Question About Sanding

-
S

soul60s

Active Member
Joined
Sep 21, 2007
Messages
41
Reaction score
0
Location
RI
Hello All,

I am sanding the 68 cuda (keep in mind that I have no clue what I am doing. So I am taking everything one step at a time. So I am working on the underside of the trunk lid. There is a lot of filler or sealer along the edge seal where the front metal overlaps the back metal. I cleaned it off with a dremmel. I am using a DA sander for most of it and the dremmel for the areas that the sander doesn't go. I am using 80 grit sandpaper for the initial removal of paint and bondo. And switch between the 80 and 220 grit. It's all I have now. There are tons of little pits and holes and dents. The dremmel helps remove the filler inside these dents. The metal along the edge is all pitted but not eaten through with rust. I can't seem to get out every little bit. If I keep sanding, there will be nothing left. This is all on the back side of the lid. How do I know if I got ALL the crap removed and what happens if there is a little bit along the seam where a tool can't go? How important is it to get everything perfectly smooth on the backside under the trunk lid? I can understand the panels have to be perfect. I have been using these tools and hand sanding to the point that my hand is constantly cramped. My husband said it doesn't need to be perfect because no one is going to see it but I need the practice anyhow. We can't afford a sandblaster right now so I need to do this all by hand. Any tips about sanding? Ideas, helpful hints? I have been viewing videos on youtube about body work and sanding but need to know what you all do.

Also, along the curved edge of the inside metal along the lower right corner, it has rotted through causing holes. How do I know if I should weld it with solder or replace the metal. It is going to be pretty hard to get that shape from a straight piece of sheet metal. Any suggestions?

Any help would be appreciated.
Joanne
 
The little pits need to be cleaned out of any rust or old filler (rust under filler spots??). A small blaster gun is like $45 bucks through Eastwood (see pic), you can buy a bag of media and bucket, spot blast the hard to reach contours or rotten pitted areas. Granted you need an air compressor...but if you are painting it yourself you will need one anyway :lol:Sure covering all those up with bondo will work, but if you dont get all the rust off/out...........in a short time you will find yourself doing it all over again and that will suck

p785B.jpg
 
If you don't want the helmet thing, you can find those small blasters like in the picture for 10 to 15 bucks at places where they sell chinese tools.
A few years ago I had a VW that I think had been towed behind a motorhome or something. The hood had pitted rusty spots all over it. I put something like Duro Extend on it. A few months later I used some stripper on the hood. It took off all of the Extend stuff & all of the rust underneath was gone. Just pitted metal. I used a bit of filler on it & smoothed it all out. Then the car got totaled.
 
Even if you get all the rust thats visible you wont get all of it.What you need is some kind of converter.Best yet coat the area with a bare metal primer that has zinc chromate in it.Any kind of primer for metal and a marine application will have high corrosion resistance.
as for the holes,yes they need to welded or the metal has to be replaced.Once theres a hole the metal around it is pretty thin.Any sort of mig weldig will likely make the hole bigger.Too much heat and too thin a metal means the welders heat will just burn a hole.A better solution for pitting and small holes is brazing or lead.Lower heat and better at filling.Takes practice though.

If you need to replace metal and you have a hard area with compound curves,do it in several pieces.Cut one section out and replace it.Keep it small.Repeat until all rust is gone.Do it like this and your patches will be very close to original.

Blasting is an excellent way to get things really clean.Dont use sand.Use ground glass.It cuts MUCH faster and thus less heat and warping.
 
Thanks all. We have one of those small blasters with the hopper on top. We also have two air compressors but they aren't that big. They might do for blasting though. And we have the blasting gun for the compressors. I wouldn't use them for painting because of the drying time. I'd be afraid that I would have to keep stopping to let the compressor catch up. Guess that isn't a huge worry with blasting. Now inside the two pieces of metal is a lot of rust. None on the outside but the holes appreared from the inside out. How do I get to this? I can't see all the way in to know if I blasted it all and I can't reach in to coat it with a converter.

It's 7:30 am and I am anxious to get out to the garage.

Joanne
 
I just glanced at your post, so I hope my experience helps with what you are going to be doing. I’m on the road this morning.
Number one: Sand blasting takes a lot of air if the job is of any size. A small compressor won’t cut it. You’ll just get frustrated. Maybe if you hook two compressor together. I've done this.
Number two: If you can’t get all the rust off. There are options. I have had good luck with Rustoleum's “Rusty Metal Primer”. This is a red primer available at Home Depot. This is what it is made for. It comes in spray and can types.
Get the loose stuff rust off and use this. I won’t say the rust will NEVER come back, but probably not in our lifetime.
You will probably want to overcoat it with a lacquer based automotive sandable primer before top costing it.

I know people have used types of rust reformers. I tried one and didn’t like it. Plus they cost a lot more.
Number three: You know that going from 80 to 220 grit is a big jump and will make you sand forever with the 220 to get the 80 grit scratches out of something. Sanding should be done in steps.
Number four: Are you using a sanding block? I have one-inch think pieces of rubber in various sizes. That is what you need to save your hand and get a flat surface.

“What the eye doesn’t see the bodyshop gets away with.”
Keep repeating this to yourself.
 
Reminds me of an old song, says "Work your fingers to the bone and what do you get ???? boney fingers." I'm sorry bu it's true.
I guess if I were trying to do what you are atempting I would buy 2 kiddie pools from walmart. I'd use one to sink composite panels like doors, hoods, deck lids, in a paint remover chemical then a rust remover chemical then rinse and dry. Then the other to sink in primer/sealer. A liquid is the only thing that will go into every little nook and cranny. The finest blasting media will only get stuck in the crevasses. Most interesting blasting media I've seen is dry ice. Leaves no residue but still ... how to blast it into those hidden places ? Cut access holes for dental tools ?
I know I seem pesamistic but I'd rather you not develope corpal tunnel syndrome or even boney fingers.
I've got a couple small rust bubbles showing on 1 rocker panel (car was painted in 92) but so what. It's nature of the beast. Someday it'll need fixed and painted again. I hope the world turns so long for all of us.
 
Redfish is right.The rust will come back eventually no matter what you do.It's just a chemical reaction called oxidation.But soaking the seam area with some kind of converter until it runs out and using a high quality primer is the best you can do short of finding nos parts.
 
Hi Everyone,

Well, I went to HF the other day and bought a sandblaster. We have two compressors at home and they are both hooked up together.
So I have no cabinet but got a new toy and wanted to try it out. The cuda is on the lift in the garage. One car garage. It is totally stripped down except for the steering wheel. We have a large clear plastic bag big enough to fit a car in it. We clipped it to the ceiling, hung it down into the engine well, pu the trunk in it, tied off the bottom and put a container under it. I wore a dust mask and the hood and proceeded to blast the trunk. Most of it was done by hand anyhow but I had some spots that still had paint and rust.

I have never done this and didn't realize the bottom lever underneath on the hose controlled the amount of media that came out. So once we figured that out, I blasted the trunk. I couldn't see well because of the plastic but I loved it! The sandblaster left a texture on the metal. When I hand sanded, it was very smooth and shiny. This was textured and not shiny. I think that is better for primer to stick on, right?

I missed a few spots but have decided to make my own cabinet. Can you buld one out of wood? I need it big enough to fit a trunk, door, or fender. I can build it. My husband and I are do it yourselfers. If we have a good strong shop vac that will help reduce the dust.

Anyhow, after I blasted the trunk, all I thought was, why didn't I do this earlier??? I did keep in mind throughtout the whole thing that I have to be careful how long I blast one area. I don't want to cause more problems. I am trying to be very careful. Not to mention I read everything I can on it, watch videos on it, and ask a ton of questions.

I have another idea for a cabinet that is more difficult. We have an old dodge van in the back yard that is goign to be dumped. So if I cut the back part off about 3 feet deep, I can use that and the whole front of the cabinet will be the rear door. Opens very wide and has a glass window already.

Not sure what to do. I am so tired right now. My husband and I are building a 8x10 shed and I am exhausted. So if nothing makes sense, it's cause I am pretty brain dead right now. Ugh...
 
Yeah I dont see why the wood wouldnt work for the cabinet, it might wear out faster but it's plywood......just replace it. You dont need to sand where you blasted, just use a good primer epoxy primer (EP789) and get it primed quickly. Dont leave it in bare metal, it will surface rust quickly (faster/slower depending on where u live). Prime the areas in sections if you arent doing the whole car at once. :)
 
Honestly, I wasn't sure of the next step. If I was supposed to put primer or rust protectant or wash it with a degreaser. I am fed up with the shed for the day. And I really need to sit down and plan out the cabinet. Do I put the primer before fixing the holes I am just not sure what order things go in. After the primer, so I sand again? Is this to fill in any scratches and such? And then do I prime again after that? When does the wet sanding come in? Sorry about all the questions.

Joanne
 
any welding or panel replacement needs to be done before primer. Since you blasted it, weld any holes or replace sections that need to be. Then grind down your welds, wipe down with a pre-cleano or wax/grease remover, and then epoxy prime. Sand the epoxy (so the filler as something to stick into to) and use filler as needed. Then prime with a high build primer ............lots of steps.

You could also use filler over the bare metal, but the epoxy will adhere better to metal than filler will.
 
filler directly on bare metal will promote rust from the moisture in the filler. Epoxy primer is a rust inhibitor spray metal with it after welding and grinding has been completed. Then sand the primer and apply filler where needed smooth and sand filler then prime with high build sandable primer.
 
A wax/grease remover. Would the purple degreaser sold in the automotive department in walmart work? It is used from everything from housecleaning to engine cleaning. Just depends on concentration of the degreaser.
 
Please be very careful to wear a good mask or a hood with outside air if you are standing in the shed or bag with the sandblaster. The paper filter type that just go over your mouth and nose are not good enough. You really need the canister type or even better yet an outside air supply through a clean hose (vacuum cleaner or similar). Sand dust will give you silicosis quickly. Not trying to scare you off from doing it, just be careful not to breath that dust.
 
NO...:tongue9:... on the Wal-mart degreaser. You need to get a cleaner specifically for automotive painting......those specific cleaners wont leave any residue. Go to a automotive paint supply store like Industrial Finishes. Careful what you buy from Autozone or schucks type places. You need to spend money of good quality primer,cleaners,and filler. Your outcome will look better and last longer.
 
rjsjea said:
NO...:tongue9:... on the Wal-mart degreaser. You need to get a cleaner specifically for automotive painting......those specific cleaners wont leave any residue. Go to a automotive paint supply store like Industrial Finishes. Careful what you buy from Autozone or schucks type places. You need to spend money of good quality primer,cleaners,and filler. Your outcome will look better and last longer.
Click to expand...

Thanks. That is exactly what I needed to know. Plain and simple yes or no and why. I will go to Car Parts and get the degreaser there. They sell all kinds of autobody stuff. Or so I am told. Haven't been there yet. Time to take a trip.

I have another question. I am going to build my own cabinet for blasting and want to make it large enough. But what do you do if your cabinet isn't big enough for a part, like a hood? Where do you blast it then?

Joanne
 
I would take it to a media blaster place, but I have blasted parts in my driveway and on the back of my property before.

I just had my engine compartment,floors and the whole underside done for $250.....cheap to me compared to the mess and hassle it is to blast at home.
 
I couldn't afford to have everything done. The car has been sitting in a field a long time. Extensive work. I like the idea of being hands on at every aspect. Helps me learn.

I have the plywood, long steel L brackets to go around every seam for reenforcement. The inside shelf, the blaster, double compressors, safety glass, pvc piping for arm holes, and either aluminum flashing or thin steel sheets to line the inside, shop light to place on top, heavy duty shop vac. And a few other things added in. It's being constructed on a aluminum table for convienence. It's going to be roughly 5'x4'x3.5'. Don't know if this size will work yet. I need the blaster to be big enough for large pieces like fenders.
Worked on building the door to the shed yesterday. Hubby was at work so I wanted it finished. I grabbed the saws and such and built it myself. Raining today so roof can't be finished. I want it done so I can start building MY csbinet!
 
Sounds like a good project, would like to see pics when you get it all done
 
You must log in or register to reply here.
-

Back
Top