420m Builds A Flowhood

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It all started with some standard grade 1/2" plywood.

Cut to size -

The inside 18" which will make the clean area are sanded smooth with Medium 100 Grit Sandpaper. This was followed up by a coat of varnish. Allowed to dry almost 8 hours - this really brought out the grit in the plywood - so it was again sanded smooth with 150 grit fine paper - and re-varnished. Allowed to dry overnight. Today it was re-sanded LIGHTLY to allow for more coats of varnish.

Here are the pieces.

The first pict - with the pieces cut with two coats of varnish.


I started to put the pieces together - and since I had no help today - I used the old flowhood piece to hold my boards up for me -- The new flowhood will be alot cleaner than the first one made years ago :-)

Here are the back and sides put together. You can start to see the shine from the so far 2 coats of varnish.

You can also see the 1x1 that I used in my first flowhood - that I later decided to change to 2x4s for sturdiness and cost - could only find the 1x1s in pine !!


You can see the 2x4 here along with the fan pannel.



OK - got the fan pannel in . . . and the frame for the 99.99% HEPA Filter to sit on top of.


The fan blower chamber


The plenum chamber and space for flowhood

The bottom chamber.

The 2x4s on the side are there to attach my plexiglass to.

The sides are just a shade larger than 24" and to step up to the next size in plexiglass from 24" was a 300% increase in price - so I figured out something else.

You can really start to see the varnish now - I had just added another coat - fact - you can see it running in this pict before I cleaned it up ( it was because I picked up the box for the photo
wink.gif )


Here it is with the filter in and the top on - the cord is going through a small hole in the back.

You can also see two tiny black screws holding the HEPA down in place so it doesn't move around - I wanted to avoid piercing it with screws.


Here is an 'upskirt' pict with the front piece on. - You can see the flowhood showing off its goodies <the filter>

By this time the clean area has had another 2 coats of varnish - I think I am up to 4 - possibly 5 coats - you can really see the shine :-)

SUPER CLEAN - I hope :-)

I added the plexiglass.

I didn't want to crack the plastic with screws - and I didn't (at this point) want to spend the time predrilling.. . .so I got some adhesive caulk and laid a nice big strip along the wood - will dry clear in 12-24 days the package said

Here is the top of the box - waiting for a prefilter. I just cut the top with the circular saw - I am guessing it is about 14x6 in size or so - I figured this was a good size - I'm open to suggestions here also!

I've got some good material care of Mycota - just didnt affix it yet.

Was thinking about some more of that adhesive caulk - but maybe I am just tired. Any suggestions?

Here's my airflow out of the box. - Could hardly keep the lighter lit to take the pict.

Woo Hoo !!!!!

Another upskirt shot of the clean chamber and the filter - all wood surfaces have been THROUGHLY coated in varathane - so they should be easy to spray down with alcohol.

The HEPA filter was also sprayed throughly ( but carefully - it is a paper filter after all! ) with 70% alcohol on two occassions.

And here it is ALL FINISHED!! (cept the pre-filter I guess)


Here is the side view pict. I am going to Home DePot tomorrow to pick up a 12x12" ceramic tile to put in there for HOT items! I am guessing Mycota recommeded formica partly because its heat resistance. You can see the handles I mounted to make it easier to move - after all I don't have a dedicated clean room - yet!!

Hope you enjoyed my project - Time for bed finally, so I can volunteer at my kids school in the morning!

~ 420M ~



That is inspirational! I guess I didn't realize how easy it is to make a flow hood. That is phenomenal! I'm going to make one as soon as I finish my closet. I'm already getting excited!!
How much did that blower run ya?
and that huge filter, how much??

Instead of all that varnish Id use one thick coat and then line the filter chambers w/ 6ml plastic sheeting stretched tight, and tacked.



You will love working under that puppy. I could not tell, but I hope you made the front opening - about 1 inch taller that a quart jar. So, they slide in & out -- easy for G2G transfers.

Just use any sort of molding strips to hold the prefilter material down w/screws through the molding, into the box top. You can find all sorts of neat 1/2 rounds & assorted molding strips in 8 ft lenghts at building supply places, for not much money.

It's gives one a great feeling of confidence, working under a flow hood.



fuckin shweet!

but i woulda put the plexi glass on with a piano hinge , and then used rubber foam to make a seal where you put the glue.

2 clips on each side to hold the plexy against the foam.
(duct tape would work in a pinch)

that would give you more space (if you need it) to put your stuff through into the work area.

could open it up to clean the inside too, instead of reaching through.

very nice job. very cool.
now i want one... going to have to wait though.




I didnt know how large to make the opening so I made it about 5 inches. Just about an inch SMALLer than the jars.

You have to tilt them on their side to move them in and out of the box, but I figured it better that way.

Lemme Know what you think.


BTW - I need some ideas on a "substance or substrate" that is SUPER EASILY contaminated. I would like to leave some open in my box for 12 hrs and then incubate to make sure the sucker works like a charm. I would use petri's but I dont have agar. How bout some some PDA liquid minus the "A"? Malt Extract in Water, Karo Jar?

How should I test this baby!?

Fred Garvin

Very nice work, how much does that puppy weigh? One person or two persons to move/carry etc?

I'm with WOP, an open jar of grain should be fine to check for efficiency.

Do you have a cost of materials list, or did I miss it earlier?

I don't know how in depth your planning was, but a cut list and and a bill of materials would make it a lot easier for lazy and unoriginal bastards such as myself to copy your fine work.

Actually, I'm not all that unoriginal, just lazy


It's so simple and so cheap fred!
Nans nook is gonna turn into the OMC flowhood club! laugh.gif

Your cost list is always gonna differ from his.....and you should ALWAYS shop around. It's ok if you're unoriginal, just don't be lazy, cuz lazy can result in shoddy work.....

You build any flowhood with two (at the most) sheets of half inch plywood, and a 2X4 or two......

Squirrel cage fans are so simple to get for cheap that your should NEVER buy one retail......you might even get one for free if you aren't LAZY....

The CHEAPEST place to get filters is filtersrx.com, but there are a thousand other companies that are just like it. You have to get a quote most of the time tho......and it takes them a while to get it to you since they are big corporations - thats the one thats gonna fuck your pocket up.

I'm sure he can lift it up.....if he's not a little girl....


Heya Fellow Nookites,

Thanks for stopping by and all your wonderful comments. I hope some others can benefit from this project as well.

Here is my HUGE concern with this project. I am not sure if the HEPA filter that I am using is "clean." I took it out of my old flowhood and by design in the old hood, the filter was subject to the air in the room, so when the hood was turned off, there was a possibility of contams landing on the filter directly < not anymore :-) >.

SO. . . I am REALLY worried that the filter itself might be bad :-(
That's why I keep hinting my concerns about the hood not working :-(

Mycota had a wonderful suggestion to clean the filter with 70% rubbing alcohol - and I DID - but how well can you really clean paper.

Please everyone - cross your fingers for me - I REALLY need a flowhood to work with and I am a good person at heart - so I think I deserve good things sometimes huh?!? < this is one of the things I want God please> :-)

Here is a picture of what my old hood looked like ( I can't find the actual one I took ) . .


70 % alc will kill any contam on it. It may be a bit degraded from use. But, so long as there are no holes in it & wind still blows through it. You should be good to go, once ya have a pre/filter - togather.

Just fyi. Every once in a while when not working under it & spray a light tiny mist of 70% acl into the prefilter, to kill anything that is acumulating.



Mycota. . .

I was just building up the stamina to answer everyone questions here and give a more complete writeup. . .but since you mentioned it. .. .

I was going to ask if I could spray the prefilter down with alcohol before and during use - if that would help or allow contams to pass even easier?


BTW - the "opening" is about 5" tall - do you see any problem with working in this area - I think jars are about 6 1/2" tall - and bags even taller - my total "clean area" is 18".

~ M ~


Not during use. A light tiny spray an 90 or 120 minutes before, is okay, as it evap's away & drys out by then.

Should have made the front opening taller, so you can slide quarts in easy. Plus - that narrow don't give you much wrist room. I have big hands. I like working room, so as it's not cramped.

I wish I would have caught you -- before you cut the pre/filter hole in the top. SORRY

No doubt, you looked at the auto air filter, as a pre/filter thread.



Shit Mycota - I'll RIP that top piece off in a SEC and replace it - that is what I figured I would do as soon as you made the car filter suggestion! What size filter do you suggest?

I would have liked more room to work in the filter too. . . . but I thought the idea was to have as little room as possible open. I could always pull this plexiglass off and get a new one for $5.99 and put some more caulk on after I clean it up.

Lemme Hear some more suggestions people! - Thanks Mycota!


QUOTE (420M)
Shit Mycota - I'll RIP that top piece off in a SEC and replace it - that is what I figured I would do as soon as you made the car filter suggestion! What size filter do you suggest?

I would have liked more room to work in the filter too. . . . but I thought the idea was to have as little room as possible open. I could always pull this plexiglass off and get a new one for $5.99 and put some more caulk on after I clean it up.

Lemme Hear some more suggestions people! - Thanks Mycota!

Don't be ripping anything up -- until you are sure of what you are doing. I don't know the demensions of the hole -- you cut. Check out an auto parts place, for a auto air filter -- that is bigger than the hole.

If you cannot find one bigger. Just add a layer of thin plywood on top the hole, rather than tear the existing top OFF.

If you work in front of this thing -- a few minutes -- now & then. A little discomfort from lack of hand space is no big deal. If you work in front of it, for several hours at a time. Hand space & comfort become an issue. That is for you to decide -- what you want.

G2G .......50 quart jars some time & you will know what I mean. My 0.2 cents -- anyway.



Samsara - The reason I made this flowhood was because I was having too many problems growing mold and everything else except mycelium. It took a total of four days due to having to let it dry and stuff, but I still figure it took me a good - oh - including planning time - at least almost like 15hrs - more like 5-6hrs total - but that is only 'cause I am a stoner and I had to stop to smoke bongloads like every 15 minutes. The HEPA cost about $60 or $70 from www.filtersrx.com .

FungusMaximus - My Friend - I was hoping you would say that - I am SO glad that this inspired you to build one yourself - you deserve it. . .especially since the hard work (planning stage) is done already for you :-) I bought the blower used from a HydroStore and paid like $75 bucks for it - but it was my buddies store - so it all worked out in the end - most likely could have found it cheaper if I tried. Came without a plug - so I wired up an extension cord. Filter cost was bout $65 I think. I'm actually glad I used that much varnish - I don't want contams hiding anywhere!!


Mycota - Thanks for your inspiration, thoughts and insight, and especially for giving me the desire to build a quality flowhood!

Mal - Thanks for stopping in and giving me your comments bro. I want that sucker to be sealed up TIGHT - positive pressure or NOT - I want ZERO - LESS than ZERO chance for contams to get in my clean area. I am a hyperactive fuker anyways - I need to slow down and take my time when doing clean work - so maybe having to work in the smaller area - and take more time moving things around in my flowhood is good for me. I am not doing this on a professional level at all ( like a 9-5 job ) - so it is not like I will be in front of that thing all day - I need to take my time - even if doing 5 G2G jar transfers takes me 15 minutes - I NEED to take that time for myself, and my cultures, to ensure their sterility!

DirtyWOP - The amount of wind IS large - I was considering putting a rheostat dial ( for a light dimmer switch ) on the side so I could turn down the flow. I think I am going to use jars of grain to test my hood - I pre-boiled the rye tonight.

Fred - That suker IS kinda heavy - you have 1/2" plywood over most of it - cept the fan blower mount is 3/4" to be studier and the front is 1/4" to make it lighter. . .but with the handles on the side (set at 28" off the ground) it is pretty easy for me to carry :-) As far as planning goes - that was the HARDEST part for me - see I am a stoner and I can follow directions REAL well - but visualization of a new design is harder for me. The planning took the longest for me - to figure out how long to make each section - then how long to make each board - and did I take into account the width of the board itself - and all that stuff. Would have been A LOT easier for ME at least if I would have had plans to work with - all I had was that FIRST picture I posted - thanks to Mycota!

Mycota - I think the top pre-filter opening is about 18x6 inches or so. It would be easy for me to remove the top pannel - remove the screws and slice the caulk. This is MY new CONTAM FREE station - I want NO halfassing! Especially since I got a real special print I want to work with wink.gif

I would think the larger the prefilter the better - since it would be easier for the fan to suck through . .any idea?

Do whatever is easy & get 2 of these (pic below) & piggyback them, on top, for a pre/filter. It is not brain surgery, to figure out how to apply them, wink.gif

If there is a U-Pull it cheap auto wrecking yard in your area. Just go -- check it out & find a metal top for a big round auto air filter. Might cost you like $3 to 6 bucks.

Then, get a 1/4 inch threaded rod & a wing nut or 2 for it @ a building suppy.

You get the picture, I'm sure.

Hell, when you are done, you can paint flames on the sides & rev the sumbitch up & make race car sounds, LOL

Mycota biggrin.gif


Here are the sizes I figured out for the box.

I started with the givens:

The Fan Height is 9" with an additional 2" clearence.
The HEPA filter is 6" deep.
The Plenum Chamber is 6" deep <I just figured on that size>

Then I decided that I wanted the "clean area" to be 18" tall and I had NO idea how large to make the opening for equipment so I decided on 5" for that.

So - I have an 18" work area - a 6" HEPA filter - 6" Chamber - 11" Fan area.

I cut the boards to these sizes:

25x41x1/2" - 1 piece for the back
12X41X1/2" - 2 pieces for the sides
25X13X1/2" - 1 piece for the bottom
25X12 1/2x 1/2" - 1 piece for the top (shorter so the front piece would cover it nicely)
25X26 1/2"x 1/4" - 1 piece for the front
24X11 1/2" Plexiglass sheet

When I laid the 2x4s on the inside - I just calcuated where the top of them would be to create my 18" of work space. I also added some 2x4s to the front sides to attach the plexiglass to.

More Questions?? - Bring it on!!

Hmmm. . .I'd rather use a rectangular filter like these. . ..

Still - . . . . - but SHIT - i'm in it this much - good spawn is worth lots more than that to me :-)

Edit: so I don't sound cheap.

Fred Garvin

If your using a rectangular filter, check out the air filter for Toyota Tacomas. They're about 5 x 10 and plenty thick. That might be enough to do the job. you could cut the hole to the correct size, and simply drop the filter in and secure the lip of the thing. You'll know what I mean if you see it.

Thanks for passing your work on to your fellow stoners, who might not have such a hard go of it now. Good man. May all your transfers be successful.


Here is my old flowhood - no longer !!

The HEPA itself.

Here is the prefiter I decided on - they were the most 'premium' filters I could find short of K&Ns.


Being frugal myself, and having already used up the entire sheet of plywood - I made the top piece that I already had work!


Here is a top shot of the pre-filter installed. Worked out GREAT - thanks for the suggestion Mycota - had a built in gasket that made it SUPER easy to install tight! See. . . .


Here's a shot from the bottom with it installed.

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