One question about a home-built spray booth

I've seen bilge blowers with squirrel cage configurations rated up to 250 cfm selling for about $100 that would probably work for you, but my personal choice would be an AC powered blower motor with the same type of fan configuration.

This is a chance you simply don't want to take. You made the booth out of sheet steel—why scrimp on the blower?

Other than the possible physical and psychological trauma of a fire and physical burns (Ever had a really serious burn? Very painful, for a very long time, plus the danger of infection.) the insurance headache could kill you. If your insurance company found out that you had built a spraybooth with an in-line motor not designed for flammable exhaust, how much money do you think they'd pay to repair the fire damage? $0.00000000000000000000000000000000, plus dropping your policy.

Just do the math…… 

HA HA!  That's where I've got everyone beat - I'm only a renter                  j/k

Anyway, I think I'm going to go with dual Detmar 751P bilge blowers - 4", 240 CFM, $22 each.

Now I just need a way to get them to run off of AC house power...

-Fred

 

Gigatron wrote:

HA HA!  That's where I've got everyone beat - I'm only a renter                  j/k Anyway, I think I'm going to go with dual Detmar 751P bilge blowers - 4", 240 CFM, $22 each. Now I just need a way to get them to run off of AC house power... -Fred

Just a renter? Your landlord (and his/her insurance company) could sue you for the entire amount of damages—which your insurance would not pay. 

I'm an electrical illiterate, but I think you can get AC to DC converters that will do the trick. Someone here is bound to know how… 

AC/DC convertors are a dime a dozen. Just be sure you use one that can handle the maximum current drawn by two of the blowers you are thinking about using. Otherwise, you could have another fire hazard on your hands.

How about a fan like this

http://www.surpluscenter.com/item.asp?UID=2007020614104729&item=16-1121-B&catname=electric

7", 340 CFM, 115 V/AC, thermally protected motor (does that mean explosion proof?) - $25

-Fred

 

Thermally protected means that it will disable itself if it overheats. What you are looking for is a motor that is not in the air stream, like a squirrel cage configuration.

 

I built my own booth and use a kitchen hood for it. I ONLY spray acrylics through it, and have made sure I have a very short venting system to reduce the possibility of any explosions. I don't recommend using anything other than the proper fan if you are going to use anything else but acrylics, and even if you do spray on 100% acrylics go the extra distance and get the proper fan. I'm seriously considering rebuilding my booth to a downdraft system and will be upgrading to a bilge style fan at that time.

DO show us pics of both the construction and completion of your booth! 

I am curious.  How do you plan to configure your exhaust ducting since you're using 2 fans?

Given the size of your booth, a good single centrifugal ("squirrel-cage") fan rated at around 325 cfm would probably suit your needs, and probably be more advantageous than trying to mount two separate fan systems.  Trying to balance a two-fan system where your airflow is equally distributed between the two of them might prove problematic, unless you are willing to install a plenum, or at the least a baffle/diffuser. I'm in agreement with Ross:  If you're making your booth from sheet metal, and you're concerned about your fans, it seems that plunking down a little more change for the right fan would be the thing to do.  Plus, I'm assuming you want this thing to last a while.  Although I haven't seen the bilge fans you reference, $22 for a centrifugal fan somehow doesn't scream "quality" to me; and I've seen a few fans/motors. 

Just my opinion.

Hope this helps some.

Gip Winecoff

Hey Styrene,

The bilge blowers are inexpensive because the manufacturer's haven't hit upon the idea of ripping boaters off the same way the cage blower guys do to contractors and DIYers.  Bilge blowers aren't centrifugal fans, they're tunnel fans which may also account for the cheaper price.

A bilge blower's one reason for existence is to remove highly explosive gasses from an enclosed area.  If that doesn't sound like the perfect fan for our application, I don't know what does.  As far as price vs. quality, even the absolute most expensive blowers are like $65 and then, that's only through a few online vendors for the big name blowers.

So I figure 480cfm for $40 is one heck of a deal.  A comparable pole blower (about 465cfm) can fetch anywhere between $175 and $250).

I figure a simple diffuser panel behind the filter should be simple enough to stablize the airflow and short length of dryer hose off of each blower to go right out the window will suffice for ventilation.

My only setback is finding an acceptable power supply.  I need to find an AC/DC converter that has 2 12VDC outputs with 10-20A ea..

I'll try to take pics as I gather parts and during/after construction.

-Fred

 

Fred,

Sounds like you have it pretty well thought out.  Have fun building, and be sure to send along in-progress and finalized pics.  I'm looking forward to seeing what you've come up with!

All the best,

Gip Winecoff

styrene wrote:

Fred, Sounds like you have it pretty well thought out.  Have fun building, and be sure to send along in-progress and finalized pics.  I'm looking forward to seeing what you've come up with! All the best, Gip Winecoff

Will do on the pics!!

Going to check out the blowers in person this weekend.  I've got a lead on decent power supplies.  Just need to finalize my construction plans and I am set.

-Fred

 

Well, I've done pages and pages of drawings and calculations and it looks like it's going to cost me about $230 before tax and shipping (not every item has tax, not every item has shipping).  I figure around $260 when all is said and done.  That price includes all the metal, the blowers, the power supplies and the filters.

It's not as cheap as some of the ebay specials, but it is built to my custom specs.  And it's certainly cheaper than the commercially available units...

-Fred

 

Fred,

Not trying to dissuade you, but before you spend all that money, and then have to assemble it all, check out www.dixieart.com They have a back-drafted Paasche booth 22 X 16 for $239 delivered, and an Artograph 15 X 20 downdraft booth for $219 delivered, and you don't need exhaust ducting for the Artograph since it "scrubs" the air with activated charcoal before putting it back into the room.

Gip

Gip-

Ignorant as I am, does the Paasche booth include the exhausting system? Hard to tell from the pic and description. I'm very new to this, so pardon my stoopid question.

SteveM 

Hey Gip,

Thanks for the tip on the booth !

But I have the same question as SteveM, it doesn't say whether or not these systems come with blowers.  I'd hate to buy one of these only to find out I still have to buy a fan system.

Does anyone know for sure if there is a fan or not?

I sent dixieart an email asking them if had included fans or blowers and what cfm they are rated for, so if I get a response from them, I'll post it in here as well.

Thanks,

Fred

Here's a question about filters.

With all the air I'll be moving, do I need those allergen filters or will a standard furnace filter suffice?  I figure since I'll be moving about 480cfm out the window, I wouldn't need the allergen filter.  Though I could see them being beneficial if I didn't want to vent outside...

Anyway, what's the opinion on this?

Thanks,

Fred

 

SteveM and Fred,

As far as I know, the Paasche, as well as their other booths, come as "plug and play".  For the Paasche, all you have to do is hook some flex duct exhaust hose to the fan, plug it in, turn it on, and have at it.  You might want to check on what, if any, filters come with the booth.

The filters you want to use are paint filters.  An allergen filter would work, but only if you're exhausting air back into the room (a no-no).  Furnace filters IMHO don't provide enough surface area to capture the smaller pigments generated during airbrushing. I would tend to think that paint filters should be available for specific booth types through Dixieart.  If not, paint stores should have what you're looking for, except you may have to trim to fit your particular application.

SteveM, there are no stupid questions in regards to this stuff.  Feel free to ask away!

Hope this helps some.

Gip

Well, I heard back from dixieart.  The paasch booth comes with a 240 cfm blower.  It's 22"x16", so 240cfm is dang close to the  244.4 (calculated (22x16x100)/144) cfm needed.

That's really tempting to go with this one.  It's a bit cheaper than my plans, and it's already assembled...

-Fred

 

Gigatron wrote:

That's really tempting to go with this one.  It's a bit cheaper than my plans, and it's already assembled... -Fred

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

Triarius wrote:

Gigatron wrote: That's really tempting to go with this one.  It's a bit cheaper than my plans, and it's already assembled... -Fred Time isn't merely money, it's life. Would you rather spend the time building a spray booth or assembling a kit?

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

 

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. 

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?

MKMT2003 wrote:

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?

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

 

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!

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