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1925-45 sheetmetal repair


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I was not satisfied with the body work previously done by my father on the Buick, so began stripping off all the primer and bondo and hammering out the dents that dad left.

First thing I noticed is how soft the sheetmetal is. It must have a low temper because it moves and stretches very easily. 

When it was time to start shrinking some of the bumps on the front fenders where the metal had been stretched, I searched youtube for how-to videos on shrinking because my prior attempts were not very pretty.  There were some videos on friction shrinking that appealed to me, so I ordered a friction disk for the angle grinder. 

Another helpful tip I learned  was to use blue dykem layout fluid to highlight the dents.  That dye is the blue color in the photos.

Friction disk shrinking process uses a heavy spinning disk to generate heat, which will then cause the sheetmetal to shrink as it cools.   Run the grinder & disk over the bump a few times,  spray it with water to cool it off, wipe with a rag, run a hand over the bump to check the progress, and repeat until the bump is gone.  

It only takes a few minutes of practice to pick up this skill and the results are very impressive.

Something else I discovered is how differently the Buick sheetmetal behaves when welding than the Ford A sheetmetal that I had learned to weld on 40 years ago.

It blows thru very quickly with oxy-acetylene torch, and with the wire feed welder.

The rear panel of the body tub had some unwanted holes drilled thru it, plus some tears in the upper corners, and some deep dents from something bouncing on the luggage rack at the lower right side.  Dad patched up several places using solder with a copper sheet backer, so I had to be real careful to get all that lead cleaned out so it does not react during welding.  After making some progress shrinking the dent patch, I started welding the holes up with the wire feed, and it was getting real ugly.

Hugh mentioned seeing his repair guy using a piece of brass on the back side of the welds as a heat sink, so I clamped a piece of copper on the back side, and started getting some decent welds.  It also  welds better when the tip is held real close to the workpiece.   The holes are now welded closed, the dent patch is almost gone, but the upper left corner of the tub is bugging me because it looks like it has been cinched in at the belt line.  I might have to cut this out and redo it.

The last big weld repair will be the rear door opening, which will require fabricating some complicated patches and removal of a lot of lead applied by my dad.

Making progress !

Kevin

front fender shrinking.jpg

rear door dents.jpg

cowl prep.jpg

cowl patch.jpg

body 1.jpg

left rear corner.jpg

rear body 1.jpg

tools.jpg

rear door opening.jpg

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Wow,  thank you for the great techniques and how you were doing in the repairs on your Buick.    I'm sure there are many 'repairs' that are a 'get by' on the repairs.     The type of steel sheet used in our old cars is not the same as our sheet steel today.     Again many thanks......

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Jim is right about the metal used in vehicles of today.  It is tempered and hail is not a good thing on this material.  I heard someone say once that three tokyomobiles could be made out of a T Model Ford front fender - they weren't far off.  Back in the day the compound curves on the bodies required some very good sized dies to make those deep draws and that required softer material.  What I wouldn't give to be able to go back in time and watch how those body panels were formed.

 

Terry Wiegand

South Hutchinson, Kansas

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Kevin, 

     You are doing some fantastic work that many of us have not stepped into.  Home welders sure are nice to have around though.  I learned a couple of tricks from the person that did my welding.  One was using the brass heat sink behind the thin sheetmetal that you already mentioned.  The other was that sometimes you can not recreate all the compounded bends and curves, and the next line of attack is to make the sheetmetal from multiple pieces and weld them together.  That was how he did the dogleg behind the back door.  This is made from 3 pieces welded together before welding onto the main section.  .  I also sometimes think about making smaller patches, but he just cuts out a big section and puts in all new.  Go big or go home.  

 

You have been busy.  I have always wanted to correct mistakes that my father made, but I guess I will have to live with my brother the way he is.     Hugh

 

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Edited by Hubert_25-25 (see edit history)
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I made a cardboard template of the right side upper rear corner and compared with the left side and it did not match, so it needs to be cut and reshaped. Since there is  already a messy bunch of welds here, the best repair is to cut out the mess and install a patch panel.   The method I have used before to form a raised bead in sheetmetal is to make a wooden form with a radius groove and press the sheet into the groove using round bar with the shop press.   The groove needs some heavy gauge flat steel fastened on both sides so the bead corner will be sharp. This takes a little trial and error to get correct bead width and depth to match the original.  A bucket of scrap steel pieces is real handy when making these odd one use tools.

Another form is made by cutting a radius in a piece of wood to match the body corner radius. Two pieces of steel are bent and fastened parallel to protect the bead from being mashed when the panel is being pounded into the form. I used the heel of the teardrop body dolly to pound the panel down into the form.

Now the patch panel is complete and it's time to lay out the cut and begin sawing.  Once the upper body flange has been cut, the sheetmetal gets real wiggly as I try to get the patch aligned and clamped ready to weld. Finally it looks good and I get it all tacked in place.  I will finish welding it up and then heat the flange corner with the torch so it can be bent and shrunk to match.  This already looks so much better than it did before.

Kevin

messy welds.jpg

patch making.jpg

check fit.jpg

cut and prep.jpg

first tack.jpg

all tacked.jpg

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I have been using a 25 year old Harbor Freight MIG welder on the body sheetmetal.  It works on the lowest heat setting on the welder, tip held close,  and needs a copper heat sink on the back side or it will blow thru.  I was trying to weld a hole in the firewall closed using the oxy-acetylene torch and the hole just kept growing like a sink hole instead of closing up -  much to my alarm.  Usually I can see it starting to blow and pull the torch back in time, but this sheetmetal acts very differently.

Kevin

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The rear door opening patch is a bit complicated because it is the intersection of a curved door opening and body curvature in the vertical direction.

I made a form by grinding the edge of a heavy piece of steel plate to match the door opening curvature and hand filed a corner radius to closely match the original.

Then I put a slight bend in the middle to approximate the vertical body curve.  A piece of sheetmetal is clamped to the form and hammered over the edge to make a flange.  I made another form out of a piece of oak to bend the second part which will be inside the door opening.  This part has a larger bent flange, which ended rumply after bending,  so I heated the flange with the torch to shrink so it would flatten out.  That's why the wood form is scorched black.  These two pieces will be welded together with another short piece at the bottom to create the door opening/ reveal  patch panel.

Kevin

flame shrinking flange.jpg

forming patches.jpg

rear door opening patch.jpg

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It took me two tries to get the rear door opening patch done right.  First photo shows the first attempt which had too much gap towards the bottom when the door was held up to it.  Also  too much curvature in the vertical direction.  So I cut it out and fabricated another patch.  Trimming and fitting the patch to the opening takes a lot of time, and after each snip the alignment had to be rechecked against the door profile.  

When I compared left side / right side measurement of this narrow strip between fender well and door opening I found one side was 1/4" narrower than the other.

A likely explanation for this is the tooling and stamping technology in use at Buick's sheetmetal shop.  The fender well was stamped by one press & die, the door opening stamped by another press & die with sloppy tooling that allowed 1/4" error in positioning.  It must have been a real challenge to assemble bodies using  sheetmetal parts so much variation. 

Kevin  

too much gap.jpg

tacking.jpg

second time.jpg

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Kevin 

I just get to see this post .. All my respects to you on ALL that work your doing there ..!

I guess I have to consider my self VERY lucky on finding a car that don't really need much wood work or body work .

Keep up the excellent work..!

Cheers ...!

 

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