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Thread: Butt welds and trim gaps

  1. #1
    Registered Member MP&C's Avatar
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    Butt welds and trim gaps

    I've always said we should be using butt welds, and trimming panels as tightly as we can get them. Some recent shop work helps to show that process, so hopefully this will help out someone with patch panels.


    The owner of the Biederman truck we had done all those rust repairs and fabrications on also has a 51 Ford F7 with a Rollback body. He was driving it down the road a few months back when the Delco Remy voltage regulator on the firewall malfunctioned and resulted in an electrical fire. The heat caused some of the filler on the outside of the hood above the fire to delaminate, showing up as circles in the paint. As we sanded these defects out it was noticed that an abundance of filler (+1/4") had been used. The more we looked, the more filler we found all over the hood. In an effort to yield some weight savings, the entire outside of the hood was stripped..





    In order to have free access for planishing out the Atlantic Ocean defects, the hood brace was removed from the inside...








    This revealed more defects that the last shop saw as fixes, but they won't leave my shop like that....
    Rather than butt weld in the proper thickness metal, a piece of about 16 gauge is slipped behind the rust hole area (from dirt accumulating between brace and hood skin) and MIG welded around the perimeter. I think we can improve on that..








    In addition to that, the brace had lost it's structural integrity, so we will remake the ends..








    To start our repairs, a body sweep is used to capture the lower flange profile. Note that a profile cut out of construction paper/cardboard works as well.





    Verifying the panel thickness. Despite this being an early 50's truck, despite this being a BIG truck, yes, the outer sheet metal here is STILL only 19 gauge.





    The affected area was cut out using an air body saw, use what you have available. Note we have no corners in the cut to help improve consistency in weld shrinkage on either side.





    The flange bend line is traced from our profile template/body sweep, and bent using tipping wheel on the bead roller (since it's not a straight bend). Here test fitted to the hood..





    An Ice Pick (something everyone should have if doing this type of work) is used to mark the area of the cut and more importantly, the cuts for the flanges.





    Next we trim the panel on the band saw leaving 1/4" extra around our marks. Next, we use offset snips and trim the flanges to the lines scribed. And ONLY the flanges.. Then the panel is re-fitted with the flanges flush with the original, and RE-scribe the round line, this time with more force to see the mark better.

    Note the scribe line has moved closer toward the flange as we located the panel correctly with flanges flush..





    Fitted... panel should be as tight as you can get it to minimize any shrinking/pulling.





    Flanges and outer surface are both aligned to the original first and I use TIG to tack on the exact corner on both ends to maintain this alignment.. Side note.... tacking only one end and working around to the other may shrink as you go, pulling other end down where it no longer aligns. So in this case, align both ends, tack both ends, and then progressively work your tacks side to side toward the bottom of the circle.





    Note here the flange was left long on our replacement. Trying to weld it in place already trimmed to fit will invariably cause the edge to burn back, making it more difficult to weld this seam all the way to the edge. Leaving the flange on our patch long makes the outer part serve as a heat sink where this burn back effect is less of an issue. Once the welds are dressed, trim the excess using offset snips..


    Robert



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  2. #2
    Registered Member Troy's Avatar
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    Thank You, you are a master!!!

  3. #3
    Registered Member MP&C's Avatar
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    Thanks, but I'd rather like to think "more practiced" is a closer description. You should see the scrap pile!
    Robert



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  4. #4
    Registered Member MP&C's Avatar
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    The TIG is used to fully weld the patches in place...

    Front side:



    Back side, full penetration on the weld..



    The weld seams are then planished and dressed. Next, the front of the hood had a stress crack adjacent to one of the rubber bumpers. To stabilize the hood prior to cutting out this area, the brace is clamped back in place..



    The damaged area is cut out, a "doubler" had been used toward the front to add strength to the area, so care is used to not cut that off..





    A replacement patch is cut out, bends added, and tacked in place. A plug weld ties this in with the doubler..





    All trimmed and welds dressed, the hood bumper hole is re-drilled in the new patch. Then we notice a bit of filler closer to the nose of the hood (arrow). Let's remove that while we're here to see what carnage lies in wait.



    Gotta love this game of dominos..



    The low area needs to be bumped up, and with little room for swinging hammers, a new tool is in order. Using the South Bend "milling machine" a die is made for the outer portion..



    Using a pair of C-clamp vise grips (there goes another pair) the die we made will be welded to one side, the opposite is giving a bit of a trim to better fit in the confines of the slight gap available on the inside..





    I missed the action shots, but the clamping of the vise grip is used to raise the low areas. Then dressed out for a much better "filler free" lower edge for the hood.



    With Mike having completed the dies to duplicate the ribs in the hood brace we did a test run on a piece of 16 Ga cold rolled steel. First upper die addresses middle rib only, way to much drawing going on to expect this out of one set of dies...





    Then top die is changed out for the remainder of the ribs...





    A bit of fine tuning needed, but looks like this process will work to repair the rot in the bottom of the brace ends..
    Robert



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  5. #5
    Registered Member Belair-o's Avatar
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    Really great to see all that you are able to accomplish - your fabrication abilities are amazing!
    Thanks for your continued posts! Doug

  6. #6
    Registered Member MP&C's Avatar
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    Thanks Doug!
    Robert



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  7. #7
    Registered Member Custer55's Avatar
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    Nice work as usual Robert. Keep the posts coming, Helps me out when I see how you do things. Appreciate it!!
    Brian

  8. #8
    Registered Member MP&C's Avatar
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    Thanks Brian!


    Now to fine tune our dies for the hood brace. Looking at our original profile template, the first upsweep (red arrow) and second upsweep (yellow arrow) are both nearly vertical as compared to the opposite side.



    Our first test run shows the first upsweep spread too wide, not enough vertical...




    Looking at the die that was made, a bit too much material was removed such that this vertical feature was lost...




    So a new die was made for the top, this time out of aluminum. The phenolic is somewhat easy to cut out but does have challenges in making crisp bend details, so lets see if the aluminum helps out..

    Next run, this time we'll do two panels in case they work... First pass to draw the metal into the center rib...



    This is about 8 passes, each progressively deeper. The circle fixture to the right in the picture (white base) is used as a back stop to keep our rib centered.




    This is about 9/16 of depth, so quite a bit of draw.. Next, the new top die is added and goes through the same 8 progressive passes.. Note in the next picture the vertical upsweeps are both nearly vertical. Success!








    Matching up to the original, this looks like the right replacement.






    Robert



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  9. #9
    Registered Member MP&C's Avatar
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    Progress on the hood, the bead details in the brace are offset on the ends to match the hood opening flange. So we use a Vernier protractor to find the angle, and transfer that to our panel. This is where the transition of the taper starts..



    Once tapered, the excess is removed from the bottom side and the outer seams TIG welded in place.



    A piece of round stock has a radius added to serve as a hammer form for the beads. They are hammered around and excess removed from the back side..



    A piece of 16 gauge cold rolled steel is trimmed to fit and TIG welded in place.





    Welds dressed and media blasted..



    The bend line is transposed from the original. As this bend is slightly convex, it was started using a tipping wheel on the bead roller to a 45* angle, and then finished on the mag brake.







    A reminder of the carnage we are repairing:

    https://www.youtube.com/watch?v=NDZyTTuUGVE

    A profile template is made prior to cutting out the old....





    Robert



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  10. #10
    Registered Member MP&C's Avatar
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    Time to get the hood brace end welded in place. The overall measurement had been taken prior to cutting off the old one, down to the 14 gauge outer plate as a reference. So the new end is trimmed to match this dimension, then held in place with rare earth magnets. The center (inside) rib is aligned and tacked using the TIG....





    Working outward, the panel surfaces are aligned and tacked as we go. Note the "batwings" left on the outside of the new brace end (yellow arrows). This will act as a heat sink when we make the outer tacks. Had these been trimmed to match prior to welding, the edge will have a tendency to burn back from the heat.



    The entire seam is TIG welded and then our batwings are trimmed using offset snips, then welds dressed..













    One down......
    Robert



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