Nothing but Hot Air...

[Kibby]

*Lassos the reader and pulls them in close*

Gotcha! Let's talk about air compressors!

I have a Craftsman 30 gallon. It was one of those $299 deals back in 1999 I think. It came with a spray gun, and a 3/8" impact as I recall. The compressor has served me well, but its pretty sad in the storage and CFM department. On top of that, its LOUD. Man, when that thing kicks on you know it.

I am sure that Craftsman does not make it anymore, but it is similar to this one: http://www.craftsman.com/shc/s/p_101...+%26+Air+Tools

I remember my dad having a compressor that was pretty quiet. It had a belt-driven pump on it, and seemed to run pretty smooth. I was looking at maybe pulling that noisy, old, hot motor/pump and set up something a little less violent. I was looking at this as a replacement: http://www.craftsman.com/shc/s/p_101...+%26+Air+Tools

Has anyone done this? For me, the shop air system is something taken for granted until I need it. I'm sandblasting/gunkoting/baking a shotgun today, so shop air - or more to the point - the inadequacy of my shop air is on my mind. I'm feeling in a rare mood today, so figured I would present this to you guys, since I value your opinions so much.

[hardtail]

If you are ever going to be doing some blasting where the job is gonna take abit I would recommend something with a least 18-20 cfm, 35 would be better but thats getting out of the mainstream handyman offerings.......go with a cast iron pump that runs slower with a REAL 1740 rpm motor with a 60 gal upright reciever and you should be on your way......those oilless are noisy.

[Kibby]

15-20 would be more than I would ever need. Most of my blasting is in a cabinet, 40psi, and 120 grit aluminum oxide. Once in a while I do ceramic bead. I mostly use my blaster on guns and knives I make.

[Black_Moons]

weird both your urls point to the same product, Lots of bad reviews on that compressor too. I really like the belt driven designs because you have a VERY simple to align motor and compressor, and can replace it with ANY stock motor or compressor head on the market.

Oh I just noticed that one is 'oil free'
NEVER EVER EVER buy 'oil free' or 'maintence free' compressors
It means it basicly uses a plastic piston, or a rubber diaphram and won't last more then a few years in use and will be INCREDABLEY noisy. Like 2~6x as noisy as the compairable oil filled.

And you know how many times a year I change the oil in my oil filled compressor? About 0.5, yea, about every 2 *years*, And that feels generious! simple and easy to do, not even $20 worth of oil and the compressor will keep kicking for years no problem.

Iv got an ACHIENT one thats this style: http://image.automotive.com/f/auto_t...ssor+photo.jpg

Really slow pump.. but 10A at 240v (or 20A but who uses 20A 120v circuits), 6 real CFM (best you'll get from 120v AC is about 5, maybe 6 CFM)
but sooo quite (after I replaced the one way valve on the compressor for a modren teflon propet style it was 1/2 as noisy), its sooo quite, you can *talk* next to it, its so quite it runs outside and you can't even HEAR it turn on anywhere in the house, I leave it on 24/7 and nobody ever complains about it pumping up during the night.

Has enough air for intermitant die grinding (light deburring, etc, not heavy roughing), intermitant air fileing, sanding, etc. great for spray painting and running air drills for small holes that don't take to long, unless your paitent enough to only be drilling about 1/3rd of the time.

Iv also got one of these:

http://www.trident.on.ca/devair/sdi-5hp.jpg

though my tank is a little skinnyer, Its an awsome 5hp compressor, 18CFM
NOISY AS HELL. can't even shout over it in the same room, And that was after removing the belt guard that made it even noisyer!
In the room next to it, you can shout and be heard over it... Costs about $1000 and will run small sandblasters and airdrills/grinders continiously without losing pace. Typicaly rated 140PSI max.

Note the 3600rpm main motor on that compressor and the single stage 3 cylinder design

Theres another 5hp compressor with a 2 cylinder 2 stage design and a 1600rpm motor (and usally 2 belts) and iv heard an older one of these that was VERY quite. but these usally sell for $1600~2000. Also they run up to 175psi usally, but you WILL need more expensive regulators/filters/etc if you use it past 150psi as most regulators/etc are designed for a max of 150psi (and say max 150psi, I would'nt go over) Also have a large cast iron intercooler beween the two cylinders for the good ones.

http://www.squaremcompany.com/industrial-air-compressors/images/216V-medium.jpg

Much like that one, the two cylinders are 'inline' and one is larger then the other.


As is, I use the 2hp 6SFM for basicly everything around the shop, except *serious* work/holes/etc, then I flip on the 5hp 18CFM and go to town.

PS: I would'nt try blasting more then a few square inchs (per project) with a 6cfm compressor, And not more then a square foot or two with a 18cfm compressor. just not enough air to do it fast enough to be worth while, much faster to sand if its flat.
Sand blasting is *KING* for detailed parts however, and inside corners where sanders can never seem to reach. Also gives that wonderful 'dotted' finish that is completely unlike sanding.

[lazlo]

15-20 would be more than I would ever need.

That sounds about right. I had a 12.5 CFM IR that I loved -- it was great for orbital sanders, grinders, etc, but it didn't have quite enough CFM for a sandblaster.

I've since upgraded to a 5 HP Champion that I found cheap on CL, but I think 17 CFM would be perfect for a home shop.

[Dawai]

http://www.eatoncompressor.com/catal...47/1710568.htm

I bought from them folks.. not had a moments trouble. Paint when it arrived seemed to not be hard.. mine is red, has a 4 cylinder pump, the 7.5hp motor requires a 50 amp service. It sucks the residential transformer on the pole dry and makes the lights flash in the house each time it starts.

The water purge valve with timer on the bottom makes me wet myself when it blows and I am *a, thinking of something else, b, nearly asleep in the barber chair, c, thinking of something I should not be..

It will sandblast easily, has a unloader valve on the tank, flip the switch, the motor runs continuosly, the air intake valves kick on and off. It never gets up to the 150psi cutoff on the electrical in this mode, only about 135..

I'd buy again, would recommend to friends. When I purchased, I wanted to paint bikes, cars, light sand blasting.. I have been surprised at the quiet in the room with it running.. perhaps it is them dual air intakes? filters?? the fact it is geared down 10hp pump?? I can talk on the phone in the 10x20 room.

[Your Old Dog]

That sounds about right. I had a 12.5 CFM IR that I loved -- it was great for orbital sanders, grinders, etc, but it didn't have quite enough CFM for a sandblaster.

I've since upgraded to a 5 HP Champion that I found cheap on CL, but I think 17 CFM would be perfect for a home shop.

You're recommending 17cfm but at what pressure? I would like to up grade also so that I can sand blast but not sure how how large to go? Also, what size motor would you recommend? I have a beautiful blast cabinet but don't have enough steam to use it!

[davidfe]

I'll second Mr. Cofer's Recommendations

I have been in a shop that has one of these in it.

Extremly nice equipment. Well worth the purchase. Quieter
than most.

Good luck.

http://www.eatoncompressor.com/catal...47/1710568.htm

I bought from them folks.. not had a moments trouble. Paint when it arrived seemed to not be hard.. mine is red, has a 4 cylinder pump, the 7.5hp motor requires a 50 amp service. It sucks the residential transformer on the pole dry and makes the lights flash in the house each time it starts.

The water purge valve with timer on the bottom makes me wet myself when it blows and I am *a, thinking of something else, b, nearly asleep in the barber chair, c, thinking of something I should not be..

It will sandblast easily, has a unloader valve on the tank, flip the switch, the motor runs continuosly, the air intake valves kick on and off. It never gets up to the 150psi cutoff on the electrical in this mode, only about 135..

I'd buy again, would recommend to friends. When I purchased, I wanted to paint bikes, cars, light sand blasting.. I have been surprised at the quiet in the room with it running.. perhaps it is them dual air intakes? filters?? the fact it is geared down 10hp pump?? I can talk on the phone in the 10x20 room.

[Kibby]

http://www.aircompressorsdirect.com/Chicago-Pneumatic-RCP-3561V/p2043.html

What do you guys think of this one?

[davidh]

try to stay away from the 3450 or 3600 rpm motors. they are noisy and are fast so as to make the little pumps work their [email protected]@es off.

1800 (1725) rpm motors mean much quieter and longer lasting equip. and of course are more expensive.

[hardtail]

YOD your going to need a real 5hp motor at 1740 to drive a 17 cfm pump, you can go with either single stage which should sign off at around 140 or 2 stage to 175 psi.

Kibby I can't see the specs on that one and normally like CP stuff but that one at a glance makes me very suspicious.......looks like possiblt a rebadged China setup, small 3450 motor and if they're inflated claims are usually the case a 3.5hp motor is more like 2hp in reality.

Where is radkins when you need him..........LOL

For reasonable dollars you are probably going to end up with a China setup but there are better out there.......try HF or Tractor Supply for their offerings.

This doesn't thrill me as the motor looks suspect (22 amps is more like a real 3hp) also but if their cfm claims are real????

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=93274

Even with the iconic IR label it looks like someone else has added ingredients to this one.......

http://www.tractorsupply.com/tools/air-compressors-air-tools-accessories/air-compressors/ingersoll-rand-5-hp-60-gal-single-stage-air-compressor-3301332

Yet another........

http://www.grizzly.com/outlet/60-Gallon-Air-Compressor/H7359

Quincy has nice offerings but probably past your budget.........

[bruto]

I have a 3450 rpm belt driven Sears (De Vilbiss) two cylinder two HP compressor that I bought new something like 30 years ago. Aluminum with oil sump, driven by a serpentine style ribbed belt. I worried about the high speed compressor, but it's been very reliable, far more so than an oilless, and would answer for most of the criteria here. But as others have pointed out, it's noisy as hell, really not much better on that front than an oilless. It rattles and vibrates and sounds like a disaster about to happen, and I jump out of my skin every time it starts up.

[Black_Moons]

Can anyone awnser this: (sorry to hijack)
the compressor cylinder head I have is designed to run at like 1400rpm, its noisy as hell, motor pully size is about 5"

but if I change over to the bigger slower 700RPM cylinder head, its got a bigger flywheel, so I only need to go about 3 1/2" motor pully (IIRC) to get the output down to 700RPM, even with my 3600RPM motor

is there any reason this would'nt work? is that just too small a pully? Would I need to go to a double belt? I can't really see electric motors being all that noisy, I think the cylinder head is 90% of the noise..

I ask because iv seen the 2 stage 5hp head for my compressor for just $400
the price diffrence beween my compressor and the better one is like $1000, and the only real diff is the tank goes to 175psi insted of 150psi (blah, i'll do without the extra 25psi) and the motor is 1800 insted of 3600rpm...

22A at 240v is the correct number for a 5hp motor. thats 5280W or 7~ HP before losses.

Im starting to think the best way to get a quite compressor is go to the store with a tape measure and read the motor faceplate and find the RPM the compressor head is running at. I think the quite ones run 600~700rpm. the not so quite ones more like 1000+

[wierdscience]

Black Moons,the noise will still be there,just at a different frequency.Have you tried re-plumbing the intake so the air intake and therefore the intake impulse noise is outside the shop?

[Dr Stan]

You may want to check what's available at the Surplus Center. I built a 5 HP twin cylinder single stage with a 60+ gallon tank using a DeVilbiss pump I bought from them for $99.00. Ended up with about $200 in it for a compressor that would have cost me $800 to $1000. The free ASME tank and a free 5 HP motor also helped. They had several hundred of them, but I believe they have sold out of the item.