No need to be anal about (pin) holes ...

[Vinnie]

... is what Trev said in one of his blog posts.

I'd like to know when a little hole in a weld is a pinhole of too large to be one. What max size would you consider as a pinhole?

And do you close ALL of them when welding a body panel or do you trust the body filler and paint to fix that pinhole?

Very curious about your opinios

Cheers,

Vincent.

 

[kcmash]

Well, you never want to warp your metal.  So Pinhole allowance is a function of welding skill.  There are tons of fillers, epoxies, and skim coats that can fill in most anything.  What you don’t want is the filler popping out or separating for any reason.  On the floor pans, you need the welding strong enough to hold everything together and sealed enough to prevent splash intrusion that will cause moisture traps and rust.  My car has the underside coated in truck bed liner, so It is durable and looks great.

Sorry about the non-answer.  Good Luck!

kcmash

 

[tony-muscle]

A good seam sealer like 3M's works depending on where the pinhole is. In an overlap weld the seam sealer would work great. However, I assume you would want to minimize the amount of holes in a butt weld.

 

[turtle5353]

In butt welds I never leave any pin holes. If I find any pin holes after grinding flush, I mark them with a sharpie then go back over and hit them with welder again. Grind back down and recheck.  I don’t trust filler to fill them because most filler and primer is porous and can attract moisture.  If moisture is under your paint you are asking for a bubble later.  
If the pinhole is in a lap joint or a seam that is getting sealed with seam sealer I don’t worry about it.  

 

[midlife]

In butt welds I never leave any pin holes. If I find any pin holes after grinding flush, I mark them with a sharpie then go back over and hit them with welder again. Grind back down and recheck.  I don’t trust filler to fill them because most filler and primer is porous and can attract moisture.  If moisture is under your paint you are asking for a bubble later.  
If the pinhole is in a lap joint or a seam that is getting sealed with seam sealer I don’t worry about it.  

+1. 

 

[Vinnie]

Thanks guys, got my work cut out for me I think ;-)