Thread: Grinding into corners?

Sometimes I want to grind into corners, like into an inside fillet. Getting rid of mill scale or rust or paint for weld or paint prep.

Wire wheels are OK but not the best. A brand new flap disc works for a brief time before the ends of the disc get worn too much. What do you guys use, what works best? Power tools at my disposal: couple of grinders, dremel, drills, don't have a die grinder yet.

Originally Posted by Legion

Sometimes I want to grind into corners, like into an inside fillet. Getting rid of mill scale or rust or paint for weld or paint prep.

Wire wheels are OK but not the best. A brand new flap disc works for a brief time before the ends of the disc get worn too much. What do you guys use, what works best? Power tools at my disposal: couple of grinders, dremel, drills, don't have a die grinder yet.

To be honest there's no best answer.Preparation before welding is the best plan of attack, using anti anti spatter and also setting the best amperage setting.

If at all possible ,cleaning the rust and and crap off before careful assembly.

Die grinders are ok but better is a needle gun but they can get pretty expensive.

Grahame

Don't say that, Grahame! I do prep well first but the biggest single issue for me as a weekend warrior is I will fit up a big job and then not get around to doing all of it in one go, so it waits for another week or two and in the meantime the cleaned area gets surface rust. Maybe I could spray it with WD40 or something and then use acetone before welding?

Or occasionally I just find a job is all fitted up and part welded and I find a dirty spot and there's no way I can disassemble it to fix that one spot. Sometimes I grit my teeth and just weld it up but the tig torch in particular makes all sorts of noises. Stick I don't really care as much. Will weld through light mill scale and dura/supagal and whatever, although I clean off the rust as much as possible. I polish with a flap disc generally but with dura/supagal often don't bother. But tig is a different story and I want it shiny clean ideally.

Originally Posted by Legion

Don't say that, Grahame! I do prep well first but the biggest single issue for me as a weekend warrior is I will fit up a big job and then not get around to doing all of it in one go, so it waits for another week or two and in the meantime the cleaned area gets surface rust. Maybe I could spray it with WD40 or something and then use acetone before welding?

Or occasionally I just find a job is all fitted up and part welded and I find a dirty spot and there's no way I can disassemble it to fix that one spot. Sometimes I grit my teeth and just weld it up but the tig torch in particular makes all sorts of noises. Stick I don't really care as much. Will weld through light mill scale and dura/supagal and whatever, although I clean off the rust as much as possible. I polish with a flap disc generally but with dura/supagal often don't bother. But tig is a different story and I want it shiny clean ideally.

There are dry anti spatters that can be welded over that might serve as a short term rust preventive. My thoughts are that if there is room to tig it,there should be room to clean it with a hard wire hand brush.Another cheap way might be soaking it in vinegar and washing with metho or acetone.To access an internal edge corner use the angle grinder cutter disc on edge (carefully of course)

Tig is not forgiving as far as contaminated surfaces. Its a sort of, can't have your cake and eat it too, type situation.

Grahame

I have known people to use a small hand held grit blaster similar to this, to clean areas as you describe. Abrasive getting stuck in the joint gaps can be an issue though. Hand Held Siphon Pressure Vacuum Sandblaster GUN KIT Sandblast Sandblasting Tool | eBay
Another technigue useful for Aluminium work is to use a sharp, 6-10mm drill bit in either a corded of cordless drill to access tight spots to both prep and clean areas to be welded. This actually works better in many cases than a die grinder and carbide burr because the drill bit is far less prone to clogging.

Generally I just use a flap disk/grinding disk or a thin cutting disk to get to the bottom of the root, in areas where that wont go such as near a corner, then I use a 1/4" Ozito router ($60 from Bunnings ) with a carbide burr in it, if I need to get right in and clean out the root completely then a Dremel with a 3mm carbide pointy burr does the trick.

Cheers

Ed.

I second the sandblast approach. For small, quick jobs, baking soda from Woolies has the advantage of not needing the level of personal protection needed for abrasive grits (I keep getting tempted by the idea of adding citric acid to the baking soda so any that ends up in my mouth is like lemon sherbert...).