Bodywork - what is the proper sander spec?

[jkskier]

What kind of sander do I need to take paint off when going to bare metal?

Here's what I 'think' I know:
- DA won't cut it for a job this big
- random orbit seems to be the best way to go with about a 5" disc
- some people are using just a straightforward normal grinder with a thicker backing pad in about a 7" disc size and claiming you must stay at or below 1K RPM to avoid warping the metal
- some people are running adjustable speed Random Orbit sanders with a 5" disc that range between 4-10K RPM

The last two options are where any pros and cons that you could share would be most helpful.

Thanks in advance!

 

[thegreatjustino]

I have stripped an entire '65 Mustang using nothing but a DA and a ton of 80 grit paper. I would do that again in a heartbeat over using an air file or torch and wire brush. I know they make DA sanders that have a 10" pad which work well for large flat surfaces. Really, other than media blasting, I think a DA and a whole lot of time is going to be your best bet.

 

[72-Madisyn]

I took my 72 to bare metal with my DA and a combo of 40 and 80 grit paper. doesnt really take all that long on a Bronco, if you are looking for the fast easy way then spending the money on having it blasted is best, i dont know what your hourly rate is but if you think about that, the cost of sandpaper, and running a compressor for hours on end then it may be a wash with the 3-500 you spend on blasting it....? just a thought. next one i do will be blasted for the sheer purpose of getting all the tight spots inside.

 

[jkskier]

I should have specified that my compressor won't keep up, so this will have to be electric. I had written that in my original draft but I guess I forgot to throw it in my final version. Sorry guys!

This is what I'm currently looking at:

http://www.tools-plus.com/porter-cable-97366.html

I figure I can hit the small spaces with chemical stripper and the use of a smaller abrasive tool. In your opinion, what would be the real world difference in intended application between DA and RO sanders?

I can agree that they would both do the job but my fear is that a DA will take quite a bit longer.

 

[777mechanic]

personelly i would take it to a sandblaster . the difference in time and quality will be like night and day . i started sanding my frame last week and quite after 10 minutes tossed on trailer took to blaster 2 days later picked it up frame . cost 135.00 and they even blasted inside tubing .

 

[Terkish]

that electric sander should work with alot of 80 grit paper. similar to how i stripped my eb. just make sure your getting a quality sander so it will hold up to the hours of sanding. good luck.

 

[jkskier]

BTW guys, thanks for the suggestions so far!

 

[ned72]

I would go with a sandblaster. I rented a portable sandblaster from a local rental company and it took me all of like 1 day to do my entire bronco

 

[jkskier]

That would be a cool option. I actually tried a buddy's sandblaster. It was a cheapy with both hoses coming out of the bottom of a very small gun. The problem was that my compressor doesn't really go above 120PSI so it wasn't enough. It's just a Craftsman one stage that puts out about 6.4SCFM @ 90PSI.

Did the rental place also supply a compressor with that one? I wonder how much that would run me...

 

[Steve]

I would never strip a whole vehicle by sanding. Use chemical stripper on everything but the edges. Much faster, especially than an electric sander. Those aren't nearly as good as an air sander. It's really easy to warp panels sandblasting if you don't know what you're doing, and it makes a helluva mess if you do it at home. You also need a huge air compressor for sandblasting.

 

[allenfahey]

I've found the best way to strip a panel is to use 80 grit on a grinder. Take it off in layers down to the sealer or e-coat. Then switch to 180 on a DA to remove the 80 grit marks and the last coat of paint. You must have a 180 or finer scratch before primer. If you don't you risk the sand marks coming back after paint.

You can also "scratch" the panel up with 40 or 80 grit. Then use stripper, the scratches will help the stripper do it's thing. After you've taken all the stripper off use a red scotchbrite and laquer thinner and wash it down to somewhat neutralize the stripper. Then finish with 180.

 

[mitzel]

I think you'll want a rotary buffer rather than the random orbital for
paint stripping. I'm pretty sure Porter-Cable must have those in their
lineup. I use a Makita 9227 and stripper kit from Len Stuart at
www.autobodystore.com and they work great!
http://autobodystore.net/Merchant2/merchant.mvc?Screen=PROD&Product_Code=MAK9227CX3&Category_Code=T2
http://autobodystore.net/Merchant2/...OD&Product_Code=FAPS6258-p80&Category_Code=T2
He also stocks a lower cost model
http://autobodystore.net/Merchant2/merchant.mvc?Screen=PROD&Product_Code=atd10511&Category_Code=T2

Once you're done painting then you use the same tool after color sanding
for final cut and buff.

 

[mitzel]

If you go with paint stripper method I would also highly recommend allenfahey
suggestion to hit the panel with some 40grit first. My autobody teacher
does a paint stripper demo hitting half the panel with 40grit first while the
other half is unscuffed. The improvement in performance of the stripper on
the scratched half is significant!

 

[PEELDOG]

x2 on the paint stripper method.the stuff i used was called "peel away" wear rubber gloves and eye protection...way faster than sanding and less dust.

 

[allenfahey]

I've used just about every paint stripper. Delta Foremost has the best hands down. First used it in the early 90's when Ford was covering the repaints of the F series under warranty. http://www.deltaforemost.com/auto.html

 

[jkskier]

I will definitely use the chemical stripper for the majority then...I had used Jasco in the past for a CJ7 I used to own (before I realized the error of my ways) and didn't scratch it up first so I suppose I should have found that out before I decided I wasn't impressed with the stuff.

If I am using chem strip for the majority then I would bet that the remaining areas won't be so negatively affected by high RPMs and that I could subsequently use just about any speed and type of sander to finish those off. That may be where that cheaper of the two sanders that Mitzel linked to would come into play.

Next question - how picky is bondo with RPMs, or would you guys be more likely to recommend that I pick up a few hand tools for that work? I have heard that you should stick with a tool that has a longer and level planing surface like the 'cheese grater' bondo planers.

Thanks for the good input guys! Keep it coming please!

 

[jkskier]

Thanks for the recommendation AllenFahey! If Ford used it for a massive project like a recall it must be pretty good stuff.