is not possible as the air passes through the spinner. In the past I have removed empty rotors from magnets on Varian spectrometers by removing the upper barrel of the magnet. On Bruker spectrometers, I have removed the probe and inserted a semi-rigid NONMAGNETIC plastic hose in the bottom of the magnet and pushed the spinner to the top of the upper barrel where it can be removed by a helper. In either case, the entire operation took between 5 minutes (Varian) and 30 minutes (Bruker) depending on how much reshimming was required. To avoid this tedious chore, I had our machine shop make a plastic tool for empty rotor removal shown below.