Drano’s fan mod – and how I did the install, w/ pictures

[drano]

I finally put the fan mod on the top of my to-do list.  Thanks to all who have done this in the past, and posted how they did it.  Mine is the electrical box version with a couple twists.  I purchased the motor and fans from Grainger.  I picked up 2, 2.5 and 3 inch fan blades.  Figured I'd experiment with them.  The 3" became my motor cooling fan, and the 2" is inside.  I initially put the 2.5" inside, but during my empty test run, I realized it moves too much air. 

Here is the finished install.  (sorry for some of the blurry pics)


Here is the assembly ready for the OBS.




Motor mounting in box.
Here's a close-up of bolting the motor to the back of the box.

Big picture, I removed the factory bolts, and purchased two 8x32 by 2" fully threaded screws.  Some details:  Spin a nut and washer deep onto the screws, run screws into motor and screw them into the motor housing.  Tighten nuts.  Then cut off the head of the bolts with a cutoff wheel.  The remaining bolt should be long enough to mount the motor to the box.  Before I did that, I put 2 washers on each bolt stub.  (can sorta see them in the photo—sorry for the blur) This holds the back of the motor just a hair off the box.  I noticed without those washers, the motor shaft did not spin as easy after being tightened down.  I'm guessing the motor got flexed a bit without the washers, making the shaft slightly harder to turn.  It didn't lock up the motor, but there was noticeable friction there without the added washers. 

I used screws and nuts in the threaded box holes to hold the box the correct distance from the smoker as I marked/drilled/screwed in the aluminum mounting rails.  They are 8x32 by 1/2" screws, held tight by nuts.


Drill the hole thru the back of the BS from the inside out.  First remove the back to make sure you won't hit the electrical wires going to the overtemp sensor.  Put a piece of tape on the back of the BS so you know where they are for the rest of the project. 
Run the fan onto a 3/16" drill bit (bit not in drill), hold it up against the back of the smoker where you want the fan (have V tray and bottom shelf installed), and spin the bit by hand to mark where to drill the hole.  Remove the upper rack, install bit in drill, and drill hole as square/straight as you can.  V-pan will catch your drill shavings to keep them out of the burner element.  Drill a 3/16" hole.  Once you have finished installing the motor assembly, you can drill the hole bigger for a little shaft clearance.  Mounting the motor with a tight fitting hole will ensure you have it centered (I thought of this after I had an enlarged hole, and getting mine centered in it).  My final hole size is 1/32" larger than 3/16.

Here's an inside pic with a shield around the fan


It took me the better part of 2 afternoons, but I work slow and methodical. 

Hope this helps the next person with their install.  I appreciate all the great info on this site. 
Drano

[Mr Walleye]

Hey Drano... Great job!  8)

Two thumbs up!  ;)

Mike

[Habanero Smoker]

I agree. Very nice work.

[Smoking Duck]

Looks great, Drano.  I sure wish I was mechanically-inclined.

SD

[smokeitall]

Nice job Drano.  I put my fan on the opposite side of the smoke unit.  Anybody else do this or did you all mount it in the back?

I didn't buy any parts for mine I used a fan motor from insided of a microwave that I was throwing out and for my fan blade I used one from a blender that my in-laws where throwing away and they let my 5 year old take apart, and I noticed a fan blade inside the blender that is used to cool the motor.  I had a buddy weld the fan blade to a home made coupler and then attached it to my motor.

I was initially worried that I would blow the smoke back into the smoke unit but my fan blade moves air more up and down then straight.

Any comments?  Should I re-install in the back and just cover the small hole I made in the side?

[drano]

Thanks guys. 
I was able to do this thanks to all the great posts here.  I just modified it all a bit.

smokeitall, sounds like you got er done at a minimal cost. Good thing to do in today's economy.  I think I read one post that someone put their fan on the side, but don't remember the results.  If it works, keep smokin.

drano

[BareBones]

Hi Drano, nice job there! Just curious as to what you are using for fan power? I hope to put a fan in soon and the power question is my only gray area now...

Thanks in advance.

BB

[drano]

BB,

120V, 60 hz right out of the wall ;D

OK.  Here's the current setup.  Auber PID plugged into outlet.  Heat element cord into PID.  Smoke generator into wall outlet also.  Fan plugged into another end on the same cord that goes to the PID. 
My PID/fan cord was picked up during a computer server re-do at work.  Its a 14 ga cord for about 2.5 feet, then splits off into three 18 ga cords that each had the type of cord that plugs into computers/servers, and same as on the PID, and Bradley heat element plug.  I cut one of those ends off, put on a regular female extension cord end, and plug the fan into that.  My fan cord was a computer power cord (also a left-over in the trash from upgrades at work) that I cut the computer plug end off of, and used wire nuts to hook the fan wires to them, and crimped a terminal with a hole in it on the ground wire and screwed it onto the side of the fan electrical box per the pic. 
I could have also plugged the fan into the back of the smoke generator since I don't use that plug w/ the PID hooked up (the main heat element cord plugs into the PID).
Some day I'll install a switch to control the plug on the back of the smoke generator that was designed for the main heating element cord, and I'll plug the fan into that, and control it with the switch.  This will work as long as the smoke generator is plugged in. 
Clear as mud?
Get smoking
drano

[BareBones]

Thanks for the info, I am going to try and do the same. I have a few ideas that I am throwing around, I'll let you know how it turns out.

Working on trimming a brisket right now actually. :)

BB