Lead loading v "pongo"

The human eye, properly functioning eyes at least, can spot low spots in body panels measuring in the thousandths.

I haven’t seen every slab sided XK out there but can recall only seeing one truly straight in all my years looking at these cars, this particular steel car was boldly done in black. The interesting thing about it was the cars panels were more convex than you typically see, obviously making it easier to achieve visual straightness. Having battled this problem dealing with the almost perfectly flat XK panels with basically no support structure behind them, I know why these cars are almost always wavy. When it comes to claims of straightness, I’ve got to see it to believe it in its final paint. Most of the time I’m not seeing the same thing as the claimant.

When I said a lot of filler, I mean cars that either entirely skim coated with it or covered with spray polyester, many times both. Not taking a shot at you Nick but glaze is body filler but with a different consistency.

BTW, what ever happened Wray Schelin? I have a few of his panels I think from a time when he was getting tired of making them, things did not go well.

He is teaching classes and marketing body shaping tools. Check on youtube and ebay.

No offence taken, Monte. Not using bondo is setting a quality standard.

The key word in the above blockquote is "different”. Consistency, yes, but also formulation, application, adhesion, performance and function. Not the same as bondo. No more than two pack high build primer - to which glaze is more closely related - is the same.

As you say, the eye will pick up the tiniest of surface ripples in a dark, high gloss finish. You clearly perceive them on this XK120 when you cast your eye obliquely down either side because there’s a sixteenth of an inch variance in surface elevation between the wheel wells. To the eye that 1/16" is large but from the standpoint of bare metal coachwork it’s minimal. Have you ever seen a car with a maximum of 1/16" of bondo?

Adhesion and stability are the two most important factors of a finish, and material build factors in. Thinner is better. 1/16" is 62 mils. Recommended maximum dry build of epoxy primer is 6 mils, though you need only 2 mils directly under colour coat. Recommended maximum build of most 2 pack primers is 16 mils, preferably closer to 12. Block that down to 4 mils build on the hills and your 62.5 mil starting point in the valleys is reduced to 42 mils, well within the maximum 100 mil optimum tolerance for glaze.

Recommended maximum build of body filler is a quarter inch, 250 mils, applied onto bare abraded metal, though heavier builds are not uncommon in practice, on top of which are typically applied epoxy and high build primers and glaze before the colour goes on. That’s a lot. And adhesion against bare metal is not nearly as good as it is with epoxy.

When I get around to final prepping, much of this body will be skim coated followed by block sanding that will remove most of the material as the hills are cut down and the valleys filled. There will be far more glaze left on the floor than is left on the body. It’s a multi-step process that begins with getting the metalwork as straight as practicable followed by getting the surface chemically clean and etched, then epoxy and high build primers before final prep with glaze then a thin epoxy seal coat before colour. I do not expect to achieve perfection, but it will still be straight.

Yeah, you’re right. I think Wray got tired of the scene. When I set out to replace the front quarter panels of this car, maybe two years back, I called to talk to him about fabbing them for me. He told me he’s out of the panel business but suggested I travel down to Massachusetts to take one of his courses, learn how to make my own. I declined, but I did buy a couple of shrinking discs from him to replace the Sunchaser discs I’ve had since the 90s. They work well.

1 Like

Nick, I think you have established, certainly in my mind that you are at least an aficionado of body work. Body man, was my first career, and I still do all my own work, to include welding, leading, prep and painting. You and I disagree on so little, this point is almost not worth making…almost.
Bondo is not an inferior product. It is no less viable than the paint you are going to spray. You don’t get a better quality job by not using plastic filler, you just get an excessive amount of work. Plastic filler reputation suffers immensely from the great volume of mis- application. Put your slapper and torch in the hands of most men, and you are not going to get superior work. I’ll put a a laser flat 1/8" of plastic up against anything. It will out last the paint, and take 10% of the time. . Now door edges, and body lines in general. I always lead.
Fine esthetics of what’s under the paint is rare air for the elite metal Smith’s ,and as I do some if this, I tip my cap to you. It is, an art from another century.

Nick , regarging my comment of feeling queasy looking along the front wings of my 120,
it`s more like the ripples caused by the wings of a butterfly on a still pond than the waves on
" Big Sur" ( short for big surge I take it) ?
BTW did you joggle or butt your wing panel ?
If a flat panel is achieved in say 15 degrees temp, will it still be flat ,in say, 30/35 degrees,
I wonder !
Peter B.

Ooh mind play, nasty :slight_smile:

No argument from me, Karl. I think a good bodyman in a reputable shop would be able to achieve bodywork within 1/8". There should be no difficulty valuing and selling their product because they’re credible. I’m sure you’ve seen the work of many weekend body men who don’t achieve a 1/8" tolerance, either while they’re doing it or what the car looks like in 10 years or so. You’ve seen some of the efforts that are shown or are up for auction. The front wings are often heavily bondoed. That might provide more temperature stability. As an aside, have you considered bonding the front mudguards to the inside of the wing as a means of stabilising it?

I don’t look at this as work, though. I like bodywork. How I relax. If I were to be paid for all the hours I’ve put into this car body since 1991 I figure it would be about $2 an hour. This isn’t some kind of investment. Not a financial one.

It’s not so much about producing a pretty car quickly but about taking the time to produce a beautiful car that will last decades.

I was in a shop a few times four years ago when I had a repair done to my E. They’ve produced an Amelia Island winner so they do good work. I was invited to see the progress as they went along. In the corner during one of my visits was a bodyman sculpting the tail lamp mount in a rear-ended 30’s Rolls out of bondo. He looked embarrassed. Insurance job.

Quality shops and known body men go on their reputations. Beyond the presentation of his final product, when an amateur body man with no credibility, like me, can say there’s no bondo in a car I think it’s a plus.

It’s the insurance and the real cost of a wreck the push use of plastic filler into abuse and ultimate failure.

Absolutely. My take is bondo used diligently is ok. +0/-1/8" is a good bodywork tolerance.

These, I mean:

off to the shower then dinner with my lady. Later.

I meant to answer this earlier, but swmbo was calling up the stairs to tell me my dinner was getting cold.

I butt weld the panels with tig. I used mig the first couple of attempts at the wing panel but wasn’t a good enough welder to pull it off. I cut my teeth on oxyacetylene in the 80s so tig felt familiar. Less heat so less distortion. Hammer welding is easier too, and much less material to grind flush before working. I also found you can work a tig weld more than mig without cracking b/c the weld is softer.

I have wondered indeed about ambient temperatures affecting the shape of that big, unsupported mass of sheet metal. Good point. I haven’t done it yet but I am considering the above manoeuvre of bonding the mudguards to the inner surface of the wing. That would fix a good part of the slab side of the wing to the very rigid dash structure.

Just tried my hand at tig, I think I need a few more tries :frowning: it’s a long time since I did any oxy welding but can see the corollary to tig
The SiL is doing this for me, it’s his tig welder anyway.

1 Like

I would love to try my hand at tig but so far have stuck with mig and gas welding since I already am set up for that. The cost of a good tig unit is a bit daunting. I am wondering if it is easier to control burn through on old metal that has been ground thin or corroded with tig as opposed to gas.

In my mind perfection is straightness when discussing body work, as in zero visible shifts in the reflection of light on body panels where it shouldn’t be. Got it close and as as good as I’ve seen except for that black car I mentioned, but not perfect and it kills me because I know I spent the time and effort trying to get there.

Anyway, I thought I’d pass along a couple of ideas that seemed to help with straightening these panels with filler. When you get right down to it, anything applied to body panels with the intention of sanding it down to blend the highs and the lows is filler. Incidentally I did quite well with the straight edge with my metal work, but I was getting panel deflection, not tin canning, but movement with only slight inward pressure making it impossible to long board the panels flat.

For the front wings, I “bondoed” the back side of the wings to get more rigidity, slathered it on there pretty thick. When finished with the outside I ground most of it off a finished it with the DA. I put the rocker shutz in for ding protection and painted it body color. On the doors I glued these aluminum channels in, two per door and left them in to get some rigidity. Did the same treatment on the spats.

Here’s a couple pics showing how extensive the body panel replacement was on this car, In hindsight I probably would have saved a lot of time fixing the original body than buying all these new panels. Everything needed major time consuming fitting. These cars are not built like Camaro’s!

1 Like

Good ideas both Monte. Big flat panel cars are a frustration, as you noted, even with a long board, you get enough subtle deflection to ruin the result. I found when doing a 62 Lincoln, with huge slab panels, I could get it straight with an airboard sander, because I could get good results with a very light touch.

You control burn through with mig and tig essentially the same way by controlling amperage and applying short bursts. It’s easier with tig because you’re modulating the amps with the foot pedal and adding 1/16" material manually as needed. With mig the trick is to get the amperage low enough not to cause burn through but high enough to achieve good penetration, also getting the wire feed slow enough not to pile up but fast enough not to burn back.

I struggled with the same issue. A dead flat panel is inherently a bit flaccid. To make it rigid you can either introduce a crown - which pushes the steel outward and makes it not flat anymore - or introduce a pulling moment. This is a pic of the left side showing the essentially flat plane of the wing, bound at the rear by the vent opening and on top running parallel to the high crown of the wing. Here I’ve established the horizontal plane and have stabilised the vertical plane while I stretch and shrink the panel into shape.

This series of pics is of the other side. First objective was to get the bottom of the front wing in line with the bottom of the door and rear wing. As it was, the rolled edge of the wing would not clear the bottom of the dash structure so the latter needed to be modified slightly, starting by cutting the wing at the curve where it meets the hinge panel (1) to allow the wing to be pushed outward for working room then cutting out the bottom of the dash structure and raising it ¼" (2)

dry fit of replacement 18 ga panel

tacked in place with the mig

welded in - a good pic, Geoff, depicting the difference between mig and tig.

after finish grinding

next establishing the line across the door and wings using a straight edge

then forcing up the rolled edge of the wing flush with the raised dash structure, introducing the pull moment in the panel, and tacking in place, then rewelding the short cut at the hinge panel.

result is straight lines across the side and bottom of the wings and door. Here I’m just beginning to shrink the door flatter.

back to the left side

Didn’t mean to hijack this thread but value the input from those who’ve tackled XK bodywork. E-type bodywork is much simpler.

To an earlier question. Has anyone considered bonding the front mud guard to the inside of the wing to stabilise it? Bonding would be in this location

which with the bottom of the wing tacked to the dash structure would form a stable box section, thus

which helps stabilise the unsupported remainder of the wing.

Still thinking about it.

hoping not to divert the thread Nick, but what are your thoughts on spot welding ?

I am wanting one badly to do original style work

I bought a Miller 230v spot welder maybe 25 years ago. Indispensible for reproducing panels with original welds, like this one, the spare tire shelf:

Bite the bullet, Tony. You won’t regret it.

thx, think I will,

btw, I think your bonding idea is good

my mate owns a fleet of buses, he uses some very expensive bonding agent to make repairs to damaged bus panels, its the stuff they use in the factory

one issue to consider is it cant be easily separated

I did not bond the panel/wing Nick I made a tight fit panel to wing then plug
welded.
Peter B