Two centrifuge buckets, both alike in dignity?
It’s a truth universally acknowledged that an ageing group leader is, by definition, out of touch when it comes to the lab. After all, we spend most of our time writing grants and papers, fretting about ever-tightening budgets and attempting to navigate an arcane, deeply political academic minefield without getting blown to smithereens.
I do keep a hand in as much as I can, but in the back of my mind I know I’m not always at the top of the game when it comes to winkling out a cane from the liquid nitrogen tank without incurring frostbite, or pipetting into Eppendorfs at an industry-standard post-doctoral rate of two or more TPS (tubes per second).
Still, I like to feel I’m needed. So I honestly don’t mind that when I pass through the large lab space that we share with a few other groups, I am occasionally flagged down for advice.
Yesterday there was a small, perplexed huddle of postdocs around the big centrifuge. I wandered over to see what the fuss was all about.
“The balance alarm keeps going off, no matter what I do,” one of them explained to me, with that particular expression postdocs get when they are ten minutes behind schedule and not at all pleased at the prospect of arriving late down the pub.
“There’s definitely nothing inside any of the holes,” another said, tipping up the buckets to show me.
“Well, let’s take out the buckets and get a closer look,’ I suggested. “Better still, let’s weigh them. If they weigh the same, the problem must be with the rotor – or something electrical.”
“Oo, I didn’t think of that,” the first postdoc said.
Both buckets were duly removed, and I saw that they were the sort that are made of stackable, interlocking pieces, in order to accommodate tubes of different heights. The scales revealed that one set was 21 grams heavier than the other.
“But they are exactly the same,” someone said. “How could they be different weights?”
And it was true: from all superficial appearances, each was comprised of a stack of five pieces of identical color and make, nested into a larger but equally identical-looking metal seat.
“Take them apart,” I ordered. “You can weigh each part separately if needs be.”
Once completely disassembled, I noticed that one of the metal seats had a cloth pad fitted into the bottom, and the other did not.
“There’s your culprit,” I said.”And look – there’s the missing pad over there.”
General surprise,relief and hilarity ensued. The pub jaunt was rescued, and I walked away feeling, if not indispensable, then at least not ready to be put out to pasture just yet.
It’s funny, isn’t it. Glad to hear stories from the bench 🙂
I remember the late professor in my grad lab always telling us to weigh the rotors with the samples in them on one of those balances where you squirted some extra water into the “equalizer tubes”. Guess he’d seen a lot of these “things are not always as similar as they seem from the outside” 😉
This is doing nothing for my abiding hatred of centrifuges… the faster, the scarier. 🙂
Good job showing the youngsters how to troubleshoot, though. 😀