Downdraft design questions

-not is used to invert a pin, say you had a limit switch you wanted to be normally open and its wired normally closed, you would put -not at the end of the text in the HAL for that switch to invert it.

thefabricator03 wrote: -not is used to invert a pin, say you had a limit switch you wanted to be normally open and its wired normally closed, you would put -not at the end of the text in the HAL for that switch to invert it.

That's simple enough, thanks!

Be sure to use Halshow a lot to see the signals and the pin names as you build this out.

Can I use a sensor for an axis home AND positive limit? I did not have limits on my old table, only home switches... so I am not familiar with exactly how limits work.

Yes. linuxcnc.org/docs/2.8/html/config/ini-homing.html

rodw wrote: Very cool. Thanks for sharing. We await the next one with smokey burning rags.... or even better a torch arc!

This video shows a 90 second duration, 600 CU FT, smoke emitter. I am unsure how well this simulates the actual smoke from cutting steel plate, but... I do know this... if you forget to connect the compressed air line to the solenoid manifold before this test, your shop will fill up with this smoke. :whistle:

Looks very good towards the beginning of the table, but a bit less towards the end.
Either way, it seems to have more than enough flow to suck the ..... smoke nicely !

tommylight wrote: Looks very good towards the beginning of the table, but a bit less towards the end.

I agree, it needs some tweaking. Though I was impressed with how well it did at the farthest end from the blower

When one gate closes and another opens, even though it's near instantaneous, the air flow is disrupted enough that I noticed smoke escaping. I need to see what happens with a delay on each gate closure, even if it's 2 seconds...

txtrone wrote:
When one gate closes and another opens, even though it's near instantaneous, the air flow is disrupted enough that I noticed smoke escaping.

Yes, but it managed to get it back pretty much entirely as it was sucking some at over half a meter above table on some parts, so in total i would say over 90%.
Keep in mind that the smoke used for testing is light and moves up easily while the plasma smoke is much heavier and easier to capture it before it gets out of the draft zone.

tommylight wrote: Keep in mind that the smoke used for testing is light and moves up easily while the plasma smoke is much heavier and easier to capture it before it gets out of the draft zone.

Are you saying the kind of smoke I have is for draft dodgers?:laugh: Lame joke, sorry.

Also you will most likely have a sheet of steel on the surface that will help keep the smoke down in the draft zone. Looking pretty good, cant wait to see the video of it cutting.