my next box

[touchofgrey]

I've been thinking of going to a smaller, more stealth box. I have this cabinet that I thought would work, it's 30"W x 60"H x 14"D. I wanted to get 2 chambers out of it but it might be too tight for that. As long as I'm running a compact variety and ScROG the hell out of it there is hope. I've worked out a design but still in the early stages and wanted to bounce some ideas off here.

the drawing

First, lighting. I'm planning on getting an digital ballast that can run either HPS or MH but not sure if I should go with a 150W or 250W system. I am planning on a DIY bake-a-round cool tube. Thought a computer fan would cool a 150 but not sure about 250?

Next, ventilation. If the light fixture is vented separately I don't need a whole lot of cfm to get 4-5 air changes/minute. I am planning on a flow-through design with intakes in both the chambers and transfer pipes between the lower and upper. That type of design worked well in the box I'm using now.

Also, had this idea for a carbon filter you can see in the drawing. I've got a bunch of the plastic trays you get at the nursery when you get a whole flat of seedlings. They're 10"x20"x2" with kind of a mesh pattern on the bottom. Thought I could strech a nylon stocking around it and fill it with an inch of carbon. The trick of course is getting air through it. That's 200 sq in and I only need about 30 cfm so I was thinking I could put in 2 or 3 of the heftiest computer fans I could find and make it work. I was looking at Artic Cooling, the noise level is low and they claim high static pressure. Not sure they will be able to push through so I ordered some up and plan on doing a mockup. I can build the scrubber and frame mounted on a board with the fans and tie a garbage sack around the top and see if it fills up. If it does I can calculate the cfm from the volume of the garbage sack.

Any thoughts are welcome...

 

[silent_lemon]

really good design, but i dont think it wont work with the pc fans. With only 2 pc fans, even the best scythe/double server inline type/squirrel caged, et al. they just cant move the air with that much resistance.

I propose they would move the air from the main cavity up into the top portion, but not able to push through the scrubber, and youre stuck at that point, and it then turns into a microwave from there. if you cant get the air out, you cant exhaust the air to draw new air in.

PC fans work well without the scrubber, though, as i have found in my own cabinet experience. I dont know how some people get PC fans to push through a scrubber, i figure it cant be done, but somehow people are doing it - just barely it seems to me.

AC 120mm axial fans would do it, they would be super noisy, and theyre hard to hush, but they have the big blades and high RPM to push a ton of air. rushing air and the whirring is pretty noisy though like i say.

or just a good quality fan to suck it out - better overkill than falling short.. otherwise looks golden.

 

[ScrubNinja]

I dont know how some people get PC fans to push through a scrubber, i figure it cant be done, but somehow people are doing it - just barely it seems to me.

Please check out the fan thread in my sig, it will demystify the subject, I hope.

Touchofgrey, that goes for you too Your carbon filter idea should work, I've done something similar twice now. I used 60 litre plastic containers with various methods to hold up a carbon layer. As long as there are plenty of holes in the trays you'll be fine. If they are actual round holes, measure one, work out the area it uses, and multiply that by how many holes you have. This will give you the very approx equivalent of the restriction size.

My current scrubber is roughly 21" x 14" = 294 sq inches surface area. There's roughly an inch and a quarter at least of carbon and kitty litter crystals, and I have used just carbon before. One of these (the 120mm) fans had no problem pushing a good amount of air through it with very little restriction. Of course it's best to pull through a filter, but I'm just sayin'. There are much higher mmh2o fans available too. Basically the whole thing is to do with the fans mmh2o rating, and the one I used in that example is 6.57mmh2o on full speed (I have it undervolted because it's too loud that way, plus I have 2 fans in line in actual usage). I doubt you would need a full inch of carbon by the way.

Not sure which particular model of arctic cooling fan you have in mind but I don't class the ones I looked at as good for pressure in any way shape or form. Fan companies just say high pressure as it's a buzz word. Look at some fans mentioned in the fan thread and you'll see what a high pressure computer fan is

 

[Hella THC]

Nice plans, touchofgrey! I work with drafting plans for a living so seeing this put me right in my work mind set for the morning Let us know as you go about putting this thing together.

I still want someone to come up with a good idea on how to do easily to bulb changes with the bake-a-round style cool tubes.

Looking good!

- Hella

 

[fatigues]

14" depth? Oiyyy. That's a problem. Most every time you'll want to try X, Y and Z, this damn depth will rear its ugly head and roar: "NO YOU CAN'T - IT WON'T FIT" at you.

Give yourself some more room bro, 18" at least should maintain stealth (24" depth, even better). Then at least you'll have some elbow room to do your thing and get clever when you need to. But only 14" for a custom cab? You won't be happy.

 

[touchofgrey]

Thanks for all the replies.

Scrub, wish I had found your thread before I ordered the Arctic fans. I looked a the Thermaltake but didn't find the spec sheet that shows the amps - .5 vx .15 for the Artic so at <1/3 the power I'm probably screwed. One thing I was trying to avoid too was the noise and the high rpm fans seemed to be louder. The Arctic has max rpm of 1500 and 29db and touted some vibration isolation features. They're on the way so it will be a nice experiment. Also, thanks for the imput on the carbon filter, in a tray it seems you can adjust the thickness easily to deal with the stink and keep the exhaust working.

14" depth? Oiyyy. That's a problem. Most every time you'll want to try X, Y and Z, this damn depth will rear its ugly head and roar: "NO YOU CAN'T - IT WON'T FIT" at you. .

Yeah, I know. It's just I have this cabinet sitting around and just got cut back on hours at work so didn't want to buy another.

Nice plans, touchofgrey! I work with drafting plans for a living so seeing this put me right in my work mind set for the morning Let us know as you go about putting this thing together.

I still want someone to come up with a good idea on how to do easily to bulb changes with the bake-a-round style cool tubes.

The bulb changes will be a bit of a challenge but you only need to switch out every couple months, right?. I was planning to hook up a sheet metal duct to the glass tube and secure with a hose clamp so I can get in there when I need. Anyone out there have a good solution for this?

TOG

 

[ScrubNinja]

Not to worry about the fans, man, the odds are still on your side imo. You still have a very free flowing filter design compared to the average DIYer, and at least it's not a loud fan. I always look for positives

Besides, if you want stealth, a big loud high mmh2o fan may not be the best choice. If you find it doesn't work, try stacking the fans in line, so they both help each other in a different way. The way you have them, side by side, will blow more CFMs in an unrestricted envirnonment, but the total pressure is equal to only one fan. If you stack them inline, you will have the CFMs of one fan (remember, this is in an unrestricted environment), but an increase in pressure (booyah, this is what's helping you get closer to an unrestricted environment and will let the fan actually blow some of those CFM). Just woke up so I'll let the pic explain it



I'm not sure if you've read any of Red's threads, but he is the master of what you're doin' here. This one has a lot of the technical details and there's also a HPS cab thread somewhere that may interest you.

 

[Hella THC]

I personally think 14" deep is enough. it may not be FUCKING AWESOME but it will do the job. You won't NEED more space, but I could see you desiring more in the future. It's your cab though.

Grow in a shoebox if you really want to

- Hella

 

[ScrubNinja]

14" is the perfect depth. I wish all my cabs were multiples of 14".

 

[touchofgrey]

Not to worry about the fans, man, the odds are still on your side imo. You still have a very free flowing filter design compared to the average DIYer, and at least it's not a loud fan. I always look for positives

Thanks, the mockup will tell the tale. We'll see if they have these fans have the oomph, but i really was trying to focus on being quiet. And I have read Red's threads, they're a great help in understanding how air works.

Whadoyathink about the height I've got? 2'-5" feels tight but I've seen tighter boxes out there. I'll have to LST young and then scrog to make it work.

I personally think 14" deep is enough. it may not be FUCKING AWESOME but it will do the job. You won't NEED more space, but I could see you desiring more in the future. It's your cab though.

Grow in a shoebox if you really want to

- Hella

Yeah, the idea here was be small. This box will fit 2-3 plants and clones with their mommy nicely. That produces enough for my needs. Anyway, I've got a big 6 plant box if I have a place for it again.

 

[Hella THC]

Sounds perfect. Good luck with everything!

- Hella

 

[touchofgrey]

The fans showed up today so I just had to try one out. Don't have time to make up the filter mock up yet but wanted to see if these guys could push at against some static pressure so I came up with a 'sperment. I took the box they came in and mounted a fan on one end then taped up the box except for down the middle. This left a slot about 1/16" wide and about 16" long, figure about 1 square inch. The fan opening is 4-1/2" dia or 16 square inches so this is a major restriction in the air flow.
all sealed up except slot down lid

Then I taped on a 13 gallon garbage sack, pushed all the air out and plugged in the fan.

It took about 40 seconds to fill up.

the sack measures to about 2 cubic feet so this calculates to about 3 cfm, very unspectacular. So I opened the slot to make the opening about 3/8" or 6 sq in and that only took 8 seconds... about 15 cfm. Much better, but still not quite there. There's hope for 2 side by side, just have to see how the charcoal tray works out. The cabinet is only 12 cubic feet and with the cool tube if I can 20 to 25 cfm through the filter I should be good. The nursery trays I've got for the filter are perfect, solid sides with an open grid on the bottom for support.
I'll just need to glue in a mesh fabric on the bottom and fill with charcoal

I'll let you know how the mockup goes but I've already got a Plan B idea to use a panasonic whisperlite and gain 5" of headroom in the bargain, I'm almost more worried about headroom than ventilation.

 

[ScrubNinja]

Excellent work buddy. I love testing stuff like this!! I have run bag tests before but I had the bag scrunched up around a small collar at the opening, so I had no idea how much air it contained. The way you have done it is really smart and I assume that's how you know the volume of the bag?

Hows about cutting a 120mm hole anywhere in that box, on the side or somewhere - then tape the fan on and you can test the results for two fans side by side.

I'll put a link to this thread in my fan thread when I finally update the first post with all the new fan things that have surfaced since posting it.

Best luck and those trays do look perfect. You've done well.

 

[touchofgrey]

carbon filter mockup

carbon filter mockup

OK, I made a quick mockup for the carbon filter design to test it out. I built a 1x4 frame to fit around the nursery tray. Then I mounted 2 fans on a piece of 1/4" hardboard and screwed it to the frame and run weatherstripping tape around the edge, set in the tray, lined with cheese cloth and filled with charcoal.

I then streched a 40 gallon garbage sack over the frame and plugged in the fan.
It took 11 seconds to fill. 5.3 cf in 11 seconds = 29 cfm. Not too bad considering I'm looking at a 12 cf box. That would be over 2 air changes per minute which would be fine if as long as the light is in a cool tube. Just to see if it made any difference I taped the fans on the other side and reversed the air flow to see if the performance was different with the fans sucking air through the filter rather than pushing. It was the same.

Still trying to decide on the final design and welcome any of your thoughts. Right now the idea is the cabinet is unmolested in appearance from the front, all the air inlets and relief is in the back. If I put the fans on the top I'd have to have holes there but the bonus would be a 5" gain in headroom. I figure I could put a cardboard box on over the holes with cutouts and lined with fiberglass to act as a muffler so it still would be fairly stealth. I was also thinking of mounting an 80 cfm Panasonic Whisper fan on top and eliminating the cool tube. I like the idea of being able to move the light up and down rather than moving the plants but don't like the idea of spending another $150 on a fan. Maybe I'll try adding a 3rd fan to the mockup and see how much more air I can I get with these guys...

 

[Work2much]

Great work on the scrubber. It's always a blast when DIY stuff works properly.

Cooling my light sources seperately from the cab was/is the key to my success in micro cabs. Without it I'd struggle to maintain control over the plants.

 

[ShamelessJames]

.

 

[touchofgrey]

the build begins

the build begins

Got started on building the box today. First step was to build the filter compartment. The fans wanted to be mounted to a computer chassis so I took some sheet metal and made a mounting flange. Then I laid out the location on a shelf and cut some holes to recess the fans into. Just gained another 3/4" of height. I built a new frame for the tray, added some endwalls to seal it up and mounted it to the fan shelf.


I laid out the new shelf heights on the side panels and located where the holes had to be drilled for the shelf support hardware. First I assembled the filter compartment and the lid.


I cut out the hole for the 3" pipe transfer pipe since is so much easier before you get the shelf in place. Few whaps with the rubber mallet and this box is almost done!


The back they give you is cardboard so I'll have to get a piece of 1/4" hardboard. They I can get the ventilation components completed.

This is my first project with computer fans so i don't know what to do with the extra wires. Is there any reason not to just cut them off? The fans are designed to get commands for speed from the cpu, there's a 4 wire molex and an extra yellow for a sensor I think. Is there some way I could get speed control if I wanted?

 

[ShamelessJames]

.

 

[touchofgrey]

Thanks for the links James. The utube guy was pretty vauge and even Scrub Ninja's excellent resource doesn't tell me if they is anything you can do with the blue and yellow wires. Everywhere I look just says cut 'em off so I guess I will. These fans are real quiet anyway so I don't think I'll need to slow them down.

The Box Update:
It's almost complete, well except for the light. Having to add a 1x1 liner at the chambers to deal with lightproofing a cheap ass particle board utility cabinet. This solution will work great though, I'll post some photos when it's done.

Also, I've tested the scrubber in place and got 33 cfm going through it so that part is going to work as planned. Might need to wait a while until I can afford a new HID setup. Got my bake a round today on ebay so that will be the next project.

 

[ScrubNinja]

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

Modern fan controllers don't adjust the fan speed by adjusting the voltage. They use PWM which requires an additional wire (usually blue). The fourth (yellow) wire is used to monitor the RPM of the fan.