Howdy,
For those brave enough to make their own spinners, there is an often
overlooked starting material for making spinners - Aluminum. At first it
sounds weird but it works very well and is easy to machine. Because of
the relationship of the geometry of spinning and the magnetic field
there are no observable problems from spinning this metal in a magnetic
field. It has very good temperature properties, especially since many of
the spinner shelves are made from Al and have similar temperature
properties.
An easy design is to shape the external part of the spinner identical to
current spinners with a cylinder about 5mm longer at the top. Then
precision bore a hole very slightly larger than the NMR tubes. Then
crosscut the 5mm cylinder with a bored hole at the top with a X as
viewed from the top so that you have 4 independent prongs around the
top. Slip an O-ring around these prongs at the top to pull the prongs in
tight on the tubes. The prongs need to be long enough and thin enough
that the O-ring provides enough tension to hold tubes. The over-all bore
should be as close to the tube size as possible but with enough
clearance to allow tube size variances to still fit.
woody_at_acornnmr.com
Received on Fri Oct 03 2003 - 08:33:34 MST