Air Compressor Question - Metric conversion


SGF, Supreme Grumble Framer
Feb 14, 2004
Nicholasville, KY
Hi. Math question for you all.
I just bought a great used Brevetti Underpinner.
Very happy with the purchase.
I need an air compressor now. It was tested on a big production shop unit, but does not require that to run. It was relayed to me from the previous owner (who I can not contact to easily) that it was really happy between 90 and 95 PSI

Manual says
6 Bars (which I have found means 87 PSI)
3 Ni/Cycle (what is that?)
90 NI/Min (what is that?)

Went to lowes with those specs and they just looked at me funny.
Question #2:
Just judging by PSI I found one at Sears on sale.
SCFM @ 40 PSI = 3
SCFM @ 90 PSI = 2
1.5 gal tank (small tank but for low volume is it okay?)
Max Compressor PSI = 150
Pancake tank

Note: Small size in a compressor is important.
It will not see heavy use. Maybe 5 frames a week.
There are 3 factors in purchasing an air compressor:

the actual pressure = PSI (pounds per square inch)
CFM = cubic feet per minute
the size of the reserve tank =the larger the tank the less the pump has to be on

2 CFM is on the low side, but will due for just one machine.

The other figures are volumn of air used
I bought a small pancake, then quickly returned it. Loud, and it "quit" after 2 nails and took forever to refill. Bought a 15(?) gal unit from home depot, the one on wheels that is easy to move around, and it worked great! Loud, but great, could do 2 frames before it kicked back on. The rice difference was around $50, and it was better to go too big, than too small. Plus the wheels gets the machine out of the way when not being used.
---I understand the whole concept of bigger is better, but in this case, bigger will not work due to space limitations. This is the only tool and will be the only took i will be running off of this. My dad has a Porter Cable 50 gallon compressor used for painting if I ever need a lot more for some reason.

Now you have to give me more credit / less slack for going to lowes. I know good and well they are not the best for advice. I went looking thinking the metric would be on the units as well, which they were not of course.

Air tools are one thing I admit I know nothing about. Never used them before. --
Question: Below are two compressors, one has a higher SCFM and one has a larger tank. Which rating is more desirable?

Heres two more I found:
Harbor Freight
2 gallon 100 PSI (max 150)

3 gallon
2.4 SCFM@90 PSI (max 125)

One option may be to put the compressor in the basement, and run the air line up through the ceiling/floor to your shop. That's what we opted to doto cut down on noise and save some space. Of course this only works if you have a basement!

Our first compressor was one of those nasty loud $99 Home Depot (Porter) units. That lil thing lasted over 2 years, to our amazement. Now we're using a 40 year old Sears unit that has an oil based system (not direct drive), which I found in a relative's garage. (it will probably outlive me) The oil type compressors seem to run quieter, and I assume will last longer than their "direct drive" cousins. Oil type compressors are in places like dental offices and labs, where the sound is a concern. (SilentAir, Bambi, JunAir, etc)

For us, putting it in the basement did the trick. (with a switch upstairs so it can be turned off at night) We have a "T" on the compressor, and have air feeds coming up at the Wizard and Vnailer. The compressor has a decent sized tank and only comes on a few times per day.

I think Pat is saying that theyre very expensive
I got it....
know all about that. Uncle Sam says my computer business has to turn a profit this year.... ;)
I paid $1300 for my Jun-Air 10 years ago. Never hear it running as it has heavy duty refrigerator type compressor. If the compressor has to be in the room with you, you will not regret the cost. Section 179 allows 100% depreciation (expensing) of listed equipment in the year put into service.

Pat :D
I have to do much cheaper than that. I have waited two years to find a great used v-nail machine due to cost.
I never knew which section / name of that "rule" but I knew about it and made good use of it. back to topic

Should this do the trick?
3 gallon
2.4 SCFM@90 PSI (max 125)

Noise is no issue. I have a small closet it can sit in and run the hose through the 1 inch gap under the door..
One of those funny numbers is the airflow needed to run the underpinner all day. It's not really going to be important for 5 frames per week. What you might find is that you do a corner or two then the compressor kicks in. Just wait for it to stop and then carry on. The Craftsman will probably be fine for what you need.
MEH that is what I figured
I have already looked into the little air filter / moisture traps.
Sears is to me like Toys R Us is to kids
Get the one from Sears first, if it doesn't work out then return it. If you order from Harbor you'll either keep it if its a lemon, or have to pay freight to get rid of it.

I go to HD. They are very helpful, and have good answers. If the person I'm talking to knows less than me, then I ask someone else! Haven't been to a Lowes, yet. The small Pancake I had was <big>LOUD,</big> and using it started to hurt my ears. Plus it sounded like it was going to break while it was running, a pained rattling sound!

The bigger units do come with power tools! and haven't you always wanted a Nail Gun!
Just came back from home depot. They had two under $200 in the store (more on line I see).
One was a 4 gallon pancake but only had .5 SCFM
The other one was a 2 gallon and had 2.5 scfm and looked VERY CHEAP....
That is why I was thinking sears, If it dont work right I will just take it back
I am not above plugging them in at sears and listening
I know the manager well

Thanks for all the help everyone!!!!
The Grumble and its members come through yet again!

Off to play with air compressors....actually gotta go pick up the v-nailer first ;)

Thanks again!
Originally posted by Steven6095:

3 Ni/Cycle (what is that?)
90 NI/Min (what is that?)
The first figure is the volume of air it uses every time you put one nail in. The second is the amount of rate of air you will need to provide if the machine is operated continuously at its maximum cycle rate.

SCFM X 28.57 = NI/min
NI/min X 0.035 = SCFM
David thanks!!! and let me just say that I received my second order from you all yesterday and I am very impressed! You all do great work!

On the air compressor front:
Sears had them on sale!!!
3 gallon tank 150 PSI max 2.4 SCFM
not too loud $99

Hooked it up last night and I can get about 6 nails before it kicks back on for a few seconds. Thats fine with me
David Waldmann is one of the Real Treasures of The Grumble.

He's also in that class of Grumblers that I can't quite figure out. He contributes selflessly and regularly on a wide range of topics and I have no idea what he gets out of it in return.

That has very little to do with compressors but I've been meaning to say that for a while. This seemed like as good a time as any.