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  #1  
Old 03-17-2017, 01:23 PM
Larry Mullen Larry Mullen is offline
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Installing an new shaped panel on rear corner of 38 panel truck
Original sheet metal is lightly rust pitted on inside and also thinner than 19ga, repair piece ,
Going to media blast and wire brush area to be butt weld panel n ew panel too .
Should add new panel is large aprox 20x 16 .
Open for suggestions / advice !!!!
Thanks Larry
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  #2  
Old 03-17-2017, 03:42 PM
Mike Rouse Mike Rouse is offline
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Larry,
Instead of media blasting, try phosphate prep first. Media blasting will stretch the surface and ruin the shape. After using phosphate you can wire brush the iron phosphate away and a little local sanding will make it good to go.
Mike
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  #3  
Old 03-17-2017, 03:56 PM
crystallographic crystallographic is offline
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hmmmm,
no media for me, either - embeds surface with hooligans, makes weird welds.

Me? solvent wash and 25% phosphoric acid wipe - Must for Rust / Ospho / etc. No rinse - wipe up excess and leave the powder.

( + Media blast leaves the fresh bright area Rust Prone to the max.)

"Better metal resto through Chemistry."
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  #4  
Old 03-17-2017, 05:56 PM
Larry Mullen Larry Mullen is offline
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Default OA welding advice

I always try and get away from pitted rust areas for welding , not possible in this case though,
Will try phosphate cleaning the edges thanks kent / mike ,Heres a shot of the panel need to get edges trimed and filed , Vert weld going to be a challenge oh boy ! IMG_0929.jpg
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  #5  
Old 03-17-2017, 08:19 PM
crystallographic crystallographic is offline
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I always try and get away from pitted rust areas for welding , not possible in this case though Attachment 40862
Larry,
You need to tack this thing where you can, first. ("look" at the weld line with the torch heat, and when the sides agree, tack there. )
After you tack where you can, then you tack where you have to.
Hammer out the tacks to line it up again.

Remember that chemistry wins - set a small tip - #0 - with a slightly carburizing/reducing flame (sumpin' tiggies cannot do). This balances the oxidized nature of one side of the seam. Flame is good when no fizz happens in the pitted weld area.

Try welding downhill between two tacks. Then try uphill. Tacks should be 1-1.5 in apart. You can lay the rod on and just melt it in (one technique for pitted-to-good weld seams, but there are others.)

Oh, are you using the torch? I assumed so because of the nature of the job .... - right?
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  #6  
Old 03-18-2017, 06:43 AM
Larry Mullen Larry Mullen is offline
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Default OA welding advice

Quote
You need to tack this thing where you can, first. ("look" at the weld line with the torch heat, and when the sides agree, tack there. )
After you tack where you can, then you tack where you have to.
Hammer out the tacks to line it up again.

Remember that chemistry wins - set a small tip - #0 - with a slightly carburizing/reducing flame (sumpin' tiggies cannot do). This balances the oxidized nature of one side of the seam. Flame is good when no fizz happens in the pitted weld area.

Try welding downhill between two tacks. Then try uphill. Tacks should be 1-1.5 in apart. You can lay the rod on and just melt it in (one technique for pitted-to-good weld seams, but there are others.)

Oh, are you using the torch? I assumed so because of the nature of the job .... - right?
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Yes using torch! after tacking start at one end and weld complete seam ?
Larry
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  #7  
Old 03-18-2017, 08:41 AM
crystallographic crystallographic is offline
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Kent
Yes using torch! after tacking start at one end and weld complete seam ?
Larry
okay, welding complete, end to end, can leave more distortion than old-school "step-back welding."
Thusly: Go to one end, and step back 2 inches then weld that two inch run, to the end. Step back 2 and weld to the previous weld. Repeat to finish.
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  #8  
Old 03-18-2017, 07:58 PM
Larry Mullen Larry Mullen is offline
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Kent
Do you use gas rod most of the time for your torch welding ?
Thanks Larry
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  #9  
Old 03-18-2017, 08:22 PM
crystallographic crystallographic is offline
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Kent
Do you use gas rod most of the time for your torch welding ?
Thanks Larry
I guess I just use the recommended welding rod for the alloy I am welding.
If I am welding 4130 then I use the rod recommended for either ductility or for heat treat, since they are different beasts, altogether.

When I was a pup metalboy I used to think "gas rod" and "tig rod" but over the years I learned that filler was filler, no matter the method - (95% of the time.) The torch can weld steels, aluminums, copper, stainless, bronze, gold, iron, magnesium, etc and usually with the same rod a tig guy would use. But most folks don't think of the torch as that versatile. It took me a number of years to get onto the torch, as I was trained as a tig-boy, and maybe that limited my thinking ...?
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  #10  
Old 04-18-2017, 11:33 AM
dschumann dschumann is offline
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Quote:
Originally Posted by crystallographic View Post
hmmmm,
no media for me, either - embeds surface with hooligans, makes weird welds.

Me? solvent wash and 25% phosphoric acid wipe - Must for Rust / Ospho / etc. No rinse - wipe up excess and leave the powder.

( + Media blast leaves the fresh bright area Rust Prone to the max.)

"Better metal resto through Chemistry."
OK - I'm a bit confused about the "no rinse".

I was under the impression that if you didn't rinse MFR, it'd just keep eating through the metal.
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