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Some Tips on Body Filling?

8K views 20 replies 14 participants last post by  DartKnight 
#1 ·
Well, hopefully sometime in the next few weeks, my father is going to be bringing my car down to me (Right now it's in Panama City, FL, and i'm in Gainesville, FL, about 300 miles :(). With the limited tools that I have, I'm not really going to be able to do a whole lot to the car except body work, and part of that is going to include some Bondo, which i've never used before. So, besides the basic instructions on how to use the stuff that come with the materials, does anyone have some nice tips or tricks to make sure i get this looking right the first time?
 
#2 ·
If you think the dent is a certain size, it's bigger. Fill and sand as you'll never get the fill perfect. Also, get a small body hammer and dolly (heavy piece to put on the other side of the dent). Work the hammer slowly on dents that look like you can straighten. You also might have high spots that need to be knocked down before you can begin the Bondo.



 
#4 ·
Do what jim said.Basically get the metal as straight as you can first.That means less body filler later.Feel the dent/mud with your hand flat on the panel try not to use just your finger tips.If your going to hand scuff your car for paint,use the flats of your hand NOT your fingertips,it will leave finger marks in the paint.If you want to get your mud as straight as possible given the fact that you are not a bodyman use a 18" flat board.If you don't have one it's a great cheap investment.If you really want to go hillbilly you can actually use a length of 2x4 but i wouldn't reccomend it.When you apply your mud just barely make a slight crown over the dent.I cut my mud in a diagonal pattern (left top to right bottom)then(right top to left bottom)until the edges start to cut.That's when your sense of feel takes over.Should feel flat.(hopefully)First cut i hit the mud a couple strokes with 36 grit,then get it close with 80 grit,second coat skim,then finish with an 80 grit or close(120 maybe).THen skim coat of "spot putty"finish with 320,then prime.Block primer with 320?400?.Lot's of preferences I'm sure there will be alot of different techniques depending on who you talk to.Choose what you like or what is easiest and build on it.
 
#5 ·
learn how to use a half-round cheese grater, especially on the first couple layers. it will save you time and sandpaper; plus it keeps a rough surface for the next layer to adhere. you dont have to worry about smooth till after you get it straight.
 
#6 ·
Jim_Lusk said:
If you think the dent is a certain size, it's bigger. Fill and sand as you'll never get the fill perfect. Also, get a small body hammer and dolly (heavy piece to put on the other side of the dent). Work the hammer slowly on dents that look like you can straighten. You also might have high spots that need to be knocked down before you can begin the Bondo.
Yeah, my dad actually already has a kit with a bunch of different size hammers and dollys which he's going to let me have/borrow, so i'll plenty to work with there. :) There's only one sorta bad spot on the car that's going to need any of that, thank god. You can sort of see it in this picture:



In that rear quarterpanel there's 2 long, skinny dents where it looks like the car was drug down the side of something. I think they're shallow enough that they might bang out easily, but the length of them is what's worrying me. Great advice too Jim, thanks :) "If you think the dent is a certain size, it's bigger." That one is definatly going to stick in my head :p

@GTS225: You know, that's also a very good point and something to keep in mind. I've always been told that the more patience you have in doing any kind of body work, the better it will turn out, but i've always only applied that to sanding and painting. But now that I think of it, I guess it would also hold very true for filling as well :)

@71demonchild: Thanks! That's a lot of really useful information :)

@eldubb440: What's a half-round cheese grater? o_O
 
#7 ·
Also, don't cheap out on the filler. Buy good stuff, it may be a little more money but you will be glad when you have to sand it. Rage Gold, Blue Ice, or 3m are all pretty good. I use Blue Ice at work and like it the best. I find it sands easier then the rest even when fully cured. If your feel is not so good, use a guide coat to show you the low spots. Oh ya and dont try to put filler on paint, just bare steel or epoxy primer(not ment to insult you if you know better but just not sure of your skill) Good luck and just take your time.
 
#9 ·
dustertogo said:
Also, don't cheap out on the filler. Buy good stuff, it may be a little more money but you will be glad when you have to sand it. Rage Gold, Blue Ice, or 3m are all pretty good. I use Blue Ice at work and like it the best. I find it sands easier then the rest even when fully cured. If your feel is not so good, use a guide coat to show you the low spots. Oh ya and dont try to put filler on paint, just bare steel or epoxy primer(not ment to insult you if you know better but just not sure of your skill) Good luck and just take your time.
Thanks, my next question was going to be what brands were best :p And never worry about offending me with even the simplest stuff, it's hard to gauge anyone's knowledge over the internet ;)

@sweaty: Wow, thanks, this place is loaded with information!
 
#10 ·
instead of starting on your treasure go to a body shop and get a couple of fenders with similiar damage and play with them for a bit to build some confidence.

work on the outside edges of a panel first then any body lines then outside crowns then work on the flat areas,do not attack the easy stuff first.

also steel has a certain time limit before it must be resanded when it is exposed to humid air same with filler,some products absorb moisture and if they are coated with whatever this moisture can expand and make a flippin' mess of your top-coat.

but definitely practice on some scrapped panels first to get an idea on how metal reacts.

wear a mask when sanding that old red paint too it has lead in it.
 
#13 ·
Not sure if I'm looking at the picture wright. If the dent in the quarter is close to the factory crease, be real easy on the hammer and dolly buisness. It's easy to goof up the body line. Just to add to what demon child said, use a criss cross sanding patern. In other words use an X patern when sanding. Thats called cross thatching. It helps to cover up your sanding marks. Also, when sandding body filler resist the temptation to keep sanding until you get that velvity smooth feeling. You want the panel to be leval, if you see metal poping up in amongst your body filler you have a high spot and you have sanded to far down. I noticed when I was doining the bodywork on the 76 Scamp (same body style as yours) there were alot of parking lot door ding's wright along that halfway up the car crease that runs the length of the car. You want to crouch down maybe at the taillight and look down the length of the car to see what I'm talking about. I think when you initialy sand the car, youl'll find spots in the paint that the sandpaper doesn't touch, those are low spots that will need attention. Again what demon child said, get a long board or inline sander for the body filler, I think mine is 11 inches. And I use Evercoat brand body filler's, they have a wide variaty, if you can't find it locally Eastwood sale's it. O.K somebody else's turn.
 
#14 ·
268darts said:
What is your best method to "tighten up the metal" when it starts to get that oil can effect? doh
heat shrink it.Get a torch and make a nickel size cherry red spot (in the dent of course)You may have to do these in several areas within the dent.When you get the spot cherry red, take a rag soaked in water (preferably cold)and totally drench the the area in water.That actually shrinks the metal and keeps it from "oil canning".It's pretty basic,you shouldn't have no problems.Good luck.
 
#16 ·
Not a cheap item to buy but if you have a buddy that has a stud gun that will save you some bondo time. Maybe able to rent one somewhere. If you've ever had any sheetrock finishing experience then it's somewhat similiar. Done rock for years and always thought i could do a car. Well i just finished my first. BLACK. People thought i was crazy but after they look at the finish product i could stay busy painting. It takes a lot of time so don't get in a hurry. Take it down to bare metal. Ask if you don't know. I like the cheese grater too.
Hey Demon: I'll have to try that torch trick.
 
#18 ·
hey Rate.....you found a half round cheesegrater yet??? it will be your best friend. you use it when the mud begins to harden, after its too hard, forget it. the amount of hardener u use will depend on the temperature. usually it gives you a good 5 - 10 minutes of working time. practice makes perfect and experience is everything!... ill post you a pic of one if you still dont know.
 
#19 ·
Instead of a surform, i use some 40 grit on a long board to knock the filler down while it is still kinda soft. That way you have a straight surface from the first cut. A surform works good as well but the sand paper on a board is easyier imo. Only down side is you use up the sand paper kinda fast but i don't pay for it at work hehe.
 
#20 ·
Within the past few months I've done a lot of bodywork on my Dart, and started painting it (with a roller and rustoleum). Here are some pics where you can see the bodywork. If you look closely at the car with paint on it, the bodywork aint *perfect*, but it's pretty good for a goofball in his garage and most people would not notice any issues. If I had painted it black it would be another story..

http://www.flickr.com/photos/xit1965/sets/72057594131616795/

If all you have is those few dents, you're lucky but I suspect you'll find more and more just like I did. Get yourself a nice longboard (17.5" I think), and I heard another great tip on here which is to make a whip out of a clothes hanger. Basically fold it into a loop with a handle (wrap some duct tape around the handle) so that you can smack the sandpaper with it to remove some of the buildup.

I prefer using 80 grit while the bondo has begun to harden. 60 or 36 grit tends to scratch up the neighboring area quite a bit, whereas 80 is a bit more gentle and you can feather it with 180 grit after that.

Also get yourself some fiberglass resin. After your final coat of bondo where you think it's OK, cover the whole area and beyond with a THIN skim coat of fiberglass resin mixed with bondo (then of course the bondo hardener). It takes longer to setup that way, so I always just let it dry for a few hours. Then start with 80 grit, then 180 then 240 and beyond. Mixing the resin in will prevent pinholes and fills in tiny scratches really well. Also the skim coat will look wet when you apply it, so you can see if it's wavy or not.

One more thing, I used the cheap Bondo and know a veteran bodyman who uses the cheap bondo for his home projects too. I'm not going to say I ever tried the "good" stuff, but when I went to buy some and saw the price tag, I figured I'd just stick with what got me there. :)

Also you may want to avoid any power sanding tools, they can just do damage faster..

Good luck!

edit, here's a good before and after. Luckily those high spots dont stand out too much with paint..



 
#21 ·
That looks like it came out pretty good! ;) As far as the expensive bondo goes, the main advantage is that it is easier to apply, smooth out, and sand. It's mostly recommended for smaller jobs. Don't bother with the crap that comes in the cheez-whiz-looking can either; all it does is make a mess and more work. doh
 
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