Hi everyone, Apologies to the late joining. XChem at Diamond light source only uses reusable bases and that since the start of xchem 4-5 years ago and we have lots of them (2000 maybe more?). Simple reason is that they are the only bases on the market which are re-usable and really easy to make replacement for: you pull out the old pins, you slot in the new ones. When preparing the pins, you can notice pretty quickly the 'bad' bases: With time, it becomes really hard to slot in the pin and the pin comes back up so you can see by eye that the overall pin length is longer than the Spine standard. The pin is also not snuggly fitting in the base. We then tend to throw away those bases. In the last 4-5 years, I don't remember us throwing away so many of those and given how heavily we use them (being frozen and thawn many many times), they seem to hold for some time. We do not use any acetone, glue etc...we clean them using a sonicator bath.
Regarding the slipping pin issue, when we were optimising the centring on i04-1 for automated centring, we have noticed that if you are not 'drying' the base at the early stage of the centring, we would not get the reliability we observed when doing reliability test at room temperature and that is because of pin drifting. We have put an 'air blowing focussed on the base' system on i04-1 and that has greatly improve the reliability. We have beamsize from ~35 to 70um and our smallest crystals are about 35um so we might have got away until now but we will keep an eye on this the day we upgrade for much smaller beam! Alice -----Original Message----- From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> On Behalf Of Andrew Purkiss Sent: 16 November 2020 19:03 To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] Stabilizing Mitegen reusable bases/mounts Hi Everyone, Just to put a word in favour of the re-usable bases. We've been using them for many years with little issue. The advantage of being able to make up "emergency" loops when needed during a freezing session being a big advantage. I have occasionally noticed the slipping pin issue (and when it occurs that base is withdrawn from use), but I've not noticed a general problem with smaller movement upon rotation. However, we do see the ice on the base issue (mainly due to impatient users freezing their samples). Here, samples can be seen to shift, even without rotation, for a few moments after mounting. Once the ice on the base/goniometer inteface has melted, the position stabilises. Of course, one advantage of the Diamond Light Source microfocus beamline, I24, is that the pin is vertical in the beam, so the mount isn't fighting gravity during rotation. Andy Quoting Diana Tomchick <diana.tomch...@utsouthwestern.edu>: > We no longer use the reusable bases for the same reasons, but we do > re-use our bases. If you use superglue to glue the pins into the > bases, you can remove the pins from the bases by soaking them in > acetone. This works about 75% of the time, especially if you are > careful not to use too much superglue when you glue the pin into the > base. > > It goes without saying that the use of acetone will dissolve the loop, > but then the main reason we remove the pin is due to imperfections in > the loop, so no big deal. > > Whenever we see the motions that you describe, we postulate that > somehow the pins were damaged and they are loose in the base. > Occasionally this motion is ascribed to ice between the base of the > pin and the magnetic mount, but this happens very rarely in our > experience. > > Diana > > ************************************************** > Diana R. Tomchick > Professor > Departments of Biophysics and Biochemistry UT Southwestern Medical > Center > 5323 Harry Hines Blvd. > Rm. ND10.214A > Dallas, TX 75390-8816 > diana.tomch...@utsouthwestern.edu > (214) 645-6383 (phone) > (214) 645-6353 (fax) > ________________________________ > From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of > Tao-Hsin Chang <taohsin.ch...@gmail.com> > Sent: Sunday, November 15, 2020 3:07 PM > To: CCP4BB@JISCMAIL.AC.UK <CCP4BB@JISCMAIL.AC.UK> > Subject: Re: [ccp4bb] Stabilizing Mitegen reusable bases/mounts > > > EXTERNAL MAIL > > Hi Patrick, > > I have met the same issue and that is very bad for any micro-focus > beam and small crystals. I have talked with Mitegen and they are > developing a new type of reusable base having an improvement for this > issue. You may get some update from them. But, I do not use the > reusable bases anymore. > > Best wishes, > Tao-Hsin > > On Nov 15, 2020, at 3:45 PM, Patrick Loll > <pjl...@gmail.com<mailto:pjl...@gmail.com>> wrote: > > Hi everyone, > > I’ve become very fond of the Mitegen reusable bases for mounting > crystals, since the reusable aspect savse me from having to discard > the base every time I break a microloop. However, once the crystals > arrive at the synchroteon, I observe motions of the loops (some > gradual, some sporadic). The the amplitudes of these motions are > becoming significant as I take data from smaller and smaller crystals. > I don’t think I’m imagining this, since the good folks at NSLS-2/AMX > have warned me about this very issue. > > I’m writing to ask if anyone has any clever ideas about stabilizing > these assemblies. Obviously, I can epoxy the pins in place, but then > I’ll probably need to discard the entire assembly when I break a loop, > and I’d prefer not to waste more money than necessary. I’ve considered > putting a bead of wax at the point where the pin enters the base > (although I haven’t yet checked to see if that will survive immersion > in liquid nitrogen). Does anyone have any other (better) ideas? > > Much obliged in advance, > > Pat > __________________________ > > Patrick J. Loll, PhD > Professor of Biochemistry & Molecular Biology Drexel University > College of Medicine Room 10-102 New College Building > 245 N. 15th St. > Philadelphia, PA 19102-1192 USA > > (215) 762-7706 > pj...@drexel.edu<mailto:pj...@drexel.edu> > > ________________________________ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > > ________________________________ > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > CAUTION: This email originated from outside UTSW. Please be cautious > of links or attachments, and validate the sender's email address > before replying. > > ________________________________ > > UT Southwestern > > Medical Center > > The future of medicine, today. > > ###################################################################### > ## > > To unsubscribe from the CCP4BB list, click the following link: > https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 > > This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a > mailing list hosted by www.jiscmail.ac.uk, terms & conditions are > available at https://www.jiscmail.ac.uk/policyandsecurity/ ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/ -- This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. 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