For those of you guys that are curious, go to my gallery and see the rust repair pics. They are the last few in the gallery. The drip rails were too far gone to save, so I will smooth the doors. Also, started in on the steps and the hinge pillar.
I hate grinding on welds....

 

Hey, Panel -

After grinding is when my welds always look perfect.

 

you too huh!

And I thought that it was just me...

On that note, do you use a MIG or other welder???

Mine seems to leave pretty good sized lumps of weld. If I raise the heat, it burns through. I still get good penatration (sp), but there seems to be a lot to grind off.

 

how high do you have the feed? you could try turning that as far down as you can without burning through and this will save time on grinding and save you some wire. just my .02

 

I do mostly spot welds while allowing the metal to cool in between. If I run the speed down, it seems like the wire is burning up before getting to the metal (speed too far down?) The welds are nice and include both sides of the metal, just lumpy. Also, what is a good gap to leave between the two sides?

 

Hey Panel -

Yeah, I'm fairly new to welding. I've been doing sheet metal patch panel work on the hood, cab, bed and some custom mods. Check out my gallery called "Hood Patch Panels". That was some serious fun. I would have preferred a simpler job for early in my welding learning curve.

I have a Lincoln Handy MIG Welder (110v, 85 amp). It has a dial control for wire feed speed and has switches for heat settings of Lo-Hi and 1 and 2. Hi-2 is the hottest, Lo-1 is the least amperage. They give a chart for suggested settings that has worked out pretty well. For 16 gage and less, I use the gas bottle and MIG weld. For the heavier stuff (up to 3/16 thick - like my bumper) I use the flux-core wire. It seems to penetrate really well, although it is messier. I have tested practice welds on everything and been very happy with the results.

Yes, high heat blows thru very easily, especially if the material is thinned by rust. That stuff just vaporizes and any remaining rust contaminates the weld. You need to cut back to good stuff, then weld. It is much more predictable. The balance is that you need enough heat to get penetration without vaporizing the metal. That would be easier to do with dial switches to control heat settings. As to the lumps, play down the wire feed speed. My welder has suggested settings for that also and I have noticed that when welding thicker stuff, the speed is down from thinner stuff. That's probably because you need to go slower for heavier thickness and need less wire feed or it will puddle up big time.

I have found the key to best welding is the prep of the joint. Putting a very small chamfer on two pieces to butt weld works wonders. The chamfers allow immediate penetration at low heat settings. I recommend this very strongly for thicker pieces.

Play around with it a little. Every welder seems to be a little different with its own personality.

Now, if you already knew all this stuff...then never mind..

 

I will try to play with the settings, I have been getting two pieces of metal to stick together and call it a day... At least it is not warping that much... Got to love this THICK metal these trucks are made of...

 

panelbeater, as you turn down the speed, you also need to tap down the heat adjustments. if you dont the section of wire that has grounded to the work will melt before the next section of wire reaches the work. this causes the arc to - - - - - - ect. hope this helps

 

That is what it was doing before. It was going zap, then nothing, zap, nothing etc. Never really getting any build up of filler material, and no penatraion.

Thanks for the input.

On a similar note, do you weld the joint completely, or leave some gaps? I can't seem to let myself leave any gaps, I don't know if it matters that much... I use kitty hair filler as the first coat of filler so if there are any holes I missed, the water won't absorb into the filler and rust out the repair... As you might know, regular bondo is mostly talc.

 

well depending where the joint is, you can leave some gaps to reduce the chance of warping, like in a low impage area where you arent going to be bumping into it, you can leave gaps and fill with filler. in a high impact area like the bottom of door seams and near hinges and whatnot your gonna want to use as little of filler as possible as it will want to crack with all the jarring around. i would soon as go for the full weld but if ur doing a patch on a big flat peice of body your gonna notice any warping when you paint so ur gonna want to do minimal welding.

 

Panel -

When I weld sheet metal, I never do a long continuous weld. The metal warps way too much. I do tack welds, evenly spaced, then keep filling the seam with tacks until it's all filled. As an example: if I had a seam 12 inches long, I would tack the middle, then each end, then halfway between the existing welds, then keep dividing the spaces by adding welds until the entire seam is done. I sometimes need to do a little hammer and dolly work to the seam as I go if I see the seam is starting to move. Just hammer the welds to spread them back out again. The warping is from weld shrinkage. The hammering returns the length of the seam back to what you started with.

I also cool the pieces as I go to reduce the residual heat that wants to make the metal warp. I use a water-soaked rag and douse the seam until the steam stops. Works great.

Also. One of my friends, who does a lot of body work told me not to use Bondo brand body filler. It shrinks and cracks over time. He recommended "Evercoat Xtreme Rage". Great stuff! It's a little pricey, but works just super! It is like cream going on and sands beautifully. My friend says he has never had problems with fills even years later.

Hope this helps.

 

good point on the bondo randy.

 

One of the things that I do that is nice is to use a air nozzle on the fresh tack. I have the mig gun in one hand and the air gun in the other. Tack...whoose, tack...whoose. It cools the area and keeps down the warping. It does take forever to do some of these long welds. I was thinking of welding up the joint where the roof of the panel was joined together, but the weld is going to be like 7 feet long on each side. I might just clean out the old seam seal and re-do the seal...

Thanks for the ideas..

 

When welding you must tune your welder to the metal thickness you welding. It sounds like your problem is you are not tuning your welder. To tune your welding get a scrape metal the same thickness you are welding and do a bead, adjust the wire feed as you hold the trigger. You should hear a zzzzzzzzzzzzzzzzzzzzz sound. When you hear that sound without pop or breaks your welder is tuned. Randy Jack is right do not try to run a bead with sheet metal take your time and tack it until the seam is done. I believe the gap you are talking about is should you have a gap between the panels when you butt weld right? It does help for penetration but I don't use them. Eastwood sales spacer clips for butt welding. I use to use them. Also lap welds are fine in some areas although a lot of people don't like to use them. Get an auto dark helmet it helps a lot of people new to mig welding.

 

I will try to set up the welder like you mentioned, I have a autodarkinging helment as well. I can set up the machine for thicker stuff and I do get the "frying bacon" sound when I do a continious bead. I have a bad habit of set it and forget it on the settings... Just have to be less lazy...