Paint booth exhaust fan

BoxcabE50 Sep 28, 2013

  1. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    I've needed to do this for a long time now, so am assembling the components for a new paint booth. Doing this brings into mind a couple of questions. They are:

    How many CFM should the exhaust draw, to easily clear the booth, yet not suck people and furniture through?

    Is a bathroom exhaust style fan safe enough in this type of application, when using solvent based paints? Or do I need to seek a squirrel cage blower style, where the motor is isolated from the duct?
     
  2. r_i_straw

    r_i_straw Staff Member

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    Well, just going from my experience, I have used a bathroom fan for 30 years and never had anything blow up. I am not sure what the stoichiometric ratio, or ideal air to combustible vapor content would even have to be to get an ignition, but the AC motor has no brushes or commutator and works on induction so there are no sparks . However, I occasionally take it apart and clean all the accumulated caked on paint from around the bearings and windings and then re-lube. The impeller gets all caked up too but a few good knocks and it all usually falls off.
     
  3. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    Russell-

    That is the style of fan motor I had in mind. I was looking at one which is 50CFM. I feel fairly certain that is enough. But figured I'd better check before wasting dollars from my starving budget.
     
  4. ratled

    ratled TrainBoard Supporter

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    Motors these days are now brushless and produce no sparks. Passche sells just a motor for about $50 if you want that. The upside of it is it's about 230 CFM. I would never use anything less than a 100cfm. That's is just me and many of folks use bathroom fans and never say they have a problem but they are only about 75 CFM. Just because it's it not solvent based doesn't mean it's harmless, there a couple of solvent free paints that still have an MSDS available from Testors (but you have to ask).

    Build or buy, one thing everyone should do is seal all of seams with caulk to ensure 100% of your draw is coming form your working opening.

    ratled
     
  5. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    The size I am looking at is about twenty inches square. I am going to mock it up, to be certain there is adequate room for a klutz like me.

    Does that Paasche come with any sort of a housing? Do you know of a link to info, or a photo of it?
     
  6. ratled

    ratled TrainBoard Supporter

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    http://www.paascheairbrush.com/products/spray-booths/hobby-spray-booths/SM-1386#Video-tab Still only $47. It's the fan/motor/housing from most of their hobby booths. I have it on my 22-16. I wouldn't trade it for the world. You can see it in this expired E bay ad http://www.ebay.com/itm/PAASCHE-22-...22-16-SHIPS-FREE-/380430707229#ht_3857wt_1285 The second photo shows it well. Not sure if it comes with the 6" to 4" cone for just the motor but Passche has great customer service and would let you know in a call or e mail

    ratled
     
  7. Hytec

    Hytec TrainBoard Member

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    Ken, before you finalize anything with an elaborate paint booth, consider painting near or at an open garage door. OK, I admit it gets a whole lot colder in northwest Montana than in coastal Mississippi, but I assume your garage may be heated slightly in winter to keep it 10-15 degrees above freezing. At any rate, I set up a card table with everything I need just inside the door, then open the door and start painting. The paint and models are the last things I bring out of the heated train room before opening the door, so they don't have a chance to get cold during the 10-15 minutes of painting.
     
  8. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    Hmmmm. Interesting! I will do a bit more exploration.
     
  9. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    Hank-

    Normally, that is what I do. In fact, only last week was painting a project out there. Our garage is not as yet fully insulated. It has no heat. Already it is too cold to use. Yesterday was forecast for low sixties, we never got past the low forties. (Another failed forecast.) We also get a good amount of wind. So, it is either done indoors, somehow, or I will waiting until next May.
     
  10. ratled

    ratled TrainBoard Supporter

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    Match that with a plastic tub from Walmart for $5 and you will have a real nice and cheap booth

    ratled
     
  11. r_i_straw

    r_i_straw Staff Member

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    My problem with a booth open in front was the dust pulled from out of the room by the fan and sticking to my still wet paint. I built a box with a Plexiglas door in front and mounted air filters on the sides. The lower front has two arm ports with sections of nylon hose stocking attached to block dust from coming in around my arms. It has a florescent light mounted in it also.
    IMG_3886.jpg
     
  12. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    Dust. Yikes! I had not even considered that problem. I would imagine a lower CFM fan might help a little.
     
  13. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    WOW! Now there is a neat idea! That would sure save a lot of carpentry. If anyone has ever done this, it would be great fun to see a photo!
     
  14. ratled

    ratled TrainBoard Supporter

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    Military modelers have been doing it for a long time, except they like to use computer fans!!!???? Do a search for DYI paint booth or plastic tub spray booth etc on Yahoo and click the image tab. Here is one thread showing his way
    http://ken-cheong.com/index.php/2007/01/11/20070111-diy-sb/

    Another http://spruecutters.com/articles/49-make-your-own-spray-booth.html

    ratled
     
    Last edited by a moderator: Sep 28, 2013
  15. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    Great ideas! I like the bin used in that first example. Now all I need is an idea for a sturdy stand which will hold it at window height, and I am in business. :)
     
  16. jdetray

    jdetray TrainBoard Member

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  17. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    That does look interesting. I am wondering about a couple of aspects. One is the cooling fan. There are two in my desk top computer. I have doubts these could pull through a filter as needed. The air flow just does not seem to be there.

    The other is I use a plastic carousel, which would need to sit upon the filter as shown. How would that alter the filtering and after a while, would the filter begin to sag under any weight?
     
  18. r_i_straw

    r_i_straw Staff Member

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    I suppose you could put a grill or something over the filter. I take it that the filter in this design is to trap the paint over-spray solids to keep them from caking up in the fan and not to filter the dust out of the room air to keep it off the model.
     
  19. PaulBeinert

    PaulBeinert TrainBoard Supporter

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    I would mount a conical shaped platform for the carousel in the center of the bottom tub and cut a circular whole in the filter.
     
  20. BoxcabE50

    BoxcabE50 Staff Member TrainBoard Supporter

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    Right. The filter is to trap solid particulates, as in paint overspray.
     

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