Introduction: Workshop Air Filter With Old Car Filter

About: Part software developer, part maker.

Hi Everyone,

Whenever I cut any material in my workshop, I get a ton of dust from my circular saw and that dust can hang in the air for quite some time. It gets even worse by me moving around, working on the project so I decided to do something about it.

My circular saw does not come with a hose attachment for a shop vac and at some point, I'll have to build that as well, but for now, I wanted to build a general-purpose air filter in my workshop that will catch any dust flying through the air. This can be from either sanding, cutting, or working with any material in any way.

To make the filter, I'll be using a blower fan from an old clothes dryer that will be enclosed in a box made out of particleboard. I do use particleboard a lot in my workshop as it is really cheap and seems to be doing fine over time. I've built a workbench, Moxon vise and a miter saw stand with it that are still in one piece and working great.

For the filters, I used 2 car engine filters, that a friend gave me out of a Renault Clio. They are what I had on hand and I'm sure that most of the car filters will work for this. If you don't own any, stop by any car repair shop and I'm sure that they will be happy to give you several for free.

Let's start building!


Step 1: Break Down the Box Material

To break down the material for the box, I used my circular saw with the DIY track guide I made for it.

The material is placed on two pieces of XPS foam to raise it from the workbench and the blade is set in such a way that it only minimally protrudes on the other side.

To get the dimensions right, I first measured the size of the motor with the blower and made the smallest possible box around it with enough space on the top to fit the filters and have a slight gap for the air to have where to pass through.

Step 2: Determine and Cut the Angle on the Top Pieces

Since the top will sit on an angle, I placed the bottom, front, back, and top pieces on my workbench and I held them temporarily together with few clamps.

What this allowed me to do is to get my digital angle finder and measure the angle at which the front, back, and top pieces need to be cut so they sit flush.

Once I got the angle, I made a template out of cardboard to set the blade on the saw correctly and I made a jig on my workbench to hold the piece at the edge so I can cut it.

In the end, the cuts came out perfect but if I had a table saw, all of this would have been much easier.

Step 3: Pre-drill Side Pieces for Screwing the Box

The box is held in place with screws so I had to pre-drill all of the holes on the side pieces or anywhere where a screw will pass through a face on the particleboard.

This is necessary in order to prevent the particleboard from cracking and also for providing a straight path for the screw to catch on the side of the other piece.

If you have a drill press, this is best done there but drilling by hand can also work. While drilling, make sure to align the holes at half the material thickness that you will screw in.

Step 4: Mount the Motor and Blower

The motor had its original mount on it so I used it to mount a piece of particleboard to it and then from the top, mount that piece to the bottom.

As extra support for the blower exhaust, I've added a small piece of scrap particleboard to the bottom so the exhaust can sit on top of it.

Once the side is added, the hole will support the exhaust even more so the motor will be really fixed inside.

Step 5: Cut Out the Exhaust Hole

To align the hole perfectly on the side piece with the blower exhaust I first aligned the side piece with the bottom and I used my ruler to transfer the distances from the edges to the side piece.

I then found the center of the rectangle that I draw on the side piece, and with a compass, I drew the circle that I cut with a jig saw.

Make sure that you cut the line a bit short so if there are any adjustments needed, a rasp can correct them easily so a better fit can be achieved.

Step 6: Assemble the Side Pieces of the Filter

With the hole cut for the exhaust, I screwed both of the side pieces to the box.

Step 7: Cut Out the Top Cover and Mount the Filters

The top of the box will have the two cutouts for the filters.

I first measured the filters and I transferred those dimensions to the top. Since the filters I use have a narrowing on one side, I made sure to alternate their position so it also looked nicer when you look at the box.

The straight cuts I made with my circular saw and its guide where I plunged it from where the hole started until where it ended.

The rest of the cuts were done using my jigsaw and I've also drilled a couple of holes in the corners so I can turn the jigsaw more easily.

As with the exhaust, you need to aim for a tighter fit in order to reduce the amount of air that can get inside the box without it first passing through the filter.

Step 8: Wire Up the Blower Motor

I kept all of the original cables from the clothes dryer so I used the motor wires as well as the AC plug from the machine.

I drilled a hole for a small switch and the cable mount and I wire everything up so that the switch breaks one of the wires that go to the motor.

The motor has three connections where one is common and the other two determine the direction at which it spins. This same motor was also driving the tumbler through a pulley thus the need to spin in both directions.

The blower has straight blades and it works the same in both directions, so there was no difference in which one to use.

Step 9: Close and Prepare the Box for Paint

With everything ready and working, I put the top onto the box and I screwed it in place from the side and from the top as well.

The goal is to provide as airtight seal as possible so all of the air goes through the filters.

I had a few of the sides sticking out a bit since they were not cut perfectly and I used a rasp to flush them off with the rest of the panels.

Step 10: Seal and Paint the Filter Box

All of the joins were filled with wood filler to seal up the box and also to seal up the ends of the particleboard.

Once the filler was dry, I sanded it smooth and I applied two coats of primer with light sanding in between the coats and a coat of paint at the end.

Step 11: Test and Enjoy!

In the end, I was amazed by the suction that the blower provided. I tested it with a piece of paper that was sticking really good to the filters and the movement of air through them was really noticeable with I placed my hand on top of the filters.

I'll add wall hooks to the box and hang it in the corner of the workshop, right above my miter saw so I can turn it on every time I do something that creates dust. This will not be a permanent placement, as I want to be able to take it off the wall and use of on the workbench whenever I'm sanding so the filtering is more local.

The exhaust is faced away from the work area and I hope that this will create a sort of circling effect to push in the polluted air through the filter. I'll see how it will perform in the future and provide updates on my social network pages.

Be sure to follow me on Facebook, Instagram, and Twitter for that, and don't forget to subscribe to my YouTube channel for videos of my projects.

Thank you for following along, and I'll see you all in the next one!