Dear Josh,
I see you have tried all the usual steps. As an addition you may try to fix
the rotor with a fine tabletop vice (I have this
<
https://www.reichelt.de/de/de/shop/produkt/kugelgelenk-schraubstock_spannfix_mit_tischklemme-335354?PROVID=2788&gad_source=1&gad_campaignid=18347782207&gbraid=0AAAAADwnxtasV_ybGC4BFqqdOWpoS_7ny&gclid=Cj0KCQjw-NfDBhDyARIsAD-ILeBIaQyNsLoWGI3bYLIMV-pR8802gbKzx1rSqWFRuZKBMjd2FlVNxiUaAjEZEALw_wcB>
one at work) and using a “Dremel” tool to enlarge the hole in
the vespel piece until you can use the dentist tool to take out the left over
part. In addition you might also try to screw in a suitable size screw into the
vespel piece and pull. The last solution would be a full drilling out of the
vespel but I would take care to use a soft drill bit (woodwork type) and not
a hardened stainless steel or something similar. These solutions have the
risk of damaging the rotor.
Good luck!
Cheers,
Riza
------------
Dr. Riza Dervisoglu
NMR Laboratory Co-Ordinator
Max Planck Institute for Chemical Energy Conversion
and ITMC, RWTH Aachen University
> From: main_at_ammrl.groups.io On Behalf Of Josh Kurutz via groups.io
> Sent: Wednesday, 16 July 2025 01:47
> To: main_at_ammrl.groups.io
> Subject: [AMMRL] AMMRL: Removing a stuck cap fragment from a solids rotor
Hi AMMRL.
I’d like your help with a practical solids NMR problem: removing part
of a cap that’s stuck in a rotor.
An attempt was made to remove a VESPEL cap from a 3.2mm zirconium rotor using
the proper Bruker cap removal tool. In the process, the cap’s top part
with the fins was sheared off, leaving a tight-fitting plastic cylinder in the
end of the rotor. The plastic face is flush with the rotor face, leaving nothing
external to grab.
The bottom part of the cap is a hollow cylinder, so I can reach through it
with a dental tool (which is strong, thin, and bent at the end, enabling the
tip to poke through and pull against the back surface of the cap fragment),
but it’s pretty stuck.
Today we tried immersing it in liquid nitrogen, which I’m told normally
lets caps pop right out, but that didn’t happen, even with coercion via
the dental tool. I’m thinking the cap might be stuck by he thick, gooey
sample material that was in there for an extended period. (We’d dissolved
most of the material with a combination of solvents and sonication prior to
attempting extraction.)
Any suggestions? Tips on how to get a good grip on a liquid-nitrogen-frozen
rotor without smashing or scratching it would be appreciated.
Thanks. - Josh
--
Josh Kurutz, PhD
NMR Facility Manager, Chemistry Dept.
University of Chicago
https://chemnmrlab.uchicago.edu/
jkurutz_at_uchicago.edu
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Received on Wed Jul 16 2025 - 04:11:36 MST