Question about grinding welds.

[Mike65 476]

Now that I am just about finished welding on the new quarter skin on the r/s I will have to grind down the welds & cover the seam with filler I was wondering how should I go about grinding down the welds so as not to warp the panels. I have been doing a little welding each day to keep the heat to a minimum & I do not want to mess it up now. BTW if anyone is interested I am using Evercoat Rage Gold filler to cover the weld seam.

[manley 13]

Sounds like you may be being overly-cautious. Just jump around. It doesn't take long for enough heat to dissipate for you to hit that area again.

[RPM 1,190]

I'd use a 4" flapper weld and apply a wet rag after a short grind, or use a 2" sanding disc on an angle die grinder. Grinding welds if done wrong can warp the metal as bad as a bad weld.

 

Bob

[bomccorkle 12]

I use 2 inch green rolocs on a 90 degree die grinder. (the 3m and ARC are well worth the money) and give her hell

[jandj1970 13]

Mike when I replace panels in my engine bay I used a grinding blade, I would grind 1 spot weld down and move to a different area. Maybe grind one area then move to the other end of the seam weld you done.

Also bob mentioned using a wet rag, this sounds like another good idea.

[mjchip 10]

Not saying that this is the right way but it works well for me. I almost always start by hammer/dolly weld to stretch the metal back to original as welding typically shrinks it. It also serves to bring the weld bead proud of sheet metal. I then use a cut off wheel with greater than 1/8" thickness to grind the weld down *close to* panel. The wheel is kept perpendicular to weld at all times and dragged down the length of the weld.

 

When the weld is close I switch over to a 36 grit disc on right angle grinder and finally move to a coarse roloc. I always try to use the most aggressive material as it requires least pressure, generates less heat and therefore creates the least panel distortion.

 

Good luck!!

[manley 13]

I guess we don't all do it the same and as mjchip points out, different methods are going to create different amounts of heat. The more time you have to spend grinding on one spot, the more heat buildup you are likely to have. I use a Dewalt 4 1/2 inch angle grinder with 1/4" thick grinding disks. When new, these things eat away metal with a quickness. You have to be careful when you get close to flush, because hitting the sheet metal will quickly thin out and weaken that spot on the panel, basically making your work moot.

[RPM 1,190]

Not saying that this is the right way but it works well for me. I almost always start by hammer/dolly weld to stretch the metal back to original as welding typically shrinks it. It also serves to bring the weld bead proud of sheet metal. I then use a cut off wheel with greater than 1/8" thickness to grind the weld down *close to* panel. The wheel is kept perpendicular to weld at all times and dragged down the length of the weld.

 

When the weld is close I switch over to a 36 grit disc on right angle grinder and finally move to a coarse roloc. I always try to use the most aggressive material as it requires least pressure, generates less heat and therefore creates the least panel distortion.

 

Good luck!!

 

I too have used this technique, with good results on keeping the heat way low. I use this always on tack wells before final bead. I'm guessing old age kept me from recalling it.

 

Bob

[buening 63]

I'm with mjchip and RPM. Planishing the welds are the only way to go