Air compressors - help?, an education Options

[VaccaRabite]

So I went to Home Depot today, armed with some scratch and the will to buy an air compressor and a DA air sander.

HD sells the husky line. So, I went to the tools, found a DA sander (Husky, needed 4cfm @ 90psi, and the box said it would work continously with 20+ gallon compressors).

Then I walked over to look at compressors. They had a Husky 24 gallon compressor that flowed 5.1 cfm @ 90 pis on sale ($225). Score! but then, on top of the motor, was a little chart with reccomended tools and non-reccomneded tools. All sanders and DA sanders were non-reccomneded.

I called over a HD floor guy, who called over another 2 guys, and we could not see a good reason for the prohibition. But, we decided that if the factory did not reccomend it, then it should not be used as such, and I walked over to the electric tool section and bought an electric DA sander. (IMG:style_emoticons/default/sad.gif)

I am going to need to buy a compressor by the spring. I'm clearly in the "hobbiest" catagory, and may not use the tool again for a long time aftyer I am done with my 914, but when it comes time to paint, it will probably be cheaper for me to buy one then rent one - given the slow nature that I work. I want to know why the sander was not reccomended, when the compressor could flow the air and had a big enough tank according to the tool. I have theories, but I thought somone here might be able to give better advice.

Thanks

Zach

[jsteele22]

Wow, a really great thread. I wish I had gotten this kind of advice on how to pick a wife ! (J/K)

I just wanted to expand a little on the 110/220 issue, in case it's useful to anybody. (Read at your own risk.) Any house in the US with electrical service already has 220 V service. What you get are two distinct phases (call 'em A and B ) that individually wave up (positive) and down (negative) with respect to neutral/ground (zero). The big (only) difference between A and B is the timing; A is pos while B is neg, then they cross zero at the same instant, then A is neg while B is pos. All of the 110V circuits in a house (plugs, lights, disco ball) have their hot wire hooked up to one or the other phase. In order to use a 220V appliance, you just need 2 hot wires : one for both A and B.

The only absolutely safe and legal way to get 220V is to have a certified electrician pull a permit, do the work, and have it inspected. Ouch. But if you just want to run a 220V appliance on an occasional basis, you just need a hot line from phase A and B to it (plus neutral, plus ground). If you already have a 110V outlet, you are halfway there. In principle, all you need is an extension cord (make sure it's rated for enough current) and plug it into an outlet fed by the other phase. (You can check with an A/C voltmeter. Each hot wire will read 110V with respect to neutral, but reading from one hot to the other will give 220V, or zero if they are the same phase).

This will work, but it's a little dangerous. To be safe, you need a way to make sure that if one phase (say A) draws too much current, that BOTH phases will shut off. You do this by making sure that the circuit breakers in the main panel that feed your A and B phases are next to each other. (The breakers in a panel always alternate A/B/A/B/....). Then, depending on the brand, there's usually a way to mechanically link them with a piece of wire or a pin so they can only switch on and off together.

Based on the above, a slightly more elegant (but still cheap and not entirely legal) way to do the same thing would be to buy a 220V breaker (a pair of adjacent 110V breakers permanently linked together), a box of Romex (10 gauge, 3 conductors plus ground) and an electrical box with appropriate socket, and make a custom extension cord. When you plan on using the compressor, you can hook up the wires (A,B, neutral, ground) to the main panel and you're good to go.

I'd say if you decide to do something along these lines, find someone who has some experience with home wiring, or buy a book, or both. My main goal here was to point out that the lack of "real" 220V service isn't an absolute roadblock to using a decent compressor or welder for the occasional DIY CSOB. Hope it helps.