Isn't it interesting that the words "blow" and "suck" both mean something is bad in today's vernacular? Coincidentally (or maybe not) things that suck also tend to blow. This is especially true for my Homemade Dust Collector! I wrote about this contraption over a year ago in my post "DIY Homemade (free) Shop Dust Collector (Disperser)" that some people have asked for more information about. It's not really that complicated and there are only a few things that you need to think about when building one so I decided to talk some more about it and make a video!! Below is a picture of most of it's parts.
You can see in the picture that it's really nothing more than a bucket with a blower motor attached to a hole in the lid. "What more could there be to it you ask?" Click below and you can find out! Try reading the original post as well for more exciting details! I'll add a few things that I may have missed in the text below.
One detail that people have asked about is why the silver metal output (blow) tube is bigger in diameter than the white clothes dryer input (suck) tube. Before I answer that I should mention something interesting that I just recently found out. The vinyl 'clothes dryer hose' that I used actually isn't used for clothes dryers anymore!. Growing up as a kid in the traveling circus we always used vinyl tube to vent our clothes dryers out into the sawdust that we used to soak up the elephant pee. For some reason that always resulted in a fire and now I know why! Vinyl doesn't work well with the hot air coming out of a clothes dryer!!! Anyway I'll continue to refer to this a clothes dryer vent hose even though that is not what it's used for.
I found all this out while doing the extensive research that I always do before writing a Blog Post!!! (yeah right). Actually I was looking to see if you could still buy this stuff because the piece that I used in my Dust Collection System was something that I had laying around the garage - it was free in other words. HERE is a link to what I am talking about.
OK back to the first question "Why are the blow and suck tubes different diameters?" The reason is simple: I already had the tubes and so they were free! I use the vinyl suck tube to suck up all the dust that I am making while sanding or turning things on my homemade wood lathe and the vinyl being longer and flexible allows me to get the opening of the tube right where the work is being done. This leads to better collection of the dust. Another thing to consider when choosing tube (or pipe) diameters is of course the Hydraulic Pressure Drop that your system will see when in operation. In addition to calculating the Reynolds Number for the tube in question you also have to know what you are doing! Since I tend to choose my pipe and tube diameters based on what's on hand rather than what is ideal I end up with tubes that are not the same diameter! I suppose I could make the argument that the larger output tube is to reduce the hydraulic back pressure that the blower is pushing against compounded by the air filter and the sudden change in fluid direction in the outlet aperture. But if I say something like that it might imply that I know what I am doing so I won't say that.
Another question that a few people have asked is "Are the holes sizes in the water pump filter important?" The answer of course is no! As I mentioned in the original post I had that filter laying around in my garage and I saved it because I thought it might make a good hat or something. In that case the holes would allow for a subtle cooling air flow to my delicate head on hot days. In this case the plastic is there to prevent the polyurethane foam filter from being sucked into the blower. Pretty much anything will do so you don't have to have a water pump filter. Chicken wire, metal grating or anything that has holes in it and will support the polyurethane filter will work. One thing that i do recommend is that whatever you use should be rather large. In other words you want to have a lot of surface area of the polyurethane foam filter exposed to the airflow. The more surface area you have the less back pressure (more sucking power) and the longer the filter will last before becoming clogged up with dust.
Here is a video detailing all the major components of my homemade dust collection system!!!
The last question that someone asked is "Why use a centrifugal blower, will a fan work?" The easy answer is yes a fan will work but not as well as a blower. There are a couple of important differences to consider as either will blow (suck) air. A centrifugal blower is better because they tend to be able to push more air against a resistance. This resistance is called back pressure and in the case of a dirty air filter it can be significant. A fan generally doesn't work as well when faced with a back pressure compared to a blower so you will get better results with a blower. Another important thing to consider is a fan usually has the motor mounted in the center of the fan blades with the air blowing over the motor itself facilitating cooling of the motor. This is OK if the fan is blowing nice clean air around but if the air is filled with dust then the motor will soon also be filled with dust. A dirty dust filled motor will wear out really fast and quite possibly over heat and burn up like elephant pee soaked sawdust. Not a nice thing for pachyderm's and circus clowns alike.
A centrifugal blower on the other hand usually has a motor that is mounted off to the side of the air plenum out of the airflow. When it's operating the dirty air is passing through the centrifugal part of the blower and not the motor. This keeps the motor clean and dust free. That is about all there is to this, not a lot to consider but like so many projects there are some things to think about. If you have any questions send me an email to at email@example.com or leave a comment!