air compressor & tool question

I avoid oil-free compressors as they are exceptionally loud and break more often. My biggest complaint about them is that they are VERY LOUD.

When buying a compressor, don't buy it based on horsepower as their ratings are meaningless. Look for the "cfm" rating at 90 or 100 psi and base your size decision on that. Air nailers need about 100 psi to work well, but they don't need very much cfm. Other air tools like sanders and spray equipment are the tools that use a lot of cfm (cubic feet per minute). A compressor with a higher cfm than what is required by your highest consuming tool is probably all you will need (but bigger is always better).

Why do you think that you could repair an oil-free and not an oil type. An oil type compressor isn't much different than a lawnmower motor - rings, piston, bearings, and the most prone to need repair item, reed valves. The reed valves are nothing more than spring steel flappers that cover holes in a plate to let air pass through the hole in only one direction. They are usually riveted to the plate, making the whole plate a replaceable part. Most of the time when these compressors have problems a new valve plate is all they need, unless you have run it without oil. Just remove the head bolts and the head, remove the valve plate, replace the gaskets and the valve plate, and bolt the head back on. In less than 15 minutes your compressor is as good as new again (and you didn't even get covered with oil doing it).

Not to mention the Grex moves as 15,000 rpm free speed. As we know, sanding slower is going to give a better finish ....

Seriously, George, consider electric. I love a flex shaft and a 1725 induction FHP motor. No real noise, good control by supporting the handpiece on the toolrest to just kiss the work, and the capability to hold the tool securely in one fist while sanding an interrupted edge or odd-shaped piece held in the other.

I would definitely go electric. No stiff hoses in the way, no worries about lubricating the tool, no noisy compressor, nothing.

A small motor spinning happily away using much less electricity than a

10 - 15 amp rated compressor that won't power a pneumatic sander correctly.

I have a Sioux close angle drill that I use as a sander that I bought from Klingspor with a goodie package of paper some years back. It has been a real workhorse and I love the lack of noisy compressor motors while working.

Even with a large compressor, you will keep it busy with a pneumatic sander or grinder. These things are essentially a blow by turbine that generate no torque of consequence, just whiz around very quickly to build momentum to do the work.

Even if you still need to buy the compressor for other things, on the sander, go electric.

Robert

Hi George

Don't know anything about Grex air tools. Do know you should go for a oilbath compressor, not a oil free one. as for the HP, just like others have mentioned, they don't mean anything, go by cubic feet per minute at a realistic pressure 90 PSI is a good one, that is the pressure most air tools are used at, What you use it for is up to you of course, but if your use is mainly sanding, than that is one expensive sander to buy and to run, just IMO.

Have fun and take care Leo Van Der Loo

as others said, don't even look at the HP, look at CFM at some reasonable pressure - I have a Quincy compressor with a 5 hp motor - it puts out (according to the manual) 21 CFM at 160 PSI, and I have my old compressor, a crafstman 2 hp unit that puts out 7.2 cfm at 60 psi (according to my memory). The 2 hp crafstman puts out almost double what many of the new cheapie "5 hp" units put out. I use my compressor for all sorts of things beyond running an air sander (I could argue with those who said go electric but I won't, let's jsut say I won't go electric), I run a bead blaster, I run a paint sprayer, air drill, and so on - my sandblaster uses the most air, most other things the compressor cycles on and off fairly infrequently. The sears unit though would run continuously when I was painting (cars) and eventually cracked a ring (and as others said, it's an easy overhaul - just like a lawn mower engine, but without a valve train). (hey, if you are on the left coast, do you want a nice compressor?) if you have the space, look for a "real" compressor like a Quincy, that can run all day, every day for decades - you get better air (dryer), more pressure/volume for your HP, and more reliability - downside - compressor weighs about 800 pounds (upside to that, no one is going to steal it out of my shop)

And make sure they mean Sustained Use. Having a compressor take a deep breath in the middle of something is not good. Which means you also have to look at the tank size.