What compressor????

[EsPeGe]

Hi all, as some might know I've just painted a bike. It was done with high quality spray cans. It came up pretty good but given all the time currently on my hands with nowhere to go I want to do another one to get it right and this time I'm buying a spray gun. To run it I need a compressor, obviously. I need some help with this so hopefully someone out there has some experience.

My main issue is the cost of a good compressor, best part of 1K. Now I'm only a hobbiest, I'll paint the ocassional surf board or bike or maybe some art every now and then so I don't want to spend that much. But to get one that will run the gun I want it seems the cheap ones may not be up to it.

So.... I'm gonna get technical. The gun needs 7.59CFM (cubic feet per min, 232Litres/min in normal speak ) at 29PSI. Technically a compressor needs to meet that, most compressors, in fact pretty much all but the smallest get up to around 120PSI so no issue there. It's the volume that counts a lot of them out.

But from my understanding, and this is where I'm hoping someone can help, If I've got a big enough tank the volume doesn't matter, just the PSI. The compressor pressurizes the tank which then runs the gun. The compressor should only run to re-pressurize the tank when you have used enough air to drop the pressure below required. Now, if I was painting a car that would be an issue as I am spraying for longer durations and running the pressure down so the compressor would be running more and then volume becomes an issue. But because it's only a bike, you're done in under 5 minutes (per coat of course) then as long as the tank is big enough I should be good right? I might then be able to get away with a smaller compressor with a good size tank?

I hope this makes sense and someone out there can help.

Cheers all, Scott.

 

[link1896]

For compressors you can buy off the shelf, tanks are proportionally sized to motors in the bottom end of the price range. Some might seem to deviate on motor size, but when you factor in duty cycle capability of the motors, they aren’t too far apart from each other.


This is where the FAD (free air delivery) specification comes in handy.


You need a FAD for this gun of 232L a minute. Ideally you want a compressor with a FAD rating of 250L a minute or more.

You can cheat though if you’re compressors FAD is under the guns if spraying a bike frame (but not a car), add a beer keg or a LPG bbq bottle or two to the system for extra storage, the actual spray time for a bike frame will be short enough that the storage capacity of the compressor tank and external tanks will be long enough, but the duty cycle for the motor over a hour would not be exceeding 50%


Compressors sure have gotten silly expensive, it’s why I built mine out of parts. More so then ever, compressors take up a lot of room in a shipping container, and shipping prices are up 200-300%

Second hand is an absolute crap shot. Most are sold because of a fault or known abuse.

 

[link1896]

Sydney Tools

sydneytools.com.au

This is about where you’re at sadly. I wouldn’t go an oil less pump, they use either diaphragms that all seem to tear just out of warranty, or are plastic pistons that bust the belt when they jam up.

 

[fatboyonabike]

have you considered a good airless spray gun?

 

[Dales Cannon]

Good reply from link as usual. I was going to calculate what size tank you need but you can get the idea. You will use a lot of air even painting a bike frame. I bought a decent 15cfm V twin compressor on 100L tank many years ago and it still runs out of air sometimes. It takes up a lot of space and now that I have compressors on the 4wds and one of those air pump skins for top ups around the place and track days it will get moved behind the shed and plumbed in.

It will come down to what you are happy to buy. A 60L tank alone is about $600. I have used 4wd tyres pumped to 60 pissies for airbrushing but it is shit. I now hook up a 6L tank to one of the little compressors if I need something portable but that won't paint a bike frame without interruptions.

 

[Flow-Rider]

Don't buy the cheap water/air separators or airline fittings either as they restrict the air flow to the gun.

 

[dazz]

Also for you FAD, 1 cfm equals 28 lpm. Plenty of online calculators/ converters. Just get Hambo to send you a link.
Edit**
Should have read your OP thoroughly, seems you're all over the maths.
And you're on the money about capacity. One option could be to keep any eye on marketplace, gumtree whatever for a couple of the cheapo compressors, turf the motor/pump and just daisy chain the tanks together to get you enough storage to cover your needs. Or even team a couple of cheapo units up to bump up the FAD to what you need when painting, the rest of the time just run one, this might be a bit tricky, as to get it to work right I think you'd need to have the second compressor turn on via a relay circuit from the first, a master/ slave kind of arrangement.

 

[fatboyonabike]

unless you have moved @EsPeGe , I recall a picture of your garage...not a lot of room to play with
A decent compressor with receiver will suck up quite a bit of room, ok if you have plans for other projects to use it on
If you live on the coast or any where warm, coming into summer, moisture in the air is going to be a big issue too...if you want good dry air, you are going to need a dryer.

 

[fatboyonabike]

see if you can find a small 2nd hand rotary screw compressor, some will have inbuilt refrigerated air dryers
if you have the room, mount it outside the garage and run your airlines through the wall
something like a small Pilot or Kaeser will do the job

 

[dazz]

see if you can find a small 2nd hand rotary screw compressor, some will have inbuilt refrigerated air dryers
if you have the room, mount it outside the garage and run your airlines through the wall
something like a small Pilot or Kaeser will do the job

How much can you get these units for??? I'd love a setup like that but always figured they are in the multiple thousands of dollars, even second hand.

 

[Flow-Rider]

You can easily get away with a smaller compressor, the more expensive sprays guns seem to atomise the paint pretty well with less pressure and flow, you generally need full pressure at the gun with shitty paints like enamel, but in any case you don't hold down the lever on full for the duration of the painting of a bike frame away. I painted this frame with one of those cheap 24l tank compressors, something like 150l/m. If you use a smaller fan pattern, you also reduce over spray and wastage of the paint.

 

[discofrank]

2.2kW - WE 18/54 - WestAir International Pty. Ltd.

15 Amp single phase belt driven air compressor. Our heavy duty belt drives are made for serious industrial applications. Slow revving bulletproof 2 cylinder cast iron pump with AS1210 certified air receiver. Low amp draw motor and German Condor pressure switch. Comes complete with 1/4" Filter...

www.westaircompressors.com.au

this will work for you

needs a dedicated 15amp circuit though

yes it is not cheap, but nothign that will last ever is

 

[EsPeGe]

Thanks for all the replies boys. I love this community.

 

[EsPeGe]

add a beer keg or a LPG bbq bottle or two to the system for extra storage, the actual spray time for a bike frame will be short enough that the storage capacity of the compressor tank and external tanks will be long enough, but the duty cycle for the motor over a hour would not be exceeding 50%

Mmmm Cunning, I could make this work but I think it will be my last option. room is at a premium for a start. Clever idea though.

Cheers Scott.

 

[EsPeGe]

I wouldn’t go an oil less pump, they use either diaphragms that all seem to tear just out of warranty, or are plastic pistons that bust the belt when they jam up.

Most painters recommend them. you don't want any oil in your paint. Is this not a thing? I literally have no idea here.

 

[EsPeGe]

have you considered a good airless spray gun?

Mate I haven't, from the limited reading I've done on them the finish isn't close to what an air gun can do. Am I wrong on this?? If so I'd definitely listen to advice on it.

 

[EsPeGe]

unless you have moved @EsPeGe , I recall a picture of your garage...not a lot of room to play with
A decent compressor with receiver will suck up quite a bit of room,

Good memory, what you don't see is a corridor behind my garage. It's full of shit but I could make a little room. Technically it's not mine so I can't take the piss too much but I could squeeze a compressor in. I think.......

If you live on the coast or any where warm, coming into summer, moisture in the air is going to be a big issue too...if you want good dry air, you are going to need a dryer.

I do, Cronulla. When you say a dryer do you mean like the heaters in a spray booth? Fuck don't give me more issues. Painting the last bike took ages cos I painted in the cold months and it took a week to be sand-able. I don't need the reverse!!!!

 

[EsPeGe]

see if you can find a small 2nd hand rotary screw compressor, some will have inbuilt refrigerated air dryers
if you have the room, mount it outside the garage and run your airlines through the wall
something like a small Pilot or Kaeser will do the job

Ok I'll do some googling. Thanks for the suggestion. I'm definitely looking at second hand very closely.

 

[EsPeGe]

You can easily get away with a smaller compressor, the more expensive sprays guns seem to atomise the paint pretty well with less pressure and flow, you generally need full pressure at the gun with shitty paints like enamel, but in any case you don't hold down the lever on full for the duration of the painting of a bike frame away. I painted this frame with one of those cheap 24l tank compressors, something like 150l/m. If you use a smaller fan pattern, you also reduce over spray and wastage of the paint.



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This is giving me hope. I dont mind paying a few hundred but fucked if I wanna fork out 1K on one. Cheers dude.

 

[EsPeGe]

needs a dedicated 15amp circuit though

theres the rub and another issue. all of the compressors that will easily run the gun need 15amp. Easy enough to get a sparky drop one in but yet another fucking cost.