SevenSixTwo - InDIYana 2018 Coax Design

[KEtheredge87]

Good Evening Everyone,

Tonight I re-learned the obvious lesson that MDF sucks up primer, no matter how expensive the primer happens to be! I set up my painting playhouse to prime both cabinets with a single can of SEM brand 42003 black high build primer surfacer (16oz). I bought that at the auto parts store when I was still considering spraying the 2K, and the advice the car guy gave me after seeing my cabinet photos was that one can would be enough for both cabinets. Oh well. I'll buy one more can of that tomorrow and finish the spray job.

Otherwise, I can report my experiences with the paint house. For one, the overspray catcher did a fantastic job. What used to be a white filter is now covered in black overspray, just as intended. My overall construction wasn't bad, but I did pop a tape seam loose where the fan was pressed up against the intake filter. Seems I need at least 2x the outlet area as I currently have. That tent was ballooning WAY out there. Not to shabby for a $20 box fan.

Oh... and since you're reading this... it's also worth noting that I thankfully did not cause any explosions, vapor flames, or other undesirable thermal events. I started the fan before I began spraying, and I cracked both garage doors about two feet to allow fresh air to circulate. After I finished spraying, I left the booth fan on for another two hours just to let the solvents flash off and the curing process begin.

More progress tomorrow!

[Drjay]

I second the idea of not trying to get them perfect for InDIYana. Every time I have rushed a finishing job during my boat building days I've regretted it. It would probably be better to use the time to get them sounding as good as possible.

Best,
Jay

[KEtheredge87]

Hi Guys,

After lots of deliberation on my own research (and quality input from you guys), I've decided I'm going to return the cans of 2K aerospray to Eastwood and move forward with less hazardous materials for painting. While I was attracted to the stuff by the idea of better quality finishes and application methods, I had not appreciated the real health risks of using this stuff without proper (and expensive) protective equipment until recently. No speaker project is worth the health risk that's possible from messing this up even once, let alone the risks of accidental exposure to my family if someone opens a door while I'm spraying. I'll stick with enamel or lacquer based paints until I can solve the isocyanate issue at a reasonable cost.

Having said that... I was also thinking about where to stop work prior to InDIYana next week. I already had a significant amount of 3M automotive masking tape applied to the cabinets, so I went ahead and finished that masking so I can spray lacquer based black primer. This way I can try to limit possible MDF exposure to moisture or other stuff while the speakers are travelling to the show. Additionally, it will look much closer to finished, since the goal was to have these parts be painted satin black anyway. After the show I can re-mask and spray the enamel paint top-coats.

So, masking is done, and I should be able to spray in my little plastic house (I'm still chuckling over that jhollander !) this evening. A few light coats of lacquer primer will cure totally in less than 2 days, so I can paint them, epoxy the crossover carrier boards into the cabinets, wire it all up, and take some final measurements before the show.

I'm almost there, and I'm really excited! My first DIY speaker show that I'm actually competing in! This is going to be fun!!!

[Kevin K.]

Probably not ideal after looking at your forecast, think it would need to be a little warmer. John's last idea sounds feasible with a little rework to your booth, spray em from outside of it. Looks like your running out of time though and it will probably have to wait until after the event. Maybe the weather will be a little nicer the following week or weekend.

[KEtheredge87]

What's your weather like right now? Can you spray out in the yard? If it's warm enough and there's not to much wind, you've got just as good a chance of getting the paint on without debris as you do in the garage.

Hey Kevin,

Indiana has been nothing short of ridiculous for the last few weeks. Weather A.D.D. is probably an accurate statement. The next few days *might* work out OK for some outdoor spraying, it's just hard to say how windy it will really be. Every time I've tried to spray outdoors I end up waiting for a clear shot, only to have the wind kick up, reverse direction, and blow all the overspray back in my face! it's like a campfire where the smoke follows you around every time you change seats!

[KEtheredge87]

I've sprayed 2K but did it in an open 2-car garage with fan blowing the over spray out. Cars were parked down the street. Your surface area is not that great. Assuming you are using a HVLP you should not have a problem. There's no way I'd get in your plastic bag house, but with a turntable, a clear vinyl window and long gloves you might be able to make a paint cabinet with you on the outside.

Seriously John, Thank you for injecting a bit of humor into an otherwise serious topic! I've been trying to think my way through this all morning to come up with a cost-effective and safe solution (with no success, might I add.) Your "plastic bag house" comment gave me a good chuckle! Never thought about turning myself into the boy who lives in a bubble!

Getting back to the actual setup, I don't have a full HVLP setup yet (that's future plans). The Eastwood "2K aerospray" spray paints are marketed as having a fan pattern more like an HVLP spray gun. That fact, and the increased quality of the paint over what I can get at the hardware store, is what attracted me to those cans of paint. I do have a turntable and was planning to use it, but that does nothing for my fumes problem.

At the moment, I am considering going without paint on the MDF for the InDIYana meetup so I can be prepared. After that I can pull the drivers and revert to a gloss enamel spray paint from the hardware store. It's not my preferred option, but at least I won't need professional grade forced air respirators to feel safe.

[Kevin K.]

What's your weather like right now? Can you spray out in the yard? If it's warm enough and there's not to much wind, you've got just as good a chance of getting the paint on without debris as you do in the garage.

[jhollander]

I've sprayed 2K but did it in an open 2-car garage with fan blowing the over spray out. Cars were parked down the street. Your surface area is not that great. Assuming you are using a HVLP you should not have a problem. There's no way I'd get in your plastic bag house, but with a turntable, a clear vinyl window and long gloves you might be able to make a paint cabinet with you on the outside.

[KEtheredge87]

Hi Guys... seems I have some thinking to do. I always knew you weren't supposed to breathe paint fumes, but the isocyanates used in these 2K paints seems absurdly nasty. I planned to use a 3M half face respirator with fresh cartridges when starting this job, but after reading 3M's own documentation on it, sounds like I wouldn't even know if my cartridges were bad and didn't block the chemicals. I do not want isocyanate sensitization and the associated asthma like symptoms if I screw this up... maybe 2K paints aren't for me.

[KEtheredge87]

The first thing that will happen is Keith will kick the outlet filter out after it clogs, then remove the inlet filter then the whole set up could get trashed, well at least it did in my house.

Ya know what John... I can totally see myself going all King Kong and tearing the building down if I got really mad at it! Heck, with as much duct tape as I needed, I may have no other choice but to kick out the filters!

[KEtheredge87]

Hi Guys,

I truly appreciate the concern! Here's what I know right now, and how it's working out in my head. I will say up front that I welcome more comments and suggestions. The better informed I am, the safer I can make this admittedly not-so-great situation.

1) The positive pressure setup is not perfect. In fact the biggest issue I have right now is needing to have an access door flap rather than 100% duct taping all the seams (can't seal myself inside or outside!) I did a few test runs tonight just blowing the fan into the booth, and the booth sure does inflate, but without a very particular attempt at securing the door flaps. Most of the pressure escapes there (back into the garage) instead of out the bottom filter. Strike 1.

2) Since the point of all this is to avoid fumes hitting any sparks from the motor, I'll need to start the fan before spraying anything and leave it running long after I am done to be 100% sure there's no danger. Although because of the door flap issue in #1, the instant I open the booth to leave it I will likely burp a bunch of fumes out as I try to exit quickly... which still defeats the point a bit. Strike 2.

3) While I don't know the exact ratios of fuel and air required to make this stuff ignite, the only real variable I have any control over is oxygen supply. That said, my goal would be to crack both garage door bays to about 2 feet off the ground to try and create a cross-draft in my garage. I realize this kind of defeats the purpose of trying to exhaust the fumes out of the garage, but if I can't control them burping out when I leave the booth, then the whole "exhausting out the garage" thing is already an exercise in futility. I figure cracking the bay doors will minimize the chances of wind blowing down my rickety little spraying booth, but still provide more fresh air to bias the air/fuel mix OUT of a suitable combustion range.

Another point that I think bears consideration is the amount of paint that I'll be using. At worst, it will be two 12oz cans of 2K spray paint, spread out over a couple hours. At best, I'll only need most of one can. If I had thought to spray an entire car's worth of 2K paints in my garage I would have immediately dismissed the idea as stupid. That level of painting is only getting done outside the garage where no fans are needed, or in a professional paint booth. This small amount of paint seems manageable.


Beyond all the careful consideration of the painting situation, Here's some photos of the cabinets stripped of their blue painters tape and decked out in some green automotive masking tape. I didn't trust the green frog tape to handle lacquer based primer and urethane 2K paint solvents without seeping paint underneath. I've got a bit more masking to do before it's all said and done, but I should be able to start spraying the black lacquer primer tomorrow evening.

[Kevin K.]

That's why he designed a positive pressure booth... The fan is on the intake side not the exhaust side so it shouldn't to see the fumes if he directs them out the garage door. Your concerns occurred to me as well.

Marvin, not saying I've never tested my luck just like he's about to do. In fact, I use fans to exhaust the fumes out of the shop anytime there's airborne spray involved. I realize he's pushing air into the booth and not pulling, but for this to be perfectly safe, his exhaust system to get this stuff out of the garage is going to have to be air tight (not likely) otherwise his intake fan will eventually see the fumes. There's an element of danger in what he's about to do and the risk level goes up in smaller areas. Don't know what the odds are for something to happen in this situation (maybe really low), but I certainly don't regret the suggestion to have another person there (inside the house, not in the garage) in case of an emergency. Better safe than sorry.

[marvin]

I have seen a guy spray pure lacquer thinner into a box fan....no flame, nothing at all except a clean motor.

That doesn't mean it was an intelligent thing to do!

[ugly woofer]

I have seen a guy spray pure lacquer thinner into a box fan....no flame, nothing at all except a clean motor.

[jhollander]

The first thing that will happen is Keith will kick the outlet filter out after it clogs, then remove the inlet filter then the whole set up could get trashed, well at least it did in my house.