question about sanding/prep/bondo

[Mike85Silverado]

Hey guys, sorry to flood this forum with all my newbie questions.
I was going to attempt to start sanding/bondo-ing/primering my truck and i have ZERO experience doing this.
All ive done is watched a couple Youtube videos...
So should i just go get one of those round, hand held electric sanders? is that the best, most inexpensive way to sand my truck?
Then do i just go get some auto filler from like a checkers?

[Mike85Silverado]

Also,
how do i remove the little peice of chrome trim by my tail lights? all the rest of the trim is gone and i wanted to take these last pieces off.  I didnt see a bolt or anything when i looked underneath...

[Blazin]

Electric sanders are great for restoring an old house when you need to remove layers of paint from wood or floors etc. Not really much good for body work.

Why does it need "bondo-ing"?
Dents, rust?
If its rust you need to cut it out, and or sand blast it. Then weld in new metal.
If its dents you need to straiten them first. Then grind the paint off with a 24, or 36 grit disc. I usually feather the grinding scratches back a little with 80 grit on the DA before I apply any body filler. ( Never put filler over paint ). Several thin coats are better than one big mother load of filler. The more you put on, the more you have to sand off were you don't need it. Thin coats cure better too.

After your first coat dries you should use a mud hog with 36, or 40 grit paper. its similar to a DA but the action is not as fine, and its pad is 8" diameter.
Second coat usually rough sand with the hog, then step up to an air board, and a long hand board with 36, or 40 grit paper. From then until your finished sanding filler you will use the air board, and long board, and or sanding blocks. Your last coat of filler will be sanded with 80 grit on them instaed of 36, or 40. Sometimes a light brushing across the 80 grit scratches with 100 grit  cleans it up a bit more too.
When sanding filler you always work at a 45 degree angle to vertical, and horizontal. sand the whole repair one direction at a 45, then go back across it at a 45, 90 degrees to your last 45. Never sand filler vertical, or horizontally.

Don't confuse smooth with strait. You can have a repair that's smooth as a babies bottom, but it will still wave at everyone that looks at it after its painted! Always run your hand over the repair with the palm and heel of you hand following your fingers in a vertical, and horizontal pass to detect high and low spots.
 
Next you will feather any 36/40, and 80 grit scratches out of the paint surrounding the repair with 80 grit on the DA. Once they are gone you will used 180 on the DA to remove m90% or the 80 grit DA scratches in the paint, and sand the paints finish back a little farther away from the repair so the primer has a mechanical bond to the paint were it over laps.
Now your ready for primer. Use a self etching high build urethane primer. I tend to just cover the filler on the first coat, or two. Then the bare metal on the second and third coats. Fourth coat you can go to the end of your sanded area. Remember the 180 scratches are not going to need much to be filled in vs the 80 grit in the more porous filler.
Once the primer has dried you can block sand it with 180, and re prime it with another one or two coats, or sand it with the DA and 320, or 400 grit along with the painted areas to prep for paint.

[Mike85Silverado]

Dude, a lot of that was over my head.  Im seriously as green as they come when it comes to automotive and body work. Are you able to dumb it down for me?
I dont know what a DA is, or a mud hog, or an air board....

[Mike85Silverado]

oh, and ya it is because of dents.

Thank you for taking all that time to go over the details though

[Blazin]

DA is a dual action sander. It sorta combines the action of say a grinder, and a jitterbug type electric sander. They have a 3" or 6" pad.

Mud hog is a bigger more clumsy version of that of you will. Its action is not as fine as a DA.  Its primary use is to "hog" off alot of filler in a short time. They have an 8" pad on them. A good body many can sand filler without one on smaller repairs. start right off with block sanding.

An air board (otherwise known as an air file) is basically an air operated long sanding board. long board is a longer version of a sanding block that usually has some sort of handle, or handles on it. When reworking a repair with a body line in it you use the long board, and blocks to sand right up to the line form both sides at a 45 degree angle just as you do when straitening a whole door panel. This is when a hand board, and blocks are an amazing tool.

As far as dents anything bigger than a dime size ding, or dimple needs the be straitend. Bent back as close to original shape as possible before. Body hammers, and dollies are the fine tune tools for this. Sometimes bigger dents require some imaginative thinking to push the dent out from the inside of the panel. Stay away from shard edges or corners like the end of a 2x4 or a pry bar. Ronding the edge, and corners of the end of a 2x4 makes it more friendly to not ruining sheet metal. Or wrapping the end of a pry bar with electrical, duct, or masking tape make them your friend too.
Speaking of tape, don't be bashfull about buying the good stuff. 3M or Norton are what I use. You really get what you pay for when it comes to masking tape. Same goes for Sand paper, middle of the road, to high end as far as price goes. You will use twice to three times the amount of the cheap stuff.  News paper is a no no as well. It will absorb primer, or paint and transfer it onto the surface its intended to protect.

Its not as simple as spreading filler, sanding it, and priming it. There is alot to body work. not knowing all the steps, and details can lead to frustration, and money wasted.

Most important is to have a good selection of the correct tools, and a decent air compressor. I recommend minimum 50 gallon 5 HP compressor. Those are half the battle right there. Learning to use them is easy if you take your time, and educate yourself.
Asking questions is educating yourself.

[Mike85Silverado]

Thanks a lot for all the advice Blazin. I'm a little intimidated to do stuff myself but I really want to learn and be blue to save some money by doing things myself. I'm still unsure if I'm going to do this, but ill keep you guys posted

[Blazin]

Make nice with a local body man that's has a clue. He might be willing to do some work on the side with your help if you have a garage, and a half decent compres or. Then you can learn a thing or two as well.
Over the years I have had many younger guys come hang out at my shop. Now they are older, an do a little body work on their own rigs. Or have me do it with them taking care of the tear down, and rebuild part. I always told them years ago. Even if you never do body work, at least now you know enough that you won't get screwed when you take your rig in to have some done.

[PromiseKeeper]

Mike,
Don't be intimidated... worse case scenario is you get to sand it off and start over. As long as you haven't put paint on it, it isn't that big of a deal to rework a spot. One thing I used to do to detect low spots was after it was primed, get a spray bomb of a contrasting color. Hold it back a bit and lightly mist the area. Now, go over it just one time with the sanding block. Any low spots will have the mist still showing. You can usually feel waves even better if you put a light rag over your hand.

[Blazin]

Most urethane primers change collor enough so you can see the low spots when block sanding them too.

[Mike85Silverado]

Ok cool, thanks guys. I just put a door and fender on that I got from a parts truck and the door lines up terribly.... Doesn't even close all the way. There's no play in it, but it fits like its sagging too low kinda. So I haven't gotten around to doing any cosmetic work yet.