It's been over five months since we took a look at progress on the spray booth. A lot of things have happened and the booth work has been interwoven with all of them. It's certainly not done, but I'm ready for some serious spraying. Warning - this is a long post - you may need additional sustenance before the end.
BEFORE: Air comes in from the compressor outside the booth through the yellow hose in the lower right corner. All the rest of the stuff here has to be mounted, hosed and wired to be used effectively in a small space.
AFTER: A quick view. I hope it works the way I planned for. The next image shows what's what and what it does.
Compressor air comes in at the lower left and loops up to regulator, which is mounted very high so I can read and adjust the tiny gauge for each specific tool being used. After going through the water filter/regulator, all lines out to the various devices are connected on the left. There's the line for the ion gun (for static control), airbrush and two separate spray guns.
All of the air tools are mounted on an angle to keep the paint pots level when they're not being used and to bring them easily to hand in a better position.
The ion generator unit is mounted down low and upside down to keep debris out and help with proper placement of everything else. All electrical switching (except the explosion-proof exhaust fan which has its own proper switch) will be done outside of the booth to prevent any arcing problems. The area below the outlet will be walled off and the switch box will be mounted there.
An overall view as you enter the booth. Tools to the right, drying and storage to the left. I'll get into the filtered air supply as I finish those sections.
The stack up in the plenum was done in CAD to keep the rampaging possibilities under control. Anything can be anywhere in 3D space until it's screwed down.
I don't think I've mentioned that the entire booth, structure and contents, are screwed together so that I can make any needed changes more quickly. It takes longer to design and construct, but has already brought many benefits.
The extra time needed also gives my thought-process a chance to meld with what is actually possible.
The vertical position of the plenum box’s bottom was determined by the ducting and fan geometry. There's about 3/8" (9.5 mm) clearance under the bottom duct tube.
Thus the height of the structure needed to support the plenum was finally determined so it could be screwed in place. Only the back and right sides are supported by this framing. The front and left are determined by upcoming additions so a temporary leg is used to support the left front.
Corner blocks with bolts and t-nuts were used to join the plenum surfaces. I can take the whole thing apart and make adjustments as needed.
Additions can be handled similarly.
Since the whole booth concept rests on isolating the fan from the booth, having a fan inlet shaped like a trumpet bell presented challenges. It must be isolated and whatever it mates to must be air tight too.
I built a box to fit close to, but not touch, the fan. This was filled with two thick layers of foam shaped to fit the fan bell and odd spaces. Depicting the box and foam development process alone would fill a lengthy post, so I've spared you that.
The box foam transitions the air flow from the fan inlet size down to the fan bell diameter. After the plenum base and the box frame were in place, the foam pieces were added and the box bottom pieces were screwed in.
The plenum box walls were added using the corner blocks. Additional holes are for mounting taller overspray walls later in the build.
Four 3D printed throat baffle supports position a nicely sized pail lid. This baffle is intended to create a more complicated path for the entering air so that it doesn't all just rush down into the fan.
A simple green vinyl coated fence support structure will hold up the plate baffle above it.
3D Printing was also used to make a customizable baffle plate made up of 16 separate sections. I calculated the open area based on some previous industry experience and went from there.
Each plate section took 6 hours to print. They're held together with 3D printed U-channels and it sits freely on the screen support.
The free space at the ends is intended to encourage some air to move away from the center to avoid excessive turbulence in the center.*
(*Please note that my degree in the science of the fluid dynamics of moving air is from MSU - the esteemed Making Stuff Up University that most of us make frequent use of.)
First test! Green filter sections and cardboard walls were added and the spraying began. Fortunately, the results were good. I was confident enough that the booth could be cajoled into further good results that I've continued apace with development.
Just to reassure you that I don't do everything in CAD, these on the spot hand-drawn projected build pencil drawing attest to some informality when that is the fastest way to get there.
Of course, the as-built version is different and therefore functional.
The previous bit of drawing was to figure out how to graft a prehung door onto the existing structure. The largish openings to the upper left of the door space are where the booth intake openings will be, complete with sticky filters.
The door was successfully installed with proper measures of patience and persuasion.
Properly drying paint is helped by both controlled heat and air movement. I purchased a good-sized enclosed drying booth and have tested it successfully on small pieces.
Fitting it into the booth has been interesting.
It will live to the left of the painting area on top of this just-started structure that will also provide some much-needed storage area.
The front glass panel folds down so it must have some support to rest on and the higher off the floor it is, the better my back will feel. It barely fits in under the plenum box and the heat adjustment knob just clears the plenum box front. Electrical connection is made in the upper left rear through a hole in the booth wall.
Before installation I lined the interior with white shelf paper to keep it from being a black cave. Even lights didn't help without using up too much space.
The available storage area below is a good start. Time will tell whether it is enough.