how to

[Mitch]

I am building some display racks for a customer and my metal supplier has problem with mill scale and i've tried just about every grinding and prep wheel. I was wondering what works good. Any input would be greatly appreciated.
Thanks mitch

[dath]

I found that the rubbery sanding disc that kind of resembles a tuffy pad used with the rubber backing pad in my drill press seems to work pretty well for me. It definitely leaves marks on the metal though. I've heard the flapper discs work well, but I haven't personally used one.

-dath

[aametalmaster]

I built lots of display racks from HR flat bar. I use a Med flap wheel or 4 1/2" discs on my angle grinder. You will use a lot of them going to shiny metal...Bob

[MD Welding]

Try sandblasting. 90 psi with good grit does a great job.

[thehat]

Another option is to use cold rolled-no scale just some oil to clean.

[Pantaz]

The easiest is to order your material P&O (pickled and oiled).

Methods for removing HR scale, other than grinding, include abrasive or shot blasting, and chemical pickling (generally acid or salt bath).

Some commercial products exist. I haven't tried this one myself, but it's been highly recommended. I don't know the price.
http://www.picklex.com/

[Rocky D]

Unless your mill scale is thick like potato chips, I wouldn't worry about it. I never grind mill scale on small stuff like 2x2 angle or square tube. On the project below I used a needle scaler.
http://img.photobucket.com/albums/v252/RockyD/Sheridan%20Stretch%20Bender/MVC-103F.jpg

[tigman250]

the only way to remove mill scale is a needle scaler, just tack the 2 pieces together and run a scaler along it and weld, you will never thought a weld could look so good!!!!

http://www.michiganpneumatic.com/default.aspx?page=category%20search%20results&CatList=640150&parent=26631&tree=26595*Percussive+Tools*0@@26628*Scaler*0@@266 31*Needle*640150@@

here is a link to some scalers