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It's hard to find one filter that will do everything. In most cases, filters are designed for only one or two applications. A smoke filter is usually only good for smoke and even at that most will not handle high concentrations of it. Best bet on smoke is to remove it completely with an exhaust fan replacing it with clean air. As for general dust and dirt, most filters will do a decent job. For paints, you need a filter that is designed to trap the type of paint you are using. I assume what you're looking at the filtering machines. I saw DeWalt has one now for around 200 bucks. I don't have any experience with these, just larger units used in mfg plants. These are generally multi-stage units with several types of filters in them. Most common is the two stage ones that have a panel type fiberglass filter on the intake for general dust/dirt and a second filter behind it for a special application such as suspended chemicals in smoke or paints. Depending on the size of your shop and amount of crud you get in the air will determin the size of the air handling unit you'll need. Unless you are serious about putting in a full system, you may be better off going with smaller single application units such as: a dust collector system for wood/metal dust attached to saws, sanders, ect. with a flex tube so you can place the intake close to work being done by hand or with portable tools. Second would be a fume extractor for smoke and paint. If used with paint, you must ensure that it is explosion proof unless you are dealing only with latex type paints which are not a fire/explosion hazard. On this unit, you'll also need a filter to trap the paint particals so as not to be venting them into the outside air which could get you in all sorts of trouble with the three letter government agencies. I know this sounds like a lot but if you have some time and know-how, you can build both systems rather cheaply and easily. You can usually find all sorts of fans and blowers at a scrap yard especially one close to mfg hubs. I got started on my extractor system about a year ago but just did not have time to get it together yet. All you need is a decent sized paddle or squirrel cage fan/blower, squirrel cage ones from a an old hot air heating unit are usually very common and big enough to handle a good amount of air volume. It does not matter if it's belt driven or direct drive from the motor. Belt drives are best since you can install most any type of motor on it and vary the speed by changing the sheave sizes. The thing to remember is that you should use piping / ducting that is at least twice the square inches of the fan/blower outlet. Best bet is usually to install the filters on the inlet side of the fan/blower as to keep the crud from crapping up the guts of the unit and duct/pipe. Paddle type blowers are usually the easiest to work with but are more limited on volume unless you get some giant size unit. Squirrel cage units will usually move the most volume but at a lower velocity, these are better used for fume extraction and general filtering for light airborn dust. Paddle units will give you a good suction velocity on a smaller bore pipe/duct which is better suited for dust collection from a machine. Most dust collectors are nothing more than an overgrown shop vac with a larger filter area. If you put some thought into it, you can get away with building one system that will do two things. You can use valves and loops to send recovered air into a filter housing to be cleaned and sent back into the shop or close off the return line to the shop and direct it outside. If you are venting to the outside, you'll also need some type of opening to allow make-up air to from the outside to enter the shop as well. The make-up air opening needs to be at least twice the size of the exhaust side of the fan/blower. If you don't have enough make-up air, your system will not move as much volume as it should. If you have an HVAC shop nearby, you may want to check with them to see if they can set you up with a good system. Most of these places can tell you exactly what you need and sometimes it becomes cheaper to buy a good professional quality system that works as opposed to spending near as much or more on something that doesn't work.
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