How to weld metal to body and fill? Who knows the right way!

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Nov 19, 2003 | 05:32 AM

AgentJam

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How to weld metal to body and fill? Who knows the right way!

I just took everything off of my 88 CRX and can finally see all of the rust. I've got acess to a MIG and will be getting rear quarter panels soon.

Once i cut out all of the rust spots...what should i do next? Should I cut the patch metal to the same size or oversize? if oversize how do i blend the uneven surace to make it match the car. Do i put some sort of rust inhibitor (POR15?) over it after i weld? or after i grind? Should i use bondo or what to smooth the body out. Also would it be ok if the bondo was out in the rain before i got it to a paint shop?

Sorry for all the questions, i can weld and i have the time to do the work i just need some tips and a procedure. I've searched but have found many contradicting things.

Thanks,
VINCE

Nov 19, 2003 | 05:57 AM

jDm_jeremy

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From: East Coast

Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

this is what i've heard. First grid with 36 grit paper to take it down, then the patch panel peice needs to be about 1" larger than your hole. after that do your MIGing with 3/8 tack welds about 1" apart. you then need to go back with 36 grit to scuff the metal for the bondo to stick. Drift your bondo line out 3-4" to get a good transition. Then apply hella primer, i'm talking like 30 coats or something. then smooth it out. Remember not to get the metal too hot when welding, if you can help it.

hope this helps....J D....

Nov 19, 2003 | 06:05 AM

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (bladeDC2)

yeah anything will help thanks a lot. About cutting the patch 1" oversize...wont it make that part of the car stick out? How do you fix that?

Vince

Nov 19, 2003 | 09:53 AM

jDm_jeremy

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Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

with the proper grinding/smoothing of the edges of the patch piece and good bondo work you will never be able to tell

Nov 19, 2003 | 10:06 AM

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (bladeDC2)

Do you weld the patch piece on the inside of the hole? and hten fill on top? I've been thinking you had to weld it on top...

Nov 20, 2003 | 06:56 AM

jDm_jeremy

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Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

weld on the outside, with the metal as lean as it can be. in my experience the welds with the mig can sometimes vary, so i would practice a couple of taks on scrap metal. i the weld comes out good, you shouldn't have to grind on the welds too much.

hope this helps. good luck man

Nov 20, 2003 | 07:15 AM

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (bladeDC2)

See the thing i'm not getting is if the larger patch piece is placed on top of the hole wont that part of the car be wider/stick out further than it should? i know you could blend it in with bondo but it will still be out further right?

Blade DC2 so i should put the patch piece on the outside of the hole and weld around the edges? because i've seen people put the patch piece on the inside of the hone and tack the edges of the hold to the patch piece...

Sorry to ask so many questions i just wnat to do this the right way. Thanks to everyone who helps

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Nov 20, 2003 | 09:13 AM

TomC

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Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

This is what _I_ would do.. Remember anytime you weld or use a grinder it will creat heat ,Too much heat will warp the metel and then you not only have to fix the rust spot but a warp around it .So take your time..Cut a patch about 1in biger than the hole , Grind around the hole , on the inside edge of the hole , and on the patch. Put the patch behind the hole , Tack it in. I would do it 4 tacks at a time with enough cool time between sets so it is cool/a hair warm to the touch ..Grind down the welds so that it is recessed into the hole.. Wipe bondo (some fokes like to use Reinfoced Bondo). Depending on how even you spred it should go something like this: 36/80 grit to knock it down (apply more bondo if needed), 180 to fether out edges.. putty any pinholes/deep scrachs 180/320 it , Primer it (dont use rattle can , it sometimes dosnt get along with Paint & You shouldnt need more than <U>3</U> coats ) , Wetsaid with atleast 400, its rdy for paint ..Also I would try to keep bare bondo out of the rain possible.. Sorry for the Story and Shitty spelling , Good Luck

Nov 20, 2003 | 09:24 AM

DownBoyDown

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From: San Diego, Ca, USA

If you have a hole, then youll want to place a metal sheet slightly larger than the hole from underneath and tack weld it from the top. Be sure to get rid of any rust berfore you do this. Also when you tack weld, start at one side, then do one at the opposite side, ect... The idea is to spread out the heat and let one area cool off while you tack the other area. If you just straight weld the metal then it will probably warp. If you have a rust spot that extends off of the car, then cut that section out. Next cut the sheet metal like a puzzle (no overlapping) and directly replace the portion that you cut out. You may have to bend the metal to match the contour of the piece you cut out. Again tack weld in place.

Nov 20, 2003 | 09:27 AM

#10

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (TomC)

TomC you're the man, thanks for that detailed reply...dont worry about the spelling

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TomC »</TD></TR><TR><TD CLASS="quote">Primer it (dont use rattle can , it sometimes dosnt get along with Paint & You shouldnt need more than <U>3</U> coats ) , Wetsaid with atleast 400, its rdy for paint ..Also I would try to keep bare bondo out of the rain possible..</TD></TR></TABLE>

Just a few more Q's...

1) What do you mean by don't rattle can it (Spray Paint?) What kind of primer should i use and where should i get it?

2) To wet sand do i just wet the sand paper and surface and sand as normally done dry?

3) So don't let the bondo get out in the rain but how about once i have it primered and sanded can it be in the rain? Not that i'm going to abuse it and leave it out in a storm for a week but just want to make sure...

Thanks again!

~Vince

Nov 20, 2003 | 10:03 AM

#11

TomC

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Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AgentJam »</TD></TR><TR><TD CLASS="quote">
1) What do you mean by don't rattle can it (Spray Paint?) What kind of primer should i use and where should i get it?</TD></TR></TABLE>
Yes Spray Paint .If possible take it to a shop and have the do it , Or if you have axcess to a Paint Gun , just goto any Big Auto Parts Store(Napa,Car Quest ect..) and get some 2k primer (Primer & Actavater). If you cant do it/get it done right away rattle can is fine just to keep the bondo out of the rain , If used befor the car/area is painted i would wetsand the rattle can primer off , primer it with the good stuff & wetsand it
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">
2) To wet sand do i just wet the sand paper and surface and sand as normally done dry?</TD></TR></TABLE>
If it is a flat pannel It would be best to use a Sanding Block by hand (If not sand by hand but make sure you keep even presher on your <U>hand</U>.. Dont just just use your fingers , Make sure you keep everything wet(The water keeps the dust from staying under the sandpaper , this helps prevent "sand scrachs")
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote »</TD></TR><TR><TD CLASS="quote">
3) So don't let the bondo get out in the rain but how about once i have it primered and sanded can it be in the rain? Not that i'm going to abuse it and leave it out in a storm for a week but just want to make sure...</TD></TR></TABLE>
Once it has Primer on it , it should be fine as long as your not going to wait a long amount of time befor you paint it (6months+) ..

Nov 20, 2003 | 10:33 AM

#12

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (TomC)

you're the man

Nov 20, 2003 | 12:53 PM

#13

TomC

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Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

Thanks , let me know how it turns out .. Good luck

Nov 20, 2003 | 05:23 PM

#14

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (TomC)

ehhhh i just cut out some of the rust...not fun. I'm sick of it already!!!

Nov 20, 2003 | 08:10 PM

#15

TomC

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Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

lol its not near as fun to just to jump in and Start cutting up your own car.. It gets fun after a while..

Nov 21, 2003 | 07:25 AM

#16

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (TomC)

Yeah i'm going to pick up a set of rear quarter panels on sunday but i'm not sure how i'm going to put them on yet. The rust is just about an inch abover the wheel well on the panel but most of my rust is behind the bumper near the frame and right underneath the door under the side skirts...it's not gonna be fun...

Another question Tom C...once i weld the new panel/patch in is there anything i can paint the back side with so it doesn't rust again? Any products you reccomend? This is mostly for the metal behind the bumper and under sideskirts because they wont be bondo'd/primed.

Thanks,
VINCE

Nov 21, 2003 | 07:35 AM

#17

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

Oh yeah i forgot to ask...is there any danger to MIG'ing around the gas tank filler area? The cap will obviously be on but to take off/replace the panel i will need to grind/weld in that area. Any ideas? would you guys drain the tank or anything? I just want to live to drive the car haha. Thanks.

Dec 11, 2003 | 10:54 AM

#18

AgentJam

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Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

Just bringing this back up...well all the rust is cut out and this weekend i took the gas tank out (wow a lot harder than stupid haynes manual said!) and have tacked a few patches in minor areas in the rear and the huge hole in the drivers side floor pan. I really want to finish it by Christmas but with working full time don't know if i can do it. I want to get some pics up soon, hopefully i can get ahead of schedule and get some up. Anyway one problem i've run into is trying to match the patch metal to the body metal. If the patch metal is too thick the mig will blow through the body before i have full penetration on the patch. I'm getting better but setting the mig up right is key. I picked up some 1/4 panels for $100 buck in Maryland that had some minor rust on them which can easily be cut out and patched. A lot less rust than. Anyway i'm rambling on just wanted to keep this thread alive so i can post up some pics...

Thanks again Tom C

Vince

Dec 11, 2003 | 01:32 PM

#19

DIY_Racing

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From: You are far from a big deal., USa

Re: How to weld metal to body and fill? Who knows the right way! (AgentJam)

DAMN, i havent heard worse advice in my life. Blade is wrong.. You cant do it like that it will look like **** and it will stick up, unless you dont mind the pound of bondo.. If done right, you wont have to use ANY filler or bondo...

Cut the area with the rust out.. Fewer angles the better... Square section would be nice.. They have a tool that you can use that you stick on the cut section and hit the button and it indents that portion. So when you put the new piece on it has somehting to sit on and its flush already... Do tack welds aobut 3 inches apart all down the seem.. dont get it hot or it will warp... THEn grind, add more weld if necessary, grind, then a bit of filler if necessary and your done... Its an artform and youll only get better as you do it.. Just take your time... I wish i knew the name of the tool you use. When you press it on the metal it will make a lip like this.
__________
______|

the bottom portion is what the new piece rests on.. The top portion is the car... Get me?? PM me if you have any other questons..