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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:
Code:net zone0 <= ddraft4x2.0.trigger-0 net zone0 => hm2_7i76e.0.7i76.0.0.output-00
I got it loaded and when I jog around the 'table' (simulated only since I have nothing connected to my Mesa card yet) the pins change as I moved from section to section. That's good stuff!
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?
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That looks right. Yes, I only did one example! The outputs may need to be different as you might already be using a pin for torch on or something.
If you upgrade linuxcnc, you may need to redo the halcompile step as the component is not native to linuxcnc.
There is also a separate zone pin that publishes a numeric number for the current zone. If you were ambitious you could modify your GUI to display the number from that pin. Or add a row of GUI LED's for each zone.
Very cool. Can't wait to see how it works for you!
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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?
I would keep all the connections in the ddraft4x2.hal file
I have used a 22mmm mount 24V LED light to confirm working but to use a LED you would need a 2.2k 1/2 W current limiting resistor
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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.
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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
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Added a speed controller (after this video was taken) and it was much smoother.
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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.
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