<whitequark>
turns out i absolutely soaked my turbopump in forepump oil
<sb0_>
how did that happen?
<whitequark>
no check valve on forepump
<whitequark>
I have this new large chamber. pumped it down. turned turbo pump off
<whitequark>
then opened the vent
<whitequark>
however, the vent on the turbo pump is tiny and the chamber is large
<whitequark>
so the huge volume of the chamber has sucked oil from the forepump
<whitequark>
it all went in the bottom bearing oilpan and pretty much destroyed it
<whitequark>
not to mention that the whole pump is splattered in oil
<sb0_>
why didn't you keep the forepump running while venting?
<whitequark>
because I'm dumb
<whitequark>
anyway, I was able to get the oil out of it completely using large amounts of HCFC-141b for flushing
<whitequark>
the problem is now the sponge that used to contain the oil for the bottom bearing, which is now pretty much destroyed
<whitequark>
141b is pure magic. You splash it on a surface that's covered with a half-polymerized mix of two oils that isn't even washed away with regular soap--it still leaves a thick film--just splash it
<whitequark>
and in a few seconds you're looking at a mirror shiny surface without any trace of oil, where the only thing you see is tool marks
<sb0_>
do they still sell CFC refrigerants in Russia?
<whitequark>
sure
<whitequark>
"it's so good, it's illegal" would make a good marketing slogan *ahem*
<whitequark>
really a pity there are few functional replacements for CFCs.
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<chiggs>
I've always wondered what on earth @whitequark is up to and come to the conclusion you're a real life VXJunkie?
<whitequark>
I have no idea what/who that is
<cr1901_modern>
I'm very confused and scared reading the subreddit and wiki
<chiggs>
There's a similarity between 09:00:19 whitequark | then opened the vent │
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<whitequark>
annnnnnnd the pump works
<whitequark>
at least, spins up to ultimate rpm and bottoms out my pirani
<sb0>
so this turbopump is using mechanical bearings? no fancy magnetic levitation?
<sb0>
I got an ebara turbopump from the dumpster once, which did have magnetic bearings... and dozens of pins for control, no controller, and as with most japanese companies a very polite "fuck you" is the answer (if any) you get when asking for docs
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<travis-ci>
m-labs/artiq#298 (master - 34aacd3 : Sebastien Bourdeauducq): The build has errored.
<rjo>
sb0: no. the ad9858 also has a pll. nobody is using it even though it is an extremely cool feature (noce pfd in there).
<rjo>
sb0: take 1<<63 as the denominator. the 64-bit behavious is not a problem if you take machine units to be w.r.t. a 1<<64 denominator, set the lsb to zero for accurate calculations and then just shift right before writing the numerator.
<sb0>
exposing 63 is much easier
<sb0>
integers are signed in py2llvm, so 64-bit unsigned is a problem
<rjo>
fine. my vague guess is (havent checked) that the negative ftws will alias nicely.
<rjo>
for a 1<<63 denominator.
<rjo>
i remember having checked that for a similar problem many years ago but i would have to go through the math again.
<rjo>
... 1<<63 denom ftw on a 64 bit signed integer.
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