Finishing off cutting ot rust and patch panels. Pretty much a beginner (welder and car guy). How much bondo (depth) is ok to smooth things out. I have panels that are pretty good where the amount of bondo is only enough to cover edge of weld (maybe 1mm) ....... but otehr areas at joints where I didnt do as well and might be 1-8-1/4" off ....... Not a show car. DD.
not mine ^^^ but similar I would think ...... Where the panel is not in full alignment with the counter of older panels ...... id definitely need a full 1/4" bondo to smooth out the panel transitions ......
well heres an actual pic of mine ....... The lip would be 1/8" to smooth between panels .......... but to align with the other panels better might need to build the entire thing to ~ 1/4" etc
This is where reading the TDS of the products you are using comes in handy. The max recommended thickness for regular fillers is usually 1/4". If you are going to be pushing that then you should use a reinforced product underneath and then skim with a regular body filler.
good point - didnt even think of that. "then you should use a reinforced product underneath and then skim with a regular body filler" - like ? Everglass or something ?
I say sarcastically, do what the professional do...or women all over the world. Layer it on, sculpt it till it smoothens out, color it up. As the song goes, she ain't pretty she just looks that way.
In my humble opinion it's okay to use as much body filler as is necessary...as long as you get the metal clean, clean, clean before applying it. Wash with soap and water, then wipe thoroughly with a wax/grease remover...allowing it plenty of time to dry/evaporate before you shovel on the mud. Be sure to rough up the surface of the body filler before applying more on top of it. As has been mentioned, a reinforced filler such as MarGlass will seal any pinholes in your welds and provide extra strength to the panel if your filler is going to be thicker than 1/4" (my personal limit!) which it occasionally is in some cases. There are MANY TOP NAME BUILDERS who use A LOT of body filler in their builds. Use a premium brand (I prefer Rage Gold) and don't be afraid of it, most people will never know unless the panel gets damaged in use. Carry on!
I could that see that might make sense for ballast in the rear if your drag racing. I don't think I've ever seen filler laid on that thick before.
Thanks all feeling less bad now. Yeah would think its 1/8-1/4" to fix most of the issues. The thicker parts (1/4" to 3/8"? ) would be where the panels dont align after fixing with patch - meaning I didnt get much of a curve in the patch to align with the rest of the truck so more straigh than curved. So might have to higher build there just to help contour and lign in ....... so to speak.
We test these products rigorously. Yes there will always be tales of someone who got away with doing something not recommended but we don't make these recommendations up on a whim. Don't be the guy who listened to the "I've always done it this way and it was fine" users and has to redo it because it failed. I deal with those guys complaining about "product failures" all the time.
yeah there was a lot more bondo on this car than I realized ...... hence why cutting it all out to put metal there. BUt my fab work is not as good as I'd like it ...... so wasnt sure.
@FAKKY in my own experience and limited bondo skills, I like to get the sheetmetal smooth enough that it needs 2 passes of bondo or less. And that is the hard part, sometimes I get to hack off my own repair and do it again!!
Hmmmm If you think about 1/4 of an inch of filler, thats a window that should be a minimum for body work. Doesn’t take a lot to get a panel within 1/4 inch of the correct contour. Location is important, 1/8 thick filler on a hood or roof could crack long before 1/4 in a door jamb ever would. Weld seams. I’ve melted out 1/2 of lead in some OE joints. If I had to go over that 1/4 inch threshold I think I’d look at a metal filler or kitty hair type product.
On a slightly different note, are you overlapping your patch panels or butt welding? A proper butt welded panel will have both panels in the same plane without the ledge you are seeing. -Abone.
When I was in the Army I had a '63 4x4 carryall that a PO wrecked and had repaired in Mexico. The replacement passenger vent glass had Hecho in Mexico printed on it. Anyway the bondo around the lower right corner of the windshield was 1/2" to 3/4" thick. I'm guessing that's too much?
You get better with practice, hopefully . Now is the time to practice. Learn from your mistakes and redo the metal work with more form and fitting.
I agree with FlamedAbone, looks like you might be overlapping your patch panels, which you really don't want to do. They should be butt welded to avoid that big ledge. Also, the entire seam needs to be welded, not tacked together like that first picture (I know you said that isn't yours, but that patch is very unfinished as it is pictured). An eighth to smooth it out is no problem if the underlying metal is clean. If you know it's going to be deeper than that (like a quarter), give a pass of kitty hair first, then knock that down until you can blend it all in with a skim coat of filler. If you know it's going to be 3/8" or more, try to work the metal more. Hammer and dolly, cut and re-weld, whatever you've got to do. It's hard (and often pointless) to get it perfect, but you don't want to do a total half-ass job either. Strive for those things and you'll be doing OK.
^ Where you cannot add passengers or gasoline, else you are in excess of the vehicle maximum gross weight before you even begin... I'm not averse to Bondo but only to fill the low points and smooth out imperfections. Troweled on with a garden shovel like that means you didn't do the metalwork right.
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