Or wipe down with solvent dampened rags. Paint thinner is a suitable
solvent if used sparingly in a well-ventilated area and allowed to dry
thoroughly before lighting off the welder. Disconnect from power
Way OT story about wiping down with solvent dampened rags (not for the
Some years ago I worked with an electrical estimator who had been an
electrician with a large contractor for 20 years or so, and I asked
him why he quit the field work for the office job. Instead of
answering he uncharacteristically went off into a story of a routine
job at some North Jersey factory with the usual loop-fed 3-section
medium voltage switchboard, where two utility feeds enter the end
sections, each of which will connect to half of the plant load and/or
to the center section, which can feed either half of the load. Either
feed is adequate for both loads so any one section can be de-energized
completely without losing power to either half of the load.
This switchboard was indoors but well ventilated with polluted plant
air, so it needed to have its buss bars wiped down with solvent
dampened rags once a year, or the dirt would cake on so thick that the
buss bars would overheat. The estimator's crew was sent out to do
this rather trivial job with several experienced electricians and a
brand new apprentice, first day on the job. Nice kid, everyone liked
him, and when lunch rolled around and the kid had brought his lunch
and didn't have money for the restaurant they all wanted to go to
since he hadn't been paid yet. They offered to buy, but he would not
accept and stayed behind while they went to lunch.
When they returned they could not find the apprentice at first, but
the last of the buss bar in the first section had been cleaned, and
the door to the next section was open. His on the job training had
not gotten to the section lockout procedure yet. They found him on
the floor, solvent dampened rag in hand, unconscious but breathing,
footprints running up the wall behind him nearly to the ceiling. They
rushed him to a hospital where some of the crew saw him the next day,
"swollen to 3 times normal size and skin turned black" was their
possibly exaggerated impression. He said he knew he was dying, and
they gave him the "hang in there you can make it" speech, but he died
three days later.
On Thu, 03 Nov 2005 06:44:36 GMT, Ignoramus26745 wrote:
A small observation and not wishing to get too involved here. Isn't putting
the water cooling stuff on top a bit of a BadThing(TM)? A small
leak/condensation etc and high current circuitry below won't mix very well
I've had to remove the cross-posts as my reader won't allow it, sorry.
Hey, I thought you said a couple of weeks ago that it did NOT have HF.
Obviously, in the lower left corner of the pics of the welder's innards,
is the HF section. Maybe you meant it wasn't working, I don't know.
I have to say the inside of my Lincoln Square-Wave TIG 300 is a lot more
organized than the Hobart. There is VERY little wiring in the main
welder section other than the main power cables. All the circuit boards
and interconnect wiring is in an enclosed space behind the control panel.
I'm almost amazed the Hobart works at all with all the control wiring
hanging out near the main power circuitry. (I do notice a big shield
between the HF and the control boards. By the way, you may be
breaking the shielding with your new wires for the cooler. They go
right by the HF section, then up near the control boards. I would not
route them that way.)
Your cooler looks pretty good. I wonder, however, if you get into
serious TIGing, if the heat will build up. I was pretty surprised at how
hot the cooler got on my TIG system after some steel welding. (Actually,
it probably gets hotter on Aluminum with AC, but I am still learning the
techniques there, so I weld for a moment and then look at the part a lot.)
I have a Miller cooler with a big fan-cooled heat exchanger on it. The
exchanger gets hot, and the water in the tank eventually gets pretty warm,
I agree: I would not run any wires into that bottom box (with the HF) if at
all possible, and if I really did need to run wires into that box, I would
keep them clipped to the metal wall so as to be as far as possible from the
HF coils, and to minimise the flux flowing in the loop between the wire and
the metal wall. Certainly don't try putting any of your new circuitry into
that box with the HF. I think the top box looks more promising as a place
for the new circuitry. By the way, you could water-cool the IGBTs, that
works really well as long as you put a safety thermal switch to shut things
down if the water stops. The method I prefer is a slab of copper busbar
maybe 3 inches wide, quarter inch thick and as long as needed to bolt down
all the IGBTs. First drill and tap it for the IGBTs, mounting holes etc.
whilst it's still hard copper and easy to tap. Then use silver solder (not
soft solder but the sort that melts when it is almost red hot) to attach a
zig-zag of maybe quarter inch diameter copper pipe to the back of the
busbar, trying not to get solder into the holes you tapped before. Make
sure that the copper pipe fits well to the back of the busbar before
starting to solder it. I would also recommend making the ends of the
copper pipe long enough so that they protrude outside the welder and there
are no joints in the plumbing inside the welder casing. This way, if you
make the pipes slope downward, then if the joints in the pipework should
leak, the water will stay out of the wiring. You can get rid of several kW
with this sort of water cooling.
I probably said that it was not working (which was true). I fixed it
and it is working. I regapped the spark gap also and had to rewire HF
to make it work (the welder was wired for a remote HF device)
There is a big shield, it shields it.
I am open to suggestions here. Maybe I should twist them?
People in sci.engr.joining.welding group say not to worry. They say
that under the worst of the worst imaginable garage welding, the water
would barely get warm.
Worst case, I have many "condenser coils" at home (12x10 inches or so)
that I could use with a fan, but I see no point now. More possible
points of failure.
I dunno, I do not have the experience to back up my opinions (but I
have plenty of opinions). As I said, it is a no brainer to add a
condenser coil with a fan, I have all the parts already.
note on the cooler getting hot;
don't know how much coolant does the miller cooler holds and why it
gets hot, but one thing for sure the new miller 250 TIGs we used at
school the fan does not come on untill the coolant get hot enough.
it may even have some sort of flow control as well, because the sight
glass with the red star in it was barely spinning at 90-120amp welding
it has been said many times by guys here, a 5 gallon bucket or ever 4
gallon will never get hot enough (not even remotely) under normal
I asked the same question back when I built mine and Ernie L. and the
other well known gurus confirmed it.
NO heat exchanger needed. unless you are blasting 300Amp continuosly.
My Miller cooler holds just short of a full gallon, including what is in
hoses. I'm using Miller coolant straight, it is supposed to help the
prevent corrosion in the torch, etc.
On mine, the fan is mounted on the pump motor's shaft, so it runs all
Sounds like a heat exchanger is needed - as one loop from the stinger brings
in hot water and pumps back warm water - another loop is placed to chill the
warming water (water to say a term only) and dump the heat elsewhere. A nice
portable air conditioner that is a heat pump or not - could be implemented
when local power was available. When in the field, a Icebox from a camper
that runs on 12 v or propane might be a nice chiller.
Naturally some kit bashing and creative mind work would have to take place.
Solar cells dumping high current into a pair of wires that in turn run through
a solid state heat sink (ever see the 12 volt camping ice/beer chests ?) easy to
Almost done for you - cooling tank and drain and 12volt plug.
Plug it in and pump 'water' through 3/8" copper tubing - (or other) to a small
that might have been a motorcycle add on kit - back to the 12 volt chiller.
The box always closed and in the shade - and the bottom (where the heat is - on
a larger sheet of metal to conduct ? - truck bed ?
Martin - just had dinner and under boosted blood stream!
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder
acrobat ants wrote:
I spent about 40 minutes welding scrap last night. 130 A or so. About
as much welding minutes per hour as I could expect. Maybe 25% of time
was actually spent welding. The water in the cooler got barely warmer
(maybe by 5 degrees C or so).
On a related note, I replaced water with pink (purple?) RV antifreeze
last night. That way, the coolant will not freeze in my garage in winter.
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