Using high volume Spary Gun on small Capacity Compressor

[Tegmark]

In regards to getting good quality results from a 8-10CFM spray gun off a 50L 180L/min compressor.

Can this be done for small jobs as long as the tank of air is full & comp doesn't need to start up. Is there enough volume up until the comp has to start up again?

thanks

[BobL]

In regards to getting good quality results from a 8-10CFM spray gun off a 50L 180L/min compressor.

Can this be done for small jobs as long as the tank of air is full & comp doesn't need to start up. Is there enough volume up until the comp has to start up again?

thanks


50L @ 120 PSI is about 15 cubic ft of air.
So at 8 to 10 CFM you have between 120 and 90 seconds worth of air in the tank.
However it will be less than this (maybe half) because you cannot keep spraying once the the pressure drops below a certain pressure.

So if you can paint the job in about 40 seconds you should be OK

[Arron]

In regards to getting good quality results from a 8-10CFM spray gun off a 50L 180L/min compressor.

Can this be done for small jobs as long as the tank of air is full & comp doesn't need to start up. Is there enough volume up until the comp has to start up again?

thanks

Yes, you can, and I do it pretty much every week.

I use a Star EVO T spray gun which is rated at 10-12 cfm, and a 50 litre 2.5 hp compressor (not sure of its specs).

The finish I get is glass-smooth.

Of course its no way to make money, and I would much rather have a larger compressor if I wasn't limited to 10amps:( .

To run out the 50 litre tank through the star gun takes 21 seconds. This means I get 21 seconds of spraying from when the tank is full to when the motor kicks in again. In 21 seconds I can spray a flat surface of about 400 x 300mm (sorry, that's from memory, not actual measure) - so I guess it depends upon what you mean by small objects.

Once the motor starts up, the gun is still atomising OK, but consumption is greater then replenishment so there isn't much point in keeping spraying unless you want a burnt out compressor. Refilling the compressor tank takes 36 seconds.

Using pre-cat lacquer, it doesn't matter much if it runs out half way through an object, I just wait for it to recharge and then resume spraying - there is no visible mark where I restart.

I also have several touch up guns, including the companion star evo-t. Nice gun, but I cannot see an advantage in using a touch up gun because your compressor is underpowered, it uses less air but takes many times longer to do the same area so advantage lost.

A useful trick to know is that most good guns have a two stage trigger. Pull it half way, and you shoot air but no product. Therefore, before you begin spraying each object, shoot away the balance of the air in the tank till the compressor motor starts, allow the tank to refill, and begin each object with a full tankfull.

You can also check out this detailed post in which I talk about the limitations on using underpowered compressors : http://www.woodworkforums.com/showthread.php?t=186151&highlight=underpowered+compressor . I also talk a bit out my experiences with cheap guns vs good guns.

cheers
Arron