Thread: Dust collection for nine lathes

Allowing an average of ~800 cfm per lathe you'd need ~7200 CFM of collection to do this all by direct DC.

Alternative 1
The Clearvue Max can do about 1800 CFM so technically you'd would need 4 of them $$$$$
I'd put the bigger lathes in pairs on each of 3 of the CVs, and put 3 of the smaller lathes on the 4th CV.
You need a 8" trunk lines for each CV to to carry that much air.

Alternative 2
To do this with a single DC you'd need about a 20" impeller and a ~15kW motor. $$$$$
Again you need a 12" trunk line to carry that much air.

Alternative 3
Use 1 CV max plumbed to all machines but direct the flow to whichever 2-3 machines were making the most dust, largest pieces of driest wood s.
8" or 225mm PVC ducting can be as a trunk line
In addition install 1-2 large Evap AC fan (total of 5000+ CFM) in the ceiling and make sure you had a couple of large (car roller door size) openings to let the air out .
This should clear your fine dust. The coarse dust you will have to be swept up, or better still locate 3m of 4" gated flexy lines ducted into the trunk line in between each pair of lathes to act a vacuum cleaner line.

Without sounding too rude about, my impression of turners clubs is there is often more jaw movement than turning going on and the rate of wood dust dust production is not as high as first assumed - that is why I think option 3 is going to work.

I wish I were closer so I could monitor your dust load.

Thanks very much for the quick reply Bob. Alternative 3 looks like it could be a good compromise. The club is putting in for a grant so we will see how things go.

Originally Posted by safari

Thanks very much for the quick reply Bob. Alternative 3 looks like it could be a good compromise.

To help firm the numbers up a bit more what is the total volume of the lathe work area.

David, instead of one Max buy two 1800's and run them at 65hz or do what Dom has done and put Max impellers in them. You still need 235mm main lines though as the 150mm really throttles a 1800 at 60hz. The only reason 150mm is used in Oz is that any size between it and 235mm is unobtanium and if you can get it the price is stupid. You could build MDF duting to closer match the performance of an 1800/16"/65hz set up but someone would need to do the maths to size the ducting.

Thanks for your ideas Chris. That's interesting about the small CV being throttled by 6" pipe when running at 60hz - I hadn't come across this before. Now that I have built the enclosure and am able to run mine at 60hz without blowing my eardrums out I am amazed at how good it is at clearing dust so it must be brilliant with a larger main trunk.

Thanks Bob, I will have to check the size of the room when I next go to the club.

The US ClearVue Website (60Hz) shows the flow the CV Max generates is 1935 CFM .
65Hz will get you a max of 8% more, so 2090 CFM for each machine.

Two CV max @65Hz will then get you 4180 CFM.
Divided by 9 lathes will get you an average of 464 cfm for each lathe..

The two CVs will have to be on separate trunk lines other wise they will fight each other for air.
In practice you will have to connect 4 lathes on one CV (523 CFM each) and 5 (418 cfm each) on the other.

The nominal 1935 CFM figure is with no ducting attached so some ducting losses have to be factored in.
Using nominal 9" PVC ducting (241 mm ID) and fittings will help maintain flow better than 8" ducting but ducting and junctions will reduce the flow by a few % so the 523 CFM will drop below 500 and the 418 will drop below 400 CFM. When all lathes are in use this would not be similar to using 2HP DCs with 4" ducting.

At the lathes 6" BMHs will have a higher but more directional air/dust pickup speed and will grab chips dust from further away than a 9" hood.
A 9" hood (relies n having 9" ducting all the way to lathe) the would grab fewer chips but slightly more fine dust, it won't be a lot more unless the other machines on that trunk are running 6" hoods and then those machine will lose overall flow at the expense of any running 9" hood.

Whatever is done with 2VCs , they alone still won't be enough to control fine dust from 9 machines except perhaps for very short spindle work (ie pens) so additional forced ventilation will still be needed. Less forced ventilation will be needed than if one CV is used, with the amount of forced ventilation dependent on the size of the workshop.