Can you effectively use a variable speed random orbital sander for auto body?

[mike758]

I'm currently restoring my truck, and have already started installing a few patch panels. However, I eventually want to strip the whole thing down to bare metal. Obviously a DA sander or sandblaster would be ideal, but I don't have the compressor for it. My biggest compressor is a 15 gallon craftsman compressor which handles my air wrenches and cut off tool, but nothing more. I would like to upgrade to a 60 gallon, but I've already spent over $700 on my welder and gas.

Anyway, my friend insists that the only tool you can use for stripping car paint is a DA sander. However, I was looking at a Porter Cable variable speed ROS which essentially seems like the electric version of the same thing. I did purchase a sanding pad for my angle grinder, but that things just too aggressive. I would imagine that the variable speed sander would work though.

 

[Evilunclegrimace]

It'll work,but, for how long? Keep the dust blown off of the brushes and it will probably do your truck just fine.

 

[dnschmidt]

It will take a thousand years. Depending upon how much paint is on the car you start with a rotary polisher to remove most of it and follow up with a DA to finish the deal. A rotary polisher run at 700 rpm using an 8" 40-80 grit (depending upon how much paint is on the car) disc is the best way to strip paint. Trying to strip paint with a DA (down to bare metal) will take FOREVER. If you only had factory paint on the car you can scuff it with 320 on a DA and put sealer over that pretty easily but going to bare metal no way.

 

[KenC]

It will take a thousand years. Depending upon how much paint is on the car you start with a rotary polisher to remove most of it and follow up with a DA to finish the deal. A rotary polisher run at 700 rpm using an 8" 40-80 grit (depending upon how much paint is on the car) disc is the best way to strip paint. Trying to strip paint with a DA (down to bare metal) will take FOREVER. If you only had factory paint on the car you can scuff it with 320 on a DA and put sealer over that pretty easily but going to bare metal no way.

Yep! Maybe speed up to 1-1.2KRPM. anything faster burns the paint(and makes it gum up the paper, esp if old lacquer) and warps metal.

Then use the 3M stripper wheels in a drill or grinder to get into grooves, door edges etc.

 

[pepi]

What's the reason to go down to metal; the paint on it now can be used as a base. Even assist in creating a good smooth surface. In other words the paint on it unless flaking has good adhesion. Blend it where body repairs are made, shoot primer and block it out.

DA sander has the grunt to do the job, rotary polisher is a polisher not a sander two different animals.

 

[dnschmidt]

A rotary polisher (Makita 9227C) is the correct tool for this job. The reason being it's slow speed. You can't use a grinder or anything fast as it will simply clog the paper which will then stop cutting. Check out AUTOBODYSTORE.NET. Len has a tutorial there on how to use the polisher for this purpose. It's very informative.

http://autobodystore.net/Merchant2/...=ABS&Product_Code=FAPS6258-p80&Category_Code=

This is the setup needed for use with the Makita.

 

[rustedgoat]

Seriously you can use a razor blade to scrape most of the paint off, just use one those holders for scraping. It will fall off in strips, no dust, very controllable mess, best of all quiet. As posted above Autobodystore.com is a great resource for material, they have a classroom section that may be helpful.

Before starting to strip the truck make sure you have a plan on what to do to prevent it from rusting.

 

[K-Dog]

I would chemical strip it.

 

[Al Borland]

36 grit on a belt sander?
Always wanted to try it, or get one of my idiot buddies to do it, possibly/probably involving beer and a beater truck.

 

[mike758]

The reason why I'm looking to do bare metal is because the trucks already been repainted before, and some of it is chipping down to bare metal which could be a bonding issue with the primer. I appreciate all the answers to my post, but I'm still a bit confused. I've heard DA sanders are what are ideally used, and that the variable speed sander would be somewhat an equivalent. Now both those statements could be wrong, but I'm open to suggestions.

 

[heytrid]

aircraft stripper and razor blades, then finish off with sander. you will HATE YOU LIFE, if you strip it to bare metal with only a sander.

 

[dnschmidt]

A DA is a random orbit sander. It's a finishing sander. It's purpose is to prepare primer for paint and final finishing of filler.

The polisher used as I've suggested is NOT RANDOM ORBIT. It spins in a circle only like a grinder but at slow speed and with tremendous torque behind it. It slices off the paint rather than trying to rub it off like a DA which moves in tiny circles. These two tools are not even close to being the same.

 

[stikman56]

I would chemical strip it.

Me too.

 

[KMdef9]

aircraft stripper and razor blades, then finish off with sander. you will HATE YOU LIFE, if you strip it to bare metal with only a sander.

That aircraft stripper works great.

 

[DTE]

I have always used a Makita sander/polisher as mentioned above, along with a 3M 36 grit disc. http://3mcollision.com/3m-green-corps-fibre-disc-31922-7-inch-36-grade.html.
Once you get a little time in it is not that bad, keep a light touch and do not heat the metal up and it will go pretty quick.

 

[pepi]

A DA is a random orbit sander. It's a finishing sander. It's purpose is to prepare primer for paint and final finishing of filler.

The polisher used as I've suggested is NOT RANDOM ORBIT. It spins in a circle only like a grinder but at slow speed and with tremendous torque behind it. It slices off the paint rather than trying to rub it off like a DA which moves in tiny circles. These two tools are not even close to being the same.

Wrong, Da will do both and very effectively, with a good DA you can control not only the cut speed, it has good torque at low speed. Finish obtained is a DIRECT result of the sand paper grit used... you ever done body work?

@ the OP, chips in paint really do not indicate an adhesion problem. Figure out how many times the truck has been painted. Take a sanding block and sand to the metal check colors seen.

Or check the paint code see if it matches what's on now.... could be the original. No mention of the year of the truck, so no one knows if you have enamel or lacquer as a base now..

The 32 I built, after cleaning surface rust and making body repairs. Had green factory paint, 80 years old. Easily proved it had good adhesion, blended the edges and sanded all the paint to open it.

primed and painted, my point being it is not necessary to remove all the paint to get good lasting results.

Without a picture this is nothing but words ^.. so before and after below V

 

[dnschmidt]

Pepi, I did bodywork for 10 years. I was the lead painter in a 40 bay bodyshop in Pittsburgh while I was going to graduate school to obtain my PhD. Yes, I know a lot about this subject. One point you are correct on is that it might not be necessary to go down to bare metal. In many cases if the paint is checked (there are a lot of what look like crows feet or check marks in the paint, then it is absolutely necessary to go to bare metal as these defects go down to the bare metal as the paint has fractured -normally caused by excessive film build.) If it is not checked then the factory paint can be used as a very acceptable base upon which to build. The DA is an indispensable tool in autobody, it is not the best tool for all applications. The polisher method is at least 10X faster than the DA for striping down to bare metal. Why fight it?

 

[Showkey]

I would chemical strip it.

36 grit on a belt sander?
Always wanted to try it, or get one of my idiot buddies to do it, possibly/probably involving beer and a beater truck.

Me too.

Or bite the bullet and soda blast .........done in a few hours, no damage to the panels, no consumables, no mess on the owners end..........the up side better job and it might not cost that much more all in.

 

[dnschmidt]

The problem with soda blast is the paint manufacturers hate it and will not warrantee their paint when used over a soda blasted car. The stuff gets everywhere and unless you really, really scrub it down with soap and water after the blasting (which of course causes flash rust) it prevents good paint adhesion.

I don't know about the new wet soda blast process which might solve a lot of these problems but I can tell you that if you soda blast you're on your own, the paint reps will not stand behind their products if the car has been soda blasted.

 

[rsanter]

Chemical strip. Then you can use 36grit to knock a bunch of the remaining stuff off then go finer in grit from there.
The electrics are slower than the air DAs so you are not going to use that alone

Bob

 

[Milton Shaw]

The orbit circle on an air DA is three or four times the circle of the electric. That is why they cut so much faster. If you have the time electric DA will eventually do the job but you will use a lot of elbow grease to get the work done. Other options with the polisher would be a lot faster but you could gouge the material if you don't work carefully.

 

[iajonesy]

How about " dustless blasting"? I have only seen videos on you tube and on My Classic Car with Dennis Gage. ( he drives me nuts)

Mike

 

[JeepsAreBuilt]

It may be worth mentioning.. "DA" stands for "Dual Action" True DA's have 2 modes.. random orbit and a way to lock up the RO action, so it spins like a grinder. Palm sanders do not have this feature.. but people still call them DA's. So, you could buy one of these DA's and use the grinding feature to start stripping paint, then switch to RO mode and finish sanding. Either way.. you will need a big air compressor. You'll need the air to spray paint anyway. I'd look for a used 2 stage air compressor.. 5hp 80 gallon vertical tank.

 

[Notgrownup]

A real air powered DA with like 36 grit will take the paint off pretty good but you need to put in in non orbital and brush your paper often... If you insist on taking it down to the metal then chemical strip.. IS there a bond issue the whole car over? seems odd, if only spots then address those and leave the rest alone for a good bonding surface,,, Seems like a lot of work if you are only addressing some spots that have some issues.