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First time patch welding

12K views 30 replies 12 participants last post by  matts37chev 
#1 ·
I have welded my first patch panel on a lower fender piece that was rotted out. I was having problems with my MIG welder using .30 wire and keeping it from burning through the panels. I carefully patched this panel (sorry I know its not the right way) but Im afarid that I might of left pinholes in between the spots. When I grounded the edges down I noticed that many of these pinholes where covered up by the grinding but I know theres still some left. My question is If I shoot a couple coats of Epoxy primer will it seal these pinholes? also there seems to be some dark burnmarks in between the tiny seems it it important to clear this out before applying the epoxy? if so what do you guys recommend?

http://i1080.photobucket.com/albums/j323/mcerda972/PatchPanel.jpg
 
#3 ·
Yes the pin holes can be a issue.A lot depends on where you live and if car will be driven in bad weather. If you live in a dry state not that big of a deal. Best way is to sand blast with a small hand sand blaster over your weld before you apply any filler to it.If you have the fender off you can sand blast the back side of your welded patch epoxy prime then seal weld area with seam sealer and undercoat.
 
#6 ·
It took me a long time before I got things right my first time. They say "practise makes perfect". Keep at it and you will get the hang of it. I cut the rust out of a car and I must have done 3 or 4 goes on each patch panel. The car itself was pretty much a waste of time but I learnt the hard way.(I think it was the best way get it right!!)

The patch panel you did looks pretty good for first time in my opinion.

mi chael.
 
#7 ·
Once again your being too hard on yourself (a sign of a good craftsman) Your patch looks fine. all you need is a couple pointers..
Try putting a drop light behind the work to find the pinholes then blast them with your welder.
The blue spots are metal ground too thin and getting overheated to fix this just get your pick hammer or a punch and counter sink the spot then weld it up...piece a cake...
 
#8 ·
deadbodyman said:
Once again your being too hard on yourself (a sign of a good craftsman) Your patch looks fine. all you need is a couple pointers..
Try putting a drop light behind the work to find the pinholes then blast them with your welder.
The blue spots are metal ground too thin and getting overheated to fix this just get your pick hammer or a punch and counter sink the spot then weld it up...piece a cake...
Thanks DBM.. I couldnt stop laughing at your last post I started.. Did an old Indian really tell you that??

I figured I was over analyzing the situation.. I was thinking that these tiny, if any, pinholes can just be covered with a couple layers of Epoxy Primer, filler, then the primers. Doesnt see how filling with figerglass resin first willbe any help. If water gets in and starts rusting the metal the resin will separate from the metal.

DBM I do see how I can just blast small pinholes with the welder but Im afraid to burn through again.. Ive had a hell of a time keeping not burning through. Im hoping that problem is that Im using too big of wire guage.. using .30 without gas. Ive lowered it as far as I can go but still cannot get it to flow smoothly. My next invested is a C-25 gas tank.. Do you think gas and using smaller guage will make that big a difference?
 
#10 ·
67Elcamino said:
DBM I do see how I can just blast small pinholes with the welder but Im afraid to burn through again.. Ive had a hell of a time keeping not burning through. Im hoping that problem is that Im using too big of wire guage.. using .30 without gas. Ive lowered it as far as I can go but still cannot get it to flow smoothly. My next invested is a C-25 gas tank.. Do you think gas and using smaller guage will make that big a difference?
the smaller wire and mixed gas will make a large difference in your welding on the thin stuff :thumbup:
if you are using 030 flux core now, you will feel like a pro with the smaller stuff
 
#15 ·
Busted Knuckles said:
I don't weld all that often either. I just use the little scuba sized one. Just remember to turn the gas off when you're done. I forgot to turn mine off once and about four months later I needed to weld something and the tank was empty, and of course, the valve was wide open. :spank:
Been there done that too!!! :pain:
 
#16 ·
Busted Knuckles said:
I don't weld all that often either. I just use the little scuba sized one. Just remember to turn the gas off when you're done. I forgot to turn mine off once and about four months later I needed to weld something and the tank was empty, and of course, the valve was wide open. :spank:
here is a pic of what size tank i use
it will last quite a while

you will also notice the "note to self" in marker on top of the welder
TURN GAS ON/OFF :thumbup:
 

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#18 ·
Get the gas bottle, and practice. Here is my GMAC welder, A Miller Autoset 180.
.

Get the smaller wire, and a few extra tips. A pair of good diagonal cutting pliers, you want to cut the little ball or nub off the end of the wire, each time time you end a weld. also get some sheet metal, and cut it up into coupon or credit card sized pieces, and weld them together, as practice. It helps if you weld some thicker gauge metal before you try to weld auto body sheet metal.

If you have a Community College near to you, you might want to consider enrolling in a welding class. That would be good practice welding, with an expert being able to help you.

I live on a smaller farm, so there are other things to weld. Repairing field mowers, fixing wheel barrels, fabricating small items like water bucket holders. Things like that. all good practice.

Did I mention it is a good idea to practice?
 
#21 ·
i'm not sure what size (cu. ft.) mine is, but its 2ft. tall
i had the small one first, and it went empty kinda quick
so last time i got it filled (exchanged) i got the size i have now
if its too big (3-4 ft tall) its a pain to move around if you take you welder anywhere
 
#22 ·
Just picked up a 60 cu. Bottle. Damn how
Money goes walked out spending $200. Purchases a nozzle, wire, a hose, and the tank . Actually got a 84/16 mix tank. Gave it to me for the same price is this mix better than the 75/25 mix? Damn!!! Just realized that I have to use a argon regulator and i dont believe the one I have is such. Do you have to use a specific Argon regulator?
 
#23 ·
If the regulator came with the welder, it should be OK. I understand there is a problem if you go higher on the CO2. It cools off more in the regulator, and freezes the regulator.

Maybe the lower percentage of CO2 is a California thing, to reduce the imagined global impact from CO2.
 
#24 ·
67Elcamino said:
Just picked up a 60 cu. Bottle. Damn how
Money goes walked out spending $200. Purchases a nozzle, wire, a hose, and the tank . Actually got a 84/16 mix tank. Gave it to me for the same price is this mix better than the 75/25 mix? Damn!!! Just realized that I have to use a argon regulator and i dont believe the one I have is such. Do you have to use a specific Argon regulator?
I think with that mix it might be easier to weld the thin stuff
100% cO2 is used for better penetration, so less cO2 might be better
did the welding shop recommend that mix?
or is that all they sell around there?
 
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