[SCHOONER]

Hi Guys

This questions comes under the heading " I never did this before, so HELP ME PLEASE

How would you attach (Mig Weld) a lower left side patch panel

Mustang Unlimited sold me a sheet metal patch panel the fits the rust I'm going to cut-out on the lower left side on my fender. Its a '66 'stang.

So guys I'm new at this and need your help. I got a Millermatic 135 Mig welder on order and I'm ready as soon as you guys kindly give me your experiences with replacing and patching a fender panel.

What I want to know is this:

Do I tack (mig) weld at certain spot in order not to warp the metal?
Do spot weld both inside and outside of the new patch panel to the fender and then run a straight bead across the entire patch panel?
What do I do for the inside of the patch panel (at the wheel well side)

What about finishing the application on the outside
Lets say you guys tell how to attach the new panel, now what about using Bondo or Leading in the seam area

My aim is to have this fender finished for painting. Only with your help

That's it guys. I do hope I got me message across. Please bear with me ~ I'm trying this for the first. However, I'm dam good at followiing instructions.

SO I'M IN YOUR EXPERT HANDS GUYS ~ FIRE AWAY.

THANK YOU ALL WHO ANS. THIS POSTING.

GOD BLESS

Schooner

[kenseth17]

You can install either by lapping the seam or by butt welding it. A lap weld may be a bit easier to weld for a beginner, but a little more inviting to corrosion at the seam. Use your patch panel and hold it up to the fender and trace where you will have to cut if possible. If doing a lap weld remember to leave enough material in from your traced line for overlapping. Also flange the edge of the cut so the pieces fit flush for welding. If butt welding cut out the same size of your patch and get a good tight gap. Error on the side of taking too little off, its always easier check fit and cut or grind more off, then to add material or place a wide weld. Don't cut until you are sure its right. Use clamps to clamp the patch in position if possible. If you lap weld you could just spot weld the seam area, but I think its much nicer, less inviting to problems if you weld the seam up. Weather lapping or butt welding, you don't want to weld the seam in one pass. You have to place short welds spaced apart from each other, leaving some time to cool in between to keep down warpage and avoid building up too much heat. Take your time and weld slow. Use a hammer and dolly to straighten the seam as you go if needed. The patch panel is not normally welded on both sides, just get good penetration with your weld. If lap welding use a weld through primer on the lap area and seam seal the inside of the lap with a good 2 part seam sealer. Coat the inside of the repair with epoxy primer or some sort of rust preventative coating. If butt welded, coat the inside with a rust preventative coating. Grind your weld, but don't grind it too thin. You can always tap the seam area in a little if you have to. Apply an epoxy primer over your repair, and finish the weld area with bodyfiller. filler can be applied over epoxy primer without sanding if its in its window. If not in its window or unsure, just scuff the epoxy up a bit with 180 grit before you apply your filler. Once your filler is sanded and straight, spray another coat of epoxy primer and after its sat awhile follow with a few coats of urethane 2k primer for block sanding and fill. If you think you might have voids or pinholes in your weld, you may want to put on a thin coat of fiberglass filler or all metal filler over the weld first before using a plastic filler. The first two are more resistant to moisture then plastic filler, but are harder to finish nicely.

[gator412]

If you need to see some pics look in my journal. I have been doing patch panels for the last few weeks.

[evilone]

Hey SCHOONER,If it were me,I would but weld it.The main thing with getting a good finished product is panel fitment.Take alot of time makeing the panel fit perfect,the maximum gap iI would allow for is 1/16 of an inch.After the panel fit to my likeing,I would tack weld it on the corners,and one in the center.Here comes the hard part........TAKE YOUR TIME!!!!DO NOT GET A HURRY!!!!Start tacking it one one end,wait for it to cool,then tack it on the other end,repeat this untill it is welded all the way across.It will look like crap,but dont worry,you can fix that.Make sure you get a good "burn" on every tack.After you have welded the whole seem,get a 24,or36 grit rollock disc,on a die grinder,and buff the weld down,as is you were trying to block sand bondo.Then apply your fillers and primes to tase!If you take your time,you shouldnt need much filler at all,and you will have a great repair!GOOD LUCK!!!!!

[Kampr]

I don't think anybody else coverd this. You can take a piece of copper and hold it on the inside of the butt while you're welding to keep things cooler and it won't be as apt to warp as much. It makes it easier if you have somebody to hold it for you. It acts as a heat sink.

Danny

[baddbob]

If you've never mig welded sheetmetal then definately do some practice welding. Do some butt welded seams and also lap welded seams for your practice runs. Butt welding the patch in is what I prefer but as mentioned already alignment is key before you start welding. If your welding skills aren't very good then flange the joint and lap it. The copper backing is also a great way to control warpage and blowthrough but you'll definately need a helper. Practice up then fit the patch. Make sure your metal is good and clean where the weld will be-this aids in puddle flow and weld quality and also decreases the chance of blowthrough. Practice, practice... Bob

[SCHOONER]

Originally Posted by kenseth17

You can install either by lapping the seam or by butt welding it. A lap weld may be a bit easier to weld for a beginner, but a little more inviting to corrosion at the seam. Use your patch panel and hold it up to the fender and trace where you will have to cut if possible. If doing a lap weld remember to leave enough material in from your traced line for overlapping. Also flange the edge of the cut so the pieces fit flush for welding. If butt welding cut out the same size of your patch and get a good tight gap. Error on the side of taking too little off, its always easier check fit and cut or grind more off, then to add material or place a wide weld. Don't cut until you are sure its right. Use clamps to clamp the patch in position if possible. If you lap weld you could just spot weld the seam area, but I think its much nicer, less inviting to problems if you weld the seam up. Weather lapping or butt welding, you don't want to weld the seam in one pass. You have to place short welds spaced apart from each other, leaving some time to cool in between to keep down warpage and avoid building up too much heat. Take your time and weld slow. Use a hammer and dolly to straighten the seam as you go if needed. The patch panel is not normally welded on both sides, just get good penetration with your weld. If lap welding use a weld through primer on the lap area and seam seal the inside of the lap with a good 2 part seam sealer. Coat the inside of the repair with epoxy primer or some sort of rust preventative coating. If butt welded, coat the inside with a rust preventative coating. Grind your weld, but don't grind it too thin. You can always tap the seam area in a little if you have to. Apply an epoxy primer over your repair, and finish the weld area with bodyfiller. filler can be applied over epoxy primer without sanding if its in its window. If not in its window or unsure, just scuff the epoxy up a bit with 180 grit before you apply your filler. Once your filler is sanded and straight, spray another coat of epoxy primer and after its sat awhile follow with a few coats of urethane 2k primer for block sanding and fill. If you think you might have voids or pinholes in your weld, you may want to put on a thin coat of fiberglass filler or all metal filler over the weld first before using a plastic filler. The first two are more resistant to moisture then plastic filler, but are harder to finish nicely.

Hi Kenseth17

First things First " THANK YOU " for such an in-depth instructions of which I just printed-out and when I ready I will refer to it.

You really know you stuff. I know I won't go wrong with your pro-instructions.

THANKS SO MUCH FOR YOUR HELP I really appreciated it
GOD BLESS

Schooner

[65comet]

http://www.jwharris.com/images/twentygauge.pdf

Here's the welding wire you want. It's meant for sheet metal and is very forgiving. It helps me be a better welder than I am.

George

[SCHOONER]

Originally Posted by gator412

If you need to see some pics look in my journal. I have been doing patch panels for the last few weeks.

WOW! ! GATOR412

What a picture show that was on your projects. Man, I sure will use some of your Right Ways To Do Patches.

GREAT JOB, AND THANK YOU FOR SHOWING HOW IT SHOULD BE DONE.

GOD BLESS

Schooner

[SCHOONER]

Originally Posted by evilone

Hey SCHOONER,If it were me,I would but weld it.The main thing with getting a good finished product is panel fitment.Take alot of time makeing the panel fit perfect,the maximum gap iI would allow for is 1/16 of an inch.After the panel fit to my likeing,I would tack weld it on the corners,and one in the center.Here comes the hard part........TAKE YOUR TIME!!!!DO NOT GET A HURRY!!!!Start tacking it one one end,wait for it to cool,then tack it on the other end,repeat this untill it is welded all the way across.It will look like crap,but dont worry,you can fix that.Make sure you get a good "burn" on every tack.After you have welded the whole seem,get a 24,or36 grit rollock disc,on a die grinder,and buff the weld down,as is you were trying to block sand bondo.Then apply your fillers and primes to tase!If you take your time,you shouldnt need much filler at all,and you will have a great repair!GOOD LUCK!!!!!

Hey Evilone

Thanks for you tips on " How Too " I will definetly keep 'em in mind when its time for me to weld-in my patch pieces.

THANKS AGAIN
GOD BLESS

Schooner

[SCHOONER]

Originally Posted by Kampr

I don't think anybody else coverd this. You can take a piece of copper and hold it on the inside of the butt while you're welding to keep things cooler and it won't be as apt to warp as much. It makes it easier if you have somebody to hold it for you. It acts as a heat sink.

Danny

Hey Danny

That sounds pretty cool
I like the idea. However, where on earth would I get some pliable cooper for strapping the joint

Any ideas where I can obtain such a piece

THANKS DANNY
GOD BLESS

Schooner

[SCHOONER]

Originally Posted by 65comet

http://www.jwharris.com/images/twentygauge.pdf

Here's the welding wire you want. It's meant for sheet metal and is very forgiving. It helps me be a better welder than I am.

George

THANKS GEORGE

That reference you posted about mig wire and voltage was GREAT
I just printed and I'm sure I will refer to it often ~ THANKS TO YOU

GOD BLESS

Schooner

[SCHOONER]

Originally Posted by baddbob

If you've never mig welded sheetmetal then definately do some practice welding. Do some butt welded seams and also lap welded seams for your practice runs. Butt welding the patch in is what I prefer but as mentioned already alignment is key before you start welding. If your welding skills aren't very good then flange the joint and lap it. The copper backing is also a great way to control warpage and blowthrough but you'll definately need a helper. Practice up then fit the patch. Make sure your metal is good and clean where the weld will be-this aids in puddle flow and weld quality and also decreases the chance of blowthrough. Practice, practice... Bob

Hey Boddbob

I sure like the idea about the cooper piece of the backing and keeping the warpage down. But I'll go nice and easy on the spot welding. Just need some advise on where to pick-up that cooper

I certainly will follow you advise just like all the other GREAT GUYS on this site who are helping me alone in my journey to completion of my '66 Mustang Convertible.

GOD BLESS YOU

Schooner

[PJMonty]

Not sure if it got mentioned, but do NOT use flux core wire. Flux core doesn't need shielding gas, but leaves slag and other junk.

The wire called "20 Gauge" by Harris (which someone else mentioned) is great stuff, but hard to find. If you can't find it, just use a regular .023 solid wire with shielding gas.

Thanks,
PeterM

[oldred]

65comet, That wire is the best thing to come along for welding sheet metal since the invention of MIG welding! I have been using it for some time now and I can honestly say that NOTHING else even comes close for ease of welding on thin stock.


Schooner, This is Jw Harris stuff and any welding supply can get it for you, even some auto parts can get it. It is "Perfect Circle" brand by JwHarris in .030 size called 20 gauge (think twenty gauge shotgun not wire size, It even has a shotgun printed on the box )
Also that power reference on the Jw Harris web site only applies to the 20 gauge wire and those settings will not work properly, if at all, with solid wire. That is what makes this stuff work so well, the fact that it will make a really good weld at such ridiculously low settings meaning less warpage, less chance of burn through and longer duty cycles on smaller welders.