What are members' recommendations for tools and abrasives to dress down MIG weld beads?   For reference, I'm talking about stitch welds on sheet metal.

The typical combinations I've seen suggested are:

1) angle grinder/flap disc

2) mini die grinder/2" sanding disc

Abrasive grade recommendations I've seen are 36-grit to start and 60-grit to finish.

I'm curious to hear thoughts on which combination(s) works best.

I found that when using this wire, a flap disc in the 60-80 grit works very well. I can not say enough on how easy it was to clean up my ugly welds using this wire.
https://www.esabna.com/us/en/products/filler-metals/mig-mag-wires-gmaw/mild-steel-wires/spoolarc-easy-grind.cfm

 

I use a die grinder with a 3" cut off wheel to dress welds down most of the way. Then I use die grinders with 2" & 1" rolocs on them 36 grit. Sometimes I finish up with a 4" flap disc, but the flap disc can remove a lot of metal really fast and there is not a lot of metal thickness to start with.

A 4" grinding disc followed by 60 grit disc and if it is visible 120 disc. If what needs grinding is in a tight spot then the die grinding bits.

 

52 minutes ago, grannyknot said:

A 4" grinding disc followed by 60 grit disc and if it is visible 120 disc. If what needs grinding is in a tight spot then the die grinding bits.

 

I have a selection of carbide bits like that, but those little metal splinters go everywhere!!!

Yes they do,  Charles, do know if they make a bit for aluminum?  I've tried the carbide bits on aluminum and spent the next couple of hours picking out of the cutting bit teeth with a dental pick.

50 minutes ago, grannyknot said:

Yes they do,  Charles, do know if they make a bit for aluminum?  I've tried the carbide bits on aluminum and spent the next couple of hours picking out of the cutting bit teeth with a dental pick.

I have some for aluminum and they have a different tooth pattern. I have seen a tip on how to prevent this but can't remember what it was.

I've used a die grinder with stones on an exhaust flange fillet weld to clean it up.

Lye will evidently clean the burrs of aluminum and beeswax is said to prevent build up but not contaiminate

Stay away from the flapper discs as they tend to grind the parent sheet metal more than desirable. A baced sanding disc 2-3" on a 90 degree die grimder, or a 4-5" backed disc on a grinder, and lern to keep it flat-ish, the biggest trap is to grind till the bead is flush, but as the weld cools it shrimks and pops up the attached sheet, leaving a lil valley on edge of the weld. 

The other absolute gun tool is a mini 18-25mm wide belt sander, but best if you have experience in using it, otherwise you can dig worse than with a flapper. 

I see qualified boilermakers and sheet metal guys get it wrong all the time in my lime of work, and many a times need to guide/coach them, which they hate, but love when they get it right, and i dont have to reject their work..... 

It does pay to get better at the welding, and this will come with time and experience. 

Nat0 

On 8/3/2019 at 10:00 PM, Patcon said:

Lye will evidently clean the burrs of aluminum and beeswax is said to prevent build up but not contaiminate

I didn't have any beeswax on hand so used an old candle, works great!

20 hours ago, grannyknot said:

I didn't have any beeswax on hand so used an old candle, works great!

I think toilet sealing rings are beeswax. Cheap and plentiful.

Sorry I had to stoop to a potty reference...