[Lab] Open Question: Dumbest Thing You've Done While Making
Pat G
purevirtualconstructor at gmail.com
Wed Jun 26 13:00:09 EDT 2013
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
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> > > > > 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
> > > > 1. subscribe http://artengine.ca/mailman/listinfo/lab
> > > > 2. then email Lab at artengine.ca
> > >
> > > _______________________________________________
> > > Lab mailing list
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> > >
>
> > _______________________________________________
> > Lab mailing list
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> > 2. then email Lab at artengine.ca
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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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