Replacing the Coldhead:
1) The coldhead can not be removed unless IGRINS is lifted above the leg height. This was achieved with reams of paper.
2) The cryostat lid can not be removed when IGRINS is lifted on paper reams. first remove the lid, then lift IGRINS to place paper reams underneath.
When lifting off the cryostat lid be careful not to bind on the pins. It helps a lot to release the wheel locks.
3) Removing the cold shield can be difficult because it is covered in tape. It requires about 6 hours of labor.
4) The cold shield sides are removed in a intersecting box (pinwheel) pattern.
5) To remove the coldhead you must first remove the getter.
6) also, remove the copper plates as shown in photos.
7) The coldhead drops out when specific fasteners are removed. Review photos to see which ones. Do not disassemble entire flange. support from the bottom.
8) Disassemble the coldhead flange, based on the photos, and replace all the o rings. Clean and degrease orings.
Lift the bellows from the bottom to avoid over stressing.
9) Lift the coldhead back into IGRINS and fasten into place.
10) Reconnect the copper strapping and charcoal box.
11) Done.
Items to be completed in the future:
bake getters annually
slit mask needs more baffles
