DC set up

[Sean Troy]

Hey all, I have always got such great help asking questions here I figured this is where to ask about DC set up. I want to run rigid pipe for my dust collection system. Metal or PVC ? Do I want to start out at the collector with 6" pipe and step down to 4" at the drops or 4" all the way. Should I install clean outs in a couple of places along the route? Where in the line is the best place to install blast gates? In the past, all I've used was flexable plastic and would rather put in more permanent over head piping.Thanks in advance for any help. Sean

[Chuck Lenz]

How big is your dust collector in CFM ? 6" is what I would start with and do as you said, and branch off with 4". I'm more of a metal ducting fan, it's easier to ground everything with metal. Blast gates can be next to the machine about chest level I would go.

[Sean Troy]

1500 cfm 9.5" max static pressure

[Al Killian]

I perfer metal as the fitting are eseir to find. The blast gates should be as close to the main line as possible.

[Jim Becker]

Sean, the general rule of thumb is to use the larger duct for your main run from the DC. This will help to provide maximum performance, which is likely about 600-800 CFM for your particular DC "in real life" with 6" duct if it's a common single stage system. Your drops can be sized as appropriate for the tool. You do NOT want to put in a duct system that is all 4" as that gives you a maximum CFM of just over 300...you can only fit so much air in that pipe!

I personally prefer metal duct because it can be sized exactly, but many folks enjoy using S&D PVC. The real design differentiator will come with your drops. PVC is pretty much limited to 4" or 6", while the ideal drop size for many tools is 5"-6", depending on the hood design and connections. Metal comes in 1" increments and is more flexible relative to duct design. Of course, it's a little more involved to install, too. There are always trade-offs...

[Mike Heidrick]

I am also in the ductwork design phase. My DC has a 8" Inlet. Does that mean the entire main line should be 8" for maximum efficiency? I plan to use 6" drops at the tools. I was playing with the grizzly free software last night. Is there a nicer free set of software I should use to design the duct work?

[Steven Wilson]

Mike, with an 8" diameter inlet I would run 8" pipe for my first section. For example, a typical first section is to run straight out from the collector and then make a gentle, large radius bend up to the ceiling. I would make that 8", then transition to 7" or 6" for the main branches at your first wye (depends on how much CFM your collector can pull) and then carry that to your drops. You'll need to take your worst case scenerio and calculate SP and velocities in the sections and make sure your velocity will support the material.

[Rob Will]

Sean,

I would use 6" spiral metal pipe for ALL of the main with 6 x 6 wyes for all the drops. Then, reduce each drop at the wye as required. At the far end of the main install a removable 6" cap (just in case you need a cleanout).

Rob

[Sean Troy]

Where is a good place to order the 6" sprial pipe and supplies?

[David DeCristoforo]

Your "main" run should match the size of your DC's inlet. 6" inlet...6"main; 8" inlet...8" main, etc. Reduce with appropriate fittings for each machine you have. Generally speaking, you should reduce to a size appropriate for the machine in qustion. For example, a power miter box will not need as large a run as a table saw. Try and match the pipe sizes to diameter of the machine's port or get as close as you can.

This is the best read I know of on DC for the small shop:

http://billpentz.com/woodworking/cyclone/DustCollectionIntroduction.cfm

[Jim Becker]

For example, a power miter box will not need as large a run as a table saw.

Yup...it may need more air flow than the table saw! Nature of the beast...and a CMS/SCMS is a bear to collect from.