Nice Work, your cabinetry is much better then I did on mine.

I chose a squirrel cage blower to keep the motor out of the stream of fumes, but AC motors don't really have the same problem with sparking that dc motors have. I would suggest caution if using solvent based paints though.

I will be interested to see what you come up with for a light. Mine has a plexiglass winndow on top that a clamp light shines through. Not an option on yours. Perhaps from the side?

Chris

if the fan is mounted on top versus the back?  I have no clue one way or the other, but my home-made booth (that I bought from the builder) has the fan up top and it seems to pull the fumes as well as the stray spray pretty well.  I'm just curious about the air flow of one as opposed to the other, if anybody knows.  Thanks!

 Hi Dave.  

According to the author of this website it does.  http://modelpaint.tripod.com/booth2.htm  

So it was a factor when designing my booth also combined of the limitations of my available space to have a booth in my work area.

You're right, the article was very informative.  If I were doing it all over, I'd have the guy I bought it from build it right in the first place!

I'm a little embarrassed to say this...but I kinda screwed up... sorta I guess...I'll explain... 

So yeah...I guess I made a mistake when purchasing the type of fan for this project.  So I hope anyone who has been following this thread catches this note before they purchase their own fan and plows forward.

I was talking to a guy who works in HVAC. Installs much larger airflow systems for a living. We got talking about my little project and when I mentioned what type of fan I was using he was like,

"So you are just going straight threw the wall right no duct run? Maybe 8" - 12" of ducting at most?"

So I'm standing there saying, " Um no,...more like in feet."

He goes on to tell me that Axial type fans are good in free flow environments and that the CFM's decrease drastically when placed inside ductwork. He mentioned that if I was just going straight through the wall to the outside, I'd be golden. He said chances are I could go ahead and see how it works, however he highly doubted that the fan would be effective at venting any fumes outside of the house. Plus the back pressure in the duct work could cause the motor to burn out faster....  

For the record...including elbows I'll have 15 equivilent feet of 4" duct work to run through with this.

I did some checking on-line and there are a couple of other websites, that confirm this, should have bookmarked the links, however I was a little disheartened by this development.  The only reason I used the Axial Fan in the first place was because, it had more then enough of a CFM rating for my use...at least I thought it had.  Secondly, the article although helpful as well as possibly perhaps a tad misleading mentions the use of Axial Fans in commercially available booths. So I figured why not use one for mine too?  

So back to the drawing board. I been looking at squirrel cage type blowers like the one Chris uses in his booth. Two Dayton Blowers have grabbed my attention in particular.

Dayton 1TDR3
http://www.drillspot.com/products/433894/Dayton_1TDR6_PSC_Blower
or
Dayton 1TDR6
http://www.drillspot.com/products/433891/Dayton_1TDR3_PSC_Blower

So there is a choice to deal with here. Either one will move the proper amount of air for the length of duct required. The 1TDR6 which I am leaning towards has a smaller outlet about 3", however if I run it into 4" duct, it will reduce the static pressure inside the duct work and allow better air movement.  Theoretically speaking of course... 

I've also decided to do a design change as well and convert the current booth into a downdraft. Reason being is that either of these blowers if mounted on the back will require an extra 90 degree bend in the duct work adding 6 more feet to the overall run. (4" duct 90 degree bend = 6' straight duct). It will also add height which I do not have. Overall advice I've been given is to keep runs as direct and smooth as possible. The fewer the bends the better it will all work together.

The design change will also require me to cut a large opening in the 20" by 20" bottom and install a 3" plenum underneath the booth. I've already figured out how I'm going to accomplish this. Another hurdle I'm trying to overcome here is that I cannot seem to find a dealer who sells these fans or a similar product in Canada! Even the local Acklands Grainger does not list it on their website. I've e-mailed them, just waiting for a reply. Shipping from the States on an item this "heavy" is going to cost me too.

Maybe I'm not looking in the right places...  

I'm chalking this one up to experience but planning to move ahead and get it done right.

I assume the fan you end up using will have a sealed motor casing so no fumes will be ignighted from sparking inside the motor?

Also, you should include a small under-cabinet light at the top of your booth to light your projects inside. Otherwise a paint booth that's poorly lit isn't exactly the most useful ...

It's always something, isn't it? Home made projects like this help you appreciate more what you're getting when you purchase a professionally designed paint booth.

 Looking at your booth, I noticed something you will want to add - a filter in front of the fan. If you don't have something there that you can replace, all the paint overspray will collect on your fan and ductwork. This will have an effect on which fan you choose, as there will be more resistance in the air flow. Furnace filter material is fine, and I think I had a piece that was only 1/4 - 1/2 inch thick. After a bit of use, looking at the filter with its accumulation convinced me it was a good idea. My own 'booth' was just a cardboard box with a squirrel cage fan behind it leading into plastic dryer ducting. Mr. El Cheapo here :o}

 Yeah...I have a 20" x 20" filter to put in it.  Began to build up the plenum this afternoon.  Lookin pretty awesome I must say.

I've been trying to figure out a way to build a paint booth for a few weeks for a low cost. I've been trying to research the most efficient and safe motor for the project and everyone says, go with a squirrel cage blower (like the link you provided or a cheaper one at 148 cfm http://www.globalindustrial.com/gcs/prod/30127642/i/productInfo.web?utm_source=google_pr&utm_medium=cpc&utm_campaign=Fans-Agricultura-google_pr&infoParam.campaignId=T9F), a fan using a pulley motor (which there is none for a smaller scale paint booth), or brushless. Well, I went with 4 120mm PC brushless case fans at 75 cfm a piece for 7 dollars a piece. I have a 90 cfm case fan that isn't brushless, but I can feel the movement of the air at 10 feet, so I was hoping 4 brushless ones will suffice.  

I haven't gotten them yet, should be here any day. But after having read your statement about the loss of flow when using a duct, I'm wondering what I am to do with these case fans  Although, I still feel that I could make them work and actually push fumes out, there is obviously a better solution and I suppose it would be the squirrel cage blower.

As for the placement of the fans/plenum, it's my belief that if you primarily work by airbrushing objects in the direction of the back panel, a cross-draft set up is best suited. If your working on small objects on the bottom surface of the booth, than obviously, the direction of the paint will be forced down before up or forward, so...a down draft would be best suited in my opinion.  But this is my personal opinion. Spray can painting would probably be a different story since it comes out in a wider mist pattern, unlike airbrushing If you had a powerful fan pulling 300 plus LFM, I suppose it wouldn't matter where you actually placed them.

I'm thinking that I will go ahead and get the blower in the link that I posted. 148 cfm is powerful enough for a mini table top booth. I don't think that placing the blower on the left or right side of the plenum would be any less affective than being in the center of the plenum. So, avoiding a 90 degree angle should be no problem if you made the plenum wide enough to accept the 3" inlet of the blower.

I tried it with the 90 cfm case fan on temporary cardboard booths. The fan was placed on the short side of a shoebox. An opening was cut out on the makeshift hood, and the shoebox plenum was placed on the back. I ran an incense test and the dead zone in the makeshift hood was barely towards the opening of the booth. I then ran the fan dead center of the plenum shoebox and the dead zone was more so along the sides of the hood, 3 inches before the center/side of the hood but still equally as strong in the center like the other setup. The dead zones are negligible when most of my over spray will be directed towards the center.

Anyhow, before I get too caught up in trying to build a cost efficient spray booth, I has to out weigh the cost that I have already put into it and most likely will lose, with all this experimenting....it appears that I've almost spent the amount that it would have cost me to buy an already made booth vs buying supplies and building my own. Could'a, should'a, just bought this......http://www.pacepaintbooths.com/pace/

Submitted by dedmonwakin on Tue, 06/09/2009 - 02:06.

I've been trying to figure out a way to build a paint booth for a few weeks for a low cost.

The blower is the heart of the system. I used a 273 CFM blower I got on ebay for $54 shipped. It took a few weeks and some lost auctions but I did ok in the end. My total cost of the project is around $80. I am very happy with how it worked out and I use it on a regular basis now. What I found is once I had it I started using it for spraying scenic pieces and putting primer layers down with solvent paint. You really want your motor out of the air stream for this kind of use..

Here is a handy reference I used:

http://www.briansmodelcars.com/tutorials/tutorial/23

(ed: its the same info in Tetters' link above but from a different place. Funny how things get around on the internet..)

Note that he references depricated Dayton parts. New blowers have taken their place that are much the same but with somewhat better AC motors. Most of them now are split capacitor type rather then shade pole.

You may wish to check out my blog entries on building it. My cabinetry is definitely not on the same level as Tetters' but it may give you some additional ideas.

http://model-railroad-hobbyist.com/node/343

http://model-railroad-hobbyist.com/node/492

One addition I plan to make to my booth now that I have used it for a while is a timer to shut off the fan. Often I finish my work and go up to bed leaving the fan on. I have to remember to come down later and turn it off. It would be nice to just leave it running for 30 minutes and shut off automatically.

Chris