Compressor and spray gun at low budget

T

Tartaruga

Hello,
I am hobbyist carpenter, and I want to get fine paint.
I want to spray lacquer, paint, stain.
I did some research, and for my understanding LVLP is better for weak compressors.
I found one at amazon that require 3.5-3.9 cfm at 30 psi

I also found in my country, a compressor with this specs:
24 liters tank (6.3 gallons)
2 HP engine
pressure is 8 atm (117 psi)
supply is 240l/m (8.5 CFM)

It seems fit, but after doing some research im not sure if the compressor is enough,
 
A friend of mine does similar work and ended up going with a Turbine instead of the spray gun and compressor. He is very happy with it.
 
Can you recommend me on something from amazon UK? Or amazon Germany?
Anyway I think that I get a compressor for other stuff, so it all depend on how much I need to add for proper compressor for painting.
 
dont plan on any spray gun using 3-4 cfm. i dont care what type it is. that cfm rating they are putting on the gun is BS. many air tools are cfm rated at maybe a 30% duty cycle. a spray gun is continuous and but they are still giving it a duty cycle rating. an lph400 is considered lvlp and its 14cfm. any full size gun will require 12-15cfm. a mini gun might be 6-10.
 
Now I see the problem.
Can you recommend on mini gun that will fit that compressor?
 
Tartaruga said:
Can you recommend me on something from amazon UK? Or amazon Germany?
Anyway I think that I get a compressor for other stuff, so it all depend on how much I need to add for proper compressor for painting.
Click to expand...
Fugi Turbines seem to be a popular choice. I have never used one so can't get in depth about them.
Here's a video dealing with selection:
 
'68 Coronet R/T said:
Fugi Turbines seem to be a popular choice. I have never used one so can't get in depth about them.
Here's a video dealing with selection:
Click to expand...
just saw it, I think that i want a paint sprayer with 3 stages, im not a professional painter, and when i paint with brush or air can, i just take what the sales men offer. but I want to be able to spray everything.
The paint gun is bought for painting furniture and other wood working that i will make.
now, the price of the 3 stages sprayer is around 600 USD, let say 800 usd if i include the tax and ect.

A compressor I will probably get anyway, the basic compressor is around 200USD. If i can get in 1000USD a compressor and a paint sprayer that will give me better results, i will prefer it, the mobility of the turbine HVLP is not something that will benefit me much.
So which compressor will give me enough juice to run a proper spray gun?
 
Some years back I fabricated and finished all trim and cabinets on site in a 3 car garage. The base molding was 7", case molding also wide and the project was large. I joined two, 2hp, 5 gallon tank, rated 4.6 CFM@90 psi, 100% duty cycle air compressors, each running on separate electrical circuits to a 30 gallon auxiliary tank to supply my HVLP conversion gun. So I had 40gallons air storage total.

Once spraying began on the trim, the compressors ran continuously, but after just a couple minutes pressure/volume at the gun would drop and I would have to wait a couple minutes for the compressors to catch up. Not ideal, but it worked. My setup DID provide enough air volume to allow spraying one cabinet box, and I'd wait a bit between spraying boxes.

If you have the room and the budget, get the largest volume tank you can (60-80 gallon is ideal). If using a smaller, 2-3-5 horsepower compressor, and expect to spray larger items, even waiting between sessions will cause continuous running, so compressor duty cycle becomes important. Most low end compressor are 30-50% duty cycle and are likely to fail if run for long lengths of time. 100% duty compressors are designed to survive and perform well if run continuously for long periods.

You may get by just fine with a $1000 or less $$$ compressors for the smaller projects you envision. There are many good ones in that price range. Think larger tank volume, even if this means adding an additional large tank into the system when greater air volume is required. Your compressor pump will thank you and you'll have the ability to spray at necessary pressure for greater lengths of time.

Happy hunting,

Lance
 
The closer you are to the output of the compressor, the hotter the air will be and shorter the compressor life. Even running a smoking hot gas engine where the air wants to come out is not helping. You can be cheap and do ok. The bottom line is if a compressor is working at half its capacity, its probably going to last a long time and produce drier air. If its always running then it wont necessarily be running for long. Reed valves bend, rings wear, then you are just trying to push your air thru filters before you can use it.

I know people thin paint too much, thin clear even though it is not recommended, those are what you need to alter to try to get by.
 
Get an 80 gallon compressor with a minimum output of 15 CFM at 40 psi.
That would be the smallest I would recommend for a one man shop. If you are using air powered tools the bigger the better.
 
Strangersfaces said:
THIS links to a site offering rather good explanations of factors to consider when choosing an air compressor.
Click to expand...
Thank you for this, very informative, helped me alot!
Compressors with big tank are expensive in my country, but your project gave me this idea.
I saw this compressor, and Ill add another aux tank:
The specs are:
24 liters tank (6.3 gallons)
3 HP engine
pressure is 8 atm (117 psi)
supply is 450/m (15.9 CFM)
this compressor combined with aux tank will be enough for spray gun?


anotheridiot said:
The closer you are to the output of the compressor, the hotter the air will be and shorter the compressor life. Even running a smoking hot gas engine where the air wants to come out is not helping. You can be cheap and do ok. The bottom line is if a compressor is working at half its capacity, its probably going to last a long time and produce drier air. If its always running then it wont necessarily be running for long. Reed valves bend, rings wear, then you are just trying to push your air thru filters before you can use it.

I know people thin paint too much, thin clear even though it is not recommended, those are what you need to alter to try to get by.
Click to expand...

I want to avoid running the compressor at 90% of his power for long, so i dropped the 2hp compressor idea.

'68 Coronet R/T said:
Get an 80 gallon compressor with a minimum output of 15 CFM at 40 psi.
That would be the smallest I would recommend for a one man shop. If you are using air powered tools the bigger the better.
Click to expand...

How can i know how much CFM compressor gives in specific pressure?
my tool are milwaukee cordless m18 (drill, impact, jigsaw, orbital sander and a router for now, multi tool and circ saw ill get soon)


How about second hand compressor? I can get much stronger compressors in my budget.
 
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Tartaruga said:
Thank you for this, very informative, helped me alot!
Compressors with big tank are expensive in my country, but your project gave me this idea.
I saw this compressor, and Ill add another aux tank:
The specs are:
24 liters tank (6.3 gallons)
3 HP engine
pressure is 8 atm (117 psi)
supply is 450/m (15.9 CFM)
this compressor combined with aux tank will be enough for spray gun?

I want to avoid running the compressor at 90% of his power for long, so i dropped the 2hp compressor idea.

How can i know how much CFM compressor gives in specific pressure?
my tool are milwaukee cordless m18 (drill, impact, jigsaw, orbital sander and a router for now, multi tool and circ saw ill get soon)

How about second hand compressor? I can get much stronger compressors in my budget.
Click to expand...

A lot of the budget line compressors overrate their CFM output. A compressor will give a higher CFM output reading when free cycling than it will working under pressure. Some rate it as SCFM or Standard Cubic Feet per Minute.

CFM (Cubic Feet per Minute) is a measure of the Volume (amount) of air the compressor is capable of producing. PSI (Pressure per Square Inch) is the measure of pressure applied. This is why the CFM rating is usually slightly lower at the higher PSI rating.

Adding an extra tank increases the volume of air you can store but in reality a gun that takes 12 CFM to operate will deplete your supply fairly quickly. If you are spraying for 5 minutes you have already consumed 60 Cubic Feet of air.

There is a formula for calculating the volume of air stored in a tank at atmospheric pressure. Divide the tank size 80 gallons by 7.48 which gives you a whopping 10.695 cubic feet of air in the tank. This would increase under pressure so at 100 PSI that tank would have about 73 cubic feet of air.

Personally, I think the horsepower of the motor also comes into play when selecting a compressor. I wouldn't buy one with less than a 5 hp motor based on my experiences with them. A general rule of thumb is that a 5hp motor can produce 10 CFM at 100psi.

So on the label of your compressor should be the following:
Air Compressor 3.JPG


Displacement is CFM produced by the compressor when not under pressure.
Notice how slight the changes are when dropping the PSI by 75. Some compressors manufactures inflate the numbers at lower PSI (like 30) to make their products more appealing but this is a matter sales marketing and not of physics and mathematics.
 
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I see, well in that case I should check how much an engine will cost, for 5.5 HW, should be around 600 usd, ill add it a separate tank second hand.
Considering that my projects are small to medium, do you think a 50 gallon tank will be enough? i dont want to squeeze the budget too much, and I will also need a proper spray gun.

this compression unit got 5.5HP and 17.6 CFM, gives me enough power so the unit lasts for long time?
 
Last edited by a moderator:
Tartaruga said:
How about second hand compressor? I can get much stronger compressors in my budget.
Click to expand...
I would definitely consider a larger used compressor in your situation. Larger (at least 5HP,7.5 preferred) industrial style compressors are designed to run continuously for many years, so a relatively low hours quality compressor will outlast a new home style compressor and provide the air you need. Nothing worse than running out of air, and air quality and volume is critical when spraying. Get the largest compressor you can afford or you will be looking to upgrade after the first job.
 
If ill get a second hand compressor, I can afford 7.5HP compressor for sure, looking in the boards and i see a 11 HP one that I can afford.
Well, considering that Ill get 7.5hp compressor, can you reccomend on a spray gun that will be best for wood? natural and processed wood.
 
I am not sure about other countries but be sure you don't accidentally by a compressor that requires 3 phase power unless you have it available. They frequently are cheaper because of the lower demand but not a bargain if you can't use it.

John
 
John Long said:
I am not sure about other countries but be sure you don't accidentally by a compressor that requires 3 phase power unless you have it available. They frequently are cheaper because of the lower demand but not a bargain if you can't use it.

John
Click to expand...
If you are buying used, its worth the money to buy it and replace the three phase motor with a single phase motor.
 
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