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Compressors and such

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bigjones

bigjones

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Here's the latest acquisition:

grinder-1.jpg


As you can see, it is model #4131, of US components but assembled in Fuji - wow! It's a global economy!

Got it on sale for $12.99 and it was the last one in the store, seriously - does it get any better??!!

Slight problem in that it works for 1.35 seconds and then has to get it's breathe back (like the owner).

This surely has to be a problem with the compressor, right? It's a Bosbitch 1.5 HP, 6 gal, 2.7 cfm @ 90 psi, which is OK for the nail gun, but no one shoots nails bang, bang, bang unless you are Frank or Rambo, right?.

Do I need a bigger compressor?

Cheers!
 
The box for the tool should have it's requirements listed on it in terms of PSI and CFM.

Based on the size of your compressor I'd go with seriously underpowered.
 
Adrian, in addition to Jody's advice, try running the tool at reduced pressure (60-70 psi instead of 90). You won't get as much torque or speed but it may be enough for what you want to do.

If you are considering buying a new compressor... go for the most CFM at pressure that you can afford. Cast iron pumps hold up better in the long run (generally) and diaphragm types are generally noisy. I'm using a small 2 HP Craftsman compressor I bought used 20 years ago. I've had to replace the reed valves in it a couple of times but it just keeps going.
 
Thanks Jody.

Box.jpg


Looks like it only wants 3 cfm @ 90 psi. The compressor is 2.7 cfm @ 90 psi. What am I missing?

Cheers!
PS. Just seen your post Doug - I'll try that! Yeah, I may be looking at getting a new compressor, so your advice is much appreciated!
 
If your air lines are 1/4" you will have a restricted delivery. That means you might have to replace all the fittings and lines from the tank out. I have the same tool and sometimes it just uses too much air. Got leaks???
 
So, I'm a bit of a pessimist when it comes to air tools. I use a working assumption that a compressor will deliver 70% of what is advertised and an air tool will consume 150% of what's advertised. This appears to work well for me.

You have to remember that while CFM and Pressure are important, there's a third factor which is compressor capacity. If you have two identical compressors with different size capacities (e.g. 2 vs. 20) the larger capacity will give you much better performance.

In addition to this, with a smaller compressor you wind up running it on a continuous cycle. This causes the compressor to heat up significantly. When you account for gas law physics and such the compression rate at the end of the air hose (cool) is lower than at the compressor (hot).

I would minimally upgrade to a mid-range unit like mine (6hp, 5.8 CFM @ 90PSI, 20 gallon), or preferrably buy a *much* bigger one. I go down to the compressor shop and keep promising myself I'll get one of the great big 220volt ones after I finish this Jensen Healey and make space in the garage.
 
IMO you need a bigger compressor. Long lines will hurt too. Did you oil it?
 
You may also be running a regulator or lubricator (or filter) that is restricting the air flow-
Try running a straight line directly out of the compressor tank with as short a hose as you have and you MAY see a huge difference (or you may see NO difference, this IS a test)
BillM
 
Changing lines from 3/8" to 1/2" means changing fittings but if you research pressure drops and 3/8" vs. 1/2" hose you will see a dramatic difference in CFM at the end of the hose. Every fitting in line drops pressure and drops it dramatically.

Google Air Compressor and Pressure Drop. I went to a 1/2" hose only 25' long and removed all extra lines and fittings. If I need to get 100' away out in the driveway I can add couplers and extra hose.
 
I'd stay away from that compressor and stick with an "oil filled" one. Oilless are noisier and generally don't last very long.

If you're looking to buy a compressor learn the good brand names and scour Craigslist.

This is roughly the unit I presently have: https://www.cpocampbellhausfeld.com/campb...eld-compressors. I certainly didn't pay their list price, I think I picked it up for ~150 to 200 dollars at harbor freight a decade ago. It's certainly been worth what I paid for it and more.

The size works ok, but I would really want a bigger unit if I were doing anything much more serious. I use this in tandem with my media blaster, and it runs out of oomp too quickly.
 
Jody, you are right about oil-less compressors not lasting as long. But I have been looking for a long time for a compressor to fit my needs. When I do airbrush work I use a small appropriate unit. For a shop where it would be used often or even daily for years I would go for an oil filled sized to meet the shop needs. At the foundry I worked at we had a 2 cylinder horizontal compressor with the large cylinder piston measuring 36" in diameter. It had an external armature motor. The armature was 8 feet in diameter and the piston rods were 12 feet long. Standing outside by the air intake made you want to grab onto something fastened down when it sucked air in.
My point is that I like the stats of this one and don't need one for a lot of extended use. Probably won't ever use it for more than 100 hours total run time.
 
Tom,

Oh, ok. That's a horse of a different color! :smile:

I'm still amazed that my compressor hasn't given up the ghost on me. It's in use often and for long durations.

Jody
 
Highly recommend a Quincy made in good ol USA at Quincy Ill. I just replaced my 55 year old Quincy not really cause there was anything wrong with it but because a salesman scared me about old rusty compressor tanks. New Quincy stays ahead of a small sand blaster rig nicely!

Kurt.
 
Hi Kurt, you were right to be concerned. A company in a small town we were living in had a tank let go. It blew the concrete back wall of the compressor room completely away. They were just lucky the outside wall went instead of the inside wall.

BTW - what model Quincy did you get. I do like the "Made in the USA" part.
 
Just like water, if you want a lot air for any length of time with consistant volume and pressure. Storage!
 
Best bet is 220 VAC if you've got 220 VAC in the garage. For me, no 220 VAC and SWMBO says I don't want that big thing in my garage. I need to settle for 110 VAC horizontal. I like one that Tractor Supply sells that is a CH, continuous duty rated motor, 25 gallon tank, 5.8 CFM I think at 90 psi, around $399. Also Sears has a Professional Model, same sized, 25 gallon rater 5.0 at 90 PSI, dual cylinder pump and continuous rated motor.

I picked up an older 30 gallon Sears oil free, as a freebie to get something. I need to replace rings but parts are available for $20.00.
 
Regarding rusty tank bottoms, there are methods to minimize that.

There are automatic tank drains that you can install on almost any compressor to replace the manual drain cock. There are electric ones that work on a timer and there are ones that cycle each time the compressor turns on and off.

I went the cheap route and bought the Harbor Freight auto-drain kit (item 46960). It taps into the unloader valve circuit. Now each time the compressor stops, the auto-drain valve opens for about 1/2 second and blows condensate through a tube to the outside of my garage. This is not a high-quality kit but it does work and it minimizes the amount of water left in my compressor's tank. Like most Harbor Freight stuff, quality is hit-or-miss. The HF web site includes reviews of this drain kit. I can confirm almost all the issues reported there. However, with a little additional TLC, the $10 investment will work long, well, and as advertised. Just don't expect perfection out of the box.
 
The Quincy I bought is approx 50 gal and at least 3hp 220v. I'd have to go to the shop to check exact model. The one it replaced was about half that size. They make mainly industrial. I can expense it on my taxes but it was'nt outrageous. I'm sure you can Google them.
No auto water dump but it seems to me the main danger on tanks would be time. I drain the water regularly.

Kurt.
 
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