From the Workshop: Building an Auxilliary Dust Arm

Dust collection, the perennial debate topic of choice for hobby and professional woodworkers alike. Some people take a laissez faire attitude and are fine just sweeping up at the end of a project while others take an almost militant approach, building elaborate and hideously expensive dust collection systems in an attempt to catch every spec of dust before it can go airborne. The real (but nebulous) dangers of dust exposure aside, I tried to take a practical approach to dust management. Being a basement shop, I don't want to spread dust to the rest of the house if I can help it, and since the HVAC system is located in the basement, I want to avoid contaminating the air ducts. On the other hand, I really don't have the room or duty cycle to justify a huge 2 stage 7 HP cyclone and HEPA grade sub-micron filter system with 8" hard lines to all the equipment. First of all, the low ceiling in the workshop means that I can't really run hard ducts without losing the precious little headroom I have left. one alternative I considered was external venting, but makeup air quality is an issue where I live and I would have to be careful about controlling humidity and thermal load in the basement during the winter. As cool as complex manifold setups are, I decided to keep it as simple as I could, with the table saw, planer, and stationary sanders hooked up to a single large DC and everything else handled by point collectors that could be equipped with 1 micron filters if needed.
With that in mind, I bought a 1.5 HP hybrid cyclone dust collector for the central system. Although 1.5 HP isn't really enough to catch all the micron and smaller particles, anything larger would be a tough fit into the workshop, both physically and electrically.
My original plan was to run a pair of 4' flex hoses bungee'd to the ceiling and move the hookups to whatever tool was in use at the moment. After using it for a bit, I added a section of 6" metal pipe to try and cut down on the length of 4" hose and gain back some of the lost velocity. I think it helped a bit and but for the most part, I was underwhelmed.
I never expected 100% dust collection, but I still ended up covered in sawdust after using the table saw, even with the blade guard installed. It wasn't so bad when I was making rips in 1" or thionner stock, but the moment the blade was more than 1/2 way raised, the dust collection chute seemed to become completely ineffective and sawdust would be thrown at my pants, although I'm not entirely sure how. When using a crosscut sled, the dust problem was even worse, with most, if not all of the dust being kicked into the air. After using the workshop for a week or so, I started coughing and sneezing pretty badly and had persistent headaches. It turns out I was sick with something that lasted for over a month, but I bet the dust really didn't help. As a precaution, I started wearing a paper dust mask (not my full-face respirator, thank god) again, but I really didn't want to have to. I also used a magswitch to clamp the second 4" line to the table to try and catch some of the dust thrown while I cut the finger joints for my drill press stand. it was a very janky setup, and if it had come lose during a cut, it could've been dangerous.
Before I bought my saw, I had looked into over-arm dust collection, but the available systems all looked too clunky or inflexible in that they required the blade guard to be installed at all times. I always intended to build some kind of swiveling or telescoping system down the road, but I didn't think it would be necessary, just a nice-to-have kind of thing. With new priorities, I looked into my options, and for a while, I thought about building a cool looking arm like this:

from pintrest

or this:

from pintrest

or even a standalone box like this:

From Airflow Systems inc

But after looking at my setup, I really couldn't imagine how it would work in my space. I stewed over it for a few months during the winter when most of my projects were on hold and then I thought about my original idea of a table mounted system. After all, it wasn't that the dust was being thrown straight up or back where the existing designs were positioned: it was being thrown towards the front of the saw, at my crotch. Being able to position the dust collector hose inline with the actual dust stream would be much more effective at catching the dust than trying to suck the dust away perpendicular to the dust stream. A permanent setup would get in the way, but something with a magnet base would be able to be positioned to the best location and then be easily re-positioned if the dust arm got in the way of an operation.

My first draft used a pair of magswitch 150s (or 95s) which are these really cool magnetic "switches" than can go from no magnetic pull to 150lbs of breakaway force with the turn of a knob. Only problem is that they run $30 each, and that's on sale. It was a little rich for my blood for a permanent installation in a single purpose jig. Still, I'd be using the auxiliary dust arm every time I used the saw, $60 was a small price to pay if I stopped hacking my lungs out after a day in the shop.

Then I remembered about dial-indicator bases; they also have a magnetic switch in the base that allows them to be securely positioned on a baseplate. And since you can get a cheap one for under $20 (without the indicator), I could have my cake and eat it too. I redesigned my arm and armed with a sketch, I went down into the basement with a rough idea of what I wanted.


My final result is a little different from the sketch, but the idea is pretty close and it looks like it'll work well:

Apart from the dial indicator base, hose clamp and coupler, and hose section, it's made with scrap I had lying around the shop from other projects. Even the hose was an offcut that I had after adding the 6" hard pipe to the system.
The best part is that it will mount to one of my 2-4-6 blocks so I can use it at tools that don't have steel or iron tables/bodies like my spindle sander: