Scraping In Pocket

Written by NTS from email 5/27/2016.

Give yourself at least a full day to scrape, so you can make progress or finish, and reload the In cell if needed. It is OK to leave it in a transit case in a lightly purging glovebag (~15-20 psi) for one night at a time, but should only be done so if necessary.
The In is fairly soft/sticky, so scraping it can be challenging.
Scraping the In pocket requires a careful balance of hard pressure to scrap the material then immediately relaxing applied pressure the prevent dirty surfaces, like the end of scraping tool or gloves, from entering the machine.
If you lose control of the scraping tool while applying lots of pressure, the tool can hit other sensitive areas of the machine and cause damage. This mainly applies to the shutter and the shutter rod.

We will start at the point of the system being vented.

Open In Port

Open the In scraping tools and slowly get the tips into the In port.
Carefully but firmly scrape a little area and get used to the tool.
To prevent damage to the shutter and shutter rod, P2 should gently hold the shutter in an open or closed position by adjusting the bellows outside the machine while P1 performs the scraping.
Always be careful.
Don't jab into the Shutter, SF cooling panel, or Cryo panel.
Fish out large chunks.
Continue to scrape
Rotate through who is in the bag, and P1 and P2.
The shutter may go from stuck, to unstuck, to stuck, to unstuck..., as we moved around the pocket scraping (careful to never scrape into the shutter). #There was a notable mound in the top of the pocket the shutter rod looped around. Due to it being a dome, instead of blobs it was hard to work on.
After getting out must In and chunks, concentrate efforts on areas where In can build up and where the shutter travels across the pocket.
After some progress, periodically test the travel of the shutter as a metric for scraping progress.
Continue to take turns scraping and fishing out loose chunks of Indium.
Get to the point where scraping has severely diminishing returns, and it looks like we exposed some actual stainless steel.

The In cell is a high vacuum component, so it is best to leave it in an UHV environment, especially over the weekend.
The In cell & nipple in transit case can be left in the glovebag with a light N2 purge overnight when necessary. If there may be some issues with parts or junk in the port, we don't want to put the cell in the pocket.
The gasket vice grips might be best for removing a gasket from the In cell. It helps for getting in there with the huge birdcage.
Put blank or In cell back on system

Be very careful with the shutter.
It's helpful to scrape the In pocket using a combination of long and short tools.

E.g. while getting some In out of the pocket, some In got stuck to the shutter, and pulling on the In pulled on the shutter and caused it to break in half.
This set off a wave of what do we do, a phone call to Seth, and formulating a plan. This will alter the maintenance schedule quite a bit.
Fish out the broken shutter piece using two scraping tools, put a blank on the In port, and pump down Bravo.
The In cell & nipple in transit case can be left in the glovebag with a light N2 purge. We don't want to put it in the pocket when there may be some issues with parts and junk in it.
The only way to get more In would likely be brand-new tools, with sharp, clean edges.
Upon review, there was a delaminating part of the shutter I was able to carefully get off with some sticky In on the scraping tool, so that it wouldn't break off on the cell.

The shutter appears to have become slightly tilted with the top side into the machine. This probably happened while adjusting the amount of bellows compression to sometimes unstick the shutter after holding it in the open or closed position for too long.
Also, one of the bottom corner of the shutter closest to the shutter rod attachment point is very bent. This probably happened because might have bumped the corner with a scraping tool or it became deformed while unsticking the shutter.