my next box

ScrubNinja said:

Is it a PWM fan perhaps? (what model is it?) I have never messed with PWM...but I found this:

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Hi Scrub: Yes it is a PWM fan. http://www.arctic-cooling.com/catalog/product_info.php?cPath=3_48_79&mID=280

I can find stuff all over that tells me how that works but nothing that says how I could use it. The wires have something to do with speed control so it seems if I got some sort of external PWM speed controller could I use those wires for control? I'll keep looking and let you know what I find.

Just finished the lightproofing and took some photos so I'll share. As mentioned, lightproofing was a challange due to the cheap ass nature of the box and warped doors. I tried bulb and foam weatherstripping and wasn't happy with either so I came up with an approach that requires light to make a 90 degree corner through foam weatherstripping to get out, which means it's not going to happen. I took a lot of photos and was thinking I could do a thread on the process if people seemed interested.

I applied a wood liner strip around the perimeter of each door and at the interior of each chamber. This allows an interior sealing surface that I can scribe to position at each location so the perfect contact is made everywhere.
Interior view of lightproofing liner strips

The box with lightproofing applied to doors and chamber perimeters.

Since the box is lightproof it's also airtight so I did a final airflow test. Taped the bag over the scrubber vent and plugged it in. Did a smoke test on the passive intakes and they were both sucking real good.
5.3 cf in 9 seconds = 35 cfm

So I'm real happy about over all ventilation and the scrubber performance resistance wise, hope it's enough area to control the smell. I'm pretty confident, 200 sq in is the equivalent surface area to a can type filter 6 inches in diameter and about 10 inches long which doesn't feel undersized for a box this size. I'll see in a few months when I get the next batch going.

Excellent.

Here is a fan controller for PWM. No idea if it will work without a motherboard. The article is a little old but he does say "I haven't seen any other fan speed controller that allows the user to manage a PWM fan, so that in itself is pretty unique."

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Thanks Scrub, that looks like it would work. I moved the clones out of my big box and now that the jet engine fan in there is turned off I notice there is a bit more noise on these guys than I would like so I think I will be trying to slow them down.

ShamelessJames said:

Is it possible to combine the ventilation of lights and the cab with scrubber?

Mounting a seperate fan in the cab proposes even more problems like cab depth and being able to mount a scrubber on the outside with a fan.

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I think so James. I don't have experience yet with smaller cabinets but had no problem in my bigger cabinet. Air will cool and the quantity of air will determine how much, you end up with a standard temp rise from ambient. This is a chart that I've seen in several threads that has this info mapped out.



Add up your total electrical load and from there it's a balancing act between how much temp rise you can tolerate and how much air you can move through. I think I could get more airflow through my scrubber but I'd get more noise. As mentioned above, I'd like to crank it down a notch to lower the noise level. According to the chart, to cool 150W HID and 130W CFL I'd need about 80 cfm.

The space taken up by an air cooled hood is part of the reason I am going the bake a round cool tube direction. It's only 4" diameter so it won't take up much height. I have enough sheet metal skills that I could fabricate a small AC hood but the cool tube is less of a project.

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ShamelessJames said:

Got it, that means I will need only need a 50 cfm pc fan to cool my 90-150 watts of cfls. And I just so happened to buy two of those plus 4 other fans. (Hint: check for open box returns when shopping online, great deals!) I just gained 4-6 inches in height as well. nice!

Much thanks man, i'm forever grateful.

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No problem James. Your math looks good. One suggestion, if you split your intakes and put on either side/end you can get a more uniform airflow through the chamber. Half the job of building a cabinet or other enclosure is figuring out the details so it will provide the proper environment for the plants. We're not just building boxes, they're growing machines.

Does each chamber have 90-150W cfls? If so that means you need to get 50 cfm through the scrubber on each side to maintain a 10 degree rise. I'm sure you know but you can't go by the rated fan cfm whenever you throw in a DIY scrubber. That's why I did the bag test on the final construction, to know what I'm getting as net air flow. My 2 fans were rated at 56 cfm each and I'm only getting 35 cfm out of the filter, but that's about what I expected. Also, mount your fans so you can get to the screws and change out the fans if you need more air/less temp rise.

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Funny thing happened on my way to build a cool tube. I was looking at posts and came across one trying to decide on how much light to put in a box. There was a post by DiscoBiscut where he patiently explained some fundementals on light orientation. He added that the bulbs put out more light to the sides so in a rectangular space the bulb should align parallel with the short side. Makes perfect sense but I never really thought of it before. So my cool tube would be blasting the center of my box and the ends are dark. Shit. Not enough room to turn the cool tube. So I've revised the cool tube to a custom reflector with glass. Yes, it's more work but I am downshifting to a 150 watt system and don't want to throw away any lumens.
the drawing. I can't do anything without a drawing

Reorienting the light will allow good lighting to the sides and maximize the wattage. I worked with the hood design and came up with kind of an inverted W shape that really gets the light out from behind the bulb. I came up with a detail for holding the glass on with wing nuts and some flat bar.

So the next task is building it. I know they don't teach it any more but I had mechanical drawing in high school (back in the 60's) and they taught us how to do sheet metal drawings like this.

So I drew it up.

If you draw 2 views of any sheet metal fabrication, one is going to have the true length of any given plane and you can figure it out. I printed out an enlarged copy and made a paper model. I'll have to look around to see what kind of metal I can come up with. White is easy to find, might try to get a textured steel or aluminum to increase reflectivity.

Built the hood today, wasn't as hard as I thought it might be.
I printed full size templates and taped them on a piece of sheet metal, traced the patterns and marked the fold lines. Then I cut them out, bent the pieces and screwed them together.
one each, air-cooled micro hood. Not an entirely professional looking build but I think it will do the job just fine. Still need to add a light socket, some duct connections, paint and the glass of course

All things considered, I think it will be better than the cool tube I was going to do. I'll get better light distribution and with this hood there is less restriction so it should give be better airflow from the little fan I'm going to run with it. Also, with a bake a round cool tube I'd always have to buy the skinny T15 bulbs which are a little more expensive. Only down side is I've already bought the bake a round....

That's pretty impressive, man! May I ask if you used tinsnips or a metal jigsaw or what? (to cut the metal). I have a bit of cutting coming up with 1mm thick metal. I remember from metalwork class in school that it would be hard going with tin snips.

I tried repping you but hit the wrong key before I finished so ignore the non sensical message if it's there.

Also, ever think about trying SketchUp? You can basically draw your hood (etc) in how it fits and looks nice, then get the measurements. If you need the area of a hole, you just draw it, then hover if I remember right, and it tells you the area - great for cabbing.

Thanks for the compliment Scrub. I used tin snips but the only sheet metal I could find easily is like .4 mm so it was easy to cut. Your 1 mm would be hard to cut with snips especially at inside corners and such. A metal blade on a jig saw would probably be easiest if you've got a lot to do.

Yeah, I've got sketchup and done some things with it but I've been drawing with CADD for 25 years and you know, old dogs, new tricks. Here's my big cabinet drawn with sketchup, I'll have to draw the new one just for more practice...
Built it back in the OG days as an overgrown NGB cabinet