Air compressor regulator issues?

[C1ph3r]

So I have a 33 gallon Craftsman air compressor. 4.9 cfm @90 psi.

I noticed an issue a while back that whenever I use a grinder, impact or whatever, the tool works great when the trigger is first pulled. But then it falls off. So to get full pressure I have to pulse the trigger. If I hold down the trigger the pressure drops quite a bit and the tool becomes useless. I have to pause and then start again.

Could this be a bad regulator?

[tinydb84]

4.9 cfm isn't that much. I would guess your compressor cant keep up. I have a 13 cfm 60 gallon and it runs pretty hard to use a DA and even an impact gun if I use it hard.

[C1ph3r]

Originally Posted by tinydb84

4.9 cfm isn't that much. I would guess your compressor cant keep up. I have a 13 cfm 60 gallon and it runs pretty hard to use a DA and even an impact gun if I use it hard.

hmm. guess that's it. I have had if for about +/- 6 yrs and thought I remember it performing better. I haven't used it for heavy stuff in a long while. at least a year or so. Mostly nailers and what not. Just recently using it on autos again. My Aircat 1500TH impact is rated at 4cfm @90. So I would have thought my comp would handle it better. guess not.

This really stinks. Oh well. Thems the breaks I guess.

Thanks for the input.

[truckster]

Portable compressors have a hard time with almost anything that continually uses air. Nailers and staplers use small amounts of air in short bursts. Impact wrenches consume considerably more air, and grinders and sanders even more. I have a Craftsman that I think is just slightly larger than yours, and if I'm using my impact continuously I have to be patient while it builds up pressure.

[Dead Parrot]

What is the max PSI in your tank? Most grinders and such want 90psi at the tool. Most of the cheap regulators low to mid range compressors come with have a bit of drop from the zero cfm static pressure to the pressure when the tool is in use. Add in the drop from your hose and your grinder may only be seeing 60 or 70 psi when in steady use. A quick check is watch your regulated pressure gauge when you operate the tool in question. You may need to adjust the output pressure a bit higher to adjust for the drop. Avoid long runs of 1/4 hose.

The CFM of your compressor is only a factor once the pressure in the tank drops below the kick on point. You may wind up with a duty cycle of 1 or 2 minutes of steady grinding followed by several minutes of the compressor refilling the tank to max PSI.

[C1ph3r]

Originally Posted by Dead Parrot

What is the max PSI in your tank? Most grinders and such want 90psi at the tool. Most of the cheap regulators low to mid range compressors come with have a bit of drop from the zero cfm static pressure to the pressure when the tool is in use. Add in the drop from your hose and your grinder may only be seeing 60 or 70 psi when in steady use. A quick check is watch your regulated pressure gauge when you operate the tool in question. You may need to adjust the output pressure a bit higher to adjust for the drop. Avoid long runs of 1/4 hose.

The CFM of your compressor is only a factor once the pressure in the tank drops below the kick on point. You may wind up with a duty cycle of 1 or 2 minutes of steady grinding followed by several minutes of the compressor refilling the tank to max PSI.

Thanks for the response. Yes when I use my tools the pressure drops. Considerably actually. I should take a video and post up.

It is a 150 PSI compressor. I am using a pretty long hose. I'd guess its at least 30 ft. Not sure of the size but I would bet is 1/4".

So should I just run the tool until it reaches its slowest speed, check the pressure, and turn up my regulator to compensate for the difference? I have tried that but didn't crank it all the way up to cover the difference. I was afraid of damaging my tools with the initial high burst of pressure.

I would be open to replacing the regulator with a better one if there was a chance it would help.

[tinydb84]

I run all my tools (except my paint guns) without a regulator. 150psi all the time....BUT I buy mostly harbor freight air tools. Interestingly none have ever broke! I dont go easy on my tools either.

[Dead Parrot]

I checked mine and get about a 10psi drop between static and running for a small Husky brand angle grinder. I have a 50' 3/8" Goodyear hose and then a 10' 1/4" Goodyear hose. Northern Tool had a sale on Goodyear hoses a while back. Not sure how much pressure drop I get through the hoses. 90psi at the regulator output gives good tool response.