GIB painting/welding question

G

Gunny-82

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Feb 24, 2013
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Im finishing up my Grinder In a Box and am prepping it for paint and to weld the upright to the base. However, im having trouble removing the gray coating (I think it's scale?). I've tried sanding it off and using a wire wheel with no success. Does anyone know if this will contaminate the weld if I leave it on and will it affect the paint if I spray a primer or etching primer on it? A friend is going weld it with a stick welder and he's on vacation so I havent been able to ask him but I want to have it ready to go when he gets back.

I've tried searching the web and forums for answers but the only access I have to the internet is with my phone so its a pain.

Thank you
 
It is scale and you need to clean it off before welding.

An angle grinder with a hard or flap disc will do it.

You can take it to a body shop and get it sandblasted too.
However after it's blasted it will want to rust.
 
You can also "pickle," it using a large tub and a vinegar. Let it soak over night and most of the scale comes off and what remains does not put up much of a fight when you attempt to sand it off.
 
Thanks for the quick replies. I will try soaking it in vinegar and let you know how it works.
 
Geesh, you guys are hardcore. I guess I'm quite the slacker. I've welded some pretty rusty, crusty metals together. I just can't picture the metal pieces from the GIB being so funky has not being able to be welded together straight out of the box. Aren't you just talking about mill scale?
 
I just wiped all the areas down with a clean rag and acetone after it was square and bolted up. Then completely welded it all up with a mig. Paint after. Still going after 2 years or so
 
Phil Dwyer said:
Geesh, you guys are hardcore. I guess I'm quite the slacker. I've welded some pretty rusty, crusty metals together. I just can't picture the metal pieces from the GIB being so funky has not being able to be welded together straight out of the box. Aren't you just talking about mill scale?
Click to expand...

I suppose it depends on the rod he will use and we have no way of knowing which one.

IMLE 7018 and 60 13 need clean steel.

Other rods are less finicky, but clean steel is still always better.
if he has the ability to prep it now before the friend comes back, why not?

You don't have to get the whole thing clean, just at the points where they will be joined.

Blasting will help with paint adhesion too.

I'v had tons of blasting done for very little cost
 
If you use the "pickle" method it is worthwhile to neutralize in baking soda and water afterwards, especially if there are assembled parts with small gaps between.
 
I work at a 100,000 Sq foot fabrication shop and we do a LOT of structural welding and we never grind back before welding and never have field failures. We just clean any oil or grease/dirt and go to town. We do blast clean to a "near white" state prior to powder coating though.
 
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