Downdraft exhaust fan

[SoundManCO]

I have a Cincinnati Fume Master 1000S that was used in a shop for a large overhead welding hood. They pulled it out when they closed the shop and it was given to me. It works great, moves a LOT of air. I am concerned that it will create a vacuum under my material and I don't know what effect that will have on my cuts or if this fan is overkill.

Specs on it can be found here.

[HardcorewannabeXJ]

That would actually be about perfect. We usually say the surface area of the table in sq ft times 125 = recommended CFM for the fan. Which puts it at 500 CFM, and that fan is 485.

It will create a slight vacuum under the table, but that is the idea, to suck away all the smoke and dust. I wouldn't block off every available air passage, leave some room around the plate to let a little air through, but overall I think it would be a good fit.

[Dave Boyd]

Originally Posted by HardcorewannabeXJ

That would actually be about perfect. We usually say the surface area of the table in sq ft times 125 = recommended CFM for the fan. Which puts it at 500 CFM, and that fan is 485.

It will create a slight vacuum under the table, but that is the idea, to suck away all the smoke and dust. I wouldn't block off every available air passage, leave some room around the plate to let a little air through, but overall I think it would be a good fit.

just so i get this right. a 4' x 12' table requires 6000 CFM?

[SoundManCO]

4x12=48x125=6000.. That is a LOT of air moving!

My plan is to build my table opening 25" x 50" so I can support and cut a 2' x 4' section easily and cover the side not being used when necessary.

[HardcorewannabeXJ]

Originally Posted by Dave Boyd

just so i get this right. a 4' x 12' table requires 6000 CFM?

For a single fan sucking the entire area of the table not being "zoned" off, and to be fully functional, yes. Most people when going on to a table that large will either zone it off or use a smaller fan and cover unused or open surface area with a light material to focus the suction on the cutting area.

[StinkBug]

I'm finally getting around to finishing up the enclosure and ducting for the downdraft system on my 4x4. I found a fan that pulls a little more than 2000cfm on it's low setting and so far have only been using it as a big window fan to clear the room, which it does ok at on it's high setting. I'm just wondering about when I'm either cutting on something small, or when the sheet I'm cutting out of is already mostly cut away. Do I need to cover these open areas, or will the fan actually pull enough air through that 4x4 opening?

[Torchmate]

Originally Posted by StinkBug

I'm finally getting around to finishing up the enclosure and ducting for the downdraft system on my 4x4. I found a fan that pulls a little more than 2000cfm on it's low setting and so far have only been using it as a big window fan to clear the room, which it does ok at on it's high setting. I'm just wondering about when I'm either cutting on something small, or when the sheet I'm cutting out of is already mostly cut away. Do I need to cover these open areas, or will the fan actually pull enough air through that 4x4 opening?

Hi Dallas!

I used to throw welding blankets over the part of the table that I was not using back when I had a 5x10 table in my garage next to my wife's car. It provided enough restriction to allow the fan to evacuate everything that the torch was throwing.

Your new shop looks great by the way. You probably don't know what to do with yourself now that you have all that space.

Bill

[StinkBug]

The space is really nice. Surprising how fast it fills up though. I'll post up some pics once I get the duct work done. The "Torchmate Room" has worked out really well so far. The only thing I'd like to do once this is done is build up a new computer and leave the tower upstairs in the office space to keep it clean, and just run long wires down to the monitor, etc.