Author Topic: Cameca sample holders  (Read 2321 times)

Probeman

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Cameca sample holders
« on: May 16, 2017, 10:48:13 am »
I learned something new today (probably obvious to everyone else!).

Our machine shop had machined some new slightly longer screws that hold the sample holder to the sample "cassette"? (that slides into the airlock "prongs"), because the old shorter screws were starting to strip out the threads in the insulating pieces. This is for the 2 + 2 sample holder for 2 thin sections and 2 round mounts for standards.

So I dutifully checked the conductivity between the sample holder and "cassette" in case the longer screws were shorting out the insulator and sure enough there was a short. 

So I backed out the screws to attempt to determine how much shorter the new screws needed to be and to my surprise there was still a short. So I checked more closely and discovered that although the sample holder looks symmetrical, it apparently can be mounted in either orientation. And in fact in one orientation the sample holder does not short, while in the other orientation the sample holder *does* short out to the "cassette".

So that might explain the odd sample current readings that we occasionally obtained!   Anyway, now the sample holder has some arrows drawn on it to show the proper mounting orientation.
john
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Owen Neill

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Re: Cameca sample holders
« Reply #1 on: June 30, 2017, 12:44:40 pm »
Related question - are SX50 and SX100 sample holders interchangeable?

Probeman

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Re: Cameca sample holders
« Reply #2 on: August 06, 2018, 12:18:46 pm »
Related question - are SX50 and SX100 sample holders interchangeable?

I just stumbled across this question from Owen that had missed somehow.  We just got rid of our SX50 instrument a few months ago, and actually never tried swapping them.  I have a memory that although the actual sample holders are identical and could be swapped, the base (what Cameca calls the cassette?) might be slight different in that contact for the sample current connection is different.  Does anyone know?
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Probeman

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Re: Cameca sample holders
« Reply #3 on: August 06, 2018, 12:26:12 pm »
I wanted to share some photos of a special sample holder that our machine shop made for us in case anyone else runs into a similar situation.

The basic problem is that a scientist from PNNL had a thick rock chip sample that cannot be modified as they want us to also do EPMA on a traverse previously analyzed using SIMS.  Also they had some non standard round mounts that were smaller than 25mm.

Here is what the samples looked like:



Note that the rock chip is very thick, approx 10 mm and needs to be top referenced on the Cameca because of the limited Z range.  Also the round mounts are very unround!   

So our amazing machine shop made this holder for the thick rock chip and some adapters for the round mount:



Here's what they look like all mounted up:



Nice!
« Last Edit: August 06, 2018, 06:59:38 pm by Probeman »
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jon_wade

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Re: Cameca sample holders
« Reply #4 on: August 07, 2018, 04:24:59 pm »
John - what would be really coooool is if, rather than a grub screw or spring, there was a coarse screw thread and base in each hole, either backed with a spring or otherwise.  I once made similar for our old 8600 but the sx5 could do with similar.    I would buy one...or two.....


Probeman

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Re: Cameca sample holders
« Reply #5 on: August 07, 2018, 05:47:33 pm »
John - what would be really coooool is if, rather than a grub screw or spring, there was a coarse screw thread and base in each hole, either backed with a spring or otherwise.  I once made similar for our old 8600 but the sx5 could do with similar.    I would buy one...or two.....

I'm interested.  Can you make a rough sketch of what you are thinking of?  I assume you are looking for a sort of adjustable bottom plate that pushes a flat sample up against the reference surface?   Maybe better to describe the shapes of samples you want to hold at a specific Z height?

The brass tabs on the holder we made could be swapped out for differently sized ones...

Is a "grub screw" what we 'mericans call a "set screw"?
john
« Last Edit: August 07, 2018, 06:22:28 pm by Probeman »
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Owen Neill

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Re: Cameca sample holders
« Reply #6 on: August 10, 2018, 10:23:55 am »
I have a memory that although the actual sample holders are identical and could be swapped, the base (what Cameca calls the cassette?) might be slight different in that contact for the sample current connection is different.  Does anyone know?

Had the opportunity to try this a while back, - the holders seem to attach to the shuttles from both the SX50 and the SX100 just fine, but the SX50 shuttle is longer, and sticks out far enough that it won't go all the way onto the SX100 stage. See below.


Changkun

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Re: Cameca sample holders
« Reply #7 on: August 21, 2018, 06:01:27 pm »
Hi all,

Recently we modified Cameca 6-holder to use spring for almost complete flat top.
(We use this holder for my 8530F.)
The idea came from both Cameca SIMS holder and Thermo(?) LA-ICP-MS holder.
We wanted polished thin sections on this holder observable with optical microscope as well.

Probeman

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Re: Cameca sample holders
« Reply #8 on: August 21, 2018, 06:20:14 pm »
Recently we modified Cameca 6-holder to use spring for almost complete flat top.
(We use this holder for my 8530F.)
The idea came from both Cameca SIMS holder and Thermo(?) LA-ICP-MS holder.
We wanted polished thin sections on this holder observable with optical microscope as well.

Hi Changkun,
Nice.

For our lab, instead of springs I made some short tubes from 25 mm Al tubing (~4 mm wall thickness) and use each tube to push the round thin sections against the top reference lip.

When tightening the set screws on these short pieces of Al tubing, one needs to push these tubes up against the round thin sections from underneath, so the thin sections are held are snug and not loose. That is one should not hear the sections rattle at all, when tapped on their bottoms.   :)
john
« Last Edit: August 21, 2018, 06:39:46 pm by Probeman »
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Spratt NHM

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Re: Cameca sample holders
« Reply #9 on: October 10, 2018, 06:59:12 am »
Hi I am currently looking for a holder for one slide and 4 x 25mm mounts as shown below. Could you give me a price for one. Many thanks
John Spratt

Probeman

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Re: Cameca sample holders
« Reply #10 on: October 10, 2018, 08:32:51 am »
Hi I am currently looking for a holder for one slide and 4 x 25mm mounts as shown below. Could you give me a price for one. Many thanks
John Spratt

Hi John,
By "as shown below" do you mean like the picture here:



But instead of a rectangular rock chip, have it hold a rectangular petrographic slide?   Are you asking if our machine shop can make one for you? 
john
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Spratt NHM

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Re: Cameca sample holders
« Reply #11 on: October 17, 2018, 01:08:06 am »
Hi John,
         Yes I am currently trying to source a holder as per your image, to hold 4 x 25mm blocks and a petrographic slide. A metal plate held by grub screws to go up against the bottom of the slide would probably be the simplest fixing scheme. We currently have 3 SEMs (two Zeiss instruments and a new JEOL IT500). These instruments have a cameca holder adapted to take any of the cameca sample holders. I would like this holder so that I can have two standard blocks installed (Astimex) with the option of adding 2 x 25mm samples and  / or a petrographic slide. The really nice thing about the cameca holders is that they are top referencing which means that moving around the sample in the SEM requires little change in Z, which is safer for the chamber furniture when students and staff are using the instruments.This also means that samples can be swopped into any of our instruments. I am currently upgrading our Oxford EDX detectors to the AZTEC software along with our suite of off-line processing PCs and have also upgraded the Cameca SX100 to Peaksite 6.2. So things here are about to get manic. I also have an adapter so that our new JEOL 5830 plus microprobe can use our cameca standards and samples. If you could give me a quotation for your machine shop to make one for me that would be good.

many thanks
John

Probeman

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Re: Cameca sample holders
« Reply #12 on: October 17, 2018, 12:31:59 pm »
Hi John,
Our machine shop says they'll make you one for US $380.

Such a deal.
john
« Last Edit: October 17, 2018, 12:59:25 pm by Probeman »
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