Required CFM for ducting

[Make It All]

Hi this is my first post so don't judge me,
I am setting up a workshop and am only going to have around 4 meters of ducting. Connected to this is going to be a scroll saw, a mitre saw, drill press, combination disc and belt sander, router table, a random orbital sander and possibly a thickness planer. The ducting will be some 100mm spiral ducting and each branch will have a blast gate. I was wondering how much cubic feet per minute I would need for the dust extractor and whether this Axminster one (Axminster Hobby Series AWDE5002 Extractor) would be alright if I built a cyclone unit and had the out feed of the extractor going outside.
Thankyou for your help.
Jack

 

[PAC1]

Welcome
Have a read at this a-guide-to-dust-extraction-by-member-siggy-7-t102025.html

The requirement for CFM is based upon the manufacturer’s stated requirement for the individual machine. If using ducting add a significant factor for the loss caused by bends etc etc.
You might find it better to get a workshop vac for all the small fine dust generators and a chip extractor just for the planer thicknesses and any other big machine.

 

[Make It All]

Thank you for replying!
Would you say a vacuum extractor would be better then. I was put off getting one of these due to there low air flow rate.
Thankyou

 

[MattRoberts]

There's no 'one extractor fits all' I'm afraid.

You'll need an HVLP chip extractor (typically come in 100mm or bigger) for the larger machinery like tablesaw, thicknesser etc, but it won't work for the smaller power tools.

For the power tools and items with small dust ports, you'll need a LVHP vacuum, which won't work well with the larger machines.

 

[Make It All]

Thankyou for replying
Ok so I would need a shop vacuum (which I was going to get any way) for the random orbital sander and belt and disc sander and then a chip extractor for the others. Would the Axminster Hobby Series AWDE5002 Extractor be alright for the larger tools if i built a cyclone in line with the ducting and had the dust collector blowing any excess that's passed through the cyclone outside?
Thank you for your help
Jack

 

[MattRoberts]

It depends on your definition of alright, to be honest.

Each component you add in an extraction system reduces the airflow. Each pipe, bend, branch and especially a separation unit like a cyclone or Thien baffle.

I believe that hobby extractor is 1hp. Sure it will provide some suction through duct work and even through a separator, but as to whether that's enough suction, it's hard to say.

I'd typically recommend a 1hp unit for direct connection to a single machine, and a 2hp unit or higher if you're running a separator and / or ducting to several machines (especially a thickness planer, which produces a huge amount of large chips very quickly)

 

[Make It All]

Ok thank you
Would you have any recommendations of budget 2hp extractors

 

[MattRoberts]

Your best bet would be to look on eBay. I picked up a 2hp extractor for about £120. It took a while to find though. If you want one sooner, SIP do reasonably priced 2 & 3hp extractors

 

[Make It All]

Ok thank you so much for your help

 

[MattRoberts]

No problem! That's what we're here for

 

[Beau]

Hi Jack and welcome

Sorry to confuse matters but there is another factor in all this and that's resistance. The HVLP extractors give great figures for CFM but when in actual use with the resistance of bends and hoods their flow rates drop. Used to have big Startright chip extractor. It moved loads of air but the the tiniest blockage would see the flow rate drop right off and then the blockage would become worse until totally blocked. I went for a LVHP extractor from Yorkleen similar to this http://www.recordpower.co.uk/product/fi ... gbLFBO0O3I. It's ducted around my workshop and just copes with my 12" planer thicknesses but is clearly perfect for all the other dust generating machines. Real word CFM and advertised CFM are different things. Clearly if you can have both types of extractor that would be ideal.

 

[Make It All]

Ok thank you I'll go for one of those then.

 

[beech1948]

Make it all,

I used to have 100mm plastic pipe ducting but changes it for 150mm soil pipe. The impact was a 30% increase in air volume using the same extractor.

I use a 3hp motor. This provides for table saw, planer, thicknesser, bandsaw and a floor scoop.

I have a Lidle screamer for the LVHP stuff. BUT I am considering changing this out for individual DC at the other machines. SEE woodgears.ca web site for info.

 

[Make It All]

Thank you all
I have now decided to go for just a shop vac and diy cyclone to start with. One of the titan ones from screwfix. I am then thinking of using 40mm pvc for ducting with individual blast gates at each machine. My question is would the diameter of this pipe be big enough for mainly fine sanding dust and mitre saw dust to pass through without it getting blocked?
Thank you
Jack

 

[MattRoberts]

That type of dust will have no problem going through 40mm pipe at all.

 

[Make It All]

Thank you MattRoberts.

 

[PAC1]

If you are just having a shop vac for fine dust why use ducting. Surely it is better just to roll the shop vac to the machine you are about to use and connect it up. The problem with ducts and bends and gate valves is they all reduce the suction. The other benefit you can gain is having a shop vac with a power take off that automatically starts when you want to start working. OK you have to clean filters more and empty the collection bag but is that worth the work in installing this system and the loss of suction!

 

[Make It All]

Thankyou for the idea but I will be needinbnit on a mitre saw, random orbital sander and a belt and disc sander.

 

[MattRoberts]

Don't assume you're going to get anything other than mediocre extraction on the mitre saw and belt & disc sander with a shop vac I'm afraid.

Both of those machines need to shift a lot more air than a shop vac can in order to provide effective dust extraction.

The random orbital will be no prob though

 

[Make It All]

Ok I did think it seemed a bit too simple and cheap. So if a shop vac would do for all hand sanding then could I use an 850 meter cubed an hour dust extractor with a homemade cyclone for the rest?