Aloha MDS
Your question, though simple, brings up a ton of concerns and safety issues.
To exhaust fumes it depends on whether or not they are flammable or not. Either way it is better to consider all vapors flammable. As you have noted, most electric motors used in household type exhaust fans use air flow to cool them and that means that the vapors and dust are going to be blown right into the motor. Where… the brushes of the motor are often arching (sparking) as they contact the armature.
There is a very good reason that building codes are highly restrictive when dealing with flammable vapors. I personally know of several “backyard” shops that have burned down, some taking the houses with them. Luckily, I don’t know of any deaths but a couple were close! Crazy, unexpected things can happen and you must guard against them… for example.
John Peck came into my shop once while I was gone. He turned on the lights which had the exhaust fan switch right next to it. He accidently hit the fan switch to on also. But, unknown to him the motor bearings had seized up on the fan and I was going to fix them when I got back. The motor or fan didn’t spin so he didn’t know that he had turned it on. The motor being frozen began to overheat and soon burst into flames even though the breaker eventually tripped. I happened to come home just in time to catch the escalating fire and put it out in time! It was one of those… “by the grace of God” moments.
There are exhaust fans that are rated as explosion proof and you should seriously consider using this type of fan. You can check some out here.
http://www.grainger.com/Grainger/wwg/productIndex.shtml?originalValue=Fan&L2=Explosionproof&operator=prodIndexRefinementSearch&L1=Fans%2C
These are propeller type fans. The wide gaps between the blades prevent them from supporting high static pressures.
The next issue you have to deal with is airflow or CFM. Once you place a filter in front of the fan you will greatly reduce the CFM. To insure that you get enough CFM you need a fan that will pull at high static pressure, like these.
http://www.grainger.com/Grainger/wwg/productIndex.shtml?originalValue=blowers&L2=Explosionproof&operator=prodIndexRefinementSearch&L1=Blowers%2C
These will likely be overkill for your use. But the small spaces between the blades allow high static pressures.
Your fans CFM rating and the SP rating and the size of the fresh air hole in your opposite wall, will all dictate the velocity of the airflow over your work space. Getting this just right will remove dust and fumes but not swirl them around too much such that they will get in your eyes.
Once again… I can’t over emphasize the dangers in cheap household fans that get loaded with flammable dust and allow combustible vapors to pass through them into electrical archs or cause bearings to seize up.
Lastly, in fairness to your neighbors and family you will want to create some kind of catchment system to contain the dust and vapors. Lest they all call the authorities on you in an effort to protect their residential peace from your industrial activities.
Hope this helps