Dust Collection on a Miter Saw Station

Knot working said:

Nice looking miter station Steve. I have the same CV dust system, what fittings do you use to connect the 4” hose
to the duel 4” shut offs?

Click to expand...

This ClearVue dual port is the same one I used on the router table except that one had separate blast gates for each branch. On the router table I used a 6" metal duct fitting to connect the 6" hose and the 4" hose connects directly to the ClearView ports. I also used Fernco connectors for the 6" main connection and at the table saw. That will be redone but at the rate the Postal service isn't delivering packages in my area it will likely be after I recover from my shoulder replacement surgery this coming Monday. Just can't have enough fun these days...I did order 6" to 4" Fernco reducers so hooking one of those directly up to the table saw should get me the closest direct connection rather than cutting into the saw base and installing a 6" connector.

I've almost talked myself into buying a good 3D printer just so I can make my own reducers. Everything I've seen commercially available have been like stack a 4" can on a 6" can. Where in my mind a good reducer should be cone shaped they have a 4" cutout in a 6" flat bottom. Doesn't make sense and it does create a ton of turbulence. I'm hoping the Fernco fittings will eliminate this but they are rubber and not sure if that will make a difference. Preference would be a smooth surface like PVC or metal. The PVC 6" to 4" reducers are shaped well but again the hose needs adapters to fit. The 6" hose fits snugly inside the PVC adapter but the 4" doesn't fit over or in. Thought just fired off, maybe I should paint the inside of the Fernco fittings before using them. That would give them a smoother surface, maybe?

Here's some photos but it's difficult to show the opening under the saw. You can just barely see the opening in the photo taken inside the mitre saw box. There's some aluminum tape around the opening. This collector box is at the back of the large drawer under the saw. In fact I had to cut down the back of the drawer to allow for the collector box in order to be able to close this drawer. The 4" DC pipe attaches to the end of the collector box. Hope this helps explain what I did.

At the expense of boring those of you who already know all this, thought I would throw in my
$ 0.02 worth of useless info.

In my not unsubstantial and varied readings and studies of air, oil and coolant flow pertaining to making my hot rodded Mustang faster and more reliable at the road course, there are many automotive systems that parallel dust collection. This includes cylinder head, intake and exhaust performance, aerodynamics (to do with generating downforce (or at least reducing/eliminating lift), coolant and oil flow inside the engine and within the cooling systems like coolers, radiators; braking system performance and air flow to cool them (duct work) etc etc.

When viewing the entire dust collection / shop vac / cyclonic scenarios and the difference between dust collector and vacuum cleaners, here are a few points I would like to mention:

The suction difference between the two systems makes a huge impact on the effectiveness (our only real concern being that it works) and efficiency of whatever it is we cobble together; flow potential and pressure vs volume..............that is the crux.

Elbow radius and neck down dimensions and curve design radically affect flow, as does the diameter and shape of the pipe / hose....smooth is good - ribbed is not. Insie outsie or outsie insie conncetions - think of the flow of air and the dust floating in the liquid.......yes Grasshopper..... air is a liquid.

Because dust collectors have very low pressure differential (suction) they require much greater unrestricted CFM of airflow. Going from a 4" to a 5" or 6" pipe on a D/C radically improves the performance over long runs - think HVAC systems with your furnace and a/c. This is why real dust collectors don't use bags - they may flow a ton for the first minute, but once they are full of dust, the outlet side of the D/C is restricted - meaning you can run sewer pipe, and your D/C system will still (not) suck......lol...see what I did there?

Here is my practical inclination to most of these highly complex problems and challenges.....without renting a wind tunnel (altho that is possible @ $2500/hr), doing your best on minimizing the compromises (like using Y adaptors not T fittings for example).

I figured that air flow can be controlled via waste gates - lots of times, less suction and more flow will actually pickup more of the dust - think air inlet on a router enclosure - not only from the top, but usually clean air to also draw across the router motor (to keep it cool) and to essentially create a main flow (river) of air the will then pull the additional air (and dust) along its path. Pls see Gr 3 level pic attached.

Reduce restrictions (on both sides of the pump; inlet and outlet; just like a cars engine) and reduce turbulence and you improve efficiency...........works on everything from air intakes, cylinder head flow, engine cooling and oiling systems, making your F1 car faster.......and improving your D/C effectiveness.

The challenge is to maximize the workings of whatever setup we are stuck with due to the various insurmountable factors - sooooo...... think about adjustability/variability to see what works best FOR YOUR SETUP.


Hoping this gets everyone thinking a little bit. Gotta say, I really enjoy being a (virgin) member on this forum, so much knowledge and skill set as well as friendly faces and comments.

I think one of the main takeaways here is that unless you're using an isolation chamber it's wise to use a mask regardless when doing such operations. Simply having a fine particle collection hung system and a DC isn't sufficient. My concern was and still is dealing with the majority of the sawdust and I think that's going to be the best it can be with this setup. The video link posted does well on a chop saw but maybe not as well on a compound miter saw where sliding action comes into play. If I were starting from scratch, and it's way too late for that, I'd build a containment system that could be mounted to the saw itself so that regardless of angle it would still be in the same fixed position. It would be mounted to the saw and not the station itself. Makes sense in my head......but that's not always a good place to work things out. At this point I simply don't have the room behind the saw to try that out. Moving that 5 cabinet assembly would be a major multi-person task and I simply don't have those resources.

The two opposing 4" ports should provide plenty of volume. One thing of note is I had my Shopsmith setup with the disk sander and took the 4" hood connected to the 4" hose on the CV1800 and although it did pick up some of the sawdust the very fine was certainly airborne. Both under and around the Shopsmith required vacuuming after sanding with the 60 grit paper. I think a smaller sized hood closer to the sander would have been a better solution. The hood was maybe 8" away. A smaller 4" diameter directed flared shaped coupling style fitting may have been a better collector and having someone direct it while sanding was being done likely even better. I tried what I had seen with some lathe operators but then again, like the miter saw, I think the intent was to capture as much as possible.