One question about a home-built spray booth

Tools, Techniques, and Reference Materials Painting and airbrushing
21

Time isn’t merely money, it’s life. Would you rather spend the time building a spray booth or assembling a kit?

22

That’s a tough one for me to answer. I love to build. I’ve been building and re-building things since I was young. I used to buy and build those quartz radio kits from radio shack (back when the sales people knew the difference between a resistor and an LED). I’d rebuild busted VCRs, TVs, toys and even carbuerators. I’d rather spend days designing and building just about anything than have to go to work. But unfortunately, the bills have got to get paid…

Personally, I’d be just as proud of the booth I built as I would be of the model I painted in it.

But, having said all that, after calculating the cost and time needed to track down parts and get them shipped and then built, I decided to go with a JCM booth from ebay. I like it better than the paasche in that it has the same internal dimensions across the entire width and depth (whereas paasche’s box slants down at the rear, severely limiting the height restrictions at the back of the box). Plus the JCM has a 350cfm which is slightly overpowered compared to the slightly underpowered paasche fan. And at the end of the day, it’s only $8 more expensive than the paasche (ebay prices for both).

-Fred

23

I have read several of these threads about trying to get around the $300 that a hobby booth costs but in the end it may be the safest and best working option. Remember, you can always sell it to your buddies later to recover some of the costs. More to the point is the fact that a good booth with carbon filter and inexpensive prefilters will suck dust, fumes from cleaning brushes with lacquer thinner, and other stinkies like zap and styrene glue out of the air you are breathing. I just run my hose out of a removable rectangular board that I stick in a window when I spray.

A good friend of mine just burned his house, belongings, and two vehicles including a hemi Dodge while using a home made shoe dryer out on the garage. Think about it.

24

Hi Fred,

Did you end up buying your both? I was hoping you’d build one with the bilge blowers and learn from your experience. I’ve been thinking along the same line, but still am a little unsure about the circuitry. I was thinking of using a wall plug-in adaptor first, but their current ratings are usually at hundreds of mA or less, not the 4.5 A that the blowers need. I am exploring the feasibility of a used PC power supply. Do you have any idea on this? Anyone else?

25

Hey MKMT,

I did end up purchasing a pre-fab from JCMfabrication on ebay, but I’d be more than happy share the info you’re looking for.

Here is the power supply I was going to get http://www.trcelectronics.com/Meanwell/s-60-12.shtml and the bilge blower http://www.trcelectronics.com/Meanwell/s-60-12.shtml

You’ll need one power supply per blower. Just need to wire the blower to the supply and plug it into the wall.

Any other questions, just ask.

-Fred

26

Thanks for the quick reply, Fred!

Yeah, I see the power supply cost can add up quickly. I was hoping for a cheaper alternative. On using two separate power supplies though, have you considered getting the one with the 10A rating, and hooking the motors up in a parallel circuit? (e.g. http://www.trcelectronics.com/Meanwell/dr-120-12.shtml) It’s not much cheaper, but wouldn’t it be a cleaner setup? - One plug, one switch, etc. But it does look pretty bulky. My ideal set up would involve a salvaged plug-in wall adaptor that can deliver 12V at 9-10A. I would then wire the two motors in parallel (each branch protected by a 5A fuse), and put a 4-position switch (if there is such a thing: off, motor 1 on, both motors on, motor 2 on; if not, two on/off switches would be no big deal) at the junction between one of the wires from each motor and the power source. You didn’t mention any plan for using a fuse. Are you counting on the built-in fuse in the power supply to limit current to 5A? If that is indeed an effective way to control the current, then your plan has the advantage of needing no fuse. Finally, I think you mentioned before that using two blowers would allow you to have two flowrate settings. I think that’s a great idea. But have you considered the potential for the working blower to draw air from the non-working blower/duct, and thus bypassing at least some of the air flow from the booth? I’m playing around with various ideas about putting in some kind of primative automatic valve in each air stream to prevent backflow. If you’ve thought about this too, let me know what your solution is. Thanks!

27

Hey MKMT,

Slow down, buddy, you’re overthinking this project. You’re going to make it waaay more complicated than it has to be. There’s no need for extra fuses and there’s no concern of cross draw or extra ventillation.

The nice part of my design was that it was simple and flexible. Here’s a step by step rundown that can hopefully paint a more clear picture of what I was doing. Just make sure to read the directions all the way through first. Some steps may be easier to do before the box is assembled, so use your judgement.

  1. build a sheet steel box, 25Wx18Hx18D and mount it to a piece of plywood. The plywood base should at be as wide as the box, but definitely deeper (figure around 25-26"). This extra space will be for the backside so you can mount the blowers and the power supplies.

  2. 2" from the rear of the box add another sheet of the steel (like a false back plate) perferated by 1/2" holes - this is the baffle plate and helps to normalize the airflow before it gets to the blowers (and your filter sits in front of this plate on the inside of the work area)

  3. In the back plate of the box, cut out (2), 4" dia. circles so that they are centered in the plate (about 4" between the two cutouts). This is where you’re 2 blowers will mate to the box.

  4. You’ll need 2 sections of 4" i.d. duct connectors (one per blower). This is how you mount the blower to the box. One side of the duct connectors is going to slide over the blower intake and get clamped in place. The other side of the duct needs to be cut and splayed. Think of making one side look like a daisy. This side is getting attached to the box. Drill a hole in each of the flaps and then line it up so the duct makes a sleeve with hole in the back plate. Use a permanent marker to mark the back plate where the holes in the flaps would be in the back plate. Now you can either drill them out so you can bolt them together or my favorite, use pop rivets - clean, simple and effective. Now do this for the other blower mounting.

  5. Now that the blower sleeves are attached, you can slide the blowers in place and make marks in the base board so you can drill pilot holes for the mounting screws. Drill your holes and slide your blower into position (don’t forget to put the clamp in place first). Now see where you’re going to mount the power supplies. Wire up your blowers, then attach the PSs and the blowers to the base board.

  6. Get 2 lengths of 4"x8’ flexible dryer duct. Attach one per blower using a 4" hose clamp. Other end just hangs out the window

  7. get one (or a few) of those self mounting, battery powered lamps so you have some light to work with, a furnace filter and you are finished.

Now you can run one or both of your blowers depending on what you want to do. If you’re venting while painting, run 2. If you’re venting while drying, run 1. That’s the beauty of my design - simplicity and functionality

-Fred