Building an Air Compressor

[GreenMachine]

   I just bought an air tank on Craigslist and was going to hook it up in line (with an air hose) with my little 20 gal. campbell hausfeld for when I sandblast. The tank is either a 60 or an 80. Now I'm throwing around the idea of buying a 2 stage compressor to put on it and maybe a gas engine to power it. I don't know if it would be cost effective to build one or just buy one as a complete assembly. Anybody done something similar or have any ideas?

[Chatt69chgr]

You will need to be able to get the electric motor and compressor cheap to make the deal worthwhile.  Check Harbor Freight for these items.  Seems like I saw a two stage cast iron compressor with pulley there recently.  They usually have a 5-hp electric motor too.  Never have seen a 7-1/2 horse motor there as a separate item.  The cutoff switch is a pretty commonly available item that you could probably source from some place like Graingers.   

[Steve P.]

I would say you are better off buying one that is built and proven. Coming up with the parts used can save a few bucks, but getting everything you need and buy to work in concert can be another story. Not enough motor. Not enough pump. Too much of one or the other. Regulating switch. Pop off valve. Then you get it all figured out and built and a few weeks later the bottom of the tank blows up due to rust from the last guy never draining the tank..

Try Sam's club, Northern Tool, Craigslist.  I prefer new, but this economy is driving many shops out of business and I have been seeing many major shop tools going kind of cheap lately.

I bought mine at Home Depot about 8 years ago. I just happened to help a guy that was returning it. He told me that he needed it for a big job and wasn't going to need it again, so he was returning it as broke. I talked to the manager to tell him there wasn't a thing wrong with it and he said it didn't matter. It was used and going on the floor cheap. I asked how cheap and the rest is history.   

One thing I would recommend is buying one with a cast iron pump. They last much longer and are SOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO muck quieter you just can't believe..

[GreenMachine]

   Yeah, it looks like you guys are right. I have hooked it up in line with my other compressor and now it's giving me about 2 solid minutes of sandblasting before I have to stop and wait for it to catch up!!!!

[Steve P.]

That's what I expected. Blasting takes a ton of air or CFM. If you plan on doing allot of blasting I would definitely be looking into a 7HP or bigger with a 2 stage iron pump and an 80 gallon tank.  I have a buddy that blasts here and there with a 60 gal. single stage and he spends more time waiting and re-blasting than it's worth.   

[Rolling_Thunder]

I think I have that exact same tank at the shop