Originally Posted by slofut
Wow ZimmeJ, That looks awesome! Really nice shop, where is the overspray going?
Hi Slofut, I'll post up the air handling system I use in my "all in one" shop. Right off the bat it goes without saying that this is just a system I have come up with based on my experiences over more years than I care to think about! Also, a setup like this is not suitable for frequent or production use. It works fine for us hobbyist types that don't have a ton of money for a real spray booth and don't paint cars very often. Probably breaks all kinds of EPA laws too!
And yes, I use squirrel cage fans because they move huge quantities of air with a relatively small size. They are not ideal for the exhaust because the blades will get a buildup eventually even with purpose made spray booth filters. I'm also aware that it is not recommended to pass the exhaust fumes over an electric motor. The preferred method is to use a belt drive fan with the motor outside of the exhaust. I have a lot of experience calibrating and using LEL (Lower Explosive Limit) instruments and I can tell you with certainty that the exhaust air stream doesn't even register on the meter. I have measured it.
Again, as hobbyists, we just don't spray enough continuously for this to be a problem. Nevertheless, attempt this at your own risk if you want to try it. So there's the obligatory cautions!
I learned years ago that it is important to keep a good airflow, or "air curtain", moving over the car while painting. This will greatly reduce particle "fallout" landing on the wet paint. The air flow simply blows them away. So the next logical step was to filter the air blowing over the car. I knocked out this air supply unit in just a few hours. I used 7/16" OSB and ripped up several 1 x 4's to 2" width. I used these for the glued on cleats. That way the box can be disassembled if I decide to keep it. The fan came from a friend in the HVAC business. They are always throwing them away. This one has a 3/4 hp motor and moves about 1500 cfm. I got a 4 x 8 sheet of plywood and cut a piece that would fight snugly inside the door frame of my shop. Then I cut a hole in the plywood that the box would fit into. To use it I just open the door, put the plywood in the door frame, roll the air box plenum up to and through the plywood. The filter size is 20" x 30". Here's what it looks like:
Next, on the inside I connected two 8" flexible ducts to the two adjustable 8" ducts on top of the air box. (Note: In this pic the air box is not in position in the plywood "door".)
The other end of the hoses connect to a "header" with two adjustable 8" ducts. The header is just hanging on my ladder.
That's the fresh air system. Next is the exhaust fan. It needs to have a bigger fan with higher capacity than the fresh air fan. I found an almost new 1 hp 2600 cfm fan online for $35. Then I built a box around it that is open on 3 sides. The 4th side has a plenum that sticks out at the bottom of my shop overhead door. It is important that the exhaust fan moves much more than the fresh air fan. The openings on the exhaust fan box are 20" x 30". I have them covered with commercial spray booth exhaust filter material.
This setup works very well. I still get a few trash "nits" in the paint but nowhere near what I get painting with no fans at all.
Another easy to make and very effective device is the light pole in this pic. I found the LED lights at Home Depot. They are very bright and come in sets of 2 lights. They come with mounting brackets, interconnect cords and power cords. The pole is nothing more than the 2" x 3/4" strips of 1 x 4's. Drilled a hole through them so that the top pole can be angled. The bottom pole is anchored by the white plastic bucket that is about half full of concrete mix. I just mixed up the concrete, stuck the lower pole in it and waited for the concrete to set up. They aren't hard to move and are very hard to tip over. Carefully placed artificial light is the key to applying just the right amount of spray. You have to be able to see the reflection of what you spray or you will most likely have dryspray or a run.