EXT250 A/C questions

[todmorg]

Finally got around to trying light aluminum, and I have a few questions

1- My cleaning #'s go from -40 to 40 not 5 - 95 like the manual

2- Using the trigger on 2T I cannot get below 20 amps on a clamp on meter, even though the display on the welder is set to 3 amps. You cannot move fast enough to keep it from burning through the bottom ring of a beer can.

edit: My start and end currents are at 3 amps. balance at 0 and bias at 0

[performance]

OK. The cleaning reading is fine, but it equates to essentially the same thing. The reading is taken by using 50/50 or 50% as the 0 point...Think of a number line that goes from negative 50% to positive 50%...This makes up a total of 100% if you take the absolute values and add them together. A setting of around 20-25% should get you around the ball park. (more penetration than cleaning).

As far as the clamp reading...First make sure your EN is not set under EP and is at least 0, which you said you have done. Next, try to lower your EN and watch and see if amps do not drop or the situation changes with your progress on a beer can...Then try to raise them and watch what happens. But if you are using a clamp meter, you may have some issues because of the HF.

Have you checked it with your foot pedal? Didn't you have an LX?

[parkour]

Also, unless it is a really nice clamp meter (and even then maybe not), it may not read correctly if there is anything other than a 50/60Hz sine wave on the wire.

[todmorg]

OK, a little more info-

On A/C, If I try to run at 3 amps, it will show between 18-20 on the welder ( edit: during the weld ) and almost exactly the same on the clamp on meter. The welder is set at 60 hz

On D/C If I try to run the amperage down while welding, it will start cycling the HF when I get below 10 amps.

I just tried lift start, and it will not maintain a flame under 10 amps on d/c, and still shows 18amps on a/c

I also tried the pedal, and it only controls the amperage slightly, it doesnt seem to want to feather down in the lower amperages.

Edit: I am using a clean, very sharp 1/16 2% thoriated tungsten, and have tried higher and lower gas flows.

[performance]

Todd, what is the AC frequency setting? See if lowering it to 60 Hz or lower makes a difference.

[todmorg]

I'm at 60hz, I've tried up to 150 with the same results.

[performance]

Also, did you try what I mentioned about the AC balance, and amplitude?

[todmorg]

Amplitude is at 0, I will try dropping the en right now.

[DVA]

I tried to turn the current down to see what happens with a Coke can and it just blew a hole through the can, this was just a few tries do not know where to start but I see this as a good test for low powered welding. The 250EX is capable of welding aluminum cans so I would assume the 250EXT should do the same. I am working on getting the water cooled torch working and then will start playing more to test on low power.

[performance]

Even at 20 amps, most experienced welders should be able to weld. I believe Jakeru demonstrated that on his old unit. Several have on the 256. Its likely that a little AC balance, and amplitude adjustment is in the works.

The EX and EXT are two different designs completely...nothing in common.

[todmorg]

Were making progress!

I set the cleaning to -25 and it brought the amperage down on the ac, now I can walk around a can very easily. So, negative must = clean.

Next, on dc, If I set the starting amps at anything less than 11 amps, it will just keep cycling the hf at about 2 or 3 hz. If I start welding at a higher amperage and turn down the amperage during the weld it does the same thing once I get below 11 amps. Could this be a gap setting? I don't remember seeing specs on the gap.

[performance]

Yes, it could be point gap. Point gap for that unit should be about .045.

[performance]

Yes, please see my explanation above and below. + is penetraion, - is cleaning.

[performance]

bias, is actually actually setting negative amps as % over or under welding amps. If they are offset, the unit will read an "average" of both...not true half cycle amps...So it is possible that you may not see true amps. So, AC balance will also affect this by the amount of spent in each part of the cycle.

[todmorg]

My gap is at .045 from the factory. I will just keep my start amps above 10.

[performance]

No, try adjusting up or down slightly. this can help improve starts. Just see, then return.

[Mike J]

So what exactly is the "point gap"? It just sounds weird that a mechanical gap setting impacts the ability of the welder. Is this a relay or device that impacts the jump from the HF start to the actual welding?

Does the 250EXT have this mechanical component as well?

Cheers,

Mike

[performance]

It sounds weird that an old car won't run without the right point gap too. Same principle applies. The tungsten is the spark plug so to speak. Point gap is the air gap between the two HF points.

[Mike J]

It sounds weird that an old car won't run without the right point gap too. Same principle applies. The tungsten is the spark plug so to speak. Point gap is the air gap between the two HF points.

Hey Mark,

Ok, but where is it to be adjusted, and does that mechanical design exist on the 250EXT? (i.e. I am trying to learn that, when I get my new welder, that I need to know this). :-)

Another reason is I am curious - must be the electrical P.E. in me!

Cheers,

Mike

[parkour]

The "point gap" is that little vertical brass thing at the right with the gap in the middle between the top and the bottom pieces.



Thanks to todmorg for the picture.