jag front end repair
I managed to spend some time working on the jag over the Xmas holidays. Maybe what I did can provide a bit of inspiration to others.
The XK headlight and parking light pods are notorious for their capability to accumulate water (I think it is mainly a condensation issue) and this needs to be addressed in almost every restoration. This is how I went about it.
The pods are lead loaded on the body. This side is severely rusted through at the bottom and has issues along the lip.
I started by removing the lead loading for the bottom repair.
Bottom part gone.
Reconstructed using bondo to get the shape.
Making a fiberglass flexible shape pattern
Cutting with a sharp knife leaves the scribed line of the FSP edge on the original part and can be used later for cutting reference on on the original. This helps fit up of the repair and patch.
Flexible shape ready.
Flattened for marking the shape and bending lines.
Tipping the bending line on my rather improvised e wheel tipping setup.
Tucking forks ready for shrinking the edge
But I ended up problems making the panel fit the FSP. I suspect I was not careful enough when referencing the edge line position from the FSP.
So I started again and tried to get better info on the bend line position using a piece of cardboard to isolate the center part, since the FSP has so much shape in the edges it that pressing it down flat does not work very well.
Shrinking using a jaw shrinker (lazy me)
But still, when stretching the edge, I realised that again the first bend line seemed to have wandered off a bit and I continued struggling with the panel. Not having the arrangement information also does not help.
I think the problem here was due to using a jaw shrinker for shrinking and stretching the lips. Since this shrinks in parallel strokes, I suspect it pushes the lips in itself resulting in a deformation along of the metal on the bend line repositioning effectively the bend line.
After struggling with the lack of proper arrangement information from the FSP pattern, I decided to pull a strong fiberglass hammerform off the pod and to work with that.
I felt I still needed to improve the bend line position information, so this time I made a FSP in the hammerform mold to get the bend line position.
Bend lines marked.
And tipping the bend line.
Ready to shrink.
I order to get away from the parrallel jaw shrinking, I went to the more traditional manual tucking and used these pliers to get finer control of the amount of tucking along the edge.
First tucks flattened.
Trying to keep the shrink in the correct position referencing to the mold shape.
Sharpening the edge of the bend line.
This is an excellent tip which was posted by Richard a long time ago. Thanks Richard.
To fine tune the shrinking in a lip, you hammer on the lip's upstanding side and support the part on either side of the lip. This shrinks the lip in itself in a very controlled manner which allows fine tuning of the shrinking.
Starting to get somewhere.
It shows that the panel needs some stretching to fit better in the form.
A slight stretch on the sandbag
Lip one ready and fitting in the mold as it should
Second bend line referenced (I is a larger radius bend so it is a bit wavy but that will be corrected later.
I have always fount the tipping wheel a little annoying when making a second bend line on a shaped panel in that it interferes with the contours of the bended area and messes up it's shape.
This is a vey simple tool I use for in panel local stretching and for tipping. It has a moon shaped upper bolt and tipps into the lower bolt covered with some duct tape. A few light tapping goes along the marked bend line makes a nice and easy tipped line.
second line tipped.
Same tool setup for local stretching.
Stretching the lip.
Slowly getting there and rough fitting in the mold.
After more tweaking and tuning, the first FSP is used to mark of the cut lines (obvoiusly the fit of the FSP is OK)
Repair piece ready
Cut out along the line scribed when making the FSP and starting the welding (more on that later).
Onto the removal of the whole headlight pod. I left it in place during the above repair to get the reapir panel to fit correctly relative to the body.
Unleading the pod.
Pod removed. A main area and lot of small areas need to be adressed.
I started to derust using the phosphoric acid method.
It is a very slow and tedious application and rubbing down, so I tried to speed up the process a bit by grinding off as much rust as possible.
But even in doing so, I still had a lot of black spots after several applications of phosphoric acid.
So I reluctantly dug up my homebuilt sandblaster. I hate using this in my workshop. I tried to confine the mess by wrapping the area in plastic, but that didn't work very well. It still blows out dust and visibility is very poor after a bit of blasitng.
So I put up some screens and blasted. (Use extreme caution, respiratory protection obligatory)
You can however not argue with the results. Speedy and thorough.
I use Picklex 20 to attack and last possible remaining specs of rust and to phosphatise the metal to keep it from rusting.
Major area rusted through and needing to be replaced.
Making the classical Flexible shape pattern with two crossed layers of fiberglas tape.
Replacement panel ready.
Held in place to start the tacking. The tape merely holds the part in its approximate position. I use one hand to support the part from the back to hold it perfectly flush when making a MIG tack, and keep correcting the panel by hammering a little as soon as it starts being held by the tacks.
OK now for the part where I expect some controversy and some people will insist this is not the way it is done: here is how I did the welding and why.
I tack using MIG spots. Why? I have found the main problem when welding is to have the adjoining metal edges perfectly flush at each and every tack position.
I feel this is easier to achieve if I have one free hand for slightly pushing (supporting) one side of the panel to keep it exactly level and visualise it form the side to see if they are perfectly aligned.
I then feel it is quite a trick to TIG the tack, especially when there is a bit of a gap at the tack location and a dot of filler is needed to prevent burning through. Quite honestly, in real life on body welding, I really struggle to get no gaps at all, especially if the panel is shaped.
MIG allows me to zap a tack in place with one hand and without moving anything (but the trigger) which gives me most chance of tacking exactly level. It also works if there is a slight gap at the tack location.
To get the panels perfectly level and in order to have maximum visibility, I tend even not to use the welding helmet but position the MIG torch, support the panel in position with one hand, keep perfectly still, close my eyes and zap the tack. (In all fairness, that is also why my tacks are sometimes not very beautiful). With a cold wire and just by the sound, it is not easy to get a nice tack, but the panel will be held and that is all it is about.
I the continue jumping around, always realigning the repair panel perfectly flush with its surround where I will position the next tack, without worrying about anything else. Even if the panel moves a bit (heat or arrangement correction) I always work it until I have the edges perfectly aligned at the next tack position and then zap it in place.
After the panel is held all over by the tacks I Mig spots consecutively to fill in between the tacks. The aim is to add a bit of filler material to the weld, which I feel I need to get the material needed to be able to a finish the weld later.
I then grind the MIG bead (composed of single spot welds) and try to get a constant amount of added filler material (very little) all along the weld bead..
The panel now has a little distortion. MIG inputs very little heat. I think that it helps if you keep the torch in position after welding and use the gas flow to cool the weld).
Since I do not yet have penetration on the back side (no irregular puddle), I find it easier to hammer the weld with a dolly on the backside to stretch a bit if needed to correct the weld distortion (always stretching to compensate for the heat shrinking) before moving on to the TIG.
I now have two problems:
The MIG weld is hard and presents a problem when planishing the panel in it's contours after welding.
My weld tacks are not penetrated (Although this could be achieved with other MIG settings, but as said I like not having a bead on the back at this stage for stretching).
To solve this I run over the weld bead with my TIG. You could of course use oxyacetylene to the same effect.
Without need to add filler rod, I feel I can concentrate fully on the weld puddle and (try to) run with constant speed and go quite fast without burning through as soon as I get a but of gap. I started doing small stretches and a bit of hammer stretching first, but found it is also possible to run in one go and take care of the distortion later. The weld is now annealed and soft and can be worked and finished in the surrounding panel.
In running over with the TIG, the penetration is also perfect, so I have solved my two above problems.
The method allows for less exacting panel fit since MIG spots can fill a eventual gaps easily.
All in all, form me, this appears to be a good method, but I am not suggesting it is in any way better than other methods presented here so please allow me do it in this way and by all means continue doing it the way you think it should be done. Thanks.
Illustration of this method:
Starting to tack
Gradually bulding up the tacks always making sure of just one thing: that the repair panel and it's surround are perfectly flush.
Further filling in the tacks
Single spot MIG welded all around.
Granding the weld to keep a constant added little bit of filler material all along the weld.
TIG welding over the weld line. I tend to wrap aluminum kitchen foil around my weld glove to keep the heat away and grab the torch around the nozzle. I find this much improves torch control.
TIG welded all around. This is inside the pod, so I went quite fast and did not bother too much for perfection.
Also the TL lighting distorts the result a bit in being extremely unforgiving.
This weld has just the bit of extar metal still in to allow grinding it flush with the surrounds without having a weld line undercut.
I use this rotary bit. It is very precise and cuts rather than grinds so there is little heat input.
There is still a bit of panel finishing to do, especially a few good sessions with the shrinking disk. Chalking in the repair and raising the lows.
The rear side of the pod itself is also corroded through, so a new piece is made.
Making a FSP.
FSP ready and bend line noted
After a bit of hammering on the bag and different steel dollies, the replacement part has the correct shape.
Ready to start tagging
First tags made. All important to keep the repair panel perfectly flush at every tack.
Most of these are still done blind (no helmet) so they are a bit untidy, but the panel is flush which is the only important thing at this stage.
The trick with the copper support when welding the edge. I don't know who came up with this originally, but thanks.
Starting to single weld fill the seam. Consecutive single welds are for low heat input.
Rear side shows no penetration blobs, which is handy when correcting the weld distortion with a dolly on this side of the weld.
Full MIG single spot welded.
Grinding down to control the weld filler material quantity for the following TIG weld.
Correction of the MIG weld distortion with a bit of stretching on the ground weld line with a dolly underneath, followed but going over the weld line with TIG to anneal the weld and generate full weld penetration.
Again the trick with the copper backing for welding the edge.
Grinding down the little remaining excess filler material
A bit of restrectching after the TIG weld.
A little trick to quickly identify remaining highs and lows. A piece of blackboard chalk is rubbed over the area, immediately showing highs and lows. I personally find this faster and less messy than the magic marker. The chalk wipes off easily for the next session.
Highlighting the position of highs and lows.
Headlight pod plugwelded back in place.
Next up is the parking light pod. Similar issues here.
Blasted and treated with picklex 20.
Wing needs a repair patch.
A piece of metal ready for shaping.
Shrinking the edge on the stump.
Wheeling to planish the lumps quickly. (Hand planishing on a dolly is also an option here).
As you can see the little work on the stump has alreay overshrunk the panel a bit.
A bit of local stertching on the sandbag.
Rotten part cut out, ready for welding.
Starting the MIG tacks.
Tacked in all around.
MIG consecutive single spot welds.
TIG penetration and annealing (of course oxyacetylene welding would have the same)
Fine grinding the weld
Rear view of the resultant weld bead.
pod back in place
First tr at lead loading. Works quite well.
I hope you enjoyed this post. Thanks for looking.
I wish everyone on metalmeet a very happy newyear and lot's of success with whatever projects they have, especially the metalshaping ones.
Last edited by hodijag; 01-05-2012 at 07:01 AM.
The Jags can bite.....
Nice that... Some nice tools you have made.. looking good
You Mig weld it first and then using Tig over it again.... Why?
Thx for sharing
If I can do it, then you might do it. I'm no wizard guy.. No big harm failing..
This is a nice thread. Even though you made repairs and not a complete panel, it shows how complex parts can be made by just breaking the part into smaller pieces. I always felt that if I can master some good sheet metal welding skills I would be able to make large complex panels. I just haven't had the need to make anything like that yet. Thanks for taking the time to post your progress. Nice work.
I never met an old car that I didn't like.
Thanks for posting , The duct tape holding the patch in place , glad it works for you . I use vice grip type clamps, patch sometimes wants to shift out of align ment with parent material.
Yes a very interesting post,
I especialy like the vise held short tucking fork, they answer a problem I have forming some 1.5mm steel, I'll knock one of those up today.
Thanks for posting.
Great post! You took a lot of time to document this for the rest of us, which I really appreciate. After my current restoration project I have a 120 DHC(since 1970) that I am sure will need those same repairs.
Questions: How does the mig gas flow help cool the weld? On my Lincoln welder, the gas flow stops when you stop welding?
You are stretching with a plastic, cylindrical hammer. How do you prevent the edges from marking the metal. My plastic hammer is round nosed. What are pros and cons of these two shapes.
Others welcome to pipe in on answering with their opinions.
In reply to the questions.
For the MIG/TIG combination I added it in the post.
For the gas flow, this especially applies to the TIG phase which has post gas flow, but I also find with the MIG, keeping the torch in place rather than pulling away immediately keeps the gas cover a bit longer, maybe it is just my imagination. For TIG I find it makes a big difference in heat input.
Maybe it is a personal thing that I need to resist from pulling back the TIG torch which probably comes from oxy acetylene practice and especially with TIG this is not optimal.
The cylindrical end to the hammer is an error. Until now I have only used the other bigger end of the hammer which is rounded as usual and I never got to rounding the small end. Sorry for that. No cylindrical end needed as far as I am aware.
Thanks for the positive replies.
Last edited by hodijag; 01-03-2012 at 12:56 PM.