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Brad S
03-30-2010, 05:36 PM
Trying to get back to the basics a bit to get better welds... just wondering what you guys use to get surfaces prepped for welding. Flap discs work well I know, but do you wipe down with anything?

IIRC I thought there was a post a while back warning about chemicals.. couldn't find it.

paulkeith
03-30-2010, 06:16 PM
I will usually hit with a flap on all substrate and then wipe with acetone. A lot of people will wirewheel which will remove rust, but getting through the mill scale is imo just as important, and this takes either sandpaper, grinder, or flap wheel. I've also recently found pretty satisfying success with a sanding discs.

The chemical warning was in regards to chlorinated brake cleaner, which when burned can produce phosgene, which is some caustic ass shit. The safe stuff is the green can, which is non-chlorinated.

I think any non-chlorinated residue-free grease removing agent should do the trick.

rstrucks
03-31-2010, 09:58 AM
For MIG I usually don't do a whole lot of prep (as far as cleaning goes) as long as the surface is reasonably clean. However, I do make sure what I am welding is physically prep'd - meaning beveled edges on notches, the right gap, etc.. and that the machine is set up properly.

For TIG I make sure it is prep'd and hit with a wire brush just before I weld.

ZJ TINS
03-31-2010, 04:59 PM
No chemicals, ever. Wire brush or flap disk till bright then weld.

zjeepin
03-31-2010, 08:53 PM
wire wheels are your friend.. make sure there isnt any rust or paint. i don't worry about mill scale on clean steel but i do bevel critical joints. if the piece has been oil soaked i'll clean it with some green can brake cleaner

xjrev10
03-31-2010, 09:43 PM
Stick welding and mig welding can tolerate alot of crap on the base material. But welding threw paint, thick scale etc, it can contaminate the weld. Your best bet is to use a wire wheel. The cleaner the surface, the cleaner the weld.

Tig welding: Metal should be as clean as possible. If welding aluminum make sure you have a stainless steel brush and that should be your dedicated brush for welding on aluminum.

ZJ TINS
04-01-2010, 12:06 PM
xj has good point, I was thinking only of steel. Never mix cleaning tools for aluminum and steel, always keep them seperate.
chemicals + heat = bad stuff usually, just not the thing to do. if oily just clean with hot water and let dry, then abrade till bright.

sasdranger
04-05-2010, 10:52 PM
Wire wheels are the shit, super fast removal of paint/mill scale/surface rust etc.. But they don't remove much base material like flapper wheels do.

Chemicals. I'm guilty of using brake clean, but ever since that article about the guy almost dying I try to stay away.. If I MUST use a chemical to clean up some metal I will use it, the blow it off with compressed air then give it plenty of time to let the rest of the chemical evaporate, then I weld in a ventilated area..

cLAYH
05-06-2010, 12:16 AM
Flap discs are all I use and I take off the scale before welding. It definitely makes a difference. I think the paint goes on better as well when the scale is off.

Flap discs were especially well on the unibody where you don't want to take a lot off. Grinders and wire wheels can be harsh on the soft unibody.

paulkeith
05-06-2010, 08:55 AM
You think a wire wheel is harder on a unibody than a flapwheel?


Disagree, sir. Respectfully, of course. :D

JolleyRoger
05-06-2010, 12:01 PM
These things work great on your Unibody...

http://cgi.ebay.com/4-1-2-x7-8-Paint-Rust-Easy-Strip-Clean-Disc-10-/270559661795?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3efe9ccee3

BigDaveZJ
05-06-2010, 12:43 PM
I got one of these to try it out, works pretty well. Zips right through surface material but doesn't do much to the metal at all.

Have you guys found anything that works well in cleaning up the metal when you can't get a flap discs or wire wheel to it? There's a couple nooks and crannies on my roof project that I can't get to. Would turpentine or brake cleaner (non-chlorinated of course) get through enough of it?

ATL ZJ
05-06-2010, 01:24 PM
I got one of these to try it out, works pretty well. Zips right through surface material but doesn't do much to the metal at all.

Have you guys found anything that works well in cleaning up the metal when you can't get a flap discs or wire wheel to it? There's a couple nooks and crannies on my roof project that I can't get to. Would turpentine or brake cleaner (non-chlorinated of course) get through enough of it?

Between a hand held wire brush and a dremel you should be able to get most everywhere that you cram a welding gun into.

SB406
05-06-2010, 01:31 PM
Sometimes, if there's a lot of gunk or paint in a nook that I can't get with the grinder, I'll burn it with the torch, then clean up with a wire brush or scrape with a screw driver. If it's rust in a nook, sometimes a file is the best way to get it down to white metal.