Downdraft design questions

rodw wrote:

Next step is to connect each trigger pin to a real output pin. (Remember what I said about diodes). I generally would do it like this:

net zone0 <= ddraft4x2.0.trigger-0
net zone0 =>  hm2_7i76e.0.7i76.0.0.output-00

net zone0 <= ddraft4x2.0.trigger-0
net zone0 =>  hm2_7i76e.0.7i76.0.0.output-00
net zone1 <= ddraft4x2.0.trigger-1
net zone1 =>  hm2_7i76e.0.7i76.0.0.output-01
net zone2 <= ddraft4x2.0.trigger-2
net zone2 =>  hm2_7i76e.0.7i76.0.0.output-02
net zone3 <= ddraft4x2.0.trigger-3
net zone3 =>  hm2_7i76e.0.7i76.0.0.output-03
net zone4 <= ddraft4x2.0.trigger-4
net zone4 =>  hm2_7i76e.0.7i76.0.0.output-04
net zone5 <= ddraft4x2.0.trigger-5
net zone5 =>  hm2_7i76e.0.7i76.0.0.output-05
net zone6 <= ddraft4x2.0.trigger-6
net zone6 =>  hm2_7i76e.0.7i76.0.0.output-06
net zone7 <= ddraft4x2.0.trigger-7
net zone7 =>  hm2_7i76e.0.7i76.0.0.output-07

txtrone wrote:

Refresh my memory, should I use some LEDs on the Mesa card to prove that the outputs are firing the same as the pins in the HAL confifuration?

Also, where does the is 'net zone' code belong? Is that the example code for zone 0 only? Should it look like this when I am finished?

rodw wrote:

That was painless!

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

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...