RE: Want to build a low budget exhaust system

[edclayton1]

Hi all,
Do you think I could make a small roll around self contained 3' by 3' cutting table and place it inside of my plasma table and then make it contain a smoke exhaust collector within it? The concept here is two fold. MY table is home built and is approx. 5 foot wide and about ten foot long. I have two issues to keep trying to deal with. One is that on account of the shear area it would be rather expensive to buy a extractor or a fan with enough CFM to work effectively for that much area and my other issue is my table has a tendency to not be perfectly level in the middle. It sags a little bit, not horrible but probably .065" anyway. So I was thinking of building a 3' by 3' table with a funnel and a pull out pan in the bottom and hooking up a fan to just that. Then it would be pretty easy to make it straight and flat and also small enough that I could more inexpensively adapt a exhaust fan or build a water table inside it. Then I could remove some of my slats and place that smaller table inside my main table frame at one end. So far I have not been able to really do 4' by 8" foot sheets worth of continuous cutting anyway with out something going wrong, so I figure I could live with a smaller working envelope for quite a while and keep saving money and come up with better modifications to the machine at a later date.
Anyway I was looking for opinions on if anyone has ever considered using a fan from a dust collector normally used for woodworking. I see them for around $300.00 used and what I was thinking as at least the motor is outside the ducting and therefore the metal particulates would not be some apt to destroy the fan in short order. It looks likes a lot of the fans being offered for plasma do have the motor inside the duct. To me that looks like trouble waiting to happen. Attached is a picture of the type of fan I was considering its only about 550 CFM but for a 3' by 3' table I think it would probably be enough to suck down the smoke and fumes and discharge them outside using about a 12" diameter duct of some sort. I would not try to use anything else from the picture I included except the motor and the fan of course. My idea for the design of the downdraft table is going to look very similar to the one that Jody from weldingtips&tricks.com made in one of his video series a while back. The main difference would be I don't have an expensive Miller extraction system so my duct attaching interface would be different that he designed. Any thoughts or suggestions would be greatly appreciated. I suspect their are lots of guys out there that would like help and advise on building a low cost downdraft table setup. I have been surprised how little information I have been able to find online concerning this topic to date. There are tons of videos for woodworking and soldering down drafts but not so much for DIY plasma tables that I am aware of.
Cheers,
Ed

[acourtjester]

Have you looked at a Squirrel cage fan setup from a home AV/heater some have the motor outside the air flow. They have a shaft with a pulley being belt driven they do move a good amount of air.

[edclayton1]

Yes I see one of those in my area for only $55.00 but its only 1/6 HP and the one I saw on the dust collector which was actually slightly different from the one in that picture was 3/4 HP if I recall correctly and that one was about $100.00 but looked pretty new. I hope you are doing well Tom. Last week I managed to upgrade from my Hypertherm PM45 to a PM65. Its back up and running and I sure like the looks of the consumables compared with the PM 45's. Tom, Do you have the RS485 port setup on yours? I'm researching that option too.
Cheers,
Ed

[acourtjester]

I do have the RS485 on my DTHC setup but not the option for amp control from SheetCam I use manual front panel of the PM65.

[jimcolt]

I use a louvered restaurant wall fan.....it is a 30" fan blade with louvers that close on the outside when you shut it off, the fan has a totally enclosed motor. I built a sheet metal box on the inside to attach my 3 8" diameter galvanized duct pipes that come from under my plasma cnc. I paid $75 for the fan on craigslist, spent a few hours cleaning years of kitchen grease off it...and it has been working very well in my shop for years.

Jim Colt Hypertherm

[VPT]

Personally I have my table right by an overhead door in the shop. I have three sides sheeted off on the table and then the side facing the door I use two plain old $16 walmart box fans side by side. I open the over head door just to the top of the box fans and go to work. It was a temporary set up that has been running for more than a few years now. It amazes me how well it works. I am at the point now where I want to run the fans/this setup till they die just to see how long they will last. I am also at the point now where if the $16 fans did die I will probably just buy two more and continue on.

[allan101]

I added a section of fume extractor pipe to a fan motor 1/2 hp that is mounted to a ibeam

IMG_0057.JPG

and vent it into a fume and smoke filter ,it works awesome,as I lose no heat in the colder months

[allan101]

I added a section of fume extractor pipe to a fan motor 1/2 hp that is mounted to a ibeam

IMG_0057.JPG

and vent it into a fume and smoke filter ,it works awesome,as I lose no heat in the colder months

[Dana gear]

On our two CNC cutting tables we installed AFC Air Filtration inline turbine fans on each table and just used regular air ducting to push the smoke/dust out through the roof. There 3 phase 1 h.p. motors.
Both of the fan units were from the exhaust system used on an old powder coating spray booth.
We are in northern California so pulling air out of the shop is not much of a consideration, For a few days each year it may hit 45 degrees and in the summer mouths it is generally over 100 .
The plus to this system is that the plasma cutting area is totally free of smoke/plasma dust.
Water tables are nice but for us the down draft was the answer.