Reference: Building a homemade spray-painting cabinet

[Jacques Reed]

I have wanted a spray-painting cabinet for a long time. For years I have been getting by with waiting for a calm, dry day to open the shed door and then cover everything in the shed before spray painting. I could spend half a morning getting ready just to paint a few items. Weather-wise it seems the available days to paint are getting fewer. Too windy, too humid, too hot, too cold. I won’t mention Climate Change. Add other commitments, and I was lucky to have a day each month to paint.

During our long Covid lockdowns I started looking into paint cabinets/booths on the net. A commercially made one was prohibitively costly. Some of the homemade designs were OK, and some were more for model makers or furniture restorers. Some I had safety concerns with also.

The design criteria I set for myself:

Build it to similar dimensions and specs as a commercially available booth.
Use standard hardware whenever possible. Bolts, Tek Screws, Pop Rivets, brackets etc. No welding required if possible.
Use standard size sheet metal and MDF panels whenever possible. MDF was used for the table for rigidity. I wanted to be able to place heavy things on it such as wheels, or heavy castings. I then covered it with Galvabond steel to keep it from absorbing paint. MDF also will be used for the rear panel to support the duct outlet.
Include an ATEX rated explosion proof fan of similar capacity to a commercially made cabinet of similar size. Single phase for home power also required. That was the first thing I acquired over a year ago.
While searching for 30 mm RHS I found a gate frame manufacturer a few km away and looking at their frames it gave me an idea to build it from them in an “H” pattern. The centre frame at 800 mm from the front of the cabinet creates a plenum 400mm deep to the rear of it and a support for the filter medium.

I contacted the small family business, and they were very helpful. They could leave the hinges and handle off and move the centre support 30 mm to accommodate the 90 mm high filter medium. Their gates are normally two piece telescopic and adjustable, but they made the side gate frames fixed at my request and only the centre gate frame was adjustable. That came in handy to match up the standard width of the MDF and sheet metal table and top. They also supplied a few lengths of 30 mm RHS for the various supports. Their costs were very low, in fact I could barely buy the steel for what they charged. Their workmanship was impeccable. Everything was on spec to their quoted sizes.

The sides were standard 0.75mm Galvabond sheet 1210 mm x 1830 mm cut exactly in half. The table and roof were standard 0.75mm Galvabond sheet 1210 mm x 2440 mm cut exactly in half also. The MDF table and rear panel were cut from a standard 6 mm thick 1220 mm x 2440 mm panel with minimal wastage and just 3 cuts.
Shown are the stages from the start. Trial fitting of the Andreae Filter medium shown. Just the roof and back to complete in the next week.

Hope this is of some interest.

[David Herbert]

Great project. It makes me think about something similar.

Would it be a good idea to put a rail in the roof to hang things from ?

David

[Jacques Reed]

Hi David,

Yes, good thought. Haven't got that far with the design yet. it has evolved as I went along so no doubt there is more to come. Could be handy for things a lot lighter than a 16" wheel!

Cheers,

[Jacques Reed]

Good day,

This week I have added the duct outlet to the rear panel of the cabinet.

Used a jig saw to cut the hole. I was surprised to find the bar included with it is not a hole cutting guide but an edge guide. I never used it anyway as I found it much better to clamp a batten to a piece of wood as a guide when ripping.

I mentioned before that this saw is a bit disappointing despite the good brand. The blade wanders up to 1mm either side of centre when cutting. This side-to-side movement of the blade is apparent when holding it. (Unplugged!). No amount of searching has found a way to cure it. Still, it did a good enough job for this task.

I modified the edge guide to a circle cutting guide. I inverted it, then attached a piece of plywood to it as a foot to bring it level with the base of the saw. I drilled a hole through the steel guide and plywood in line with the front edge of the blade and put a machine screw through it as the pivot point.

I wanted a more robust mounting than just putting screws though the outlet and into thin MDF board, so I used 1/4" carriage bolts and large mudguard washers. It also allows easy access to remove the outlet to install the flexible ducting.

Hope this is of some interest.

[Jacques Reed]

Well, after a few delays I got back to working on the spray-painting cabinet.

Installed the rear panel today and just have the top to put on.

Note the 4 clips on the centre frame used to hold the filter medium at the sides. A piece of aluminium angle will be attached to the roof in front of the filter to hold it in place.

Cheers,

[Jacques Reed]

Good Day,

I have almost completed the cabinet today. Final test fit and just 25 Tek screws left to fasten the roof to the frames. That's tomorrow's project. Shed's warming up so it's cold beer time.

I added an external angle halfway along the painting compartment. Helps to support the sheet metal and lets me use magnetic hooks there to hang small parts if I choose. Didn't want anything permanent there to encroach on the painting area.

Shown is the angle at the top inside the roof used to secure the filter. Air pressure keeps it in at the bottom as I was told by the filter salesman so no need for anything in front of it on the table.

As shown, an engine cover fits there with room to spare so it is a good size for painting large parts.

A Merry Christmas to all on MLU.

Cheers,

[Jacques Reed]

Good day,

Well, with the festive season well behind us, I finished installing the flexible duct and decided to give it a test run.

The length of the duct allows the fan to be placed another 4 metres outside the door and allows the booth to be oriented to get the best light under the Laserlite roof panels.

Tested the airflow with a lit candle and the flame was only slightly disturbed at all places within the cabinet.

I pulled the bottom of the filter away and there was enough of a pressure difference to snap the filter back into place when I let it go. Just as the filter salesman had told me! My fears of a "wind tunnel" effect were unfounded.

The acid test of course will be when I fire up the spray gun, but not while it is 35C outside and 40C inside the shed.

[Jacques Reed]

Good Day,

Gave the booth its first run. I cheated a little using aerosol etch primer.

I had these NOS step plate brackets that I stripped of old paint and storage rust. It worked well. Usually when I sprayed aerosol etch primer it leaves a pretty strong taste in the throat. The fan took all the fumes away and yes, I should have worn a mask also.

Tomorrow I will put a coat of aerosol metal primer on them then add them to the collection of things to get a final coat of KG3 (via spray gun).

The trolley was an idea I had to make a turntable. Instead of making that, ALDI had these for $13 a couple weeks ago so I grabbed one and it worked well. Makes it easy to rotate parts to any position for spraying.

Cheers,