I skimmed through my paint booth posts to see what I might have missed and found a comment that "DeVilbiss wants the resistance to earth from the gun to be less than 1 MΩ to dissipate electrostatic charge due to flow through the gun." I hadn't checked that resistance before, so did it today.
Even recognizing that the soil is wet from the monsoon, I assumed the resistance would be large so I used a megohmmeter. However, as can be seen, with one probe simply stuck in the ground the resistance to it from the quick-connect air inlet is just 30 kΩ.
It might seem the shed "should" be electrically isolated from the ground by the construction, there also are four rebar posts through the base to keep the wind from blowing it away.
Since the resistance of the air hose itself, from the wall to the gun, is much greater than 1 MΩ, I'll wrap a wire around it to complete that connection.
Originally Posted by NYBSAGUY
I had to laugh when I noticed the count had dropped to 997 when I started to upload this post, and was at 996 when I re-read it afterwards. Apparently, someone was upset by the number and has started removing their 'Likes' to deny me the fame and glory. Jeez...
Last edited by Magnetoman; 08/21/228:45 pm. Reason: 1001
I I had to laugh when I noticed the count had dropped to 997 when I started to upload this post, and was at 996 when I re-read it afterwards. Apparently, someone was upset by the number and has started removing their 'Likes' to deny me the fame and glory. Jeez...
To quote Hercule Poirot: “From now on, it is our task to suspect each and every one amongst us.” Or, Inspector Clouseau (Peter Sellers): "I believe everything and I believe nothing. I suspect everyone and I suspect no one."
It's pretty funny that someone was so upset by something so trivial that they would spend the time it must have taken to locate their 'likes' and 'de-like' them. However, as a result, now I know exactly how someone feels who won an Olympic Gold Medal, only to have it stripped from them for some transgression. Poor, poor pitiful me...
Thanks to gunner (THANK YOU!) I have a good set of Terry's spanners for the tool kit.
Originally Posted by NYBSAGUY
Whoever removed their dozen or so likes a few days ago to deny me the inestimable honor of being first to 1000 must be turning over in his grave (although, I already had made it to the 1000 mark, so removing the likes was pointless even if it hadn't made it back above 1000 again).
Although it may seem like gilding the lily, I added angled inlet/outlet fixtures to the A/C system, to replace the duct-tape flaps I had on them up to this point to keep rain and insects out. The next photograph shows the one for the inlet, with two of the four small SmFeCo magnets I attached with epoxy to hold the flap open when in operation, and to keep it clamped shut when not.
After taking the photograph I wrote a reminder in fat red paint pen to 'open' the intake flap as I walk by it. I had to remember to open the duct-tape flaps so it's not like I didn't have to remember anything before. The exhaust only needed one pair of magnets, to hold it firmly shut, since the strength of the blowing air overcomes the strength of the magnets as well as holds the flap open during operation.
Although the silicone caulking isn't visible in the above photograph, I used my finger to smooth it and have no doubt it would pass Gordon Gray's most rigorous inspection (if done on a moonless night, blindfolded, with his hands tied behind his back…).
with the wire grid present should keep out any snakes, lizards and other creatures whilst in use.
Where's the fun in that?
I noticed that, although I was very cautious for quite a while when entering No Man's Land behind the garage, scanning the ground ahead of me for rattlesnakes and Gila Monsters as I tip-toed my way to the booth, I've been back and forth so many times than I've started treating the path as if it weren't laced with land mines. I'm afraid at some point that lack of caution is going to jump up and bite me, so to speak.
I learned from a few minutes on google that there's an average of 2 snake-bite-deaths per year in Australia. While the U.S. has 5 deaths/year, we have 25× the population, which means the fact I survived five trips to Australia without being bushwhacked by a brown snake is nothing short of a miracle.
Last edited by Magnetoman; 08/24/224:50 pm. Reason: added photograph
I learned from a few minutes on google that there's an average of 2 snake-bite-deaths per year in Australia........the fact I survived five trips to Australia without being bushwhacked by a brown snake is nothing short of a miracle.....
But only a minor miracle.
You could visit snakebite world record holder India, land of the King Cobra. Now surviving THAT would be a miracle! WHO reckons they have 58,000 snakebite fatalities annually.
With the last of the switches and vents in place, the SOPPB™ (Seriously-Overbuilt Personal Paint Booth) was now well and truly done (fingers crossed…), so it was time to test the air flow to see if all the expense and effort had paid off. Hey, it had to work, so why bother testing it before now?
I hooked up the fan (but didn't turn it on yet), connected its power cord to the correct recently-installed socket, turned on the A/C, and returned roughly an hour later.
It's overcast today, with the possibility of monsoon rain later in the afternoon, so the outside temperature in the shade was only 89 ℉.
I hadn't waited long enough for the inside temperature to have bottomed out, but I decided 72 ℉ was good enough to run the experiments.
In an earlier experiment I used a spray can on a day with a gentle breeze to determine that "Spraying paint sideways into the breeze, 2 mph was sufficient to bend the "beam" of paint by 90° before it had traveled 1 ft. Even 1 mph, the minimum the instrument reads, would carry much of the overspray into the filter." I flipped the recently-installed switch inside the booth to 'on' and, as can be seen, the wind conditions in the SOPPB are ideal for painting.
Although the photograph only shows one reading, I measured between 1 and 3 mph over a fairly large diameter "beam" of air flowing between the louvered inlet vent, and the outlet on the other side of the booth. This was with the highest efficiency filter in place and the fan on 'high'. If I wanted a wider beam, which I don't think would be necessary, I could adjust the louvers to achieve that, although losing some velocity in the process. As a reminder, the purpose of the wind is to carry the paint cloud away from the area to increase visibility as well as to keep it from settling on the fresh paint and possibly affecting the finish.
The next part of the experiment was to determine how fast the air inside the SOPPB heated up due to the wind of hot outside air. In an earlier post I calculated that the output of the fan in 30 seconds was equivalent to the volume inside the SOPBB. However, that doesn't mean it will increase the temperature inside the SOPBB to that of the outside in 30 sec., because much of that hot air blows directly across the booth and exits through the outlet.
I don't know the time constant of the Abbeon Cal thermometer I've been using, but I determined the one in the first photograph has τ≈30 seconds, which is fast enough for present purposes. I noted the time when I started the previous experiment to measure wind velocity, and ten minutes later took the following photograph.
The Abbeon Cal had been hanging on the wall behind the A/C unit, where it always hangs, but the other thermometer had been sitting on the top of the A/C unit itself. I didn't wait to take the photograph after setting it on the Abbeon Cal, accounting for the difference in temperatures they display. In any case, whether it was 75 ℉ or 77 ℉ after ten minutes, it was perfectly comfortable. All the more so since the A/C would have been blowing directly on my back as I painted.
Next is to, ahem, dust off the SOPPB and transfer the ancillary equipment to it (respirator, coveralls, booties, etc.).
[which means the fact I survived five trips to Australia without being bushwhacked by a brown snake is nothing short of a miracle.
Snakeology being taught here is that 90% of folks who are bitten by snakes are trying to kill them. And 90% of snakebite symptoms are fear/stress, rather then venom. And 90% of city slickers (at least ?) have probably never seen a venomous snake
I've had to give up on House of Kolor (owned by Valspar) and am now searching other manufacturers. The technical information HoK has on-line is out of date, with some products I would need no longer manufactured in the form listed, so I needed to find their best current combination of paint, catalysts, and undercoats for both steel and Al.
I sent an email with my request to the address listed on their web page. After several weeks there still wasn't a response. I then sent a request through their on-line form. Again, I gave them several weeks (because it is monsoon season, so I wasn't in a hurry), but never received a response. I then tried calling their technical help line. A few levels into the menu it gives the choice of whether I'm in an eastern or western time zone. I selected west, it rang a few times, then disconnected. I tried again with the east, but it went to voicemail (it was early afternoon, so wasn't close to either lunch or quitting time), and there was no subsequent response. What a way to run a business. Based on my experience, I wouldn't recommend that anyone waste their time with HoK.
A local paint supplier here has (quite) a range of their products on the shelves. I've ogled all the fancy shades and effects, but not used them. A lot seem to be candies, and airbrushing types. You see them mentioned on quite a lot of custom builds.
Although there's a lot more to write about paint, I've already written quite a bit in earlier posts in this thread so I won't repeat that information here. Basically, what I want is "simply" a black, single-stage, not-clear-coated, urethane paint, so you might (incorrectly) think finding an appropriate one would be fairly easy. To limit my search, as well as minimize possible supply chain issues, I looked for major U.S. brands. Unfortunately, there are something like a dozen such brands, which doesn't make my job easy. Also, more so than with other items, on-line reviews and comments about the "best" automotive paint are highly subjective and almost-entirely dependent on the unknown expertise or bias of the person writing a particular review.
I would be happy if I could find where someone had sprayed 'jet black' paint from several suppliers on flat metal panels and measured their chromaticity (i.e. how far they deviate from being truly black) and gloss. Then subjected them to accelerated aging under UV light and measured those properties again. Is that too much to ask? Well, it is. Instead, terms like "highest gloss," "highly durable," "fade resistant," etc. are used without any supporting data or explanation.
I saw all that. If you threw ' chromaticity' into your enquiry, I can well imagine they wouldn't reply !! Black and very very glossy is the correct terminology !!?!!
I think you'd have to take 'fade resistance' on trust, modern paints are sooo much better than of old. PPG is one of the widest commonly used car paints here. (made in the USA ?). I'd have to say the rows of gleaming hot rods you see at shows here say that it is GOOD. And race cars - they proudly show the PPG logo prominently.
I think I mentioned that when I bought black paint, I requested that it was black black, with no red/green/blue/pink/white/grey/etc in the formula. This did indeed produce quite a very dark black. Noticeably more so than common black I'd had before. But it wasn't urethane.
Can you look up your 'local' HoK supplier, and run your questions past them. Most paint folks are fairly knowledgeable on common stuff. And know what was flying off their shelves.
P.S. And, to a very limited extent, I do my own 'durability testing'.
This pair have been hanging on a fence for the past few months. No sign of fading or rusting yet. The true test will be over summer - maximum UV 6 months on a fence would equate to how many years in a garage ????