Under rated air compressor?

[johnnyh55]

If I get an air compressor that can supply 5.5 CFM at 90psi, will it run an angle die grinder? I would only use the grinder to clean wheel hubs or the head of an engine. I won't be doing any major body work. Do you think that compressor will allow me too do this? Also, would you guys go for a 20 gallon or 30 gallon portable compressor?

 

[f575gtc]

You could run it, will most likely test your patience with it, and once the air compressor kicks on, it will continue to operate until you stop grinding and will dip below 90PSi affecting the grinder performance.

 

[BDT/NWMN]

You need to compare the specs of the air tool and the compressor.
Bigger is better with an air tank..
A smaller compressor and air tank will run an air tool, but not steady if the compressor cannot maintain the needed volume and at a specific pressure.. At that point, just hold off and let the compressor catch up... For your occasional use, I see no problem..

I have a 1/2 hp twelve gallon portable compressor that was bought new in 1969.. Little unit still sees occasional use with air tools,,,,

 

[sberry]

A big tank will help some as will technique. So will a smaller tool. But I got to confess, never tried it with one of those that small.

 

[johnnyh55]

Do I have to match the CFM of the air tool at load? IF so, I would need a stationary compressor because I haven't seen a portable one that can produce 16-19 CFM.

Also, Why do manufactures specify 2 CFM ratings, one at load and the other is average cfm?When you buy an airtool usually it's too perform some work so why wouldn't they just give the "at load rating"?

 

[PT Doc]

my 80g 2 stage 5hp quincy will keep up with me but it is running frequently if I don't take a break. it puts out 18 scfm.

 

[sberry]

They want to put it in the best light possible. You do not need to match the tool unless the run is continuous. I mention technique because being conservative is the same as making more but leads to long pump run times.
All this doesnt mean squat to a hobby guy, you got to wait a couple minutes cleaning a head isn't a deal breaker.
The air tools are rated for industrial averaging,,, its for calculating systems for multiple users.

 

[sberry]

I try to rum a pump continuous. You can wait and resume sanding just prior to pump kickoff to get the longest run. If you let it shut off it has to drop tank to kick on pressure before the pump resumes. Use a whip hose, it will reduce a little waste on starts. Put a regulator on.

 

[BDT/NWMN]

Do I have to match the CFM of the air tool at load? IF so, I would need a stationary compressor because I haven't seen a portable one that can produce 16-19 CFM.


For steady, continuous use, if you air tool hogged 16-19 CFM, then yes you would need the whopper air compressor to match, or better yet, exceed that demand... However, a smaller compressor will work, but you will have to stop to let the compressor catch up on pressure.... This should not be a disaster for occasional use.


I believe there is a full herd on respondents giving you the same basic answers

 

[johnnyh55]

Ok, is it pretty easy to tell when the compressor needs to catch up? The grinder will start to turn slower? Is it bad for the compressor if you keep going or the air tool will just run out of air and there will be no damage to the compressor?

 

[RogueFab]

Just an FYI - smaller compressors are one of the most common tools that is marketed with "questionably optimistic" specifications. They know you aren't going to bench test them, so they put whatever numbers they want on them.

I say it depends how much grinding you're going to do and how patient you are. I would save my $$ for a compressor that can do closer to 10 CFM at 90 psi.

 

[sberry]

You will run out of power and most of them do not do well with continuous runs but again,,, this is a diy scheme, give it a try.
I agree with the post above, you can buy a cheap 240V unit for not much more that puts out 2x the air and would allow real work.

 

[Astro_Pneumatic_Tools]

Practically all of our die grinders are 3CFM at constant use. A good reference is usually 1/3hp models are going to be 3CFM while 1/2hp will be 4cfm.

So it comes down to if you trust the rating of said compressor.

Good luck
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[Tronyadorable]

HF Purple Gun uses 12 cfm @ 45 psi.My 3 horse 100 liter runs constantly when spraying and shuts off about 3 seconds after I let off the trigger. My air drill behaves the same at 90 PSI and is "consuming" 6 cfm @90.
The compressor is a 230V "rated" at 10 @90. That a stretch.
I consider it minimal.Anything less is for inflating tires.

 

[larryq]

Not much to add here, other than to note that grinding and sanding are two of the most intensive uses of an air compressor possible. A 20 or even 30 gal won't be able to keep up for long, so unless you're doing very occasional work with those tools a 60 gal is a minimium (preferably 2 stage, and definitely 240v.)

 

[boosteddsm92]

I had a Crapsman compressor that was rated at 6.5cfm@90. It couldn't keep up w/a die grinder. You WILL have to to stop frequently and wait.

I now have a 23cfm@125 60 gallon and I can run a die grinder all day