Diy Laser Engraver Filtration Table
DIY Laser Engraver Filtration Table
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Learn how to make your own air filtration system for laser engraving and other smelly fumes.
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In this article I'll show you how to make an air filtration unit. The one I'm building here is meant for a small-ish laser engraving / cutting machine but this general idea could be scaled up or down and possibly used for other things that produce smelly fumes. Note that this is not intended to be exact plans to follow but I'll write this in a "how to" style cover all steps along the way.

Background

The filtration unit I designed had very specific dimensions I had to go by to fit through doorways, up stairs, as well as holding a certain size of laser engraving machine. If you build an air filtration unit, chances are good your dimensions will differ, but this will give you a rough guide to follow.

Also note that my intent was not to filter out 100% of all smelly and harmful fumes. I still vent the "dirty" air outside but wanted to be kind to others nearby and make sure they weren't smelling any wood smoke. I haven't scientifically measured how this filter performs but initial "sniff" tests would suggest that it filters out well over 75% of smells from lasering wood as well as all visible smoke.

Later in this article I'll talk more about how you can upgrade and expand this system as I planned for those options in case I ever wanted to filter the dirty air further with a bed of activated carbon.

Stuff You'll Need

Let's talk tools first, at least the most major tools you'll want to have.Next up are some of the main materials you'll need.And then some filtersAnd then some miscellaneous stuff

Building The Frame


The frame of the air filtration cabinet is what defines the overall size and shape, it's the skeleton and structure. The idea here is to create the structure in the above photo. If you've built anything before you can probably figure this out easily but I'll detail it out a bit anyhow.


We'll make the bottom first. This is done by making a rectangle out of the 2x2's. Mine is 48" long by 25.5" wide. It's that size so that it fits through doorways and also to hold the larger 25" long filters I'm using. Chances are good, your cabinet will be a different size.


In constructing the base I cut the 2x2's, used butt joints with glue and screws, and then used the handy right angle clamps you see in the photo above. These aren't required but make things easier and help ensure it is all squared up. I then double check all is square (see How To Square Up Framed Boxes if you don't know how to do that), and then covered one side of it in the 1/4" MDF (using glue and screws).


I made a second one of those rectangles which becomes the top. I then joined the top and bottom pieces with some vertical supports. In my case, I went with eight supports total with each one at 24" long. Why eight? Because I wanted to divide my rectangle into two separate boxes while making it very strong in the middle. One side will become the actual air filter while the other will hold the exhaust blower fan, air assist pump, and electrical bits. I call these two boxes the "filter box" and "fan box" from now on.


The above image shows the dividing wall (1/4" MDF) between both boxes along with the 4" port where the filtered air will be sucked out via the exhaust fan. So, dirty air enters the filter box at the top, gets filtered, and the cleaner air now comes out the bottom.


This port sticks out (hangs into) the fan box since a piece of metal duct will attach to it and the blower motor later. The blower motor will be sucking the air out.


This photo is to show the detail on the dividing wall between the two boxes. As you can see, just more 2x2 lumber that frames that dividing wall in place. Glue and screws are used as usual and it later gets silicon caulk in all seams to ensure an airtight seal.

Add Filter Shelves


Next I added shelves that will hold the HVAC style air filters. I'm using four 1" thick filters along with two 5" thick filters. I've gone with this configuration so that I can later upgrade the filtration if needed.

Meaning, at any point I can pull out the bottom 5" thick HVAC filters and replace it with several inches of loose, activated carbon. In theory, a 3-5" bed of activated carbon should completely filter any smell out. If I ever needed that option, I could build a tray to fit that 5" tall opening that would hold the carbon. In fact, I did just that which you can read at Laser Engraver Activated Carbon / Charcoal Filter.

For now, the filtration works as follows. All are sized at 25"x20":

Filter #1 is a cheap 1" thick fiberglass HVAC filter. This one will get the dirtiest, be changed the most, and is the cheapest. I also coat it with fire retardant spray (affiliate link) as an added safety measure.

Filter #2, #3, and #4 are standard, but higher quality, HVAC filters that are pleated, also 1" thick.

Filter #5 is a 5" thick MIRV 11 HVAC filter. These get a little pricey so the idea is that filters #1 through #4 do most of the dirty work and thus filter #5 will last longer.

Filter #6 is a 5" MIRV 16 HVAC filter with a coating of activated carbon which does a final cleaning on the smell. A true 3-5" bed of activated carbon would be far superior if you really need to scrub your air, see Laser Engraver Activated Carbon / Charcoal Filter for more.


Workin on the filter box side and from the bottom up, I started adding shelves. On the bottom most shelf I framed in the shelf base with 1"x2" lumber on all sides. This will be able to support a load of heavy activated carbon if needed where 1/4" MDF alone may not. I then topped it with a 1/4" MDF rectangle with a large hole in the middle for the air to come through. The MDF is also notched on each corner to fit around the 2x2 vertical supports.


Working my way up, I added more of these MDF shelves which are the same rectangle shape with a large hole in the middle. All shelves above the bottom one get 1x2 supports on the sides and back only.


Adding a 1x2 horizontal support on the front would get in the way when it was time to change filters and I was trying to keep the overall table height to a minimum so stacking the filters as closes to each other as possible was important.


Here's a closeup that shows the MDF shelves in places. The small gap under the top shelf is where the 1" #4 filter will go. It will slide snuggly in place to avoid air leaking around the sides. You can also see that we built small vertical side walls between each shelf (and caulked all seams). This also ensures that virtually no air will try to go around the sides of the filters.


Here's how it looked with all shelves in places and after it was painted with fire proofing material (affiliate link). Note that the fire proofing liquid, which is clear, can be applied directly to wood or mixed into paint. We chose paint since the MDF would bubble up and expand if it got wet from the spray directly and MDF doesn't like watery liquids.

Skin It


It's now time to skin the filter box by putting MDF on the back, side, and making a front door / cover. In the photo above you can see how another 4" port was added. The port sticks out (hangs out) of the back of the unit. The laser engraver exhaust will connect directly into this port, so this is the intake port for the dirty air.


I also made a door out of the same 1/4" MDF. Those strips you see are more 1x2 lumber and what I attached the door latches to. If you were using a thicker material like a 3/4" MDF the strips wouldn't be needed but we had to use 1/4" to keep the weight down.


Next, I filled all of the screw holes with wood filler and sanded everything smooth. The entire unit was flipped upside down and the bottom painted first, then rolling wheels attached. We used two lockable wheels on the front, and two non-lockable wheels on the back.


Now the unit was flipped upright onto its new wheels and painted with black paint and a flat roller. If you wanted a showroom finish then spraying is the way to go but this isn't exactly fine furniture so rollers were fine for our needs.

Final Steps


I then added the filters into their proper places (note that the #1 filter isn't shown in this photo, use your imagination).


Door latches were added and the door was put in place. Not shown in this photo is the 1/4" thick weather stripping added around the frame of the door. The box is under suction so it's more likely to leak fresh air in and not blow smelly air out but leaks mean a loss of efficiency which isn't good.


I added sound deadening material because I wasn't sure how loud the blower motor would actually be (it hadn't arrived until the cabinet was done). Turns out, it's actually not as loud as I feared but it's not quite either. Like a vacuum cleaner, maybe even quieter. Still, the sound deadening material does make a major different even when only on three sides of the fan fox.

The filter box output (cleaned air) goes right into the blower motor which is sucking air out of the filter box. Remember, it's easier to pull air than it is to push air. The exhaust of the blower motor (which is now pushing the cleaned air) is connected to a flexible metal tube that runs to a piece of MDF that I can fit in my office window.


I also added a shelf above the blower motor to hold the switches (and other stuff as needed). I'm using a three in one switch so that we can power on the laser with one, the air assist pump with the second, and the exhaust blower with the third. All power controls are easy to access in case of emergency. Fire extinguishers and a water squirt bottle are kept on hand at all times in case of any fire.


The switches get wired into a duplex outlet box and each of those three items I listed gets plugged in. The duplex box then plugs into an outlet strip which plugs into a 15 amp wall outlet. The major power draw is from the large blower motor which pulls 6.5 amps when running so nowhere near hitting the 15 amp breaker limit. The air assist pump and laser engraver only add a couple of amps more.

Finishing Up


Here is the finished unit which runs in my office. When I need to laser something I pop the white MDF board picture on the right into my office window and can blow the cleaned air outside. When lasering MDF you can smell some minor wood burning smell coming through the final exhaust port (again, a bed of activated carbon may eliminate closer to 100%, see Laser Engraver Activated Carbon / Charcoal Filter) but it's very minor.

Once the port is placed in the window and window closed on top of it there is no smell inside at all. You wouldn't exhaust this into your work area, so you'll still want a window (etc). Outside, once you're a few feet away you can't smell it at all and that's all I wanted to achieve.

What I'd Do Differently

My biggest issue with this project was building the cabinet without the blower motor, laser engraver, or air assist pump on hand. We had a 4 week delivery date on all of those parts and wanted this done when they arrived.

We were going on certain measurements that we weren't 100% sure of. For example, I had two different measurements on the overall size of the laser engraver. The blower motor measurements felt like a bit of a guess as well. So we had to give ourselves extra room in some cases and flat out guess in others.

As soon as we chose 25"x20" HVAC filters, that locked in a big part of the overall dimensions. I didn't know how small filters would handle hundreds of CFM of air suction and didn't want to risk them pulling through the shelves which is why we chose the large filters. I might instead go with 20"x20" filters. That combined with the smaller laser engraver depth measurement being the right one would have let us make a table a few inches less deep.

Otherwise, there really isn't much I would change here. The unit works very well for our needs. If you're planning to make one we hope this article helps you get started! You may also want to read Laser Engraver Air Compressor Line Dryer Installation as well and consider adding a line dryer to your air assist pump.