Design of workshop dust extraction ducting

Frank Creates - Shop Tour Part 2: Dust Collection

Other youtubers Matt Eastlea and Marius Hornberger

Wow! I now have workshop envy.

I have one run of soil pipe about 4m long over head, with 4" flexible pipe up from the chip collector, and same again down to planer or thicknesser. The chip collector is only about 1hp, and only just about copes. But it will collect the larger chips from the big machines, and I am not aware of any accumulated dust in the pipe runs, although more power and a proper cyclone would be better. (I can't run adequate filtration to use that setup for fine dust).

For fine dust, I use a shop vac with its normal hose transitioning to a length of 34mm hose that hangs over a ceiling joist and drops down to the tool (usually a sander) in use at the time. In the past I have used an intermediate home made cyclone, but don't really have the space to include that at the mo.

Thanks, that soaked-up a couple of hours. There are some talented people out there.

Thanks! That's one helluva cyclone - home made or bought?

My chip collector is also only 1 HP and I suspect that, once the system is running, I'll want to upgrade it to something with a bit more oomph. I have an accessible roof space above the workshop so I'm starting to wonder whether it would be possible to put a cyclone and extractor up there, with the cyclone outlet dropping into a bag suspended from the ceiling and with the exhaust going through a roof vent to the outside world. I suspect the answer is to experiment with ducting (110mm, based on your and other responses and searches) and then later, omce the system is working, explore using the roof space.

It is home made and based on a galvanised flower pot that Ikea used to sell - no longer available.

I think this links still works and should show my set up.

I have a feeling its the long (ish) lengths of flexi hose I need to get up to and back from the fixed duct that does much of the damage in terms of loss of flow rate.

Commercial systems tend to vent outside, while smaller ones often return the air to the workshop with large pleated filters of some kind. The former is easier and probably gives cleaner shop air, but at the expense of throwing a significant quantity of heated air outside in the winter.

I quite like the idea of moving the collector out of the main work area, just as a way to keep the added noise down.

Thanks for trying, the link doesn't fail but nor does it show a picture.

As my thoughts develop I'm now very tempted to (eventually) put a blower and cyclone in the roof space, and drop a pipe down through the ceiling from the cyclone to a large bin on the workshop floor. 110mm ducting around the ceiling, y connectors to rigid initial drops and then waste gates and tapered reduction to 68/63mm, then minimal hose to the machine. Machines will be modified to improve collection. The question is going to be where to get a meaty blower (that can withstand wood chips) for a sensible amount of money.

Initially I'll get things going with the 1HP Kity and the shop vac and work from there. First I need to finish the re-wire, finish fitting some skirting, and keep the garden under control :-)

Here is another mid sized cyclone setup:

How about a DIY solution:

Eh... I used a portable commercial fan-cyclone-filter-plastic bag with the same sort of hose that the video shows. Hose pulled off the table saw, and sucking up the loose dust inside the table saw. There was a spark about 1" long from the spiral hose wire to the saw every few (say 5) seconds... This was reproducible, frequent, and a nice bright spark. Nevermind the dust, they also used NC lacquer in that shop (occasionally even as a fire starter, so they were not very risk-averse. Using NC thinner to re-light a hot waste oil burner was one trick they didn't repeat:-)

The hose wire was not electrically connected, and built up a static charge. I stripped all the plastic layers off about one or two inches of wire at the fan end, bent it back inside the hose, and reconnected to the fan with the jubilee. This connected the wire to the metal fan casing (grounded, assuming a grounded outlet -- not a given in that setup...) and sorted the problem.

Would I run an earth wire? maybe...maybe not. Would I strip a bit of wire end and bend it so it touches the metal bits? yes, now I would, seeing that it's just a quick strip-and-bend.

Thomas Prufer

I would be happy to try DIY'ing if I knew how to design a blower, but I'm the wrong sort of engineer and have zero knowledge of fluid dynamics. I may be wrong, but the people on youtube (like the guy you linked to) and elsewhere just seem to stick some bits onto a disc and hope it works, rather doing sums or copying a proven design. I'd been thinking that the impellor would need to withstand chips but, as Bob Minchin said, these will have dropped-out in the cyclone. I guess this means that any blower would do the job, providing it moves enough air and that the impellor doesn't stall when sucking. I either need to do some swagging on the airflow requirements and then start shopping, or just pick-up a second hand 2HP jobbie to "suck it and see".

It's so easy to add a wire that it seems like a no brainer. I've got a roll of copper braid left over from an ancient project so I'll just run that through the pipe (and branches) and earth it at the sucking end.

Well there are several approaches to this, including fluid dynamics and sums. However you will likely get "good enough" with an empirical approach. The main requirements seems to be getting a mechanical load that matches the output of the motor well enough to allow it to reach speed, but not so little that you don't extract the work required from it.

Probably worth noting that Matthias Wandel is a proper engineer as well as a you tuber / inventor of crazy stuff, some quite interesting stuff on his site:

Your traditional bag style collector is a "dirty fan" solution. However as you say adding the cyclone pre-filter, that will eliminate the bulk of the large stuff before it gets there.

Yup, an off the shelf collector could be cannibalised for a blower.