[Lab] Dumbest thing done while making(Pedro)
Pedro C. Peres
pedro at ncf.ca
Thu Jun 27 12:58:39 EDT 2013
Playing with disposable camera flash, accidentally grabbed both ends of the discharge path. I formed the R in the RC tank circuit and felt the diminishing discharge as described in first year electronics books. First discharge was high intensity low duration from left hand to right hand (through head and heart and whatnot) then slightly lower voltage longer duration from right to left and so on until it was completely discharged. My ears were ringing for quite a while after that. I was amazed at how much pain could be provided by a single AA battery.
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Today's Topics:
1. Re: Open Question: Dumbest Thing You've Done While Making (Pat G)
----------------------------------------------------------------------
Message: 1
Date: Wed, 26 Jun 2013 13:00:09 -0400
From: Pat G <purevirtualconstructor at gmail.com>
To: Lab at artengine.ca
Subject: Re: [Lab] Open Question: Dumbest Thing You've Done While
Making
Message-ID:
<CACbhOUzHKWUQ4oHrxozfW6DSyRxwPG2b3xayeW8xpU27LSze7Q at mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi, folks new to the list.
Stupid shop things. I had an out of town customer who had purchased and
returned in succession two high priced ceiling fans ~$500 each (this was a
while ago). For the third attempt to get him a working one, I used an
extension cord and two alligator clips to rig a test cable. I remembered to
only attach one clip at a time which was fine until I steadied the fan
housing with one hand and picked up the second clip with the other. Only
110 but right across the chest.
On a later occasion, I was working with 1/2" plywood sheet. and a radial
arm saw. I measured out the cuts with a large square, set up the saw and
prepared to cut. I couldn't figure out where I put the square but figured
it must be somewhere safe. I started the first cut, there was a loud clang
and the square hiding under the plywood shot through two layers of drywall
in the wall behind the saw. That was a little unnerving.
Fortunately both of those are well in the past.
The most recent one - I had my laptop hooked up to the USB port on my
Mendel printer. I was getting ready to unhook everything to move the
printer when I snagged that cable and popped the USB socket off the board.
That would have been ok since I still had comms through the port, but I
decided to be clever and solder the socket back down. That would have been
fine too had I noticed the tiny solder bridge to an open pad on the board.
Of course I powered up and fried the board. Ouch. Luckily I had a slave
board and was able to switch out the firmware.
Pat
On Wed, Jun 26, 2013 at 12:21 PM, Richard Guy Briggs <rgb at tricolour.net>wrote:
> 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__(*)__(*)________(*)(*)_________________
> > > > > >
> > > >
> > > > > _______________________________________________
> > > > > Lab mailing list
> > > > > 1. subscribe http://artengine.ca/mailman/listinfo/lab
> > > > > 2. then email Lab at artengine.ca
> > > >
> > > >
> > > > 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__(*)__(*)________(*)(*)_________________
> > > >
> > > > _______________________________________________
> > > > Lab mailing list
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> > > > 2. then email Lab at artengine.ca
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>
> > _______________________________________________
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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__(*)__(*)________(*)(*)_________________
>
> _______________________________________________
> Lab mailing list
> 1. subscribe http://artengine.ca/mailman/listinfo/lab
> 2. then email Lab at artengine.ca
>
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