Another DC question

[meika123]

I have been adding blast gates in my main trunk when using my 4" ducting. I have since seen many systems that only have the gates in the drops. Is that the proper way to do it, or was my old way the way to go. I am confused.
Would someone who is more knowlegeable than me please
respond, so I will get it right?
BTW: I have decided to purchase the 5.0 hp Leeson motor from Ed Morgano as the power supply for my cyclone. Also, I'm reducing the size of my impeller to 16" OUCH!!
Whaddayathink?

[JimmyC]

Dave,

One thing that I'm thinking is that a 16" impeller and 5hp motor are going to need 6" lines if the system is fairly tight. If you insist on using the 4" lines, you may want a gate open to the air to help with the flow. Two 4" pipes have the same sq/inches as one 6".

Just my .02 worth

Jimmy

[meika123]

Sorry Jimmy, but I believe you misunderstood. I wasn't perfectly clear either.
I am building a cyclone and switching to all 6" lines. I was just inquiring as to the best placement of the blast gates.

[Jim Murphy]

Put the blast gates at each machine... that is, at each drop. I have my gates between the flex hose and the mains. I've also seen them between the flex hose and the machine. It doesn't matter, it's all about convenience and access.

You are running 6" everywhere except when you get to a machine with a 4" port, right? And when you can, you're expanding the ports to 6" if you can it without a cutting torch and welder, right?

The 5hp Leeson and the 16" impeller will suck the chrome off a hitchball and a bowling ball through a garden hose at the same time with enough suction to spare to eradicate all the chips the jointer or planer can throw. You'll be pleased.

[JimmyC]

Dave,

If the system is tight I don't think it will matter (you will have more than enough suction) . Most people have them close to the machine to make it easy, (open gate, remote start collector, start machine). The only problem that I can see on using main trunk gates is inconvenience or having too many machines opened at the same time.

Jimmy

[Alan in Little Washington]

No need to put blast gates anywhere but at the machines, maybe one on a drop that you might use for a vacuum hose or floor sweep. You don't need to block off branch lines.

If you are running new 6", then follow these guidelines:

• NO T's
• Make straight runs
• minimal bends
• where bends are necessary, try to limit them to 45
• Avoid 90s. Use wyes + 45's instead of 90s.
• If running PVC, do not use glue, use a small screw to keep it from slipping if you think you need it, and also if you want, a small bead of silicone on the outside of the fitting (it rubs off easily with just a finger) when (not if ) you change a piping run.

[McRabbet]

With an appropriate blower housing and impeller (do have an impeller source?), your motor/impeller combination should produce about 1900 CFM (comparable to the ClearVue MAX), so even an 8" main duct with 6" branch lines might be the best option to maintain better airflow. ClearVue has an 8" main od SDR-35 (the green PVC) running down the center of their shop and used 6" drops on wyes.

I agree with Alan and Jim (both cyclone owners) that blast gates should be placed close to the machines, plus I'll add that you should plan to replace the 4" dust ports on your machines with your own 6" versions (I'm planning on making mine from 1/2 of a 6" S&D Coupling glued into plywood or MDF using Gorilla Glue). If you leave the 4" ports in place and reduce your duct to that diameter, air velocity will drop right where you need it maintained at high to pull all of the wood dust and chips through that port. Keep it at 6" to maintain hight CFM.

Good luck!