In the final part of this series on dust extraction, I want to revisit my own system and have a look at some of the improvements I’ve made over the last few weeks as well as one or two other issues concerned with this menace.
I’ve mentioned in an earlier article that it’s the fine, almost invisible dust that’s the real danger and it’s this that we should, whenever possible, try to contain or at least give ourselves the barest minimum exposure to the stuff. It’s not always practical or easy to do, but as long as we’re aware of the danger, we can, as woodworkers, do something about it. I’ve come to the conclusion over the last few weeks when I’ve been scribbling these articles that the danger of sharp tools and spinning blades is much easier to safeguard against compared to the invasiveness of fine wood dust.
Previously, I examined the idea that ‘prevention’ is relatively easy to achieve but it’s not necessarily the most practical or neighbourly method; in the UK and elsewhere, the vast majority of woodworkers strive for ‘protection’, but this depends on an understanding of how to go about tackling the problem which includes setting up a reasonably efficient regime to sort out wood dust in all its guises.
There are a number of sources of wood dust that need to be identified and most hobby workshops will encounter all of them from time to time. Planer chippings are the biggest and quite easy to cope with, followed by large sawdust produced by a bandsaw or table saw. There’s fine sanding dust or the sort of stuff produced when mdf is machined and lastly, there’s the accumulated dust and wood shavings on the floor and other surfaces.
My system has to manage all of this type of waste; planer chippings, sawdust from the bandsaw, fine sanding dust from the lathe, Jet Disc Sander and 16-32 Drum Sander. The source of the air flow is a HPLV (high pressure, low volume) twin motor, 2hp Camvac, which in the original setup, was connected via a dustbin lid separator to a large 220L water butt or ‘drop box’.
The dustbin lid has now disappeared and in its place is an Oneida Dust Deputy Super cyclone separator, which removes approximately 99% of everything sucked into it, leaving only the very finest dust to pass into the Camvac drum. Part of the old dustbin lid was siliconed to the top of the water butt onto which I bolted the 12mm ply top, secured with eight dome headed nuts.
The top inlet connection is a Hose Reducer which was slightly too small to fit the American made cyclone, so I made a very serviceable joint by butting the two together and wrapping with a couple of turns of duct tape and a few cable ties. For some unaccountable reason, the 100mm section of the reducer was ribbed, which made it extremely difficult to fit over a hose; the ribbing was easy enough to remove in the lathe.
When fitting a cyclone, it’s essential that everything below the inverted cone must be airtight or a huge amount of workshop detritus will get sucked up into the Camvac! The ply top was sealed in place with ‘P’ section rubber draught excluder, there are leather washers under the domed nuts and all the cyclone bolts are sealed with a smear of silicone.
Although they hold a lot of waste, water butts aren’t particularly strong and are prone to collapse at the drop of the proverbial chapeau…which is precisely what happened when I switched on the Camvac with all the blast gates closed. So rapid was the collapse, in less than three seconds the water butt managed to tear itself free of the dustbin lid before I managed to switch off the Camvac.
The solution to this problem was very simple and that’s to fit a PRV or Pressure Relief Valve, which was very simple to make from an 8mm rare earth magnet, a 5mm countersunk bolt (onto which it stuck itself), two nuts, a gash plastic waste fitting and an old tin lid; total time to make was around 20 minutes. This video from the excellent Peter Parfitt explains why they’re needed and how to go about making one. The other great advantage of a PRV is that if I shine a torch down the hole, I can instantly see how much is in the water butt.
There have also been a couple of other big changes to the system, one being that airflow has been improved as the old T-junctions have been replaced with Y’s and much better aluminium blast gates have been installed in place of the old plastic ones.
The other major change is that a floor gulper has been fitted near the lathe, using an oddment of 100mm ducting, a slinky retractable hose and a rubber cuff which means that everything on the floor smaller than my thumb nail now gets gulped up into the drop box.
It’s impossible to collect large chips of wood turning waste as it’s produced, simply because it’s thrown towards the turner…hence the use of the gulper at the end of a turning session. The only waste that can be collected is fine sanding dust and, as my lathe is too close to the wall for a proper stand, I fitted a short piece of Stayput hose which does an excellent job. It also means that I could dispose of my previous ‘Heath Robinson’ stand contraption which was ungainly and took up far too much room.
Many years ago, Axminster used do a basic extractor called a WV100, one of which I’ve retained to extract from my BS11 bandsaw, but the other one (which was my ‘shop vacuum) has been replaced by the ever popular and extremely powerful NVD750, onto which I’ve attached a smaller Dust Commander cyclone. The yellow bucket shown in the image is one that originally contained pond fish food and as such had to be airtight. I also use the ‘shop vac to clean up anywhere that the gulper can’t reach (under benches etc) so that my faithful green dustpan has been consigned to other cleaning duties in the garden. Such is the efficiency of the cyclone that I anticipate disposing of the bag inside the Numatic drum in around twelve months’ time.
The new ‘shop vac is now used with all the power tools and others that create dust but it also plugs in underneath the router table. I made a connection by using an oddment of 100mm duct and a rubber adaptor, again joining with a couple of turns of duct tape. It works very well for extracting from the Dust Extraction Box and also means that I could dispose of an older 100mm extractor with very limited airflow which wasn’t very efficient.
This series of articles on Dust Extraction Basics in the hobby workshop should have gone some way to answering many of the queries, but if you have any further questions, please don’t hesitate to leave them below.