Depth threshold for dent pulling vs filling
 

A newb question I know. On a blind panel at what depth should I opt for pulling a dent rather than using filler? At some point it's obvious even to me ... a dent 1/4" deep needs to have the metal addressed first ... but the numerous door dings along rear quarter wheel wells, same with doors? So far I've been pretty successful reducing the filler that's going to be required down to maybe 1/16"-3/32" on larger dents. Am I better off filling shallow dings rather than pulling them with a stud welder? (actually I tack on a small piece of TIG rod and pull on that).

Or maybe a quick shrink with oxy/act and then use filler?

Recently saw a very cool gadget ... little welding type power supply and tool with a built in slide hammer that neatly tacks a reusable pointy copper tab to a dent and you immediately give it a pull, tack it on again, give it another pull. No stud used, for small dents and dings, or slowly working larger dents.

I will usually work a shallow ding with a hammer and dolly from the back of the panel if I can see it or acess from the trunk or inside the door ect. If it's shallow and can't be worked with out pulling I usually won't bother if its only going to require a credit card thickness or less. I skim the whole panel with filler and then sand 80% of it off anyhow so most of that is covered. Of course a small straight edge will tell you if the sheet metal is high around the ding as that will need work because you don't want to fill the panel to match that.

My advice for a novice would be to stay far, far away from using a torch on the body. It can get you in trouble in a hurry.
A shrinking disc is a much better way to go if you need to shrink. However small high spots usually come out using with a hammer and dolly. A body file helps acts as a guide to check the flatness. But a quick pass with a shrinking disc can work wonders too.
My goal is to get a panel to within 1/16" or less and the fill for that can be achieved using polyester primer and no filler. Sometimes I don't quite meet my goal though and end up spreading a skim coat of filler to help out. Since polyester primer is just sprayable filller, a skim coat of filler can be applied over sanded polyester primer if necessary. If only a small amount is needed, I use a spot filler and I think USC Icing works well for that.

Pave right ovah the small stuff

So far my wife has been my gauge, I ask her "can you feel that dent" ... if she says "What dent" I know I'm good to go :)

I'd say right now I'm in the 1/16 ball park almost everywhere I've worked on. I'm impressed with how well lots of patience and light tapping works on high spots. Mostly using some nylon tipped PDR tools I made.

Yes, most of the small dings look like it would make more sense to "pave" them over if there are no high rings around them.

I've watched bunches of the shrinking videos .... I still find it hard to believe that the highs are actually being heat shrunk, typically the necessary heat for the recombination of metal's crystalline structure is at minimum red hot. With the run-out of most of the disks I see it appears to be more of a very fast low impact "hammering" that precludes the need for a dolly, and the act of physical urging of the metal in high spots over into low areas, similar to the soft glancing blows of a body hammer.

MUSLCAH .... you anywhere near Keeser Falls? Used to race SuperMoto at a small track up there.

I'm using a stainless shrinking disc from Wray Schelin. Zero hammering. Have you watched any of his videos? Metal does not have to be red hot for shrinking to occur. In thinking about this use mig welding as an example.
Only red hot there is at the weld itself but you create a heat affected zone (HAZ) that spreads out from the weld bead. That entire zone will have have metal shrinkage.

Here's one I hadn't seen yet. Man this guy goes for perfection. He obviously strives for using no filler at all. It shows it can be done but I don't see the reason to get it that perfect when filling that last 1/16" of an inch will save so much time. Plus, us guys are working with panels that aren't on a bench a lot of the time. Of course you want to make sure you don't have high spots and that's where the shrinking disc really helps you. Plus, us guys are working with panels that aren't on a bench a lot of the time.
When I installed patch panels on my '69 quarters recently, I did consider removing the quarters from the body to repair them but opted not to.

https://www.youtube.com/watch?v=IgS_...ShaperWorkshop

You obviously are joking about removing the 1/4 panel to work on them…………………..aren’t you ?

Nevah heard of the place……Iam 15 minutes southwest
of Concord NH

Roger, yep I've watched a few of his videos, on all kinds of techniques. Discs obviously work, as numerous people here swear by them. I should probably worry more about using them and less about how they work.

Need to see if my Metabo angle grinder turns slow the right speed.

Road raced vintage bikes at NHIS for about 15 years, you gotta know where that is.

After watching that video today, I decided I want one of those 2" D/A air sanders. I don't have one and it looks like it would be very handy. I did some searching and I swear the one he's got is a Harbor Freight.

While your wife may not "feel" a dent, you should use a tool to get your really really close.
Get a "sure shot" sprayer and a couple gallons of Kleen Strip wax and grease remover.
You can pressurize it, spray your work and look at it in the light for a min or two. This will show you want
it might look like with glossy paint on it.
Evaporation eliminates any damage to your work.

I've got both those items already, will give it a try.

Here is the panel I am working on now. Driver side rear quarter has a indentation that follows the lip of the wheel well across the top and down the front and back a bit.

https://forums.maxperformanceinc.com...2&d=1623743237

Below are some "before / after" shots after I got inside with some tools I made and urged out as much of the dent as I could reach from the inside. Square is a little 6" machinist square so it's not as deep as it looks.2

https://forums.maxperformanceinc.com...3&d=1623743244

https://forums.maxperformanceinc.com...4&d=1623743249

https://forums.maxperformanceinc.com...5&d=1623743255


And a photo below showing as best I can the results so far. You can see along the top center of the well lip there is still an indentation I can't get to, seen in the third (worst) of the before/after shots above.

https://forums.maxperformanceinc.com...6&d=1623743261

Here is a shot after I applied some layout ink and did some sanding. The only one of these lows you can really feel is the long one that runs along the top. The body should be proud of the lip along there and it's still about 1/16" low for sure. The dark ink makes the lows look a lot lower than they are.

I'm not sure how to proceed from here ... weld on some studs and pull it some? Fill it? It's a critical area, very visible and easy to screw up the lines of the lip. This area was all filled back in the early 70's at a shop or the factory, looked great, never even knew it was there.

https://forums.maxperformanceinc.com...7&d=1623743683



And a couple pics of a deep reach around pick I made a while back. Going to order a shrinking disk right now.

https://forums.maxperformanceinc.com...8&d=1623743700

https://forums.maxperformanceinc.com...9&d=1623743705

Wow, that pick you made is awesome! I'm super impressed.
And photos are really worth a 1000 words. That dent couldn't be in a harder place to get to for sure. I struggled to remove the remove the patch panel welding shrinkage in that area on mine using a long dolly I had made. Also impressive that you are in NY and have zero evidence of rust in that area. Another thing I see from these photos is how seriously you are about doing this car right. I remember you saying this was going to be a driver quality paint job. Somehow I think most people are going to see it as a show quality one.

That is an odd spot to have damage like that. Maybe the panel was damaged before assembly and filled before it went to the paint area on the assembly line.

I think a stud welder would be a good option if you are determined to get it better. Do you own or have access to one? I haven't really needed one enough to ever make a purchase but a few times I've welded 5/16" washers on-end to the panel and pulled with a slide hammer with a hook on the end of it. Not as elegant but it does work well.

IMHO, the practical thing to do is fill it. With the procedures you would to use for filling, there just wont be a repercussion from it. An 80 grit D/A sand scratches followed by 2 coats of SPI epoxy primer followed by a high quality filler like Evercoat Rage would be a vastly superior procedure to the one that was previously used and you know how well that lasted.

Good filler, sand with half round DuraBloc with 80 grit. Repeat that a couple times till it “feels” right then prime /sand 2k primer a couple times till it “feels” right then prime one last time with 2k and move on or you will stress over this till summer is gone.
It’s a car, not the Mona Lisa

I would fil it as well. It's easy to make matters worse if you don't have clean acess to it.

Car has very little rust because it lived in TN, I bought it graduation day from high school in 1976, in TN. I only drove it about one year in NY. I think most of the rust came from when I was stationed in FL and for some reason liked to drive it in the surf at Daytona. Probably all the actually rust penetration on the car would add up to be the size of your palm.

I don't have a stud welder, what I have been doing is welding on a short piece of TIG rod, grabbing that with a pair of vice grips I modified with an adapter for my slide hammer.

I'll leave this for filler then. My objective here is to get all the metal work in condition for epoxy primer, not necessarily to make things a finished product now, but to be good enough I'm not removing any primer down to bare metal later ... if I can avoid that.

Can't wait to try a shrinking disc, I have some areas that are like jelly bean size highs and lows that I just can't make much sense of and I don't have access to the back. Hoping a disk will take down at least the highs.

Any tips for using a disc? I assume no lubricant of any kind, clean metal only? How much pressure compared to say grinding.