[Sem] HOLD THE PHONE! DO NOT SCRAP!

Sat Jun 6 20:35:34 UTC 2015

Under no circumstances should a piece of ISI equipment be scrapped. Especially not a column. The probability is very high that any control equipment designed by ISI can be used with any column designed by ISI. 

I'm a high vacuum specialist. I can understand the frustrations of a vacuum leak, real or imagined. Without having reviewed this thread, I would suggest there is no hard issue here that stronger pumps or replacement  o-rings cannot solve. 
When my MINI-SEM started to take a crap, I assumed it was an o-ring problem. As best I can recall, I found no less than 30 o-rings available for user replacement. I ordered replacements and 2 spares each in Viton from a Bay Area company. This company had an o-ring "comparison jig" and one of their minions must have spent an hour or more sizing my old o-rings. I got at least 90 Viton o-rings back for a maximum charge of $150: quite probably a whole lot less. 
Other concerns took over soon thereafter. In particular I became far more interested in designing a universal digital controller for SEM's (and was successful in doing so) more so than in being interested in the health and welfare of any particular SEM, including my own. 
There was a dangling thread regarding O-rings. Although I felt effective in having discovered MOST o-rings, I suspect(ed) that there must be at least 3 key o-rings and considerable feed-throughs (hard or soft)  in the column which were not readily apparent. 

I can't promise to bring the SIIIA column back to life, but I am eager  to offer 2X scrap value for the column itself. If only with a sledge hammer, I am keen to gain any insight into the column o-rings and feed-throughs by forensically examining the column. 
I don't have room for the console, but I would be interested in the back panel. One of the key barriers in moving forward with my project was the dilemma as to whether to order a slew of mil-spec connectors on the one hand, or to cannibalize my working console for the connectors it holds. The voltage divider incorporated in the scan/mag switch is also of prime interest. 

WRT to leak detection, certainly it is an art unto itself. Industry would have us believe that the only avenue to effective leak detection involves a helium spectrometer of some kind. I suggest otherwise. Because the properties of Helium are so widely different from air in so many respects, virtually any vacuum gauge can differentiate between Helium and air. Thus in many if not all cases the only piece of exotic equipment required (above and beyond the vacuum gauges usually found on vacuum intensive equipment) is the bottle of helium. I have a bottle of balloon grade helium and a regulator I'd be glad to lend out (assuming I closed the bottle valve properly: been two years since I cracked it, may be empty by loss at this point) if you should decide to re-uptake the project of finding the leak yourself. I also have very sophisticated spectrometers, but they don't travel well so I'd be loath to lend them out. 

That having been said, I've noticed ISI cut corners on vacuum gauging in my MINI-SEM. You may be in a particularly disadvantaged position in this respect. Unless you have a discreet thermocouple and/or ion gauge, you may be screwed. 

>From a practical standpoint, you may well be better off taking your chances with another (possibly far more capable) SEM from ebay, especially if spending time farting around with a leaky column interferes with time better spent earning cold hard cash.
I must say that my interests in going forward with mid-grade SEMs is purely philanthropic. My dream was to outfit a MINI with turbo-mol and diaphragm pumps for instant-on, discard the console and replace with my digital controls. The idea was of an SEM in a briefcase, which I could trot around to high schools etc. in order to inspire kids' interest in science. Although reasonably attainable at the time, and despite the fact that I've spent nearly $8K in acquiring %95 of the parts for this project, I've faced struggles in my own life with basic survival since. Now this goal seems laughably lofty. I cannot say with any certainty that I can afford to re-uptake this project. In fact, I may be forced to re-sell the turbo-mol and other pumps earmarked for the project. But one never knows when my fortunes may turn again for the positive. 

I do have a car now, so could pick up the stuff loosely on offer. 
Oh BTW, I consider it especially imperative that Mike Khan/Noisebridges MINI not be scrapped or otherwise fall beyond the reach of practical recovery. As far a I'm concerned, the current custodian of this equipment has it on indefinite  loan and disposal, for profit or not for profit, would be improprietary. 

-Jeff

      From: John McMaster <johndmcmaster at gmail.com>
 To: Chris Murphy <chrisnoisebridge at gmail.com> 
Cc: "sem at lists.noisebridge.net" <sem at lists.noisebridge.net> 
 Sent: Thursday, June 4, 2015 7:35 PM
 Subject: Re: [Sem] Scrapping Super IIIA

Blanking off has been pretty effective.  Using that, I'm fairly sure the 
leak is in the column.  I started trying to take it apart and had some 
problems.

On 06/04/2015 10:20 AM, Chris Murphy wrote:
> I hate to think of it being scrapped but I can totally appreciate how much work it is to get going. Even then, you have the glorious experience of tweaking layers of analog controls.
>
>  What techniques have you used for leak detection thus far?
>
> I hope it finds a home even just temporarily because I've learned a lot from using the one at Noisebridge (now it's in the east bay). Someone else with patience could do the same with yours.
>
> Chris
>
> Sent from my iPhone
>
>> On Jun 4, 2015, at 9:00, John McMaster <johndmcmaster at gmail.com> wrote:
>>
>> Due to vacuum leak problems etc that I'm tired of troubleshooting, I'm going to scrap my Super IIIA and get something more modern / more plug and play.  Before I do, does anyone have interest in it? Haven't decided if I'd want some money or it would be free.
>>
>> If I do scrap it, most likely what that means is I will e-waste recycle all of the electronics and keep the column / vacuum system for the pipe dream that some day I will fix the leaks and design my own control system for it.  (this part is a mere fraction of the entire system size)
>>
>> Note: I'm keeping the small ISI SEM (M7) so will not be disposing of my extra filaments, etc
>>
>> John
>>
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