DA sander and compressor

[rjkoop]

I have this compressor from harbor freight.

http://www.harborfreight.com/8-gal-2-hp ... 68740.html

It says 4.5 CFM @ 90 PSI. This is one of the DA sanders I was looking at getting for color sanding.

http://www.princessauto.com/en/detail/p ... -p8344541e

It says air consumption is 2 CFM @ 90 PSI. Does this mean that my air compressor should be able to keep up no problem? Everything I've read says that you need a really large compressor for DA sanders. Am I missing something?

[azruss]

This compressor is too wimpy for the job. The compressor will not stay at 90 psi but will run at 50 with the DA. this means the DA will be slow or barely run at all. the compressor will constantly overheat and shut off. I have a 3 hp full industrial compressor and it doesn't have a chance trying to keep a DA going for hours. I bought an electric DA...now that's the cat's meow. I use the compressor for a pneumatic long board and HVLP spraying.

[rjkoop]

This compressor is too wimpy for the job. The compressor will not stay at 90 psi but will run at 50 with the DA. this means the DA will be slow or barely run at all. the compressor will constantly overheat and shut off. I have a 3 hp full industrial compressor and it doesn't have a chance trying to keep a DA going for hours. I bought an electric DA...now that's the cat's meow. I use the compressor for a pneumatic long board and HVLP spraying.

And is an electric DA sander the same as a electric random orbital sander? I find the terminology confusing. Is this what you are referring to?

http://www.harborfreight.com/6-in-57-am ... 69924.html

Also there seem to be ones you hold in your palm and ones with handles. Which one is best for color sanding to spruce up a paint job? I'm thinking the palm ones have more control and the ones with handles are more aggressive. So I'd probably go with a palm held one.

[azruss]

A DA (dual action) and RO (random orbit) are terms used for the same sander. Some have the ability to lock the random part and turn it into a drill style sander.They are also called orbital sanders. For a palm style, look at a Dewalt D26450 or D26451. There are advantages to each. The palm style have a dust collector system that is very nice. But they are tall so have a hard time reaching into some places. They are easier to keep flat on your work. The handle style allows you to put more pressure on a section of the pad or use the edge for more aggresive sanding like you can with a angle grinder. I had a handle style air for years. I bought the palm style when i went to electric for doing the beast. The one thing i would do is get rid of the velco style wheel and paper. They wear out fast and develop round edges and the paper is not high quality. The disc just unthreads and any autobody supply house will carry a variety of discs from low profile aluminum, to the thick yellow foam jobs. You want to get a disc with a flat bottom and buy sticky back round paper. This gives you far more control of the flatness of your surface. If you buy good quality paper in a roll, you will get a better bang for the buck as the paper lasts much longer and sanding an entire car will eat through lots of paper. I ran on to some paper that had a blue tint and they lasted 4 times longer than anything else i used. I can get a name when i get home. Dont leave the sticky back paper on after sanding as you won't be able to get it off after a few hours. This stuff is for dry sanding only.

[rjkoop]

A DA (dual action) and RO (random orbit) are terms used for the same sander. Some have the ability to lock the random part and turn it into a drill style sander.They are also called orbital sanders. For a palm style, look at a Dewalt D26450 or D26451. There are advantages to each. The palm style have a dust collector system that is very nice. But they are tall so have a hard time reaching into some places. They are easier to keep flat on your work. The handle style allows you to put more pressure on a section of the pad or use the edge for more aggresive sanding like you can with a angle grinder. I had a handle style air for years. I bought the palm style when i went to electric for doing the beast. The one thing i would do is get rid of the velco style wheel and paper. They wear out fast and develop round edges and the paper is not high quality. The disc just unthreads and any autobody supply house will carry a variety of discs from low profile aluminum, to the thick yellow foam jobs. You want to get a disc with a flat bottom and buy sticky back round paper. This gives you far more control of the flatness of your surface. If you buy good quality paper in a roll, you will get a better bang for the buck as the paper lasts much longer and sanding an entire car will eat through lots of paper. I ran on to some paper that had a blue tint and they lasted 4 times longer than anything else i used. I can get a name when i get home. Dont leave the sticky back paper on after sanding as you won't be able to get it off after a few hours. This stuff is for dry sanding only.

Great information. Thanks for taking the time to put this together.

[rjkoop]

Found this brand new one on kijiji.

http://www.kijiji.ca/v-power-tool/ottaw ... nFlag=true

Thinking about getting it. Would this work for wet color sanding? I don't think it has variable speed. Would this be something I need?

[azruss]

That is a typical palm style unit. You can see how tall it is. You can also see how the dust collector works with the holes in the sandpaper. This works great for sanding bondo and the like. When you get to 320 grit and higher, you need the flat pad with the sticky back paper. None of these sanders are designed for wet sanding. I gave up wet sanding years ago. dry paper is so well worked out now, you don't need the big mess wet sanding makes. Wet sanding may be the best choice when you are getting in the 1000 grit range as it keeps the paper clear. You will be doing that with a hand block.

[rjkoop]

This one looks good and it goes on sale 1/2 price on Friday!

http://www.canadiantire.ca/en/pdp/tools ... dUzg7JVhBc

Not sure about the 'hook and loop' system vs sticky or velcro pads though...

[DieselSpider]

This one looks good and it goes on sale 1/2 price on Friday!

http://www.canadiantire.ca/en/pdp/tools ... dUzg7JVhBc

Not sure about the 'hook and loop' system vs sticky or velcro pads though...

That looks more like a high powered straight grinder polisher and may be more than you need or may have the skills to handle yet. Also with hook and loop you may not find anything finer than 220 grit so they are not really that well suited to automotive paint work and are better for bare metal prep and working body filler.

The comments on the site seem to imply that 80 grit sanding discs are all that they have available for it there.

Note as to your original post that there are many differences in DA air sanders and the volume of air required to run them. If you compressor delivers double what the sander requires you may be Ok however your compressor will be on quite a bit and generating a lot of heat. I would put in fresh high quality oil and audition the original air sander or one similar to it from Harbor Freight. No sparking electric motor brushed or electric wires in the work area is always a good thing.

I have the Harbor Freight 21 gallon vertical compressor and that would be a better choice over the compact tank unit you have. The oil lubricated cast iron head in both though is a plus. I also have one of their older oil lubed pancake style compressors which basically has the same power head as yours and that does surprise you even running my 625 ft lb impact wrench when servicing 19.5 inch truck tires when mobile.