[joesimmers]

I have a new vf2 that was just activated on friday by the haas guy. Every thing seems great so far but I notice when the spindle is on my air compressor is kicking on about every ten minutes. I am a one-man shop with 1500 sq. feet and if the compressor is going to run that much it is going to drive me crazy!

I am interested to hear what others have done to solve this. Before the vf2 my compressor would only come on 5-6 times daily.

My current compressor is:

Ingersoll Rand model SS3L3
60 gallon
3 hp 7.9 hp peak
11.3 cfm @ 90 psi

I am interested in something "quiet"
Something that won't cost 5k.
Something that wont dim my lights every
time it kicks on.

Thanks for any help you can offer.

Joe Simmers
Simmers Machine
Mansfield, ohio

[Geof]

Quiet and below $5k is probably not possible but you could look into getting a small screw compressor. These are quiet, much quieter than the VF2 when it is doing something, but they are not cheap.

Also while you are at it you should look into getting a good air drier; clean dry air is essential if you want to avoid annoying shutdowns because a solenoid valve sticks.

[GaryCorlew]

Would it be possible for you to put on a small addition just big enough to house the compressor?, also you could find a comressor with a bad motor/compessorand use the tank for extra storage, that way it would come on less often but would run longer when it did.

[joesimmers]

Geof, what would be a good air dryer? I have a small decanasint (sp?) filter in my line already. Are you speaking of one of the refrigerated models or are there other options that work well?

Thanks,
Joe

[miljnor]

Ingersoll /rand makes a 20Hp screw machine for under 5k and their drier (refrigerator type) is about 500.00 dollars

[Geof]

The dessicant dryer are okay provided you remember to replace them. I have several machines so it justifies a refrigerated dryer along with a 30cfm screw compressor.

[Geof]

Ingersoll /rand makes a 20Hp screw machine for under 5k and their drier (refrigerator type) is about 500.00 dollars

Give me a link!!! Please!!! I paid a lot more than that for my 15hp Kaeser and I think soon I am going to have to upgrade my system. VF2 number three arrives this coming Friday.

[nervis1]

I just got a new Vf-2 myself and had the same problem, my Home Depot special was running all the time.

http://www.tooltopia.com/index.asp?P...D&ProdID=10765

I got one of these a couple months ago 62 db quiet enough for you? Sounds like a washing machine.

Under 5k too.

Dave

[joesimmers]

Nervis1, looks like a great price on a rotary, how often does yours kick on when you are machining?

How far away from your vf2 is it located?

Mine is about 15 feet from my mill and even closer to my pc that I use for cadcam work.

I did not find what the full load amp was, does it say on your unit?

Thanks again for your help.

Joe

[fpworks]

I have to get one of these also...the new ones on ebay look real good (from Eaton and US Air)

(search ebay for rotary air compressor)

I was going to just buy a rotary compressor and run a hose to the tank of my existing reciprocating unit. This way I will have a backup.

Only downside is that the power requirements are fairly high...but I guess that is what you can expect from a 15-20 hp pump.

[nervis1]

It's about 15 feet away on the back side of the garage. You can have conversation in a normal tone of voice standing next to it when it kicks on. Runs for about 40 seconds to go from 100 psi to 150. Kicks on about about every 5-10 min depending on how much I'm using the air gun.

Runs off of a single phase 30 A breaker. They also have a 3p unit there on that site and one with an air dryer attached.

I bought the air dryer seperate.

I guess you may consider a larger model if you have plans to expand, they have 3-30 hp on that site I think.

Dave

[Geof]

...Only downside is that the power requirements are fairly high...but I guess that is what you can expect from a 15-20 hp pump.

Don't equate reciprocating compressors and rotary screw compressors horsepower for horsepower. The duty cycle on reciprocating should be kept below 50% or you run the risk of overheating; a rotary compressor has a 100% duty cycle and is more efficient. This means that a rotary will give you twice or more the available air per horsepower and that is comparing real hp not the mythical peak hp some reciprocating compressors are rated at. Also if you look at rating for a reciprocating compressor very often it is based on 90 psi but on a rotary it is often higher; the units nervis links to have 120/150psi for the lower and upper limits. Also on a rotary if you drop these limits the effective cfm is increased; most CNC machines are happy with 100/110psi.

There is a 3hp, 8.5cfm unit also on Tooltopia and this would possibly run three VMCs.

P.S. Nervis;
Good link!

[fpworks]

Geof,
I was referring to electrical power. I think you are misunderstanding the meaning of duty cycle. Duty cycle is the percentage of time that the pump is running. i.e. 50% duty cycle means that the pump runs for 30 minutes out of each hour. (and not necessarily continuous)

I am worried about driving a 20 hp motor with three phase, and I'm somewhat limited since I'm running off of phase converters. A 20 hp motor will have the same electrical power requirements whether it is running on a 5% duty cycle or a 100% duty cycle.

I wouldn't put my money on a 8.5 cfm compressor running three VMCs. (if that is rated at 100 psi) The machines I've been around need at least 4-5 cfm each. An air-oil spindle may need 2-3 times that.

[nervis1]

http://www.practicalmachinist.com/ub...ic/14/170.html

Heres a pic of it in my garage, it does not take up much room at all. The bigger units have a larger box on top but the floor space it takes up is the same, tank size is still 60 gal.

[Geof]

No I was meaning duty cycle correctly. What I was getting at is that you might need a 20hp reciprocating compressor, with a matching high amperage supply, which runs at 50% duty cycle. The air supplied by this could be provided by a 10 hp, or possibly 7.5hp, rotary running at 100% duty cycle. Your electrical supply requirements are halved in terms of amperage. You use the same amount of electricity.

I am fairly confident that a 3hp 8.5cfm rotary would do three machines. I have seven Haas VMCs and five lathes on a 30cfm rotary that has a 7.5hp motor; all the VMC spindles are air/oil. The only time the compressor cannot keep up is when the lathes are doing small parts with many tool changes or when somebody plugs an air grinder into the machine air supply.

[fpworks]

My apologies Geof, we're on the same page. It just sounded like you were using duty cycle rating to increase capacity ratings. (duty cycle is the ability to maintain capacity)

I suppose you are correct about a 8.5 cfm compressor running three VMCs. I just timed my 11 cfm compressor with the Fadal running, and its running at 25%. It just seems like more since it is so damn loud.

I just got a quote for a Mazak that needs 7 cfm and an Okuma that needs 13 cfm. (both air-oil spindles)

[1ctoolfool]

The cheapest Ingersoll with dryer I could find is a 5 hp right at $5000.
Would I be better off buying a regular unit and installing a separate dryer? Do you save any money?
Ingersoll looks to be about $1200 more for the same size rotary.
There is about a 400 lb difference between the 5hp Ingersoll and the 5 Hp Chicago Pneumatic.
Anyone know why?
Joe V.

[nervis1]

CP is a good brand, Ingersol is more$, don't know why, if you want sticker shock get a quote on a Keiser, dig the cool yellow paint job too. Wish I could afford one.

I really don't know why the price and weight varies so much. Maybe ask over on the practical machinist forum, more likley to run into a big (20 hp) rotary AC user there.

You will save a couple hundred buying the dryer seperate, got mine from MSC 600 bucks. Mcmaster carr and lots of other places sell them too.

[Geof]

....There is about a 400 lb difference between the 5hp Ingersoll and the 5 Hp Chicago Pneumatic.
Anyone know why?
Joe V.

Does this include the tank? And is the tank the same size? Bigger tanks get heavier quickly not only because there is more area of metal but it has to be thicker also. The 60 gallon tank on the Chicago Pneumatic is on the small side.

[miljnor]

You don't need a big tank for a rotary screw compressor as its there only for spikes in usage and so that the motor can cycle off if not in use!

So if you use something that is a huge short term air user (like a tire machine) then get a big tank otherwise the smaller tanks that come with most of the screw machines are fine.

the Older rotary screw machines that I've seen don't use a tank. The guy that used to be next door to me just had the thing running all the time. His electric bill must have been threw the roof though!