The dust buster is not capable of much suction. Just keep your working orifice roughly equal to the size of the fan inlet.

You say ".5 thick". Is this a material thickness or an opening width?

.5" will be the opening width of the orifice picking up the dirt (by 11" long). I'm not exactly sure how big to make the orifice to the "catch bin" where I will put the dustbuster. (Were looking at .5" wide by 2-3" thick). The fan is really a turbine with the intake about 2 to 2.5 inches wide (diameter). That gives me an area of about 3 to 5 inches^2. Using the .5 by 11 is 5.5 inches^2...is that close enough.

Is the "working orifice" considered the side that "picks up the dirt" or the side that exits to the "catch bin".

To the best of my recollection, I can't say I have ever seen a vacuum device where the "trash" passes through the "pump".  What usually happens is that the filter element is located upstream of the "pump", sort of like the air filter on your car.

Something to consider is that the suction power you need.  If you just look at the velocities you'll get an idea of your suction.  By changing the cross section, you'll be seeing different velocities.  The inlet to the pump might be one area, but the vacuum's pickup point might be smaller in area.  The reason is that it would be like focusing the energy to one point.  If you distribute this sucking force over a larger area, you'll not have enough suction to even lift sugar off of a table.

I would look to the orginal design and try to determine what the manufacturer was shooting for.

Also, keep in mind that the longer the duct work, the rougher the walls are, the smaller the ducts are the more losses you will see.

Try to give some info about what the project is shooting for and advice will usually be more tailored to something that can help.

The trash will not be sucked through the fan. The fan will be located behind a filter at one end of the catch (trash) bin. At the other end of the bin is an orifice with duct work leading down to the intake orifice. (See Diagram below)We want the trash intake orifice (where the dirt will be sucked in from) to be 11" by .5". Then we want to taper that down to the orifice leading into the catch bin (approximatly 2" by .5"). The catch bin is a 4" by 4" by 4" cube. The overall height will be about 8 inches. As mentioned the turbine (fan) intake is about 2 or 2.5 inches in diameter. It comes from a dustbuster vacuum. We will be using the motor and motor housing from the dustbuster mounted to our catch bin and intake. The original dustbuster trash intake orifice is about .5" by 2". This whole unit will be mounted on a robot. The robot is the true scope of our project, but its intended purpose was to serve as a vacuum cleaner. Were not looking to make the next Hoover WindTunnel. We just want it to pick up a little trash. We may even use something like confetti for our trash. Does anybody know if this will work, or will i need to get a bigger motor/fan, or what. I don't want to design the attachment if its not going to work.


    <---------------                  ------
  fan and |        |                 /      \
  filter  |catch | |                /        \
          | bin  | |               /          \
          -------| |              /            \
                 | |             /              \
                 |_|            /________________\
                Intake                Intake
                Orifice               Orifice
           
          SIDE VIEW                 FRONT VIEW     

Jason,

I'm fairly sure that you will not be able to suck air quickly enough through an orifice that large (11 inches by 0.5 inches) to pick up anything heavier than (perhaps) confetti. Look at the orifice at the business end of your dustbuster as it came from the store. Anything much larger than that and the performance will drop right off.

Howard