Arc Blow Is .....

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  #1  
Old 09-01-02, 07:15 AM
NutAndBoltKing
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Arc Blow Is .....

I haven't had any formal training in welding; and all I know is what my Grandfather, who was a blacksmith, taught me, and what I've learned from trial and error.

One of my Grand-daughters has taken a liking to welding and has made some impressive metal sculpture using 7018 lo-hy and my AC machine.

Lately she's begun experimenting with my Grandpa's old DC machine (that used to be mounted on his old chain drive Mack truck) and 6010 wire and is doing fine, but she has been getting some arc blow.

To combat the arc blow she's experimented with different heat settings, hand speed, electrode size, and with polarity (it's an old machine without a polarity switch, so she's got to change cables to change polarity).

I've tried to explain arc blow to her by telling her what my Grandpa said - that DC current only goes in one direction and as a result the work becomes magnetized causing the arc to wander.

Am I telling her the truth, or did my Grandpa pull my leg - again?

What's a real or better definition for arc blow?
 
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Old 09-01-02, 12:34 PM
Ed Imeduc's Avatar
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Wink Re: Arc Blow Is ..... Yes

What's a real or better definition for arc blow? [/B][/QUOTE]

This goes way back. I dont know the #### of the rod or wire as you call it. But with the old DC welders you had to have a polarity switch if not like you said you have to change the cables if you are useing what is called reverse rod.

We used reverse rod most of the time for over head and going up with a weld. It sucks the rod in .So if your polarity is wrong and you use a reverse rod we said it would spit at you. "Hey he didnt pull your leg" ED

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Last edited by Sharp Advice; 09-02-02 at 06:21 AM.
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Old 09-02-02, 05:24 AM
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reverse rod 6013 and such .we have rods made for use on a dc welder at work if you try to use say a 6010 on dc it dosent work very good
 
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Old 09-02-02, 08:24 AM
NutAndBoltKing
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Thanks for the information!

Yesterday my Grand-daughter spent a couple of hours working on a tricky sculpture with low-hydrogen wires and the AC machine.

Later she got adventurous and fired up the noisy old DC machine to weld some pretty heavy steel plates (with a hammered finish) into a cone shaped base for one of her other sculptures.

While using 6010 and the old DC she had her arc dance away.

It looked to me that she had prepared her joints just right, and even though the pieces were very tough to clamp, the fit was very good.

She changed her polarities, tried a couple different iron-powder rods, tinkered with the heat, let the machine cycle, and the arc blow went away.

She can fix the problem of arc blow; but she doesn't buy into my explanation about 'magnetism' being the cause.

It is magnetism - isn't it?
 
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Old 09-02-02, 08:50 AM
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Thumbs up your "RIGHT"

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It is magnetism - isn't it? [/B][/QUOTE]
ITS LIKE I SAID THE OTHER DAY. Rods use to come in reverse or straight polarity. Now if you had a reverse rod and it spit back at you, change the polarity by switching or changing the cables.

Now there is your magnetism ,and it will pull the rod in as you weld. You go this way for over head and an up weld or change the cable's...
ED
 

Last edited by Sharp Advice; 09-02-02 at 09:25 AM.
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Old 09-03-02, 03:25 PM
S
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Sometimes moving the ground helps. 6010 ad 7018 are dcrp rods. There are now 7018 formulated for ac also. I found Hobart at Tractor Supply and bought some as a graduation gift but havnt tried them yet myself.
 
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Old 09-04-02, 03:53 PM
Steve U S Alloy
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arc blow

Grandpa was right on the money. Arc blow is common to DC polarity due to the constant flow of current. Especially in an enlosed area or a corner. The magnetic field will not break down. Moving the ground closer to the weld area after grinding a good clean contact area will help. To eliminate arc wander and arc blow, you should use AC polairty. Each time the current reverses, the magnetic field breaks down.
 
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