On 3 Nov 2005 06:09:35 -0800, Winfield Hill
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 first.
Way OT story about wiping down with solvent dampened rags (not for the squeamish):
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.
I may try to clean it just a little bit, but I would rather leave it a little dirty inside than break circuits etc.
scary stuff... I once had a collision of my car with a moving train...
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 IHMO.
I've had to remove the cross-posts as my reader won't allow it, sorry.
I think that you have a good point, but my welding machine is made in such a way that water would not get inside, it would flow over the sides.
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, too.
Jon Elson wrote:
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.
On Thu, 03 Nov 2005 16:08:14 -0600, Jon Elson
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 use.
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.
acrobat ants wrote:
My Miller cooler holds just short of a full gallon, including what is in the torch hoses. I'm using Miller coolant straight, it is supposed to help the pump and prevent corrosion in the torch, etc.
On mine, the fan is mounted on the pump motor's shaft, so it runs all the time, too.
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 bash. 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 radiator 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!
Martin Eastburn @ 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.