An eye on the dust

How’s your dust bag?

Mine? I know it is getting full. But there is full, and then there is full.  I’m sure I can fit the sawdust from just one more saw cut in there.  And again, and again.

I have the extractor in the attached shed: saves on noise, saves on the otherwise lost floor area, and any dust leaks (if any) don’t matter.  But it does mean out of sight, out of mind.

I finally got around to changing the collection bag.  What a mission! It was rather fuller than I thought, and it was cumbersome, heavy, and a right pain.  Yes, I know I should have changed it earlier.  Yes, I know I could have checked more often.  Coulda, shoulda, woulda.

A great pile

So.  I need to keep a closer eye on the dust collection.

One thing that’d help is to do a pre-separation.  By placing the pre-separation drum in the main shed, I can keep a better eye on it.  There isn’t the issue with dust escaping from the collector as this is not the end of the line, and the inside of the drum is maintained in a negative pressure.

Rerouting the corner

I had a bit of a win doing the rerouting necessary to fit this drum in.  Got rid of a MDF cabinet, fitted the drum in, and then while trying to think of what to do with the two sanders, I happened to notice the Walko sitting there which I had used at Ballarat and hadn’t gotten onto putting back into the other shed.  Perfect fit!  Sure, a bit cramped (where in my shed isn’t!), but a solution where I wasn’t sure if I’d find one.

Walko is in the house

Getting back to the dust collection, and added an extra feature: an electronic eye to keep a watch on the dust collection, and let me know when things get too full.  This one is pretty cool!  It is the Trupro Dust Sentry from Woodworking Warehouse.  It may seem like some others, but for one very unique, clever feature.  But more on that shortly.

The sensor

The sensor fits very easily – drill a hole.  There are nuts on the threaded sensor that fit either side of the mounting position, holding the sensor in place.  The sensor has a maximum range of 40cm, and that meant it found the other side of my drum.  However on the side there is a small pot, and that can be wound down giving a decreased range.

Mounting position

You could use that sensitivity range so the sensor pointed straight down to where the dust was gathering, building a pile towards the sensor, or you can side mount it (as I have here) so it ‘sees’ the pile when it reaches that height.  I may change this location when I change the lid, but this was a good trial point.  (Lid change discussion at end!)  When the lid is changed, I’m likely to mount the sensor looking down – means I won’t have to remove the sensor each time I wheel the bin out for emptying.

Sensor range

You can test the sensor by waving a hand in front of it.  When it ‘sees’ you, a light comes on at the back (and a signal is sent to the control box).

Control box

The control box has the circuitry inside, and plugs into the wall for power.  It has the audible alarm, and an adjustment dial – all to do with a very special feature of this specific dust sentry….but I’m still not quite ready to tell you what that is!


Mounting the control box is very easy – couple of screws in through the back into a beam.

Dust speed

Ok, ok, the special feature.  This dust sentry is unique (as far as I can tell), as it doesn’t get fooled when a large quantity of heavy dust flies past it.  This sensor can be tuned to ignore passing particles that otherwise give a false reading, and triggers only from the stationary dust – the true level of dust in the bin.  This sensitivity can be tuned to your particular requirement.


So here is the unit all set, ready to sense. Ready to keep an eye on the dust!

Lid change: well, once I got all this set up, it was all working well…..except the pile of dust in the bin didn’t seem to be increasing.  At all.

I did experience this when first playing with this lid a few years ago, and was mucking around with all sorts of combinations of plumbing fittings to create a swirling, pre separation thing.  Really can’t be bothered trying to fix a bad design this time, so am looking at replacing the lid with this one (also from Woodworking Warehouse).  Chalk and cheese on the design!

Jet 2 stage

Deconstructing the Dust Kit

When I saw the kit for the new Carbatec dust collection system (and the clear tube setup), it wasn’t going to be long before I was fitting it to the shed.  And the timing is rather appropriate – the system needed a revamp with the various item moves that have been happening.  A dust system needs to be flexible, both to deal with vibration and minor machine moves as well as being able to be reconfigured with minimal fuss when a new arrangement is required.

I use flexible hose in some cases to maximise the flexibility of the system, but it does result in quite a bit of suction loss so where I can I use straight tubes, with flexible pieces near couplings.

In the new Carbatec kit are a who swag of connections

What's in the box?

T sections, 90 degree corners, 45s, blast gates, adapter rings, mounts and 8m of clear tube

Curves, Corners, Clamps and Clear Stuff

It would do a small setup, but mine isn’t small!  I’m going to use the clear trunking where it is sensible to determine that flow is occurring (and showing where there are blockages), so for the long, straight runs it makes sense.

Extra accessories acquired

The reconfiguration will also include the blast gate mounts I got from Rockler early this year, and reusing some of the PVC downpipe I have been using in the shed until now.  The dust collector is again in the lower shed, and so I am back to the old problem: how to remotely start and stop it, given that it has a no-volt release on the switch, and the branded remote control is over $300.  I don’t want to have to go into the second shed just to start the collector, and I don’t want to have to do something like have a broom handle passing from one shed to the other to try to hit the start (like a ‘remote control’ from one of those US sitcoms, or cartoon shows)!

Starting the refit

I’ve started at the tablesaw, and I am trying to do each part of the setup just that little better.  The previous setup design was good, but having the tube running along the ground meant it has always been a bit in the way.  Lifting it up to just below the table means it is out of the way for storage under the tablesaw wing (and is the level I want for the tubing for the rest of the run).

Rockler Blast Gate Mount

I’ve screwed one of the blast gate mounts directly to the back of the tablesaw.  This specific gate at the back of the saw will normally remain shut – it allows access to the length of tube at the back of the saw in even of blockages, and also to plug in flexible hose for cleaning up that end of the shed (and I suspect I will still use a temporary run to the jointer, rather than try to run a full length of tube across the entire shed just to get its waste!

More to come as I progress the system.

Vacuum Storage

The other question I had recently was about the CT36 – the Cleantex Vacuum from Festool (Ideal Tools)

Storage of the components (particularly for transportation) for the CT36 is very easy – there is a holder at the back of the machine to wrap the power cord around.

The hose coils up into the cavity in the top of the machine, and you can also store the floor nozzles and tubes in there as well.

Hose Storage

Alternately, you can use a Systainer1 which is a perfect size, and of course attaches directly to the top of the Cleantex

Systainer for Nozzle Storage

Finally, as far as the size of the cavity – 36L sounds like a lot of dust, but what the dust collection area looks like:

Dust Compartment

No – I didn’t suck up a blade – I put it in there to give a sense of scale!  That is a 10″ blade (250mm), so just a little more capacity than the standard house vacuum!

I’ve given up on house vacs (even though I was buying them cheaply) for the shed.  My record so far

Vacuum 1: barrel model: melted, to the point that the motor physically fell off the back of the vacuum when it had melted its way free.

Vacuum 2: modern barrel: caught fire.

Vacuum 3: shop vacuum (upright barrel): became better at producing ozone than suction, then became useless at both.

Vacuum 4: ShopVac: current, and still going strong (still pretty new), using a cyclone as a preseparator

Vacuum 5: Festool CT36: what can I say!

Sometimes it pays to buy quality.


I’ve been giving some consideration to the pre-separator I was using in the 4″ system before the TruPro Dust Collector.  The original was too large for a small workshop, so I decided to cut it down.  Thought it would be easy enough to remove the base, cut off some height and reattach the base.  Doing it that way would retain the metal top edge and handles that aided sealing, and lifting the full bin.  I was wrong 😦  Spent ages trying to get the base on, and in the end had to give in.  I then came up with a different idea – putting a dust collection bag around the outside of the drum.


Not too bad, other than one problem – creating a partial vacuum inside the drum sucks the bag up and into the nozzle, no matter what I’ve tried so far – heavy weights are no match for the power of a vacuum.  I haven’t come up with a solution yet, but primarily because it hasn’t been on the top of the to-do list.  The principle is not bad, but a different drum may be in order.

Other than that, I’m quite happy with the location and size of the pre-separator.

Developing the Dust System

I’m not sure if a dust system ever gets finalised.  At least it never seems to in my shop – I seem to be constantly changing my ideas, tool positions, and dust system layout concepts.  Oh well – it’s like a real-life jigsaw puzzle that can be assembled many different ways, and how well it works tells you which picture you’ve created.

As I’ve mentioned recently, I have capitulated and have moved the dust collector back into the main shed.  There are a number of reasons for doing so, and a number of reasons why I didn’t want to have to.

Reasons why I wanted the DC located in a different shed (or at least outside the primary workshop)

* Noise. DCs are noisy (not brushed motor noisy), but still, sounds of lots of air moving would be better elsewhere if possible.

* Dust. If air is passing through a filter, then there is a probability that dust will also be carried through, even if the filter is a 1 micron filter.  If the unit is in another location, some minor dust leaks are inconsequential.

* Space. The footprint of a dust collector is going to consume about 1 metre square of valuable shed floor space.

Benefits of having the DC in the main shed

* Starting and stopping. There isn’t the issue of requiring expensive remote starting systems.

* Blockages. Easier access to clear blockages, empty dust bags, clean filters.

* Airflow. Simply the less distance the air needs to move, the better the system works.

Relocated Dusty

Relocated Dusty

I’ve relocated the dusty into the same corner where the original 4″ tube to the other shed went, but now instead of joining the two halves of the system into one pipe, I’ve coupled each arm up to its own intake. In addition, I’ve also run the 15″ thicknesser directly in to maximise its collection.  More on that in a sec.

My primary influence on relocating the DC was performance.  After my recent air velocity tests, I decided that I was compromising the performance too much to have the luxury of it being in the other shed.  There are some other minor benefits as well, but they were not enough to sway the decision either way.

I haven’t decided if I will do anything to counteract the additional noise, other than running it when I need it rather than constantly.  I might investigate building a fake wall around it with noise dampening, but that is a project that will probably never actually eventuate.

To counteract any issue with fine dust leakage (and dust during bag changing), I have located it right near the overhead air filtration unit (which is also a 1 micron filter), so between the two, any dust I collect shouldn’t end up back in my environment.

Underneath the DC, I have used both 4″ inlets, as much to allow a smoother entry of air as anything.

DC Inlet

DC Inlet

I’m not happy with the result however.  The tubes you can see are – from the right hand side is a solid connection from one of the 2 main shed trunk lines.  It doesn’t have any flex section at all, and this is what I want to modify.  As much as flex sections have a greater internal roughness, a short section is going to have a tiny effect on the overall flow.  It would however, make removing the nozzle to clear out blockages much easier so that is the first change.

Into this same trunk line through a Y section is the output from the thicknesser.  However, after testing it out, it failed. Inside the DC nozzle are some grates/blocks to catch heavy particles before they hit the fan.  The amount of chips produced by the thicknesser formed a mass that caught there, and immediately blocked the pipe.  Without any airflow, the thicknesser then rapidly clogged its discharge nozzle.

I have 2 ways forward.  Removing the grates (which I am still dubious about their value), but I’m not sure if that will then result in the blades becoming blocked up, and accessing them is even harder.  The other solution is a pre-separator to catch the majority of the output from the highest producing machines.  I’ll start with this, and see if it is enough.  Damn- it looked to be an elegant solution.  But this is Bauhaus – form must follow function.

In the background is a flex end to the second trunk line, and that works well.

To improve functionality, I have replaced the flex hose to the tablesaw with another length of PVC pipe.

Tablesaw Extraction

Tablesaw Extraction

I’ve used a Y section which I’ve capped to allow cleaning of the system, and also as a way to add a bit of flexible hose when cleaning up around the place.

Jointer/Planer Extraction

Jointer/Planer Extraction

I’ve kept the extra flex from the jointer so I have the ability to move and angle it depending on the length of stock I’m trying to plane.  Each item has a blast gate (my modified version).

Flow Rate Dropoff

I’m starting to work on a collection of different air flowrates in the DC system, to see the effects of different fittings, fixtures, and layout on the resulting flowrates.  With this set of data, you can start planning a dust collection run which takes into account the power of the dust collector itself, and just how much you can add to it / distances you can run it and still get an adequate collection rate.

Some initial figures that came out already have me rethinking the location of the dusty itself.  I have it in a separate shed, partly space, partly so any dust escaping doesn’t end up in my breathing air (although with a 1 micron filter on it, that is not really a concern), and the main reason is the noise!  The bigger the unit, the noisier it is.  Air flowing through pipes is noisy enough, let alone hearing the suction unit.  However, the dropoff in performance is remarkable over the distance of run that I have, so I’m wondering now whether I should just bite the bullet, accept the additional noise and have it relocated back to the main shop.  Having it there has the advantage that I can easily turn it on and off as I need it, and clearing blockages does not require a expedition to the other shed.

Hmm, decisions decisions.

The figures that I got on the first couple of DC runs were:

Running the dust collector through the 1st stage collector, and measuring near the tablesaw collection point: 16.1 m/s

Running the dust collector through all the same pipes, but with the 1st stage bypassed: 19.3 m/s

So there is a bit of a loss (expected) of about 15% caused by the 1st stage collector.  That is probably not too bad, so long as you have that extra capacity spare of course.

However, when I measured the flow directly at the DC, I got a reading of 34.3 m/s – double the flowrate that I am currently achieving at the tablesaw.  That is significant, and although I don’t expect to achieve a perfect flowrate, I’m not sure if I should accept such a dropoff.  So my trial is going to be to return the DC to the main shed, and connect it into my fixed collection system with straight PVC piping, rather than having about 2m of the flexible tube at the end that I have at the moment.  Future tests will show just how much of a difference that makes, but I’m just interested in seeing if it makes a significant increase in the TS collection flowrate.

Hmm, much more testing required!

Episode 35 2nd Stage Dust Collector

%d bloggers like this: