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Monday, April 26, 2021

Adding a Dust Collection System

Dust Collection
After cleaning up my shop (and a lot of dust), I decided to add dust collection. A dust collection is composed of a motor and impeller that sucks dust into a collection bag. Each sawdust producing piece of equipment is connected to the impeller through pipes.

One of the big things I learned midway in this project is that if you're adding dust collection, chances are you will need to put it on a separate breaker. Since I was doing electrical work in the shop at that point anyway, it wasn't a major issue.
It also isn't likely to be an issue if you don't have any big pieces of equipment like a table saw. If you don't have any big equipment, it's unlikely you would be installing a dust collector anyway.
Harbor Freight Collector

I started with the 2 HP Harbor Freight dust collector. A mandatory upgrade is the filter. Many people upgrade to a Rikon 60-200 impeller upgrade, but I didn't want to spend the $110 for it.
I did a lot of research in how to setup the piping. You want to maximize air flow which means as many straight runs and as few curves as possible. Any branches need to be wyes, not tees. I have a straight run of pipe running down the wall with a branch that goes up the wall and across the ceiling.
At any 90* turns you want to use two 45s and a straight run of pipe instead of a 90* elbow.

You want to minimize the use of flex pipe and use tapered reducers to equipment ports if possible.

General Requirements:
Piping List (Specific to My Set up/Equipment):
Materials for Blast Gates (x11):
  • PVC pipe cut to 2.5" sections (or a coupler depending on your setup)
  • 1/2" Plywood or MDF for the Gate Body
  • Smooth Hardboard for the blades, laminate, or MDF (I used 1/4" MDF)
  • Cost- roughly $40 depending on how much scrap you have
Materials for Thien Baffle:
  • Plywood top and bottom (roughly 18"x18")
  • Plywood Pipe Port
  • PVC pipe
  • PVC Hub Coupling
  • Hardboard
  • (4) threaded rods
  • (16) washers
  • (16) nuts
  • Cost - $20-50 depending on how much scrap you have
Materials for Equipment Hookups:

Total Cost: $600 range depending on various factors

Pipe
The inlet of the HF collector is 5", so there is no reason to exceed that size pipe. There is debate as to whether the HF collector can provide sufficient air flow for 5". I selected 4" PVC pipe due to cost and availability. Use PVC sewer and drain pipe instead of the heavier, more expensive schedule 40 PVC. You want to maintain the 4" up to and including the machines if possible, though many machines simply can't fit a 4" line. Enlarge the ports of machines when possible. When you have to install a reducer, a tapered reducer is preferred to help airflow.
At a few machines, band saw, router, table saw, I wanted two pickups. You want to use as little flex pipe as possible, but at the machine it's unavoidable. You need enough flex pipe to move the machine as well. For any 90* bend, use (2) 45* connections with a straight run in between. A 90* bend reduces air flow.

Use wyes instead of tees, again to avoid 90* bends. My pipe height was dictated by counters. It's roughly at 42" above the floor.

At each branch/Wye, you need blast gates to close loops and maximize air flow suction.  I made my own gates. They are better as there is no track for dust to fill up and are much cheaper.

 I also made my own pipe wall brackets out of 2x4s.

It's recommended to fasten joints with screws rather than glue so you can open the system easily to dislodge jams. With my pipe brackets, everything stays in place. The only thing I might do is to caulk a joint if it appears to not be sealed well.

Filter Upgrade
I bought a Wynn filter for two hundred dollars. The out of the box HF filter woefully under performs. The Wynn filter drastically increases filter surface area and will stop much finer particles.

Flange
Worm gear straps
The pleated design increases surface area which increases flow. The Wynn filter is designed to retrofit to various dust collectors.
I cut out a plywood flange as the dust collector body slopes. I caulked the flange in place. The filter has worm gear straps that attach from the dust collector body to the filter. It's a neat design. You drill a hole for a screw and the bracket. The worm gear has hooks that attach to the bracket and to the metal guard on the filter.

To reduce the amount of dust that reaches the filter and to reduce any wood chips that could hit the impeller, you need a chip separator.

Chip Separator/ Thien Baffle
I built a Thien baffle. It separates chips and dust before they reach the impeller and filter. A clean filter maximizes air flow. The baffle is placed inline before the impeller, with the baffle mounted to a trash can to collect chips/dust. Read my how to for the details.

My 4" PVC pipe runs right into the Thien baffle, no turns. I wanted to maintain airflow. I remounted the HF impeller directly on top of the baffle in a top hat configuration. I used the supplied HF pipe to connect the impeller to the collector bag in a straight run that is ~4" long, avoiding the longer curve of the out of the box setup.
The trash can is mounted on blocks to get it to the right height that matches my pipe which had to clear the counter.

To make the baffle, I built a circle cutting jig out of scrap. See my how to.

The trash can has a 17" diameter. The baffle is roughly the same. With a 1.5" interior slot. The inside clear height is 4.75". 

I considered a Thien baffle and a cyclone. Based on space and anecdotal evidence I went with the Thien.

Motor, baffle, trash can

Grounding
The following is based on my research. I haven't installed any grounding yet. Whether I do depends on whether/how much I get shocked. I'm not worried about a fire with my setup.
A static ground for non-conductive duct work can prevent static-charge buildup. At a home shop it's more for comfort and to avoid small shocks. It's unlikely static build up will start a fire. To install one, simply run a wire along or around the pipe. Insulated or un-insulated 18- or 20-gauge copper wire, either solid or stranded, works fine. At pipe joints, leave slack in the wire or install bayonet connectors  to facilitate opening the system in case of a clog.
Run a ground wire along each branch, and splice each into the main wire. Connect the ground wire's conductor to the dust collector's metal frame or housing. The other end should extend to the outlet port on the tool, but it doesn't need to connect to anything, except to keep it in place. The wire acts as an antenna rather than a conductor in a circuit.

If you use coarse screws for PVC connections, this also allows for tying in grounding.

Pipe Brackets
The brackets are made from 2x4s with a bracket roughly every 48". I sketched a shape across (2) 2x4s and then cut them out on a band saw. I then sanded them to smooth out the cuts and smoothed them with spackle. I drilled a hole dead center to mount to the wall and two more to attach the clamp to the base. Then I painted them. Make sure that if you use masonry anchors, the screws are long enough to fully engage the anchor. That either requires longer screws or the screw to be recessed in the bracket.

Make sure the screw is long enough to fully
engage the anchor.

Installation
I had a few restrictions. I wanted the system in a corner that was only 18" wide and had a garage door swing arm in the space. This meant the filter/bag could not fit in the corner. To make this work I needed the trash can to fit in the corner. I opted for a galvanized trash can with concerns a plastic one could collapse.

My pipe ran attached to the wall, which meant the Thien baffle inlet had to be against the wall. The pipe had to be higher than 36" to clear my counter, which meant the Thien baffle had to be above 36". That dictated the trash can height which would needed a 10.5" riser. The motor mounted to the top of the baffle dicated a riser for the bag/filter body. so that the impeller housing outlet lined up with the bag/filter inlet.

I used masonry anchors to attached 3/4" plywood to the wall to mount the motor. I bought longer screws as the ones that came with the anchors weren't long enough to go through the plywood and fully engage the anchor.

Bolt heads need to be recessed since this is the back

The Thien baffle hangs from the motor, I used scrap metal channel and threaded rod to create a clamp.

Mock up with baffle clamped to motor
Recesses to mount to the bottom of the
HF platform.
Platform lift
Scissor jack trash can lift



I had to raise the filter/bag bracket to make all this work. I add 2x6 blocks with a 1" deck board topper between the stock base and casters. I did have to drill out for bolts and bracing on the existing platform.

To dump the trash can, I bolted 3/4" plywood to the smallest scissor jack I had on hand. Lowering the jack lowers the trash can from the Thien baffle, allowing me to dump it. The plywood is cut round with a 1/4" channel for the trash can bottom edge to sit into for stability.

I put the trash can and impeller in place, a mock up to start cutting pipe. I went one piece at a time, figuring out the best place for the wye. The process went quickly. I did not caulk any joints yet, I want to make sure everything is in the right spot. That will be the last step, if necessary.






Blast Gates
Blast gates restrict air flow to one tool, otherwise you wouldn't get enough suction. Gates are made from 1/2" MDF as it's cheap and smooth. I need 11 for my set up. Here is a tutorial on how to make your own blast gates.

I've got a blast gate at each piece of equipment and where my piping branches from wall up to the ceiling. I located blast gates as close to the main run as possible. My goal is always to reduce line length or effective line length when possible.

Once the gates are in place, caulk all the joints. You want to stop any air leakage to maximize efficiency. I have a ~2.5" piece of 4" PVC on each side of the gate. At a few gates I have a 4" to 2.25" adapter caulked into the gate. You want to caulk last in case you need to move/change/undo the layout. You could get away without caulking the joints unless you notice suction.

Connecting Equipment
Each piece of equipment has a different size port, or none at all.
I boxed in the table saw with plastic and added a pvc floor flange to one side.
I also boxed in my router table and added a PVC flange. I was going to split the pipe to collect from the base and top of the router table, but didn't have the space.
I also created a port on the band saw. I didn't box out the band saw as the pipe runs almost all the way to the blade. I boxed out the other equipment to increase suction at the blade.

The opening is lined with EVA foam so the metal
doesn't cut the PVC pipe.





I measured how much 4" flex pipe I needed. After coming up short, it seems a 1.5 multiplier for how much you need is a good rule. Since the flex pipe is exactly 4" it won't fit over the 4" PVC. I cut 4" lengths of PVC and split them along the length removing 5/8". This proved an effective adapter. I used duct tape to increase the tension fit as needed. I used a hobby knife to cut through the vinyl of the flex pipe, make sure my start and end of the cut ended on one of the wire supports. I then used a wire cutter to cut through the wire.

I ended up using 4" to 2.25" reducers from harbor freight. They don't taper which is preferred, but the price is right. I had considered making homemade PVC tapers, but didn't need to.

I got 2.5" flex pipe, not realizing the mismatch in size. I used EVA foam to fill the gaps from the 2.25" reducer to the 2.5" flex pipe and from the flex pipe to equipment. I used contact cement to glue the ends of EVA foam together.

While I want my flex pipe runs as short as possible, I need some slack to disconnect equipment. Duct tape at one end of the flex pipe to compress the pipe is the solution to reduce slack.



 
At the belt sander I used a 45* elbow that directs right at the top. An adapter didn't seem necessary.

I also will have an open flex pipe to the work bench. I plan to connect a PVC flange to the end, but not sure it's necessary though it would provide an object to clamp.
 
I did a few tests to see how much splitting the pick up at the table saw and band saw would affect suction. Suction is better with only one pickup, but ultimately I decided to employ two pickups. Even with a split suction from both pipes wasn't cut in half. Also two pickups is the best way to reduce sawdust.

Conclusion
The system provides great suction. The first piece of equipment I connected was the belt sander. I sanded foam as a test and it got everything.
The next tool was a scroll saw. I wasn't able to box out the scroll saw well, but suction was still impressive, eliminating some of the sawdust covering the top. If I could box it out it would perform even better.

I had planned for double pickups at a few tools. I was unable to do this at the router due to space, but I don't think just one pick up will suffice since it's difficult to get a port right at the sawdust producing portion of tools.

The dust collector is loud, though I already wear ear protection when using any tools with a motor. It's also one extra step before I cut anything. I have to switch it on and make sure the correct gates are open.

References
I didn't incorporate all of these ideas or suggestions, but they were all part of the research process.
Dust collection project
Dust collection system tips
Dust collection system
Dust collection tips, tricks, accessories - drill press clamp
Router table dust collection - two pickups
Wynn filter 35B222NANO
Wynn filter instructions
Thien baffle plans
Thien baffle sizing
Make blast gates
Make pipe brackets
HF DC with Cyclone
Make a mini-cyclone
Make a cyclone
WEN air cleaner ($238) in conjunction with DC
Grounding
Automated dust collection

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