Hi to a fellow engineer ?

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My saw has the riving knife hood which I heavily modified to increase airflow but it still doesn’t get all the dust, especially if cutting a small amount off so the teeth are not fully buried in the wood.? I suspect the overarm guard would help as you can get more airflow.? I have a 6” duct to the saw which splits off to a 4” hard duct over the saw which connects to a 3” flex hose connected to my modified dust shroud.? The overhead duct branches off to a 5” duct to the saw which connects to the 120mm port on the side of the machine.

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I strongly recommend the Oneida Smart collectors but I am biased as this innovation was my idea and I worked with the founder of Oneida to commercialize it. ?I just shared the idea at a woodworking show and we communicated back and forth for about a year.? I don’t have any financial interest in it but they did upgrade my system with a new fan motor and control system.

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Basically the more air a fan moves the higher the load on the motor.? Run a collector with no pipe and most motors will overheat in less than a minute.? When the inlet is clogged the motor spins faster and the sound pitch rises but the motor current is at it’s lowest.? The idea was to use a VFD to automatically adjust the motor rpm to keep the current at like 95% of full load rated amps.? There is a max speed cap to keep the fan rpm under max rated current.? So when my collector which has a 7” inlet is connected to my wide belt sander with 7” duct it runs at 60hz and rated rpm.? When connected to a machine with a small actual machine port at the cutting location it speeds up until I hit 95% of FLA.? This resulted in about 2X more cfm on all machines with small ports.

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The first free step is to modify any machine you can to maximize the passage air flows through.

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Biil Pentz’s stuff is accurate but sadly most people take too simple of conclusions away.? Bill started with 4” duct and found that cfm was much higher if you use 6”? So now people thing you should run 8” or larger mains and 6” drops to machines with tiny air passages.? The reality is that you need to maximize the port.? Then use Bill’s spreadsheet to estimate the pressure you will have at that port, and then optimize the duct run to keep velocity over 3500 ft per min.? I’ve used Bill’ sheet to model my last shop and measured at every machine and his model is really good.

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