Tuesday, May 19, 2009

Visual inspection.

My day job has been intense the past few months but a month ago I did get some time in the shop. I did some clean up chores and was finally ready to do some art. Plugged in my trusty foam cutter and it did not heat up. Got out the multimeter and everything seemed fine so I decided my power source, an el cheapo battery charger, had died. I was getting 12 volts, but the multimeter does not measure amps so I concluded something was wrong and I needed a new power source.

Another week and I scored a laptop charger - 15 volts and 4.6 amps or 69 Watts. Close enough to my battery charger which is 12 volts and 6 amps or 72 Watts. Plugged it in and nothing.

Now there is absolutely nothing to foam cutter circuitry. My cutter is a piece of MIG wire, tensioned by a spring, that goes to two terminals. Hook up the battery charger and the wire turns red - what could be simpler? The laptop charger by itself produced 15 volts, but when connected to the cutter produced 0 volts! Then I remembered when I first built the cutter several years ago I tried to use a power supply from a computer. It too did not work and I concluded that the power supply 'saw' the foam cutter as a short circuit and shut itself off. Maybe the laptop charger was smart enough to do the same thing. Another week at work went by.

Back in the shop, I remembered a posting on the Miller welding site. Someone had a problem with their welder, lots of people chimed in with solutions, and it finally turned out there was a loose connection. The guy with the problem had wasted everyone's time trying to analyze the problem and one of the experts in frustration posted, 'Never ask for help until you have performed a visual inspection!'

I carefully examined the foam cutter. Everything was fine. Then I looked at the battery charger and noted that the ground clamp had some corrosion. I was ready to throw the thing out so, what the hell, I cut off the clamp and hooked up the bare wire to the cutter. Mirable Dieu, it worked perfectly.

One step backwards, one step sideways, I was finally ready to make some art. So I did, went to take some pictures, and the camera batteries and the two sets of spares were all dead. Maybe the universe is trying to tell me something.