Register now to get rid of these ads!

patch panel question? WELDING

Discussion in 'The Hokey Ass Message Board' started by slamdpup, Oct 25, 2006.

  1. slamdpup
    Joined: Apr 27, 2005
    Posts: 1,094

    slamdpup
    Member

    when welding on a patch panel over the rusted through area is it nessary to weld the panel solid or just tack around the panel?..or when peaking a hood when welding it should it be solid or tacked ?..reason for asking ..i have been welding everthing solid and a friend of mine was telling me he didnt think or see a reason for welding solid on these areas....i have alot more mods to do on my car and if i dont need to weld everthing solid and can get by with tacking up all areas it would be faster..but i was taught to weld it solid..what do you guys think or do on your cars?(mig welding )if that matters....i have seen some folks section a car and only tack it every couple inches and then bondo it...i would have never thought that wouldnt crack ..i would think a hood when peakin would reslly need to be solid because of the flex when opening and closing the hood...VERY INTRESTED IN WHAT YOU GUYS HAVE TO SAY ABOUT THIS
     
  2. chopo
    Joined: Feb 20, 2006
    Posts: 1,265

    chopo
    Member

    I soild weld for sure. I just think it ends up being a longer lasting fix. I always figured that a body does flex and with tack welds there may be a chance that it could crack the filler. just my 2 cents
     
  3. chopolds
    Joined: Oct 22, 2001
    Posts: 6,323

    chopolds
    Member
    from howell, nj

    Solid. And don't just weld a patch "over" rusted out areas. Cut out all the weakened metal, and butte weld your patch in.
    I repair more "tacked" panels than I care to think about, going over other people's work!
     
  4. lehr
    Joined: May 13, 2004
    Posts: 602

    lehr
    Member

    Weld them all the way around or your filler will crack also I dont weld over rusted out areas I would cut the area out and butt weld the patch in . Pat
     
  5. brandon11130
    Joined: Sep 20, 2006
    Posts: 50

    brandon11130
    Member

    im used to working on old jeeps, i usually cut out the old steel and get cut the new metal to fit as close as you can. you can use magnets or whatever to hold the metal in place before you get the first few tacs in. then what i usually do is go all the way around just because old jeeps flex. just make sure you give the metal time to cool, dont weld it all at once or you run the risk or warping the metal. somone told me wait untill it is cool to touch then do another inch. im not a body man by any means but its been working for me.
     
  6. I'm not a body guy... just a loooooowwwly welder.

    What's you guy's thoughts on using a flanging tool instead of butt welding...?

    [​IMG]



    JOE:cool:
     
  7. Petejoe
    Joined: Nov 27, 2002
    Posts: 12,570

    Petejoe
    Member
    from Zoar, Ohio

    A true patch panel should be welded solid and not on top of the existing skin. It should be butted right up to good existing material.
    Welding solid prevents any moisture transfering into the seam.
     
  8. ratt7
    Joined: Sep 23, 2005
    Posts: 362

    ratt7
    Member

    I was going to ask the same question to, thanks for the tips :)
     
  9. HemiRambler
    Joined: Aug 26, 2005
    Posts: 4,207

    HemiRambler
    Member

    Nothing inherently wrong with flanging your repair. The factory has used overlapping seams ALL OVER cars during construction - common practice. Repair work being only slightly different. Some find welding flanged panels much easier than butt welding - especially if your welder or your welding skills aren't up to the task. There are pitfalls - one would be that IF you warp it it is now more difficult to rework since metal is double thickness in places. Also as mentioned you could invite future rust problems IF you don't seal the seam when you're done.
    The benefits of a butt welded repair include easier rework to fix warpage (and IF you weld you're definitely gonna have SOME warpage) - higher end guys will hammer weld as they go - this is far easier on butt welded repairs. The other advantage is a near invisible repair when complete. Gotta like that - especially if it's in an area that can be seen from behind. Butt welding can potentially be a much nicer repair, but doesn't make it the only acceptable way.

    Take your pick - do what you feel comfortable with.


     
  10. lolife
    Joined: May 23, 2006
    Posts: 1,125

    lolife
    Member

    We did that on my old Dodge truck. Cut the part out, used a flange tool and punched holes in the replacement panel every inch, and then welded all the holes up. Took a ton of bondo with fiberglass strand product to clean it up. Bondo, sand, bondo, sand, bondo sand.
     
  11. Ole Pork
    Joined: Sep 4, 2006
    Posts: 581

    Ole Pork
    Member

    Yeah, but I would think the seam would actually be stronger. About the only tool I don't own is a flanger, and I been thinkin' of buying one. But yeah, you would have to seal the seam from the rear to keep out moisture...Ole Pork
     
  12. Thanks guys.

    I have one, but sorta figure it might build in stress prior to welding, and make the warpage worse. Hadn't thought about not having a flat surface on the back to set a dolly flat, either.

    I guess it's got it's place.

    Butt welding sounds like the answer though.

    Now I have to go practice welding with my butt...


    JOE:cool:
     
  13. Roupe
    Joined: Feb 11, 2006
    Posts: 723

    Roupe
    Member

    Remember if you want to hammer weld you should Tig or gas weld it. Mig welds are to hard and will crack when hammer welding.
     
  14. Chaz
    Joined: Feb 24, 2004
    Posts: 5,016

    Chaz
    Member Emeritus

    The flange also forms a trap for moisture making the patch area more prone to rust in the long run. butt welding is the preferred method Sometimes its sure a bugger to line up the patch, though
     
  15. manicmechanic
    Joined: Sep 27, 2006
    Posts: 210

    manicmechanic
    Member

    Exactly... If you metal working skills are not very good then a flange would probably be the best way to go. The right way is to butt weld the metal and then massage out the weld job.[​IMG]
     
  16. palosfv3
    Joined: Jun 26, 2006
    Posts: 1,541

    palosfv3
    Member

    Patching Procedures: 1. Establish the extent and size of the rust repair panel needed. 2. Before removing any paint or material cover the rusted area with overlapped 2" masking tape (at least 2 layers) ,including all flanges that are affected in the repair patch panel area. Draw the cut line for your patch panel on the tape and then cut on the line with a razor blade, Trace any body line or edge that is also on the patch area as these may be additional cut or bend areas when making your patch. Remove the tape section over the rust area leaving the remaining tape on the panel. This will become your template for the patch panel. 3 Form your repair panel from the template. 4 Check repair panel fit and adjust as necessary . Dont trim any material from the butt joint area. 5. When a satisfactory panel is completed , Remove the rusted area from the panel (drill out spot welds ) and remove the metal up to the razor cut edge of the remaining tape.6. Check fit of panel . Adjust accordingly. 7. Remove tape, surface rust and paint from all surfaces to be welded .8. Apply a good weld though primer to all overlapped areas . Apply a good epoxy zinc primer to any inner area that has been taken to bare metal. Remember to keep the weld area free of paint and grease. 9. Drill holes for plug welds in repair panel to replace factory spot welds . Fit repair panel and tack in place. 10. Weld patch panel in place. SOLID WELD THE BUTT JOINT!!!!!!!!!! 11. Place a light source on the opposite side of the patch and check the butt weld for any small pinholes or missed weld areas. Make sure that any gap is welded shut as this will ensure that moisture will not find its way under any filler or paint. 12. Clean weld residue from inner areas and spray the inner area with a epoxy zinc primer. Dont be afraid to flood any lower flange area. 13. After the epoxy has cured apply a rustproofing coating such as 3M #08892. The rest of the procudere is clean, fill and prime as necessary. One of the biggest mistakes made in this type of repair is removing the rusted area before making the template and patch and not welding the butt weld solid.
    Larry
     
  17. chopolds
    Joined: Oct 22, 2001
    Posts: 6,323

    chopolds
    Member
    from howell, nj

    Actually, flanged seams are NOT that good, for a quality job. The factory uses overlapped seams in hidden places, or leaves the seam AS as seam, as in catwalk to quarter panel (in back of rear w/shield) The only place the factory finished off overlapped seams in in the roof to quarter panel seam, and that was COVERED in lead.
    Besides the metalworking and invitation to rust problems, a flanged joint can be too strong. In a place like the middle of a flat panel, it will not flex like the rest of the panel, and eventually crack. It can even show up as a "witness" mark in the middle of the panel, especially during extremes of temperature.
    Sharpen your skills and do butte welds!
     
  18. CURIOUS RASH
    Joined: Jun 2, 2002
    Posts: 9,635

    CURIOUS RASH
    Classified's Moderator

    As far as taking care of any warping,,,

    If the mig welder is your only option, what is the best way to take care of any warping that might occur?

    I've welded plenty a patch with a mig and warping is always a problem, no matter how careful I am. I always stitch a very small area and then move to another area, stictch, move, stictch, move.

    Maybe not the way to do it?

    What about quenching?
     
  19. Vance
    Joined: Jan 3, 2005
    Posts: 2,135

    Vance
    Member
    from N/A

    Rashy, I hope you're right. That's how I'm doing all the work on the chop on my coupe. I was told that with my MIG, it's the only way to do it without warping. So far it's working great. Lots of sticthes and no visible warping. I'll just have a lot of gringing and smoothing to do. But at least I'M doing the work!

    Vance
     
  20. loogy
    Joined: Mar 6, 2004
    Posts: 1,238

    loogy
    Member

    Warping happens! The flatter the panel, the greater the affect of shrinkage (which causes the warpage). The more curve or crown, the less affect shrinkage has on it. Welding causes shrinkage no matter how careful you are.

    This why flanging panels is less than ideal. Butt welding your panels lets you have some control over what you do to the panel after it is welded. Flanging limits the amount of control.

    Quenching really does nothing except for making the metal harder to work. Think of it this way, gas and tig welds cool realively slowly leaving a relatively soft bead. Mig welds cool very rapidly and leave a hard bead. Same thing happens if you heat a piece of metal red hot and cool it slowly versus quickly.The amount of shrinkage will be nearly the same if you quench or let the metal cool naturally.

    This thread might help.
     
  21. El Caballo
    Joined: Mar 3, 2001
    Posts: 6,332

    El Caballo
    Member
    from Houston TX

    Instead of stitch welding on sheetmetal, I would suggest that you tack weld and go to the other end of the patch and tack. You will end up with a patch that will look like it was put on with metal boogers but you won't have the warping as much. (It also depends on the size of the patch as well as your heat settings and feed rate. What kind of wire, flux core or are you using argon? Size? Can you see what you are doing?) Lots of variables... :cool:
     
  22. man-a-fre
    Joined: Apr 13, 2005
    Posts: 1,311

    man-a-fre
    Member

    When welding in roof inserts i learned that after i go stitch it in i grind the welds down then stich beteen them then grind then stitch i have found if i dont grind the welds it tends to not allow the heat to make it through the weld and tends to warp more ,so tack them then grind then tack again then grind till its all welded.my.02
     
  23. 49ratfink
    Joined: Feb 8, 2004
    Posts: 24,286

    49ratfink
    Member
    from California

    not sure what people mean by stitch... but if you ar doing a sheetmetal patch you tack weld. tack a few spots far apart to get the patch to fit. then go around and do some tacks between the tacks.

    heat is the enemy... touch it with your hand, let it cool before you weld again in that spot.

    you can also warp the metal in the grinding proccess. watch that heat!! I like to use the edge of a small cutoff wheel on my die grinder. I cut down only the weld not the sheetmetal. when it is all looking good I finish it up with a regular sanding disc. again watching the heat.

    don't just sand like a madman, as you are thinning the metal. sand just enough to make the weld seam disapear. if you are going to mud it anyway, it does not need to totally disapear
     
  24. El Caballo
    Joined: Mar 3, 2001
    Posts: 6,332

    El Caballo
    Member
    from Houston TX

    A stitch weld is anywhere from 1/2 inch to 1 inch long to me.
     
  25. 49ratfink
    Joined: Feb 8, 2004
    Posts: 24,286

    49ratfink
    Member
    from California

    oh.. to clarify, you tack until it is fully welded. take your time. I like to have a couple of spots going at the same time so I can go from one patch to the next while the other cools.


    remember most rust comes from the inside out. if you have a 1 inch hole on the outside, you probably have a 5 inch area of rust on the inside. here's what I do....cut out the rusted sheetmetal to where you think the rust has stopped. look at the backside of what you just cut out... is there serious rust up to the edge of what you just removed? cut out some more.
     
  26. 49ratfink
    Joined: Feb 8, 2004
    Posts: 24,286

    49ratfink
    Member
    from California

    ... oh.. I never weld on sheetmetal more than about a quarter inch in one spot, unless it is a floorpan or something where warpage is less of a concern. never on a body surface.
     
  27. 49ratfink
    Joined: Feb 8, 2004
    Posts: 24,286

    49ratfink
    Member
    from California

    here's another thought on this subject. do every patch as if you are good enough to do it without bondo at all. don't go in thinking I'll weld this up and slather on the mud when I'm done.

    sure, 9 times out of 10 you'll still need some mud, but making the effort to do it without will make you better than those that don't even try.
     
  28. HemiRambler
    Joined: Aug 26, 2005
    Posts: 4,207

    HemiRambler
    Member

    chopolds, you bring up some good points - I agree. What I am trying to suggest is that there ARE places where there's nothing wrong with an overlap seam. The factory used them - and they weren't places that invited rust any worse than other places. They didn't always hide or lead finish them. Sometimes they left them right there in plain sight. Again it all depends on the job at hand - and make no mistake I too would prefer a butt welded joint - I'm just trying to acknowledge that there's more than one way to skin a cat.
    BTW here's a pic of a factory overlap seam - exterior - non finished - factory job and NOT a place that was prone to rust out.

     

    Attached Files:

  29. stickylifter
    Joined: Feb 21, 2005
    Posts: 1,299

    stickylifter
    Member
    from Detroit

    MercMan1951 lent me a video on How TO Chop A Merc by some old southern guy. He had a great technique for MIG panel patching. He would tack, one tack at a time, (no 1/4" long stuff) all the way around a given patch at, say, 4" intervals. Then he'd go back and start the next round of tacks so that his wire was right on the edge of the last tack. This new tack would then attach the two adges of the panels, but also dig in to the previous tack a little. When he was done (it took him a long time) the welds all overlapped one another and it looked just like the classic "row of nickels." That's how I weld patches.

    For floors and things you can't see, I have found that welding a half inch at a time and then skipping to another area works fine. If the metal shrinks up a little or oilcans, tap it back down into shape with a body hammer. What took me a while to learn is how to dial in the wire speed and amperage. I used to think that you welded sheetmetal like you put on caulk in the shower.. in one long pass. So, I either had the heat so low to prevent burn through that nothing would penetrate, or I was burning holes in the metal after about an inch.

    What I didn't know was that heat builds up on the panel as you are welding and that causes a burn through. So now I set my heat so that I get good penetration and only weld in short bursts... in 3/4 time actually, like a waltz: ZAP two three, ZAP two three...

    A long, long, lonely waltz.
     
  30. 1954HCCA
    Joined: Oct 10, 2006
    Posts: 61

    1954HCCA
    Member
    from LA

    As far as patching a panel,I strongly believe in butt welding.But I thought I would add that on smaller jobs,such as shaving antennas and door handles I tried 3ms panel bond.It has held up for 7 years on a thin metal truck.(Not telling you guys what it was.:rolleyes: ).I had no fear on metal warp using it.
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.