Large Scale Central

Paint booth in a tub

Last November, I threw together a rough “paint booth” for the Joe Douglass loco painting.

The filters are now clogged, and the box needs replacement. But here’s the design basis that I gathered from this effort, and will apply to something more reusable. Your preferences may vary, but here’s mine.

  1. Outdoor Vacuum Blower. Basically a blower that has a vacuum hose connection, and can operate in that mode. Some “bounce house” blowers seem to fit the bill, but I haven’t evaluated them.

For safety reasons, the motor has to be outside the airflow path. Fumes getting near the motor brushes are dangerous, due to ignition from sparks. And the paint coating on any electrical rotor or other contact areas can’t go on for long, I’d expect. I’m using, therefore, a high-CFM blower with its motor to the side, each with their own cases, and separated by the shaft bearing.

The blower can be portable, and the hose as well, and connected only when in use. In my circs, I already have an exhaust system for a laser cutter, and will just hook the paint booth up to that.

  1. Paint Booth Design. For model-painting purposes, the “booth” needs to be as big as any anticipated model. And if the model is bigger, it can go out in the dang garage.

Filters need to be easily gottable – like furnace filters. Maybe two or three, because the outer filter will always get trashed first, so a filter rotation should be workable. Any, use a standard size, maybe a size already used in the house, so if push comes to shove…

A “plenum” space is needed between the filter and the vacuum inlet, to get a better airflow of suction across the face of the filter. I chose a 2" gap, just because I needed to make a decision, and it seemed to work in the cardboard version.

There’s a million ways to keep a furnace filter 2" from a hose inlet. Discarded grille, fencing, rods, whatever. I chose a 1/8" plywood box, with its pieces lasered and glued.

The enclosure can be anything as well. For me, a plastic “storage tote” worked. This was after walking around Home Depot for an hour between their furnace filter and storage tote areas.


So, here’s the design model.

More to come…


What’s the dimensions of the interior of the tub? Doesn’t look quite big enough to be able to rotate 360 something like longer than 1’

This is interesting. I’ve been thinking of building a paint booth. I assume you used a Sterilite 50 Gal tote and standard 16x25 filters?

Craig, the plex “table” thing is 27"w x 17"d, with 8.6" of the depth being within the box. I found that the air flow (of my particular blower) was sufficient to have the painting in front of the box, vs. entirely within it. But the backup plan is to make a foldup wing & ceiling thing to fully surround the table.

Dan, spot on. 16x25 filters, with a Sterilite like this:

It’s big, and doesn’t fold up; but I’ll be able to put the hose & fitting into it and shove it under a table.

Thanks Cliff. Big enough that you fit a 50’ boxcar in my scale at least.

I keep going back and forth about a paint booth. I know I really should use one even with acrylics but I’d want to build one that I could put a lazysusan into that could spin a 50’ boxcar ( 2’). That makes it at least 4’ x 4’ which is huge in terms of a CFM management and storage.

If you center the lazy susan, isn’t it still 2 feet wide?

I have one of these and never considered using it for anything but the bouncy house. Mine doesn’t have a vac port but maybe it could rig it up as a Venturi? Hmm. Thanks for mentioning this and putting the idea in my head. I may now find other uses for that blower!

It is 2’ wide but you still need 2’ of depth…

So I guess I would be 2x2 vs 4x

Fuzzy math. In my history world 2+2=5 for some reason. :stuck_out_tongue_winking_eye::grimacing::thinking:

Made some more progress today, starting with a cardboard version of the… filter holder? Plenum box? This was to correct the fits on sides, and also the perimeter squishy foam.

Here it is with the front foam and filters. The idea is for the foam to hold the box to the tub, and also hold the filters in place. So far so good. The vac blower will keep things sucked back, so the fits are mainly to keep in place when the blower isn’t turned on.

After lots of trial side fitups with cardboard to get the geometry right, I cut and glued up the plywood box.

Also the plex work table. I didn’t have any stock wide enough for the full 27", so used what I had for 23" wide.

Then the vacuum connection. I lasered an acrylic interface plate and bonded a 6" ABS duct connector to it. Then added velcro and self-adhesive foam sheet for a seal.

The velcro isn’t sticking to the tub very well, maybe cuz it’s oldish. Might need some fresher stuff.

That’s it for today, hopefully this’ll be wrapped up tomorrow.

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I finished up this morning with this, so here’s a few final pics and notes. Here’s the plywood (1/8") box in place.

Ready for work, on a tarp, all hooked up.

The light is an under-cabinet 2’ long LED fixture, with brackets allowing the unit to be unclipped. It’s in a transparent plastic bag for protection.

Air flow seemed pretty good near the center, and fair at the outside corners.

By sliding the work surface out, I could get 24" of depth if needed.

Here’s the gear all packed up.

Well, that’s about it. I’m sure there’s better ways to do it, but this is what occurred to me, using the materials (foam, 1/8 plywood & acrylic) & tools I had on hand.

888::> Cliffy


brilliant idea. I love how it all folds up and stores inside itself. That would be very useful. I will be coping this for mine.

37" x 48", 79’ Pullman:

Thanks Devon. Copy away!