[Lab] Open Question: Dumbest Thing You've Done While Making
Richard Guy Briggs
rgb at tricolour.net
Wed Jun 26 12:21:08 EDT 2013
On Wed, Jun 26, 2013 at 11:53:52AM -0400, James Allanson wrote:
> Multiple Ultimaker burns, from my own Ultimaker as well as the first
> Artengine Ultimaker. Usually doing something stupid like cleaning the bed
> while the machine is moving the heated head around. I don't think I've
> learned my lesson on that one as I've made the same mistake many times.
> But I have been conditioned now to yank my hands out of the machine when I
> hear the stepper motor(s) engage.
>
> I did learn I have an extremely foul mouth when I burn myself though. :D
Heh, I do tend to have a much more foul mouth with inanimate objects
when I think nobody else can hear me. ;-) It usualy comes from bikes
or parts thereof not staying where they were put, falling on me when
trying to get at something else in storage in our overcrowded garage...
> On Tue, Jun 25, 2013 at 8:07 AM, mike Jans <mjans at live.com> wrote:
> > I had a similar experience at a young age, I had a habit of prying things
> > open to see what they had on the inside. I got my hands on a disposable
> > camera and used a flat screw driver and a pocket knife to pry it open. I
> > couldn't see it, but I managed to get each tool on each of the capacitor's
> > leads. I sat for a couple of minutes trying to understand what had happened
> > and then I went to tell my dad. He showed me what happens when you short a
> > full charge. I still have that screwdriver with those scars on it somewhere.
> >
> > > Date: Mon, 24 Jun 2013 17:31:13 -0400
> > > From: rgb at tricolour.net
> > > To: jason.cobill at gmail.com
> > > CC: lab at artengine.ca
> > > Subject: Re: [Lab] Open Question: Dumbest Thing You've Done While Making
> >
> > >
> > > On Mon, Jun 24, 2013 at 04:53:04PM -0400, Jason Cobill wrote:
> > > > That's amazing! I had no idea the uO solar car generated that much
> > current!
> > > > What kind of motor was all that power being used to drive? I was under
> > the
> > > > impression it was a tiny motor running at high RPM and geared down for
> > > > torque.
> > >
> > > It was a Uniq Mobility 10kW motor. That motor/controller combination
> > > wasn't nearly as effective at shorting out the battery pack as a small
> > > gold ring. ;-) Much of the competition was using Solectria motors at
> > > that time. Within about 5 years, pretty much the entire field had
> > > switched over to in-wheel motors made by New Generation Motors (NGM), a
> > > company founded by a number of George Washington University solar car
> > > team members.
> > >
> > > > Zot's a pretty cool nickname, though. ;)
> > >
> > > It makes me think of the "BC" comic strip... (I say this as I watch a
> > > huge black cloud criss-crossed by jagged white lines completely fill my
> > > large west-facing 4th-floor window at UQO on Tache in Gatineau.)
> > >
> > > > -Jason Cobill
> > > >
> > > > On Mon, Jun 24, 2013 at 4:49 PM, Richard Guy Briggs <rgb at tricolour.net
> > >wrote:
> > > > > On Mon, Jun 24, 2013 at 04:00:51PM -0400, Jason Cobill wrote:
> > > > > > Experiments gone wrong? Tools gone out of control? What's the
> > dumbest
> > > > > > thing you should have caught before you nearly set your house on
> > fire?
> > > > > What
> > > > > > did you learn from it?
> > > > > >
> > > > > > Me first: I plugged in a table saw without checking the switch
> > first -
> > > > > > it was on. And it was covered in 2x4s and sheetwood scraps, which
> > it
> > > > > > proceeded to launch across the garage and nearly take out a window.
> > > > > > It _should_ have been off, but I _should_ have checked. So now I
> > > > > check.
> > > > > > Every. Time.
> > > > >
> > > > > Oh, this one's easy. ;-) I have two related to electricity.
> > > > >
> > > > >
> > > > > 1) When I was about 10 I had a power transformer that I had taken
> > out of a
> > > > > wood-cabinet vacuum tube TV set. I had learned to solder when I was
> > about
> > > > > 8.
> > > > > I knew which side was the primary and I wanted to test the
> > secondaries. I
> > > > > knew
> > > > > they would be high. I had a cheap analog multimeter from Radio Scrap
> > with
> > > > > a
> > > > > 750V rating. I carefully attached and shielded the primary wires to a
> > > > > standard two-prong plug. I was sitting on my bed (so no danger of
> > > > > grounding out, plus it was an isolated secondary). I pinched one
> > > > > secondary wire with the meter test lead, then grabbed the second test
> > > > > lead and went to pinch it with the other secondary... (It was about
> > 350V.)
> > > > > I haven't done that ever again! Now I used insulated leads.
> > > > >
> > > > >
> > > > > 2) In my last year of Electrical/Computer Engingeering at U of
> > Ottawa,
> > > > > I was working on the U of Ottawa solar rayce car RALOS-II, wiring up
> > the
> > > > > main power backplane of the car (I was the Electrical Systems
> > > > > Co-ordinator) working on some low-voltage wires on one card that
> > > > > happenned to be facing a high-voltage, high-current card connected
> > to 7
> > > > > car batteries in series (90VDC, 1000A?). As I pulled my hands away
> > from
> > > > > my work something sparked. Naturally I pulled back, jamming my family
> > > > > gold ring into the high-voltage card. Once the sparks stopped, two of
> > > > > my fingers were black. After a quick throw of the main power switch
> > for
> > > > > the car to avoid any further incident, one of my teammates packed me
> > off
> > > > > to the hospital to clean things up. On the way to the hospital, I was
> > > > > babbling with all the wire cross-sectional diameters, materials and
> > > > > resistances per metre still fresh in my mind, calculating that must
> > have
> > > > > been a 100kW arc welding burn.
> > > > > I was lucky. I still have all my fingers, but one has an
> > > > > interesting ring-shaped scar (that was 20 years ago this month) and
> > the
> > > > > bloodstone with the family crest in the ring cracked. I thought of
> > > > > getting it repaired, then decided to leave it as a reminder. I was
> > very
> > > > > lucky it didn't instead hit the iron ring on the adjacent finger
> > that I
> > > > > had earned not 2 months prior. Gold is a much better conductor, so it
> > > > > didn't heat up much compared with the other parts involved. The two
> > > > > one-inch spade terminals on the card along with 1/2" PC board traces
> > > > > vanished. I had to check a second identical card to find out what was
> > > > > there. I earned the nicname "Zot" for that one...
> > > > > I now remove my rings when working with high voltage/current.
> > > > >
> > > > >
> > > > > I still love electricity! :D
> > > > >
> > > > >
> > > > > > -Jason Cobill
> > > > >
> > > > > slainte mhath, RGB
> > > > >
> > > > > --
> > > > > Richard Guy Briggs -- ~\ -- ~\ <
> > > > > hpv.tricolour.net>
> > > > > <www.TriColour.net> -- \___ o \@ @ Ride yer
> > > > > bike!
> > > > > Ottawa, ON, CANADA -- Lo_>__M__\\/\%__\\/\%
> > > > > Vote! -- <greenparty.ca
> > > > > >_____GTVS6#790__(*)__(*)________(*)(*)_________________
> > > > >
> > >
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> > >
> > >
> > > slainte mhath, RGB
> > >
> > > --
> > > Richard Guy Briggs -- ~\ -- ~\ <hpv.tricolour.net>
> > > <www.TriColour.net> -- \___ o \@ @ Ride yer bike!
> > > Ottawa, ON, CANADA -- Lo_>__M__\\/\%__\\/\%
> > > Vote! -- <greenparty.ca
> > >_____GTVS6#790__(*)__(*)________(*)(*)_________________
> > >
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> > > Lab mailing list
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slainte mhath, RGB
--
Richard Guy Briggs -- ~\ -- ~\ <hpv.tricolour.net>
<www.TriColour.net> -- \___ o \@ @ Ride yer bike!
Ottawa, ON, CANADA -- Lo_>__M__\\/\%__\\/\%
Vote! -- <greenparty.ca>_____GTVS6#790__(*)__(*)________(*)(*)_________________
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