project finish question

admin

Hi all. Thanks to Lugweld, specter, and dave powelson for steering me from purchasing a MIG welder to my choice of a Miller Thunderbolt XL AC-DC machine.No surprise is my first project of a cart to move the machine around. It has been many years since I used an arc welder and haven't been in a related business so this question might sound dumb. I am wondering about the coating or scale that normally comes on new mild steel. Should I use an abrasive to remove it for painting with primer? Or is it okay to just primer over it for a long-lasting rust-free coating? See attached photo. If I need to remove the coating is a portable grinder with sanding attachment the best method for limited budgets?Thanks for all replies.Steve Attached ImagesJunkYard Tools .com
Reply:don't worry about the mill scale.  i would use whatever rod you had on hand.  good choice on the welder.
Reply:Run a bead on plate with and without mill scale and you can notice a little difference, but not enough that anyone will notice.Common sense in an uncommon degree is what the world calls wisdom.
Reply:Thanks Scott and Brainfarth,but am mostly wondering how well paint or primer adheres to the scale. SteveJunkYard Tools .com
Reply:Originally Posted by rookie_steveThanks Scott and Brainfarth,but am mostly wondering how well paint or primer adheres to the scale. Steve
Reply:Originally Posted by rookie_steveIf I need to remove the coating is a portable grinder with sanding attachment the best method for limited budgets?Thanks for all replies.Steve
Reply:Originally Posted by Broccoli1Scale isn't a problem-erl' is, so just wipe with a good degreaser before painting
Reply:"erl": 10w40 fer instance. 9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:Originally Posted by Craig in Denver"erl": 10w40 fer instance.
Reply:If you're using oil base paint, just use the same thinner(mineral spirits are best, longer flash time, longer wet edge) to clean the metal.Get a coffee can, and a cheapo bristle brush.  Brush it on, and wipe it off.  Use gloves because it will absorb thru the skin.  All solvents do.  I didn't learn this as a young person, and I have some issues with my joints in my hands to this day.  It also goes thru the bloodstream to the liver and brain.  These solvents aren't water soluble, so they build up in the liver over time.USE A RESPIRATOR"Any day above ground is a good day"http://www.farmersamm.com/
Reply:solvents dont touch mill scale. mill scale will pop off in pieces over time. if you care about the paint job grind off the mill scale.
Reply:Originally Posted by farmersammThese solvents aren't water soluble, so they build up in the liver over time.USE A RESPIRATOR
Reply:Originally Posted by weldbeadsolvents dont touch mill scale. mill scale will pop off in pieces over time. if you care about the paint job grind off the mill scale.
Reply:Any way you can sandblast it? It gets in the corners and cracks where you can't get with anything else.
Reply:If you are at all THAT concerned with the final finish Angle iron would not be my choice because as mentioned you'll be spending way too much time getting the Mill scale off- might as well buy a different material to begin with.but... it is fine for carts tables etc and wiping it down then a rattle can will last a good while.I just hit it with the sanding disc quickly and then paint- The painting is key though- Most folks put a second coat on way too soon.First coat and then a light second coat within an hour- then at least 24hrs before the second, and another 24 before the final coat. Sucks watching paint dryEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Removing all mill scale before painting isn't practical. And whatever you use to get it off will leave a worse finish than what you started with. Use a wire brush in a 4 1/2" grinder to clean the welds, wipe it with a solvent and squirt it with a rattle can. It isn't furniture, it's a welder cart. Everything can't be perfect, I tried. Heck, I hate removing the mill scale just where I'm going to TIG. 9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:While mill scale can be welded through, painting it will result in problems sooner rather than later.  Use a fine 'cup' brush with your grinder, followed by wiping down with denatured alcohol.  Grinders/flap wheels leave too many scratches, ok for the welds but the brush does better finishing.  Cup brushes are reasonably fast - something the size of a cart should only take 10 - 15 minutes.  Media blasting (glass beads produce a real smooth finish) is best but more expensive, especially if you don't already have a sand-blaster. If you really want a nice finish uses 2 - 3 coats of primer and sand between coats with 600 grit sandpaper or fine steel wool.  This helps cover a lot of small scratches.
Reply:I would go to WalMart and buy a quart of Rustoleum, direct to metal hammered finish paint.  It is an excellent paint and millscale or even slight oils left on the metal do not appreciably affect it. I think you will be happy with the finish as well. It is nearly the quality of powder coating.  You can buy it in spray bombs as well.  It drys quickly.  If you need to thin it, buy a quart of Xyol(Xelene).  It does a good job to help thin when spraying from conventional guns.Esab Migmaster 250Lincoln SA 200Lincoln Ranger 8Smith Oxy Fuel setupEverlast PowerPlasma 80Everlast Power iMIG 160Everlast Power iMIG 205 Everlast Power iMIG 140EEverlast PowerARC 300Everlast PowerARC 140STEverlast PowerTIG 255EXT
Reply:I'll 2nd the Hammer finish paintEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:I agree with Lugweld,Xylol is good stuff!Take Care,John
Reply:I agree with reefera4m... also, here is a diagram for your tack welds. works pretty goodCharlton
Reply:Great tips guys, thanks all. I followed weldbead's advice and used an old worn out flap disk to grind the scale off. It almost looks like stainless because it polished up so well. I'll post step-by-step pix of the complete project if my welds look half-way decent.But things like rain, two root canals and my day-job has been keeping me from moving forward on the cart project. Also had the same problem as "fishon91" where I needed to build a pigtail to connect my genset to the welder, http://weldingweb.com/vbb/showthread.php?t=27565... so I haven't even had the chance to fire it up yet.That's a GREAT diagram crl283! I saw that earlier and intend to follow that. THANKS.Steve Attached ImagesJunkYard Tools .com
Reply:Hee-hawww! I just noticed that I've been promoted to "WeldingWeb Apprentice" from "solderer." Thanks WeldingWeb!SteveJunkYard Tools .com