View Full Version : New table build, fume extract ideas...

17-07-2015, 11:40 AM
Looking for some ideas on downdraught extract on my new table.

Its a 4x4 / 1250x1250 size table, so 4 x bigger than my existing one. Currently i have an extract system i cobbled together that does work pretty well providing i keep the unused parts covered to maintain airflow. It is a cross-draught really, air in at back and out at front, it has a water tray too but i don't use that anymore as its not as effective as extract.

So, on the new build, I can't simply bung in a big-ass blower as i have limited power spare and its only a small shop (double garage).

I am looking for smart ideas that could work, maybe some type of zoning system??

This is the type of fan i have...

I have ducted the outlet to outside, pipe is 4" and i know i can improve a bit on what i have by fitting rigid duct instead of the poor flex-foil stuff i have now.

Any suggestions here?

I have not built the bed yet so anything is possible.


17-07-2015, 12:08 PM
Hi Dave
I assume this is a Plasma Table ?
Think the best option is going to be some sort of enclosure so you can draw air over the cutting area and extract outdoors as per your existing setup.

17-07-2015, 12:29 PM
Yes , that what is needed, but 1250x1250 is a pretty large area, obviously some of it will be covered by plate/job.

What i need is a way to get the highest extraction rate from a small blower - get smart not bigger ;)

Boyan Silyavski
19-07-2015, 04:37 PM
From what i have read ~1500 CFM blower will do the job for sure and ~700CFM could be the minimum for your table, but of course depends on your setup. translated to W it means somewhere from 250W to 1KW blower and around 10"-12" pipes/ hose, the bigger you go.

This (http://www.ebay.es/itm/Garage-Extractor-Fan-Exhaust-Welding-Grinding-Sanding-High-Suction-High-Power-/291492954807?pt=LH_DefaultDomain_3&hash=item43de5582b7) could work for sure but i would do a search for " industrial extractor" , not "fume extractor".

One main point in all that is the shorter the way, the better, the smaller the motor could be, all transit should be fluid lined. If filtered better, but will stop flow.

Hence after knowing all that, conical shape that goes into the blower which is below the table, air changes direction in the blower, then short straight pipe from blower to outside on the same level.


19-07-2015, 05:06 PM

so conical collecting pan below table, short duct to fan, short duct to outside, smooth ducting all round.

The exhaust duct may need to be longer, say 10' as the walls in my shop are reinforced concrete slabs and don't take nicely to having holes cut in them. Above 6' its wood so easy to cut about, the ducting will need to go from fan, up wall and out.

19-08-2015, 09:30 PM
Extract duct....


Boyan Silyavski
20-08-2015, 02:03 PM
Nice one. I have to make exactly the same thing. Is that a door at the back so you grab from there any fallen small pieces?

20-08-2015, 02:58 PM
Yes, 12" x 12" door with two twist-locks for easy access.

I plan to fit a coarse welded-wire mesh of 25 x 50 x 3mm below the slats to catch the drops and bigger junk, can hook that out easily then, the smaller stuff can be emptied when needed.

The duct was made by local air-con install company for 300 delivered, I could not make it that good for that sort of money, its spot welded and riveted in places, fully seam-sealed too.

It should just drop into my table and sit on a couple of 1" support beams across the bottom cross-members.