Downdraft design questions

rodw wrote: That was painless!

The pain is still coming, I have not yet connected anything to my Mesa card yet, just the card to the PC and a 5V power supply.

I got a small desktop 8U rack (last night) so I can start putting everything together for testing. Maybe this won't be as complex as I am imagining, no... I bet it will be.

rodw wrote: This article suggests 3200-3600 CFM for a 4' x 4' table
www.hypertherm.com/learn/spark-the-blog/fume-control/
So for a table that size you would need a LOT of air. 16000 cfm.
Most commercial tables are zoned

Assuming you are going to use Linuxcnc's Plasmac, I would suggest you add an air activated shutter on each of the 8 outlets that is triggered based on the position of the x & y axis. You don't need seperate compartments to contain the air. Better that you don't
so by using 8 zones, you would reduce the air flow requirement to a much more reasonable 2000 CFM

Do you think either of these two fans would be up to the job?

www.grainger.com/product/DAYTON-7-1-2-HP...ressure-Blower-7D752

www.grainger.com/product/DAYTON-High-Pressure-Blower-7AV38

Working properly with the correct 5/2 valve. Thanks Rodw!

Added a speed controller (after this video was taken) and it was much smoother.

This is gunna be an awesome experiment! I can't really advise on the fan size but I suspect either will do. You have a fairly small duct so perhaps the pressures will be higher...

Also, you when you get it going, you could look at using an or2 component on zones 0 & 1, 2 & 3, 4 &5, 6 & 7 so both zones open together full width of your Z. but will need more fan output... BUt we can leave that for another day...

rodw wrote: This is gunna be an awesome experiment! I can't really advise on the fan size but I suspect either will do. You have a fairly small duct so perhaps the pressures will be higher...

What would you go with? Direct drive 7.5HP open drip proof motor, or 5HP belt drive totally enclosed fan cooled? Performance wise they both have pros and cons, the belt drive does seem to have more 'torque' for lack of a better word, the CFM output falls more slowly that the direct drive. Somewhere between 5 and 6 in/SP the 5HP belt driven model passes the 7.5HP direct drive in CFM. I don't know if that makes a difference or not in my situation.

I am leaning toward the 5HP for some reason, normally I would be all about direct drive.