Dust collection

[Rex Guinn]

Hey guys,
I am ready to put in my dust collection and have a couple of questions.
my shop has 10' celing. I wanted to put the 6" ducting on The celling, and the 2hp harbor freight DC in the attic with drops of 6" down the walls reduced to 4" for each machine. Will there be enough to lift the dust and chips up and out the wall to outside? Will only be using one machine at a time. One guy said it should be all on one level. I will also make sure to seal so there are no leaks.
thanks

[Jim Andrew]

My ceiling is 9', and I put my pipe on top of the joists in the attic. My cyclone is a 2 hp woodsucker, and it has no problem lifting the wood chips up and through the system. I have no small 90 degree bends, all are the large 90's or Y's and a 45. My table saw grabs knots sometimes, and there is one rattling around in the pipe right now, but it will suck it up before long. What kind of ceiling do you have, would it be easy to make some brackets to hold up the pipe? The down side of putting your pipe in the attic is that in winter, you are exposing your system to cold, and heat in the summer. Attics get really hot, so your pipe is too. If you AC your shop, might be a concern.

[Michael W. Clark]

Hi Rex,
Its mostly the duct length and fittings that affect your losses. As Jim says, use laterals and long radius 90s where possible. Air is much lighter than water, so feet of head or lift is not really a concern. (Feet of head and lift are both measures fo pressure capability).

Strictly from a system loss standpoint, you may be better to run horizontal through the attic and drop down through the ceiling with a lateral and 45 elbow at each location. If you 90 down out of the blower inlet to get through the ceiling, then 90 again to go horzontal, you have added two extra 90s. Plus, you have a 90 on the inlet of the fan which will also reduce its performance as opposed to having a straight duct.

[Rex Guinn]

I will put the 6" metal duct pipe along the celling, the whole shop is insulated. Will not do any 90deg bends only 45 or less.
thanks for the input