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

Vinnie

Project manager "Project AmsterFoose"
Joined
Nov 7, 2013
Messages
1,493
Reaction score
88
Location
Amsterdam, The Netherlands
My Car
1973 Mustang Grande 351C 2V, built on the very last production day (July 6, 1973) for Grande's.
... 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

VIP Members
Joined
Sep 2, 2012
Messages
1,428
Reaction score
89
Location
Blue Springs, MO
My Car
1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
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

 
Joined
Aug 14, 2014
Messages
3,374
Reaction score
374
Location
Madison, WI
My Car
1971 M-Code Mach 1 w/408C stroker
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

VIP Members
Joined
May 15, 2011
Messages
3,420
Reaction score
247
Location
PA
My Car
1971 Mach 1 Mustang
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

Shorts checker
Joined
Jan 24, 2012
Messages
4,001
Reaction score
398
Location
Tucson, AZ
My Car
No Mustangs at the moment.
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. 

 
Top