Hi All...

With my typically bad timing I posted this question just before the great software change-over...so now I'll post it again here and hope somebody sees it this time.

Conceptual design of my folding, wall-hung spray booth is complete.  The working face (the opening) is to be 32 inches wide by 20 inches high, and the depth is about 22 inches.  Before I do the detailed design and start fabrication, I ask for the wisdom of the group:  is this big enough?

What's the biggest object you would think a large scaler with primary interest in narrow gauge prototypes and "old-tyme" western buildings will be likely to want to stuff into a paint booth?  And how much clearance around the "paintee" is required for airbrush access?

As always, I will listen carefully to all advice and helpful hints from the MLS crew.

Thank you,

Dawg

Hi Dawg,

  I  don't know what size to recomend but here is a link to a plan to build one. I intend to make one and i want a turntable in it about 48 inches in dia.

http://1stclass.mylargescale.com/LawrenceWallace/booth.htm  

Well guys, I don't know what size Larry Wallace recommends, but it should be large enough to take a passenger car with plenty of side to side clearance, front to back clearance, and height to put in a coffee can to get it off the floor of the booth. Also get the largest lazy susan type platform you can to turn it around. Mine is 12 inches in diameter and not large enough. Good luck.

Hi, Chuck

Wow...you're gonna need a BIG booth to hold that turntable!

Thank you for the link.  I actually had read that article and factored many of its features into my own design...Yogi's a very creative and helpful guy!

Dawg

Greg,

Good suggestions, thanks.  Especially the lazy susan.  I'll certainly want to add that.

Why the coffee can?  Is that for painting from a low angle, or what? 

Dawg

I had replied, but as you said....locked in the move.

Anyhow, from years of working around, evaulating, and setting up spray booths for work, everything from bench top ones to ones holding three 1:1 railroad cars, figure your biggest size you need, and then some. I see a lot of folks that build or buy one that outgrow it shortly. Remember spray pattern, even with the lazy susan, you need to be able to freely swing past both ends, and need clearance for air around whatever you are painting.

The link referenced above has floated around several forums (train and non train) for years. While it has some positives, there are a LOT of negatives and potentially dangerous misinformation in it, especially the rationale of the brushless motor with the stove hood fan.

EDIT: I think this may be the origin of the booth design above: http://pages.interlog.com/">http://pages.interlog.com/~ask/scale/tips/booth.htm

EDIT 2.0: For some reason, the link above will not complete, you will need to cut and past it.

That is one reason Dawg, but the most important one is that in order to paint the bottom of details, I always start by inverting the model, shoot it on the bottom to get the under side of any details, then carefully turn it over and get the top, plus fill in any bare or partially covered spots on the sides. The coffee can keeps the bottom of the model from sticking on what ever you use to sit it on; ie lazy susan, newspaper, etc. It just helps keep things neater and cleaner and helps to keep your finish from getting messed up. Good luck with your project.

Here is a MUCH better booth design I found for modelling, Vs the one shown above.

Here, the modeller points out the drabacks of finish quality and massive paintloss with an updraft design such as the "stove hood" idea.  The last updraft booth I dealt with for work was an absolute disaster for its owner, costing them in both product and legal issues.  Also discusses flow rates and fan to booth sizing.

He also addresses the electrical issues and discusses how some of his ideas are and are not fully Kosher.  Granger is the place to go for fan units however.

The link is good, you may need to cut and paste it if the new MLS cuts it:

http://www.briansmodelcars.com/tutorials/tutorial.asp?TutorialID=23&CurPage=1

Good tip, I have used blocks of wood, large size nuts, etc.

Another trick I have used for years on cars is a pair of "paint trucks" that I mount to the model when painting, and remove when done.  Holds the model up, plus gives you a point to touch to move it if needed.

Garrett,

Thanks.  Actually, I had read that thread, too.  Lot of good stuff out there if you search.  I agree hanging dirty filters above the model isn't the best idea.

I found a "like new" Dayton 4C444 shaded pole squirrel-cage blower for my paint-booth-to-be for about half Grainger's price on eBay.  The motor is located completely out of the process airflow for safety.  Should suck the paint right off a model, too.

Dawg  

Dawg, from your photo, you look like a former co worker of mine....

Anyhow, is this your blower?

Not sure what happened up above, I am sure a moderator can fix it tho......I do not even see a button for BLUE FONT!!!

I wrote it in Word, then did a cut and paste for spell checker, so maybe this is why?

Garrett,

Much food for thought there, thanks.  To answer some of your questions...

Yes, that's the model blower I found.  I do have the full spec sheet and fan curve data for it.  It is an HVAC type blower, not the "non-explosive" sealed type.  The fan housing and impeller are steel.  The motor is "open dripproof," not TEFC, but it's located outside the process airflow and has its own separate cooling flow.  Paint buildup in the blower and exhaust ducting should be minimal, as the fan intake will be well-filtered.  The filters should also stop any metal fragments entering that might spark on impact with impeller.

I'm reasonably comfortable with the safety of the blower and the filtration I plan to use.  However, I hadn't considered your insights about making the booth itself out of metal to contain a fire if one should happen to start.  I'll give that some more thought.  Thanks.

Experienced inputs like that are what make MLS so useful to me!

Dawg

P.S.  I was in the workforce so long almost everybody in the laser field thinks they know me!  Where might we have met?

Dawg:

Thanks for your reply.  You are probably right on your assumptions on your fan for the amount of spraying you are doing, just don't tell your homeowner's insurance.....

Metal....the fire codes specify this, but for low volume spraying (not daily), aluminum or other substantially non combustible materials (ahem) can be used....  I would be leary of using wood, especially if you had a spll as it will wick anything.  However, coverings are allowed for wood flooring, such as sheet steel....see where I am going .

Another option, what you may want to look at is the HVAC section of the local BigBoxHardware and see what they have, you may be able to find a galvanized large plenum or the like, or even a local HVAC contractor that may have something like this laying around....

If you really get bored (or interested)  the code of reference is the NFPA (National Fire Protection Association) #33.  The code costs $$ and is not availble free online (a co worker found some older ones somewhere) but, OSHA 29 CFR 1910.107 is an older version (1970 or so) of the same code adopted by Fed OSHA, and can be found at www.osha.gov and search for spray finishing or the code number.

You may see me if you go to the post office much, those little posters on the wall....

I have a question,  I think i read some where that if you use a water base paint in an airbrush or spray gun, you do not have to worry about a big bang as water base paint fumes will not explode. Can anyone confirm if this is true or not??

    chuckger

The funky blue post deals with this very topic.  The mist and vapor are not, but the dry overspray can be combustible.

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