Downdraft design questions

thefabricator03 wrote:

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.

I can hardly wait. I have a small amount of config left to do with the sensors, then I believe it's time to install plasmac and setup THC.

You could use the timedelay component to keep the zone open for a bit.
typos excepted something like

So now we send your trigger signal top the time delay
and send the delayed output to your output pin
the settings above turn the zone on as soon as the zone is reached but turn the prevoius one of 0.25 seconds later.

rodw wrote:

the settings above turn the zone on as soon as the zone is reached but turn the prevoius one of 0.25 seconds later.

Will try that in the morning with the same route and smoke to see what kind of difference it makes.

I really look forward to cutting with this new rig!

I'm watching this topic with interest.
I just added the time delay to my downdraft a few month ago. I have it set at 4 seconds, which might be set extra long. I only have 4 zones on my 5ft. x 10ft. table. It works good if the table is mostly covered, but it sure would be better to have a few more zones.
Earl W

flamecutter wrote:

I'm watching this topic with interest.
I just added the time delay to my downdraft a few month ago. I have it set at 4 seconds, which might be set extra long. I only have 4 zones on my 5ft. x 10ft. table. It works good if the table is mostly covered, but it sure would be better to have a few more zones.
Earl W

What type of fan/blower are you using? What about actuators? I would be super interested to see your setup.

I had been exausting it outside with a small cyclone dust collector. Then a few month ago I exchanged it with a used bigger 5HP Torit dust collector. I'm not sure of the CFM. It pulls the air through 2 sets of round filters. Maybe eventually I will be able to exaust the air back into the shop so I don't loose so much heat in the winter. The filters have reverse pulse air valves on them to clean the filters. I just connected them to my Linuxcnc plasma to pulse the filters using ladder logic.
My plasma table is divided into 4 zones, 2X and 2Y zones. Each zone has a 6in round tube entering it from the end manifold section. At the end of the tube I have an air cylinder with a round steel plate attached to the end of the ram. When the cylinder extends it blocks the tube. Everything is underneath the slats and a cover, so I can't very well show you with a picture of it. That part works well, but I wish I would have added more zones.

flamecutter wrote:

Then a few month ago I exchanged it with a used bigger 5HP Torit dust collector. I'm not sure of the CFM..

I looked at the Donaldson Torit model 20-5 (which sounds like the model you have) and even tried to find a used one. Those are nice! According to the brochure on Donaldson's website the cfm is 1500-2500 depending on the filters.

Here in Texas I am not too concerned with the loss of heat from the building, but I would like to eventually have a 'collector' outside for the dust particles.

Thanks for the input. It sounds like you have a very nice setup!

Ooops. I think the timedelay addf needs to be added for each one eg seperate addf entries for
timedelay.0 to timedelay.7

tommylight wrote:

Motor wires seem very thin, that will limit the torque and speed by quite a margin.
4X0.75 is the absolute minimum for small Nema17 motors that i use, for anything bigger i use 4x2.5mm2.

tommylight - I ended up ordering some of this wire to redo the home-runs between the drivers and the motors. www.alliedelec.com/product/belden/73405ws-008100/71076339/