I am welding a frame together overlapping a plate over the crack and I wonder how much good it does to paint under the overlapping plate to prevent futher rusting.

Thanks.

Jack

 

If you do it correctly, you won't have any moisture in between the plate and the frame. here is how to do it.

First, sand or grind the rust off the area so that the metal is shiny, around the patch metal as well as underneath. Clamp, then lay your bead around the perimeter of the patch metal.

On the inside, using the edge of a grinding wheel in an angle grinder (or equivilent tool), notch the crack. Then lay a bead into the crack, which seals it from the other side.

Then prime/paint as you would any frame.

If there are no holes in your welding beads (be careful of the corners) and your welding of the crack also has no porosity, that repair will outlive the rest of the frame.

 

Thanks Fredric. Do you think to much welding can be done on a certain area of a frame. I am actually welding a 77 front end onto my 64 frame. There is 1/2" gap. I plann on laying in a plate on the inside and welding it. Then a plate on the outside and then another plate on the inside reaching from the top of the frame to the bottom. I guess you call that boxing it in. The I want to lay a plate across the top and the bottom of the frames. Each plate is going to be around 16" lonng. Hopefully that will be enough to strengthen it up. I plan on using 6013 rod and covering it with 7018. I have an AC welder. If you have any more ideas let me know. I am using 1/4" plate for the reinforcement.

Thanks.
jack

 

Warpage depends on heat penetration. You want penetration obviously, but if the material is thin, the material will warp significantly. Thicker items like frames, rarely warp with any toy welder you or I would have in our garage.

I've welded around metal patch plates on frames before with no problem, using a medium setting (C on my Lincoln, and 3 wire speed) with no frame warpage. If you're really concerned, you can zap your weld, then heat the area with an oxy torch to relieve some of the stress.

I've never bothered, and nothing has ever broken, even on abused vehicles like off-road only trucks, and my former tug-of-war truck.

Yes, that's boxing it in. You can lay beads in 2-3" sections, then leave a 2-3" gap, then anothe rbead and so on, then fill the beads in between the spaces, giving the metal a chance to cool between. that also helps prevent warpage.

Be careful wth the arc welder unless you've done this before... arc welders can make tremendously hot arcs if you're not careful. I sold mine for that reason, I couldn't do anything thinner than 3/8" without burning massive holes. Obviously, I didn't have the technique down.

my 170T Lincoln is much easier.. and it's a one-handed process which is better for me, since my left hand is not as controlable as it once was (I'm left handed, now suffering as a righty).

 

Jack, thats a bold move! you're tested on your welds, yes? I would do it too! Your plate seems thick enough, your going to grind and clean everything; I would have the frames held in alaignment with stong angles or whatever......what gets me, why run a root pass with the 6013? a hot vertical or flat will be ok for all those filet welds...7018 is a great rod spec....but not all makes or manufacturers will be equal , especially on ac. I have had brands that were real hell to use,,and others that weld thru rust and test aok... again, 1/4 plate with a single 3/16 filet would be stonger than the plate, and the frame ...good luck

 

No, I have not been tested on my welds but that is why I am using heavy plate on both sides and a lot of it. I do a lot of grinding to clean the welds up and make sure they are penetrating. I tried using the 7018 for my root pass but with an AC welder it really sucked especailly doing vertical ups or downs. But I am pretty good success with the 6013. Thanks for the info.

Jack

 

As a retired Industral painter(bridge and tank work)what we had to do is,If it is NOT acceble to paint you have to seal it.We used a 100% solid expoy.It was a two part materal.Kind of like JB weld.
If a good job was done welding BRUSH a light coat of primer on the welds only.The reason for brushing is to make sure ALL pin holes are filed.
If you didn't get a smooth welding job the small area you are talking about I would seal the welds with JB weld (THIN COAT WELDS ONLY) then prime it.
A paint job is like a chain,The weakest part is as strong as it is.Hope this helps. Don

 

Very good information and will try to incorporate it into the finishing of my project.

Thanks.

Jack

 

By the time I flipped my old crewcab lengthwise (an 81, or 82, I forget), the frame was essentially patches front to back. The factory frame was not up for the abuse of wild jumping and bouncing with heavy, 48" tires on it. The lift was extreme, and while a lot of fun to wail around in the woods, mud, rivers and such, the frame and the front driveshaft were definately the most unhappy parts of the truck. But my welds held. Kept rusting everywhere else though