[3DEM] 626 cryoholder pin

Bill Tivol tivol at caltech.edu
Tue May 2 11:50:26 PDT 2006

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On May 2, 2006, at 5:28 AM, tgstechnologies wrote:

> Dear Bill,
> It is unforntunate the user can not "feel" the stopping point when the
> airlock pin hits its mechanical limit inside the TEM - Unfortunately 
> this
> has happened in the past.
> Your are being prudent in requiring the user to inspect the airlock
> actuating pin prior to each use.  Small cracks can form at the base of 
> the
> airlock pin due to minor bends of the airlock pin, and these cracks can
> weaken the SS pin.
> However if someone rotates the cryo holder too far (CW or CCW)during
> insertion or retraction, I believe the pin can break even if it had 
> passed
> the pre-use inspection, i.e. pre-use inspection does not reveal any 
> cracks.
> You probably know this already; the airlock pin is only activating a 
> micro
> switch in the airlock assy., but it's when the pin reaches the its
> rotational "mechanical limit", and the user can not feel this limit, 
> is when
> the bending/breaking occurs.
> FYI - In terms of a repair, the entire barrel (main axis) of the cryo 
> holder
> must be disassembled and a new front barrel installed.
> I hope this has helped you in some way.
> Best regards,
> Tom Schmelzer
> TGS Technologies
> 900 Glenwood Court
> Cranberry Township PA  16066
> Ph:  724.453.3865
> Fax: 724.453.2968
> E-mail:   tom at tgstechnologies.net
> Website:  http://www.tgstechnologies.net
Dear Tom,
	Thank you for your comments.  Both Bill Anderson, our FEI service 
person, and I have instructed our users to be very careful not to apply 
too much torque to the holder when inserting or removing it.  I was 
made aware of the repair process when I questioned the high repair cost 
the first time this happened.  Since SS is stronger than the material 
(phosphor bronze?) used on the room temperature holders, and we have 
had no problems with those pins, I have to wonder if something about 
the use conditions--low temperature--or temperature cycling is causing 
the problem.
Bill Tivol, PhD
EM Scientist and Manager
Cryo-Electron Microscopy Facility
Broad Center, Mail Code 114-96
California Institute of Technology
Pasadena CA 91125
(626) 395-8833
tivol at caltech.edu

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