Harbor Freight Dust Collection Mod – 14 through 17

Harbor Freight dust collectors are a great value and relatively decent quality but you do get what you pay for. This is an inexpensive alternative to the more expensive dust collectors offered by Powermatic, Laguna, or Grizzly but something is better than nothing when it comes to dust collection. This video series, linked above, is a how-to on turning this single stage system into a more convenient and improved 2-stage system equipped with a chip separator and a fine dust filter. I spent a great deal of time scouring the internet reading and watching all the various ways that this modification has been done before and what I came up with is what you will see in the following article as well as the embedded video playlist above. This is a 4 part series so sit back and get a pad of notepaper because there are a lot of steps involved and several operations that have to be performed. I hope you get as much out of this modification as I did because its well worth the time it takes to modify.

Part 1 – Written Tutorial

Breaking Down MDF Breaking Down MDF #2

The first thing I did was break a large sheet of 3/4″ MDF, medium density fiberboard, down into smaller more manageable pieces. I do this using a straight edge guide and my circular saw. I should have been wearing a respirator while cutting this MDF because it shoots fine dust particles all through the air. It is probably incredibly bad for your health, so if you use MDF please go out and invest in some dust masks to protect your lunges.

With the pieces smaller and more manageable I used my table saw to rip them down to there final widths. These are square panels so there is no need for readjusting the fence during this operation. Make sure to use the factory edges of the material so that you can ensure squareness of the panels from the offset.

Next I needed to find the center of each panel so I used a large t-square and connected each corner and marked straight across. Where the lines intersect is the center of the panel.

After making the center with an ice pick, an awl can also be used, I used my drill to create the hole around which my router will pivot. I didn’t want to go too deep so I used a piece of tape to mark the depth I wanted on my drill bit.

This next part was a tedious process because the diameter of the baffle was difficult to pinpoint. What I did to work around this was to set my circle jig to route slightly less than the approximate radius. After taking an shallow initial pass I checked the radius against my routed slot. When it didn’t fit I set my router circle jig to a fractionally larger radius and took another shallow pass. I continued with this procedure until I had a very tight fit between the baffle and the routed slot, then I took a final pass plunging the router depth to its final depth. Without changing anything on the router jig I then use it to route the same slot in the second piece of MDF. These MDF panels will sandwich the baffle enclosing it to create the chip separator. The dimensions and radius of the slot can be found by referencing the plans associated with this build.

One more panel needs to be cut to size. I use my table saw to do this. There was no need for the straight edge and circular saw because the MDF was manageable enough now to handle outright. This panel will become the lid of the waste bin used to collect the chips. The dimensions are the same as the previous two panels that I cut.

Another channel needs to be routed in this new panel. I follow the same procedure I described earlier to route the slot for the waste bin. Again, this was tedious but since the diameter was hard to pinpoint it was the most effective way to accomplish this task. The only difference between this step and the baffle step is that the pivot point that is drilled goes all the way through the MDF. This is required for when we route the through slot for the waste bin panel.

It’s time to route the through slot where the wood chips will fall when the dust collector is in use. This slot starts at the port where the wood chips initially enter the baffle and follows the contour of the inner radius of the baffle channel I routed earlier. It might be useful for me to tell you that this is the piece that becomes the bottom half of the baffle. There is something more I have to do to the top piece but I will describe that later. There are two radii that make up this step and the router jig has to be re-positioned for each one. I took several passes to get through the material taking a little more material away with each one until I was through the MDF. The start and stop points of this slot are simply freehand routed then cleaned up with a chisel.  As with the previous steps, all dimensions can be found in the detailed plans available for download.

The exact same through slot is cut in the MDF panel that will become the bottom half of the lid to the waste bin but this time I adjust my router to cut slightly inside the final radii. It is also worth noting that the bottom half of the lid to the waste bin is also the bottom half to the thien baffel. Once that slot is cut I then align the two panels, with the through slots cut into them, ensuring the slots are facing in the right orientation and secure them together using screws, pilot holes with countersinks are drilled first of course. With the two panels secured together, I can then use my router, equipped with a flush trim bit to bring both through slots into perfect alignment. If any of this in unclear at this point it might be worth it to you to view the video tutorial above. Seeing me complete the last few steps may be easier to understand.

The last step in the creation of the chip separator portion of this build is to cut a 4″ diameter hole into the panel the makes up the top portion of the thien baffle. This hole is where the fine particles will be drawn up into the motor and out through the fine dust filter. I first drill a through hole then use my jig saw to rough out the hole. It doesn’t need to be precise so your best freehand effort will do. A 4″ dust collection collet will be screwed into place covering this hole.

With that step complete I can now secure the two panels, with the through slots, permanently together using glue and the same screws once more. This assembly is both the bottom half of the thien baffle and the lid to the waste bin and is the most important and most complicated part of this modification.

Part 2 – Video Tutorial

Part 2 – Written Tutorial

In this part of the modification, I start building the structure that will hold all the various components of this dust collector. I begin by cutting the 2 x 4 Kiln Dried dimensional lumber that will make up the frame to length at the miter saw.

I will be using pocket holes to assemble the frame so lots need to be drilled. Luckily I have my Kreg Foreman pocket hole machine to bust them out. This was a little repetitious.

2 1/2″ pocket hole screws are used along with glue to assemble the frame. Although gluing end grain isn’t something that folks usually do, it does add another element of strength to this otherwise very strong joint.

There are two identical sub-frames that make up the left and right sides of the dust collectors structure. They are rectangular in shape and have a cross-brace that is strategically placed to support the thien baffle assembly. After measuring I use a square to mark for their placement. 2 1/2″ Pocket hole screws are used to assemble.

With the sub-frames complete I get started cutting down the 2 x 4 pieces that will connect both sub-frames together. I do this at the miter saw. These are attached using pocket holes as well, I drill for them using my Kreg Foreman.

Glue and 2 1/2″ pocket hole screws are also used to attach these pieces to the sub-frames.

Assembly is pretty straigh forward. I used 2 1/1″ pocket hole screws and glue. Above you can see the sequence in which I attached everything

To add a little more structural stability and to square up the frame as best I can, dimensional lumber sucks!, I cut some 45-degree corner braces using my miter saw. In hindsight, I probably could have used pocket holes to attach these too but I didn’t. I attach them using 2 1/2″ interior screws drilling pilot holes with countersinks first to prevent splitting.

It now time to construct the mount for the motor. I begin by cutting 2 x 4’s to length at the miter saw. Like the rest of the dust collectors structure, pocket holes are used to assemble the motor mount.

Because the motor is so heavy I attached cross braces which will carry it’s weight. I first drilled pilot holes with countersinks to attach it to the frame. I use 2 1/2″ screws to attached the braces.

The motor is attached to the mounting assembly with 1 1/4″ interior screws and fender washers.

Part 3 – Video Tutorial

Part 3 – Written Tutorial

It’s time to build the fine dust filter. In this installment of my dust collection modification series, I begin by cutting 3/4″ MDF to size using my table saw.

To begin shaping one of the MDF panels into what I need it to be, I first drill a hole large enough to receive my jigsaw blade. I then use the jigsaw to cut a circular portion from the center of one of the panels. This hole is large enough to fit over the exhaust port of the dust collector motor.

I smooth the edges of the diameter of the hole and finalize its size using my oscillating spindle sander.

After marking another radius on this piece of MDF I cut it out using the band saw. This is just one portion of the inlet port of my fine dust filter. And once more I use the spindle sander to smooth it.

The second panel is identical in size and diameter. The only difference is that I used my jig saw to rough out both diameters instead of utilizing the band saw and brought them into perfect alignment using a flush trim bit at the router table. They were ganged together will glue and brad nails before routing.

More MDF panels are needed to create the housing for the fine dust filter. I cut these at the table saw. I then trace the same diameter on both panels, one also has an inner diameter, and cut them out at the band saw. The panel with the inner diameter has its center cut out using the same methods I have already shown.

Again I use my spindle sander to finalize the diameter of one of these circular pieces of MDF. I test it’s size against the inner radius of the dust filter until the size is correct.

I tack the two circular pieces temporarily together with brad nails then go back to the spindle sander to make their diameters match perfectly. You’ll see why shortly

After separating the two circles I finalize its diameter using the spindle sander once again. This inner diameter circle is equal to the inner diameter of the circles I cut previously. I understand if it is hard to picture what I am building at this moment, but hang in there you will be able to soon. There are a lot of repetitive processes in the project but hang in there.

I know, I know.. more MDF strips. These ones are going to become the top and bottom of the filter housing. I again use the table saw to make square panels as I did in previous steps.

Once more, I cut an inner diameter circle from one of the MDF panels. This again is equal in diameter to all the other inner diameters we have cut thus far. The spindle sander is used to smooth this one as well.

With both of these panels tacked together temporarily using brads I cut them to shape using the band saw and smooth them at the spindle sander. This is the last step before assembly.

I am going to do my best to show you the assembly process in pictures. The images above are my best efforts at showing each step individually. I use glue and brad nails to assemble the top and bottom pieces of the housing. If the pictures didn’t make this part clearer for you I suggest that you take a look at the plans linked in this article. There you will find pictures and a SketchUp model you can reference.

To begin prepping for the dowel cage that surrounds the filter I drill holes in both top and bottom pieces. I do this using my drill press.

I cut the dowels to size using my miter saw.

The process by which I attach the dowels is a little haphazard but I will do my best to describe it. I first use the pilot holes I just drilled to drill pilot holes into the top of the dowels then secure them using a screw. I then flipped the entire assembly over and drilled pilot holes into the bottom of each dowel, countersank the holes, then drove screws in permanently. I then flipped the entire assembly over once more, removed the screws, then countersunk the opposing sides pilot holes and drove screws in permanently. With that, the filter assembly is assembled and complete.

Although I don’t show this in the video I had to lower the front rail of the dust collectors frame to accommodate the filter assembly. I compensated for this in the plans.

With the filter complete its time to assemble the baffle portion of the chip separator permanently. I use clear silicone adhesive to bring all the parts together. I apply it to the insides of all the channels except for the one that excepts the dust bins top lip. I also apply it to the outside of the baffle where the baffle meets the MDF. All other holes where air might escape are also filled. This includes the bolt holes where the support structure of the collector’s original frame attached. I use my finger and soapy water to smooth out the silicone and to ensure it is firmly pressed into all the nooks and crannies.

With all the silicone applied and dry, I attached the four-inch fitting I showed early on in this build. I use silicone adhesive and pocket hole screws to attach it.

To make the baffle easier to remove when emptying the waste bin I attach two of these handles I found at the hardware store. I first mark for their placement, use a punch to establish the hole location, then secure them with pocket hole screws. There is a handle on both sides on the baffle.

It would be to difficult to describe how all the pieces come together in words so I opted to show some images of how everything connects. I use a series of rubber couplers, hose clamps, and dust collection hose to attach the motor to the baffle.

All that’s left to do now is test the dust collector. As far as I can tell the dust collector is working as it should. There were a few problems that resulted from my design when it comes to air flow. I don’t want to get into them here in this article but they are all documented in the comment section of this YouTube videos post. If you have any specific questions you can visit Part 3’s video post of comment here on this article and I will answer all your concerns or questions.

Part 4 – Video Tutorial

Part 4 – Written Tutorial

Part four is all about my dust collection hose set up. Its more of a VLOG style video rather than a how-to so I decided to omit it from this post. If you are interested in how I set-up my dust collection tubing please click on the embedded video above to watch. Constructing this modification was a time consuming and challenging build. It took me almost a month to film, construct, and edit this series. I hope you all enjoyed the video’s I published and learned something from this adventure of mine. If you haven’t done so already please take some time and hop over to my YouTube channel and subscribe. Every subscription helps my channel grow and lets me know that you all are enjoying my efforts. I also have an Instagram account where I post behind the scenes pre-video updates of the goings on in my workshop. So if you are interested subscribe to me there as well. I hope you are having a great day and thank you for reading.


Microsoft Word File

Printable .PDF File

Trimble SketchUp File


  1. 1 Why 3 in vs 4 in/
    2 t fittings vs yfittings
    3 Can you show how you empty can/
    great jod enjoyed your build of dust collection

    • I chose 3 inch because it was much cheaper and the CFM of my dust collector isn’t great. I figured the less air volume it has to pull the better suction I would have. I chose t-fittings because it was what best suited my particular situation. I don’t have any plans to do a build update just yet but when I do I will be sure to add footage of me emptying the dust bin.

  2. How do you remove the trash can? Do you use the handles and lift dust collector up and remove the can? If your hands have the collector…..???
    Tom Barnes

Leave a Reply

Your email address will not be published.