Update: Watched a guy try to feather edge with a grinder on a quarter panel

He was working on a 2018 Civic in the bay next to mine and went straight at it with a 40-grit disc, no blocking at all. I had to stop him before he went through the metal and explained you need to use a softer block to spread the pressure. How many of you still see people skipping the blocking step on a big repair?

3 comments

3 Comments

the_ruby3mo ago

That's a classic move, but the real problem is using the grinder for the whole job. You need a DA sander with 80-grit to get it close, THEN switch to a block with 180. The grinder is just for taking down the high spot of the filler, not shaping it.

tara7003mo ago

Oh man, that's painful... @the_ruby is right about the DA sander, but even before that, how do you get the filler profile right without a block? I've seen guys just push the spreader with their hands and end up with a huge hump.

christopher_flores461mo ago

Watch how much filler you're mixing up too. Thin coats dry faster and let you see the high spots before they set. Thick filler just hides your mistakes until you're sanding forever.