vab wobble stick: misalignment of outer/inner magnet and stuck of pincers inside UHV

[Kai Huang]

Hi, friends,

I have a wobble stick from VAB Vakuum. (the new style, magnet coupled, can do rotation and translation motion). It came in as part of a whole spm system. The wobble stick  started to act up lately, as below:

That is,

(a) The outer magnet cannot be fully retracted to the end of the wobble stick tube.
(b) The pincers inside UHV are stuck at “close” position.

Both observations can be seen as in the attached picture. We tried to pull the outer magnet back to the end of the tube, and it indeed recovers the issue. But this action would often lead to open of the pincer, and hence sample dropped inside the system. And it started to happen a bit too often. (once last week, and 3 times this week)

We have now vented the system, and in case anyone has the experience, could you kindly advise us on how to look upon this issue further and fix it, please? Really appreciate it if there is a manual that we could make use of from VAB vakuum? 

Many thanks,

Kai

[Navrotski, Gary]

Hello Kai Huang,

 

I do not have this particular version of a UHV wobble stick but I took a quick look at its design using  drawings available on the DEMACO web-site (https://www.webshop.demaco.nl/product-category/vacuum-manipulators/rotary-wobble-stick/).

 

It looks like a simple concentric rod-and-cylinder device.  Example below is the VAB Vacuum Demaco MDWS-Z0-50 (but there are 50 thru 300 mm extension designs).

Unless one of the three designed-in motion-limiting stops has slipped or jammed, I don’t have a quick answer to your problem.

 

Feel free to contact me directly if you would like me to examine the drawings for your exact model and provide whatever information they contain.

 

 

Best regards,

Gary

 

 

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Gary Navrotski, P.E., Ph.D.                Navr...@anl.gov

X-ray Science Division - Beamline Instrumentation Group

Advanced Photon Source                  Office:  401-B3200

Argonne National Laboratory           calendar link

9700 South Cass Avenue                   Ph:    (630)252-7576

Lemont, IL 60439-4801                     Fax:  (630)252-9350

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Many thanks,

Kai

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