Doright wrote:Epoxy is preferred over bare metal.

When welding your patches should have little or no gap.
Skip around and yes grind it off but continue till No gaps, no Holes, you can use a Light from behind to find Voids in metal.
Yes after epoxy a skim of Fiberglass filler is acceptable.

Thanks,

I did wheel well rust on '95 F150 years ago:

viewtopic.php?f=12&t=22944&p=173750&hilit=95+F150+rust#p173750

For inner wheel well I trimmed back and fastened thick rubber to fill the gap so it could be kept clean.

If I were to ever do it again I would find a clean rust free bed OR replace the entire bed sides. The time/effort to "patch" and then end up with a lower quality repair compared to "replacement" I will never patch truck bed wheel wells ever again.

You think you are saving money patching instead of replacing bed sides. But you aren't because of time/materials to patch will nickel and dime you to death its faster/better replace the panels. Plus full bed sides can be panel bonded on no welding needed.

Once cab of my '95 started to bubble down low I done sold it bought a new truck which stays in a garage. But no worries I have a huge pipeline of projects in queue.....

69cuda340s wrote:I did wheel well rust on '95 F150 years ago:

viewtopic.php?f=12&t=22944&p=173750&hilit=95+F150+rust#p173750

For inner wheel well I trimmed back and fastened thick rubber to fill the gap so it could be kept clean.

If I were to ever do it again I would find a clean rust free bed OR replace the entire bed sides. The time/effort to "patch" and then end up with a lower quality repair compared to "replacement" I will never patch truck bed wheel wells ever again.

You think you are saving money patching instead of replacing bed sides. But you aren't because of time/materials to patch will nickel and dime you to death its faster/better replace the panels. Plus full bed sides can be panel bonded on no welding needed.

Once cab of my '95 started to bubble down low I done sold it bought a new truck which stays in a garage. But no worries I have a huge pipeline of projects in queue.....

Wow nice work.

So getting ready to weld.
Backsides cleaned,new panel sanded to remove primer on both sides.
Ill go with cut and butt,worked in prior patches.

So now this hammer dolly deal,do you hammer right after ea tack? Ill do one every 6" or so to get it all sitting flush.
Do you grind down the welds first then hammer?
My plan was to do 8-10 spread out tacks then hammer each one.I can get behind with the flat dolly.Wait repeat.I have a cordless hand held blower to cool as I go.

Cheers.

Well that went easy. Used the saws all in some spots on the corners to cut at an angle. All nice and flush with little gap. Having a beer now. Don’t want to jump ahead too quick. I’ll have to stand back and look at it for awhile.

I like to flatten heads of welds before adding more welds. I also like to wire wheel after each tack weld. You can over heat and warp a panel badly when grinding the welds. Need to grind slowly don't use muscle and let panel cool down. Or you can be like me mess stuff up and learn the hard way and say gee maybe I can do better next time?

69cuda340s wrote:I like to flatten heads of welds before adding more welds. I also like to wire wheel after each tack weld. You can over heat and warp a panel badly when grinding the welds. Need to grind slowly don't use muscle and let panel cool down. Or you can be like me mess stuff up and learn the hard way and say gee maybe I can do better next time?

Yes thanks good tip,easy to over grind.
I have more welds to do today,Im about 50% done.Ill grind slowly.

Haven't hammered anything,reading had me worried about cracking so haven't bothered .

Warm enough today to use my die grinder and a roll lock. Keepin it clean between rounds. Going over with my straight edge most all is low so don’t need to grind anymore. But some spots could use a little pounding. So is it as simple as hitting it with the pointed end? No dolly? Thanks.

myke wrote:Warm enough today to use my die grinder and a roll lock. Keepin it clean between rounds. Going over with my straight edge most all is low so don’t need to grind anymore. But some spots could use a little pounding. So is it as simple as hitting it with the pointed end? No dolly? Thanks.

Absolutely not! When you weld, the heat will shrink the metal at the weld bead. Not in the surrounding area (so stay clear of hitting there with anything!). To stretch the weld seam, you must hit it with a relatively flat hammer, with a dolly immediately on the other side of the weld bead. Direct hit. This is called hammer on dolly technique. As opposed to hammer off dolly, which is used to raise low areas, or knock down high ones. You should hear a loud ring when you hit it just right. It does take practice to get this right. It also takes even more practice and experience, to gauge the power of the hit, and how much to hit it to stretch the metal back to it's original shape. Believe me, it's not easy!
You need to stretch each tack, and stretch the whole seam when you are done, or stretch each segment as you weld it. Easier for a beginner to stretch as you go, and keep the metal from getting away from you Yes, you can over-stretch it, by too much hammering.

Working the Mig weld Bead
Yes Bead itself needs to be stretched as my friend Chop is saying.

The idea that is trying to be duplicated is shown in this Video. Keep in mind this is a Technique called Hammer welding done with Gas which has the softest weld bead of the three welding techniques. But the idea is the same.
https://www.youtube.com/watch?v=Rv5bKXJ3kEM

When I am gonna stretch a Mig weld bead I have had better luck Grinding away most of the weld bead away first then stretching it Hammer on Dolly as Chop explains.

Care must be taken not to overstretch.
As well great care must be taken to stretching evenly!
A panel as large as this will begin to distort as welding progresses as well as when you start stretching the Beads avoid the urge to start working Dolly off hammer trying to straiten panels till all beads have been stretched evenly IF you work the stretching evenly the panel will settle down and straiten itself.

Working off Dolley to soon can lead to all sorts of problems such as Oil canning.

When your repair panel fit up has Zero Gap fit up before welding you give the bead very little room for shrinking of weld bead, As welding progresses the panel starts to distort due to the weld bead shrinking the two pieces together showing you the need to stretch the beads to get the panel to settle back down. When their is a large Gap between the two panels the shrinking is greater and the distortion is greater.