3 Jan 06 Notes on Cool Hand Luke. Chain had been in service for months and was working quite well. LN2 was turned of on 24 December. Today I've removed the lid and the carousel from Luke dewar. Here are some notes: The dewar was completely dry. It was clean, with no particles of any kind visable. There was very little of the "white reside" which can some times be seen on metal (Aluminum?) items that have been left inside LN2 dewars -- a tiny bit on a few of the Ell sample holders. For the record, here are some measurements, observations, etc. The Carousel rests on 1/8" extruded angle brackets which run along the inside length of the dewar. It's the same material that the sample holder Ells are made from. The Carousel base is 1/4" Al screwed to a 4" wide U-channel which has had it's legs almost completely milled flat. The base and it's U-Channel support are a total 0.780" high. The base itself is 5.00" wide and is 19" long. The inside of the Dewar is ~20" long and can easily slide back and forth on the extruded angle material; there's ~1/16" of side to side play. The carousel needs to be positioned so that the 1/2" NEMA-G rod to the drive sprocket is centered in the ~5/8" hole in the lid. Chain position for sample #1 has the face of its Ell bracket aligned with the center of the down-stream screw which holds the "idlepos" support for the tongs. This is also the position in which the Ell bracket of #14 is exactly aligned with that of #1, but facing the other way, the prefered method of alignment. (When the lid is inplace, however, #14 is not visable, so this "prefered" method can't then be employed.) There's a arrow drawn on the spocket; it points to the edge of #12 when #1 is in the "mount" position; (this only matters if you want don't want to lose the encoded motor position). Roller bearing disks on each end of carousel have 2 flat washers (spacers) under them. The 1/2" hold-down bolts have brass lock-nuts under the their sliding supports. The disks are Very loosely attached to their supports, but the bolts and lock-nuts were tight. The spocket is the one which had been modified by removing ~0.050" from the lower side in order to provide more up and down free play. The sprocket rides LOW, i.e. it can be pulled up ~0.035" before it makes contact with the top of the chain, thus the chain is supported entirely by the Ell brackets on the rails -- it is not supported by the sprocket at all. The chain can be pulled up by the Ell brackets ~0.060" before it makes contact with the sprocket. Therefore, the entire "slop" is ~0.090". The sprocket rests/turns on ONE brass washer/bushing. The (1.00") RAILS are 1.058" above the base -- they rest on single fat #10 flat washer/spacer. #4, #10, & #18 brackets each have one screw which can turn by hand, but the lock nuts are secure on the screw and the brackets don't wobble on the chain. Each of the drilled-out, brass allen screws (which have the magnets glued into them) has a single washer behind the head of the screw. All of the magnets appear to have a bit of their Nickel (?) plating peeling off -- or is that just the epoxy (that had leaked around to the face of the magnet) that's flaking off?? 4 Jan Started filling Luke dewar. Wanting a slow fill I thought I'd reduce the inlet supply pressure to the Supply Dewar. Inlet gas pressure (readinging the gauge attached to the pressure regulator/diaphram, with my finger holding down "high pressure" relief valve and closing valve into supply dewar) showed ~5.75 psi. I reduced it to 1.5 psi, but this was below the natural pressure (~2.5psi) built up inside the Supply Dewar. Filling under those conditions did not produce enough flow into Luke to prevent frost build up on the tong's resting platform, so I incresed it to 4 psi. That seemed a bit too much, so reduce to 3psi. I then powered off the Luke exhaust fan, since the heat exchanger was frosting up, and there was sufficent boil off to carry away condensed ambient moisture. ~10 minutes later the flow seemed a bit to low so increased to 3.5 psi. Note: The "high pressure" relief valve is definitely leaky. It seems to function well enough, but perhaps it should be replaced.