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For those of you who have chop saws or sliding mitre saws and are not happy with the poor (if any) dust collection capabilities of your system, this article is for you. For other information related to this topic, and to see where I got my inspiration for this project, check out the Forums on woodworkweb.com - Dust Collection section, to read and see pictures of what others have done.
For my saw, I am for ever cleaning up the dust, and even though it has one of those "industry standard" dust collection socks, that actually do (barely) work. I did not want to build a honking large dust collection hood around the saw, but rather something small that would be efficient in dust collection. I have seen the pictures and read the reports from others who have made similar adaptions so this would be my prototype to see if, and how well something like this would work on my saw.
One of the great things with doing prototyping is that you learn things you might not have otherwise discovered and confirm other things you suspected ...
Since it was a prototype, I didn't want to invest a lot of money until I could see that it would really work, so a trip to the Dollar Store saw me picking up an inexpensive plastic tube that I could cut down and shape according to needs. I also happened to have some bits and parts from some former plumbing jobs and, some time ago I picked up about 50 feet of vacuum hose at a garage sale that I hoped would be handy for making dust collection adaptions just like this. Unfortunately the hose is a bit small in diameter, and by now it's seeing signs of age and not nearly as flexible is once was, but it will do.
The actual construction of the prototype version can be watched in the video, what is NOT in the video are some of the details ...
One of the great things with doing prototyping is that you learn things you might not have otherwise discovered and confirm other things you suspected.
The first thing I wondered about when I was putting this together was the amount of air that my dust collector would be able to draw. The old vacuum hose had a small inside diameter, like 1.25 inches. Even though there were 2 of them this would severely reduce the volume of air the dust collector could draw, thus reducing effectiveness.
Going along with that was my shop made wooden adapter from the hoses to the main dust collection hose, these connections were ok, but not perfect and I was also losing air at all of the joints.
After running the prototype dust hood and watching for the saw dust that did not get pulled into the dust collector I really began to notice some of the shortcomings.
Where I had connected the hose to the back of my plastic dust hood was not ideal, there was a large rim that would prevent some dust from entering, that needs to get solved. Perhaps even attaching 2 chutes in the back of the hood might work better, but that also draws away from where the saw dust is being propelled which at the tip of the saw blade and directly back from it, so this may not be an ideal solution.
When I looked behind the new plastic hood at the dust that got past it, even more enlightening news. From my hands and knees I could see that in fastening the plastic to the frame of the saw, where one screw head broke off there was a gap large enough that significant amounts of dust could blow through. In the future this would need to be sealed.
When you really pay attention to the patterns of dust there is even more revealed. Dust was being blown UNDER the main pivoting portion of the saw and evidence of that is by looking at the pattern of the dust between the 2 pieces ... see picture.
This needs to get solved, but because it pivots, I am not sure what the solution here would be. Perhaps a flexible plastic skirt that would help prevent dust from getting under this pivot point.
Dust blown from the sides of the hood was another issue. I’m not sure this can be solved all together, but fixing how the hose attaches to the back of the hood might solve some of the side blow that happens.
The first thing will be to secure a sturdy, probably metal dust hood and with the correct design, a hose connection port could be welded or soldered to the back which would alleviate that collar sticking out.
The could be some sort of a gasket between the hood and the pivot point of the saw so dust cannot go between them.
Some sort of a plastic skirt that attaches (maybe with velcro?) between the base and the pivot point. This may be overkill but it’s worth looking at.
Larger hose size and larger ports with better connections to the main dust collection system will also improve the air flow and thus the collection of dust.
In the end ... this is easily one of the most enlightening prototypes and woodworking experiments I have tackled. I learned a lot and have a much better idea on how to improve the collection of dust from my sliding mitre ... now all I need is time to do it ...
Copyright Colin Knecht