Chip extractor duct - questions

[Helvetica]

Looking for some expertise here. I have read Siggy_7's excellent post, and many others and have a rough plan for my DX:

Source machine is a Sedgwick CP 16" planer thicknesser. Extractor is Rutlands claimed 1150m3/hr (677 cfm) with 100mm port. I plan to build a tiny outhouse from corrugated sheets so the dust can vent outside. I will not use blast gates, but connect directly to the PT, same for any future machines. I'll try to keep any bends to 45° - I might get away with no bends but semi-rigid hose from the wall to the PT. So here are my Q's:

* I have a run of 10 metres between PT and the wall I want to vent through, plus 3 metres from wall to the PT - can this machine keep suction over this length without stalling?
* who makes good quality semi-rigid 100mm hose?
* if I need to, can the DX handle sucking dust vertically to 4 metres height, then the 10m wall, then back down?
* if the extractor comes with a 100mm port, is it feasible to fit 150mm pipe to get the benefit of larger volume?
* if I must fit blast gates, should they be on a vertical stretch of pipe? are the aluminium ones worthwhile- particularly the Lee valley ones that claim to never clog?
* should I forget extracting outside over that distance and buy a cyclone instead?
* where can I find a 100mm port cyclone?
* would a Thein Baffle be more suited to 100mm hose extraction?

Thanks for any input. Probably this extractor is underpowered but budget etc. Currently using an Axminster RDC100H 180m3/hr HPLV type which is not brilliant, I'll keep that for the bandsaw.

 

[PAC1]

Extracting to the outside is an excellent aim if you can do it. Your 16inch thicknesser will need at least 1000cfm at the point of extraction from the machine. You then have to consider the length of duct and bends you will loose 25% even on an efficient designed system.
Ideally you want 200mm duct with slow bends. You then need an extractor that suits both the machine and ducting
If the port on your extractor is 100mm there is no point having 150 or 200mm duct as the restriction is the port. The air will not squish through the 100mm port and then work as if it were an unrestricted duct.
You will be much better with rigid steel duct as it is smooth whereas semi rigid pipe has ribs which cause turbulence. Further reducing the suck.
I do not know the Rutlands machine but I have a 1100 watt extractor with 6m of 150mm duct which copes with a 16 inch thicknesser. I cannot see how half the motor with half the duct size and twice the distance will have the same suck at the machine. Also the bag on the extractor is tiny. You will be forever walking to your extractor shed to swap the bag or if you leave it too late clear the blockage.

 

[Mike Jordan]

It's a master stroke to put the extractor in a separate building and keep dust levels in the workspace down. Keeping the internal roughness of the ducting to a minimum is very important, the effects of turbulence are very marked.
I feel that blast gates are essential for an efficient system as is using larger diameter pipe for the main range pipe, make sure that vertical pipes joining the main pipe enter through the side so that chippings can't fall down other risers and block the system. Don't waste money on plastic pipes which have no fire resistance and only give a minimum saving over the proper kit. Do the job to a proper standard and you will not have to do it again if you get more machines or a larger extractor.
Finally don't forget to provide adequate escape venting in your tin shed and allow replacement air to enter the workspace easily through good sized vents. An efficient system will cool the workshop down in the winter but you must have air flow to make it work.

 

[RobinBHM]

What is the port size on your Sedgwick?

Really you want your ducting to be that diameter as a minimum.

If you start at 100mm at the extractor and increase the dia that will result in a reduction in air velocity which as a result you may find the velocity ends up below the minimum required to carry chippings.

If you are on a tight budget you could look for a second hand 1 bag extractor, like a startrite and buy a new filter for it. Itll be 3 times the power. The best machines to buy 2nd hand are those with metal impellers. Hear before you buy to make sure the impeller hasnt been hit by a lump of wood and knocked out of balance.

I think you would be disappointed by the model youve suggested.

The distance isnt a problem with a half decent extractor. I would suggest you will need 150mm pipe for the long run. Toolstation do quite cheap soil pipe which may be ok. I dont know risks of static though. Clip metal ducting is the ideal but very expensive for a home shop.

Bear in mind that ducting layout needs to be balanced so the basic principle is that velocity drops due to drag over a distance so duct runs are designed so they reduce near the machine which has the effect of increasing the velocity. Mirka for example make a flexible plastic vacuum pipe for their sanders which is slightly tapered over its length.

 

[MattRoberts]

I think you'll really struggle with that extractor and the length of ducting.

A bit of a long read, but some great info here : http://billpentz.com/woodworking/cyclon ... uctingSize

 

[Helvetica]

Would a cyclone work better with it than that length of duct? I've been gifted the rutlands so I'm stuck with it for the moment! Just have to get the best out of it.

Im actually reading Pentz' static pressure calc sheet at the moment, you can know too much about air flow! I didn't do as much research when I was servicing the carburettors of my BMW R80
http://www.billpentz.com/Woodworking/Cy ... iccalc.xls

 

[PAC1]

A cyclone does not make more suck, in fact there is a loss of efficiency. A cyclone will separate the chipings from the air. So a cyclone and a large container will reduce the number of times you have to empty the bag but that is all. If it is what you have then use it and see how it works next to the machine with a short length of flexi hose. Can you get a better filter for it?

 

[Helvetica]

A cyclone does not make more suck, in fact there is a loss of efficiency. A cyclone will separate the chipings from the air. So a cyclone and a large container will reduce the number of times you have to empty the bag but that is all. If it is what you have then use it and see how it works next to the machine with a short length of flexi hose. Can you get a better filter for it?

I believe a filter will also constrict airflow no? If I add a cyclone I could vent directly outside behind the machine as I won't make a mess of the front of barn, and bypass the filter.

I guess I could just open the barn door and place the extractor outside while I'm using it.

 

[PAC1]

If you do not have to worry about pollution and neighbours then a cyclone and duct to the outside with no filter will work well.

 

[siggy_7]

That Rutlands extractor looks rather small for a P/T and duct run of that size. From the image I would say that has a 300mm blower at most so will not generate that much suction pressure. I would suggest you consider a simple drop box (bin lid with two holes) rather than a cyclone or Thien baffle, both these types of separator only work efficiently at the expense of a biggish pressure drop which you will want to avoid at all costs given the extractor size. The main problem with planing is the sheer quantity of waste produced which the separator will help with, the smaller dusts make a tiny fraction of planer waste but take all the suction effort to capture effectively. As the extractor isn't in the workshop I'd not lose much sleep over it!

Sent from my SM-N910F using Tapatalk

 

[sunnybob]

any flexible hose has a huge friction inside as the air spins around the ridges. Run in rigid 4" plastic pipe if at all possible, use 45 degree angle fittings, the pipe doesnt need to be horizontal unless you are really concerned about looks.

With that air flow, it would be wise to ground the pipework to stop static bulld up causing sparks.

 

[deema]

I also have a CP, brilliant machine.
The Sedgwick CP needs a larger diameter duct than 100mm for the collector. I think it's either 125 of 150. The machine can really take off a lot of material, and needs a big duct otherwise it will get jammed up very quickly. If your going to connect up other machines you must have blast gates or you will lose a lot of the suction.

I've located the take up and blast gate directly above the centre of the machine, just so I can reach it. This enables the flexible to be very short and also I've found makes it much easier to move the chip collector from planning to thicknessing. I had it originally running down the back of the machine to table height, however the flexible duct always got cought on the fence arm / rear blade guard.