compressor question

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Hi all !!!I just had a compressor given to me by a relative. It's a Campbell Hausfeld 3/4 horse Power Pal. It's rated at 2.7cfm @40 psi and 2.0 cfm @ 90 psi. I want to run a small right angle die grinder which needs 3.0 cfm 90 psi to run according to the box. Will this compressor handle it for short periods of use? There is a chart on the compressor that states it can run sand blasters and impact wrenches, all of which need more than my little die grinder ever will.I hope it will 'cause the price was just what I could afford.  Anyone know about compressors out there?
Reply:It should run the grinder for short periods and the length of that period will depend on the size of the tank as well as the HP of the compressor.
Reply:You would be working that compressor pretty hard if you use the grinder for extended periods.  While these small compressors are handy, they will not stand up to heavy, continuous use. The compressor obviously will not run the grinder continuously.  Whether it will fulfill your needs is completely a matter of your expectations and usage.With the tank filled, when you start the grinder the tank pressure will drop to the cut-in pressure gradually or rapidly, depending upon the size of the tank.  If you are running at full tank pressure (possibly excessive for your grinder), you would start to see gradually decreasing performance immediately.  If you are regulating the supply to the grinder at around the cut-in pressure, there would not be any decrease in performance until the tank pressure dropped to a few PSI above the regulated pressure.  When the compressor cuts in, the rate of descent of pressure will decrease, but not cease - you will be experiencing decreasing performance, even though the compressor is on until the tool becomes ineffective.  If you continue with the grinder on, things will equalize to a steady state at some pressure below 40 PSI, at which pressure you would not get any use out of the grinder.So, the answer is, it depends.  Yes, you can get full performance out of the grinder for a short time - possibly less than a minute, depending upon tank size.  Then either you will have to put up with decreased speed and torque or you have to wait for several minutes for the tank to recharge.  If you are building a trailer, you would be very frustrated.  If you are deburring a pipe between cuts, it will do fine.  I have been very satisfied with such a small compressor for light, intermittent die grinder jobs like deburring a bandsaw cut, and very frustrated while building larger projects.But what the heck.  Try it out and see how soon you run out to get a bigger compressor.The comment on the compressor box about running a sandblaster is a joke.  Pure marketing hype, commonly referred to as a lie.  It could run a common home-type sandblaster for an even smaller duty cycle than your die grinder.  They could even claim it will run a pavement breaker, which it would for a couple of blows.  It will probably operate an impact wrench in home use fine because of the small duty cycle of an impact wrench in ordinary home use.Enjoy it and save up for a bigger compressor.  Don't forget to oil your grinder with a few drops of air tool oil into the air port every hour or so of use.  You cannot over-oil an air tool of this type because any excess is just blown out the exhaust immediately.  Messy, but good insurance.awright
Reply:My 5 hp, 20 gallon Craftsman compressor can't keep up with a grinder.  I get a minute or so before speed starts to drop.  The compressor can maintain a reasonable speed, about 75 psi, but not the full power, 90 psi, of the die grinder.  The compressor is rated for something like 4.5 CFM at 90 psi.
Reply:Like 76GMC1500 says, air tools in general and even the little die grinders gobble up the resources pretty dern quick. More than likely you'll get a quick course in frustration management.
Reply:76GMC1500, if your "4.5 CFM at 90 psi" compressor can't keep up with a 3 CFM at 90 psi die grinder someone is fudging the ratings.  Are you using a die grinder rated at 3 CFM or a larger grinder?  Actually, I just looked at the box my toy Campbell Hausfeld TL 1020 25,000 RPM Die Grinder came in and it says 2.0 CFM at 90 PSI.Now, we know for sure that manufacturers fudge ratings of their products.  The most common lie is "5 Horsepower Peak."  There was a court settlement about this cute bit of deception a decade or so ago with some common shop tool (I forget which tool, but I think it was compressors).  Manufacturers have gotten into the habit of competing for the biggest "peak horsepower" value.  There is no such thing as "peak horsepower."  Power is the ability to do work over time and you, the equipment user, get absolutely no benefit from some fictional "peak horsepower" of a compressor.   You get benefit from the power output of the equipment averaged over the time that the equipment can operate without overheating, and that's a lot less than the number they usually plaster all over their boxes.  At least welder manufacturers rate their products at a specific duty cycle.To find the maximum possible true horsepower of equipment you are buying, multiply the rated voltage by the rated current (both RMS values - the value you would measure with a true RMS DVM) and divide by 746 watts per horsepower.  This is an approximation because it does not take into consideration possible power factors less than one, i.e., phase shift between the voltage waveform and the current waveform.  But it is a pretty good assumption for a properly loaded motor and is the highest possible value of horsepower for the equipment.  Any deviation from unity power factor will decrease the true horsepower output of the motor.Have fun.awright
Reply:We run air screw guns , linishers , die grinders and mist sprays they all say 3, 4.5 , 6 or 8 cfm and they all use a lot more than that.In compressors you may have a say 10 cfm compressor but that means at the rpm of your motor you have a piston displacement of 10 cfm. What counts is a thing call "free air delivery" you  would be lucky in any compressor to aheive 70% of your displacement.I know for a fact that a linisher we have says 8 cfm and our 35 cfm (probobly 20-25 free air delivery) can only just out run it
Reply:1) many tools, especially low end ones, have understated air usage. Your 3CFM die grinder may be taking more than twice that. Or, may not. The better makes are  rated pretty accurately, the cheapies tend to suck air like W.C. Fields sucked a bourbon bottle.2) At 90PSI, you get about 4CFM/HP delivered to the air pump. Period. Two stage improves this a little, but not much. A '5HP' compressor rated '4.5CFM' is BS. The power delivered to the pump will be around 80% of the electrical power, so if it runs at 15A, 120V actual, this is about 2-1/4 electrical HP, for about 1-3/4 delivered to the pump, for about 6CFM, assuming everything is working right. Less as the compressor wears. 5HP should be about 17 to 18CFM.
Reply:I think I'll keep this thing to fill up the tires on the kids bikes, save my arms and shoulders from all that pumping with the manual bike pump. Then I'll save for the bigger compressor.