[Sem] All in on the mini-SEM?

Tue Dec 16 02:54:36 UTC 2014

BTW I saw your blog, sounds like you need a new filament. They burn out every 25 hours or so. I hope you got the filament holder/whenelt. They are consumables but $$ and frequently pirated. I think most for ISI are the same, I have a few in fair condition I might sell one.
-Jeff
      From: John McMaster <johndmcmaster at gmail.com>
 To: Jeff Miller <mysterylectricity at yahoo.com>; Chris Murphy <chrisnoisebridge at gmail.com> 
Cc: "sem at lists.noisebridge.net" <sem at lists.noisebridge.net> 
 Sent: Friday, December 12, 2014 7:09 PM
 Subject: Re: All in on the mini-SEM?

 Heyo,
 I haven't followed the noisebridge unit, but some updates on my side if anyone is curious.

 I traced the vacuum leak to the column in my Super IIIA.  I'm having trouble safely taking apart the column to troubleshoot further.

 Over the previous weekend I picked up a small ISI SEM similar to the noisebridge unit ($500 + drive to LA and back).  Some details on it here: http://uvicrec.blogspot.com/2014/12/theyre-multiplying.html

 The guy also threw in a carbon coater.

 Anyway, it has a broken PMT and needs a small vacuum adapter that should have come in the mail today.  PMT has unknown ETA but I could steal a spare off of the Super IIIA if I wanted to test sooner.

 I also have a *huge* (over 100 lbs) pile of ISI documents (schematics, mechanical drawings, service notes, etc) I've been scanning in that one of their retired lead techs gave me.  Maybe this weekend I'll finish the digitaization process and begin uploading/organizing them.

 I have a small Pfeiffer/Balzers turbo pump system I assembled off of eBay for under $500.  It was chosen specifically because parts for this particular system are readily available to piece together.  Of course, it would be hit or miss if the bearings are sub-optimal but I imagine often times they will be good enough for hobbyist use.  I'd suggest others looking into the same route before dropping 1k on a restore kit.  I haven't decided if I'm going to attach it to the SEM once it works better.

 I get class 10k using a high power Honeywell HEPA filter in my bedroom.  Very cheap and easy to setup.

 John

 On 12/12/2014 05:56 PM, Jeff Miller wrote:

  I think we should give the mini-sem project a second chance. 

  I've been thinking about what the SEM experience at NB drove home. 
  We should think small and practical. 

  Rather than a clean room, let's think glovebox. Small glovebox, easy enough to fab.

  The manual vacuum controls have to go. It should all be electric valves, interlocked and goof proof. 
  The coater should be integrated, and interlocked with the SEM to use the same pump(s). 
 Perhaps a small, low temp vacuum oven for drying bugs and plant samples, too.

  The console has to more or less go. We have to commit to the digital platform I developed, or develop a new one.  
  Ideally, the diff pump and forepump should be replaced.with a turbo and a diaphragm pump. With that we get instant on, no exhaust fumes. and no periodic cleaning of the column parts. 
  Alcatel makes a high speed molecular drag pump. I may be wrong, but I don't think it has stator blades. So I think you can up-to-air it at full speed with no damage, and it may be able to choke down a grain of sand or two without exploding. It will be mounted upside down of course. 

  The vacuum isn't as deep as theoretical for a turbo or diff pump, but is more than sufficient for a SEM and coater. 

  I have a bunch of these pumps.  So many in fact that I'm thinking of coughing up the $1,000 for the factory toolkit (probably a bearing puller and two precision bore steel plates, if that)  to rebuild them. I think the bearings alone go for $300, but it shouldn't be hard to find a pump with bad bearings for ~$250.  The pumps have a very high foreline pressure tolerance, 30 torr I think: I've seen them backed with run-of-the-mill two stage diaphragm pumps from Gast.  Meanwhile, high performance four stage diaphragm pumps seem to be fetching less than half of what I was getting for 
  them 5 years ago, $150 might buy a working pump and $200 more might effectively rebuild it. 

  As it turns out, I've already done some of the heavy lifting. It's probably been close to ten years now since I first wanted to make the mini-sem portable, to bring to classrooms. To that end I had custom pieces milled that attach to the top and bottom vacuum ports, and convert them to the KF standard.  Short lengths of stainless bellow also show up cheap enough these days. 
  Perhaps as much as anything, it would highlight vacuum technology as well as the SEM itself. 

  I might have almost everything we need on hand. I can see lending the core components for proof of 
  concept , or until they can be found serendipitously on ebay.. 

  For all the little pieces and parts, $200-$300 might be a good guess and represent a good working minimum budget for retrofitting the valves and 
  piping.  If we have to do it from scratch, the glovebox could be another $150 or so but further down the line. 

  I say pitch it as far more user friendly and less invasive, and see if we can get funds allocated.  
  Anyone care any more? How are you guys coming along with your SEMS, coaters, and turbos? 

  -Jeff 

      From: Chris Murphy <chrisnoisebridge at gmail.com>
 To: John McMaster <johndmcmaster at gmail.com> 
 Cc: "sem at lists.noisebridge.net" <sem at lists.noisebridge.net> 
 Sent: Tuesday, September 2, 2014 12:13 AM
 Subject: Re: [Sem] Picked up a sputter coater

 Well that's a breakthrough. Maybe Alan has something to coat. 

 Sent from my iPhone

 > On Sep 1, 2014, at 22:41, John McMaster <johndmcmaster at gmail.com> wrote:
 > 
 > ...3.5 hours of driving each way later.  Hit me up if you need to coat something.  I have a gold target for it
 > _______________________________________________
 > SEM mailing list
 > SEM at lists.noisebridge.net
 > https://www.noisebridge.net/mailman/listinfo/sem 

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