Making DIY Blast Gates For Dust Extraction

In this video I make some DIY blast gates for my new dust extraction system.

Part 2 - Dust Cyclone Separator: https://youtu.be/ao2NztU51Ww
Part 3 - Dust Extraction System: COMING SOON

Bosch Holesaw bit: https://amzn.to/2NoWnn6

In this video I'll be showing how I made blast gates for my new dust extraction system.
I'm going to be putting out three videos about my new system, this first one is about the blast gates, the second one will be about my cyclone dust seperator and the third one is going to cover the extractors that I'm going to be using, how I installed the ducting, how I connected up all my machines, installing a pillar to my workshop from which to run not only dust collection, but also power, and compressed air.
Before I get started, in case you don't know what a blast gate is or what it's used for, it's quite simply a way of being able to control where you want your extractor to extract from. So for example if I want my extractor to suck from my tablesaw, I can turn that blast gate on, and make sure that all the others are turned off so I'll get really good suction and airflow right from at that tool, which makes the extraction much more efficient. 
To make my blast gates I'm going to be using some offcuts of 12mm MDF. I chose MDF mainly because it's what I had, but in the past I've used plywood to make similar gates and they were just as effective, in fact plywood is actually better in some ways, and I'll talk about that in more detail a little bit later in the project. 
I started by cutting some squares of the MDF at the table saw.
And then I ripped some thin strips of the MDF.
These strips got glued and pinned to the square, flush to two opposing edges.  You could just use glue and clamps here but I'm using brad nails just to speed things up so that I can carry on working.
I then added glue and added another of the squares pieces on top, again making sure to keep all the edges nice and flush.
Next, at the mitre saw I trimmed away the excess to get the edges flush.
I can then measure the internal width of the opening.
So I cut some more MDF pieces to about 1 or 2mm less than that measurement to make sure they would fit nicely inside the opening with a tiny amount of play so that they would slide in and out without getting snagged.
Then I trimmed those pieces to length at the mitre saw, and mine ended up being about XXX
So now I have something that works like this, but I want to add some stops to this sliding piece at each end, so I glued and pinned a couple of strips at each end.
I then marked up the centre of the square by drawing a cross by positioning the ruler from corner to corner.
I then made sure that the sliding piece was pushed over all the way to one side, and then I drilled a pilot hole at the centre point using the pillar drill, I'm using a 5mm drill bit here but the size of the bit didn't really matter and I drilled all the way through all three layers of MDF
I bought a 68mm holesaw bit from Amazon, which is the same size as the ducting pipe that I'm going to be using for my dust extraction system. This one is by Bosch and I'll link to in the description box below if you're interested.
Now this holesaw bit works great on solid wood and plywood, but it doesn't do too well with MDF, and that's why I actually regret choosing MDF for this application, and I wish I'd used plywood.  I set my pillar drill to it's lowest speed setting by moving the belt as per the instructions on the lid. 
So the problem I had was that the teeth on the hole saw bit just repeatedly got clogged up with MDF dust, even though I kept lifting the bit while drilling to try and clear the dust.  It definitely helps to have the pillar drill set to it's lowest speed, but it was still a really slow process drilling through the MDF.  I drilled through from both sides to make sure I got a nice clean hole.  Occasionally the MDF dust getting caught in the teeth would also stall the pillar drill motor, which was really annoying.  But anyway eventually I managed to get the holes in all of my blast gates drilled all the way through.
I decided to paint the inside of my blast gates green to represent their "on" position, so here I'm masking off the areas where I don't want to get any paint and then I can spray the inside.  I was careful here to only add a very thin layer of paint because I didn't want the thickness of the paint to interfere with how the gates open and close
I also wrote "on" and "off" markings with a marker pen just so I can easily see at a glance which gates are on or off.
I cleaned up the edges of the gates with a block plane followed by a bit of sanding.
To add the PVC pipe to the blast gates, I make sure that they're switched to the off position, and then I add the length of pipe that I needed, butting the end up to the internal sliding part of the gates.
And I added a bead of hot glue around the perimeter.  When I made similar blast gates in the past I actually used silicone for this, and over time a few of them failed, but using hot glue works great, and gives much more hold, which makes them really solid.  I added pipe to both sides of the blast gates and now they're ready to install to my dust extraction system which i'll be showing in more detail in another video.  As soon as that video is available you'll find a link to it in the description box.
So you might be wondering why I decided to make my blast gates rather than buy them.  Basically, all the ones I've seen that are available to buy are very loose fitting, they don't seal well which means that air can leak out, which means that the air flow is going to be less efficient and that compromises suction.  The blast gates I made seal really well, so there are no air leaks whatsoever.  Also for the diameter of pipe that I'm using, these blast gates are obviously a perfect fit because they are connected directly to the same size pipe that I'm using for all my duct work.  You can buy blast gates that are 63mm which might be a good fit for the internal diameter of the pipes that I'm using, but I'm not sure, as I don't have one of those to try it out.
The diameter of pipe I used in my system is 68mm which is PVC downpipe designed for guttering applications and I'll go in to more detail about that in my video about the ducting which will be linked in the description box when it's available. 
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In this video I'll be showing how I made the dust cyclone for my new dust extraction system.  This is the second of three videos about the new system, and you can find links to the other videos in the description box below.
If you're not familiar with what a cyclone separator is, or what it does, here's a quick explanation. It's basically designed to collect the majority of the dust that gets sucked up by the extractor before it reaches the extractor itself. This offers two benefits, it keeps the filters in your extractor cleaner for much much longer, which means less cleaning and maintenance to the filters, and if you've ever cleaned a filter that's clogged full of nasty fine dust particles you'll know that it's not a very pleasant job, and secondly because the filters are clean, the extractor is able to perform better, suction is more powerful and more efficient, and also it's much better for the motor in the extractor so it's likely to keep working well for longer.
First I'll talk about where I got the components to make the cyclone.  First of all, I bought this secondhand on eBay for £60 from another woodworker locally to me who obviously made it himself.  I bought it for the top part alone, the cyclone itself which is the Dust Commander HD, it's really nice, solid metal, nice and robust, and it retails at over £100 so paying £60 was worth it just for the cyclone.  The dust collection bucket that it came with was a 30l one, and it was too small for my needs, so I bought a new dust collection bucket, one of these 60l airtight barrels from Amazon, cost was about £25.  And that's what I was planning to use, however when browsing facebook marketplace one day, I came across someone selling these airtight metal barrels for £10 each.  I thought this would be an even better option because a) it's made of metal so there's no risk of the it being able to compress or distort with suction from the extractor, which can be a big problem with the plastic barrels .  That problem is not insummountable though, and my friend Matt on the Badger Workshop has a very good video about how to re-enforce those plastic barrels and I'll link to his video about that in the description box below.  I was originally going to follow his instructions to do that, until I found this metal barrel which doesn't need any re-enforcement so that's going to save me some time. b) these barrels have much more capacity at about 200l, which means I won't have to empty it out very often at all which is always a bonus.  and c) it was green! So it'll blend in well with my surroundings!  The only downide of using this metal barrel is that it weighs quite a lot on it's own, and once it's got dust in it it's going to be even more heavy.  So I'm going to get around that by only letting it get perhaps around half full before I empty it out.  And I can also use my sack barrow to move it outside the workshop when I went to empty it.   If you want to find one of these barrels, I'd suggest looking on any classified ads website like facebook marketplace, gumtree, craigslist, whatever you have wherever you are and just type in metal barrel or metal drum, sometimes they're even sold as incinerators.  But make sure that whatever drum you buy it has a removable lid with one of these springloaded mounting brackets, and a rubber seal on the inside, because it's really important that the drum is air tight - as that's what makes the cyclones work so efficiently, you do not want it to leak air.
My drum was a bit rusty on the inside but that doesn't matter.
First I removed the cyclone from the lid of the small dust collection bucket that it was originally attached to, and I found that it had a rubber gasket with it which I presume would have come with the dust commander when it was originally bought.
I measured up a centre point on to the lid of my metal barrel, it didn't need to be particularly accurate but I wanted it to at least look centred.
Usually cyclones come with a drilling template, but because mine was second hand, I used this piece of MDF that was mounted to the underside of the lid as a template - the person who made it would have added that to re-enforce the plastic lid on the old smaller bucket.
I had the idea to use a bit of spray paint to mark the holes, as I couldn't find a pen to fit through the holes, and that kind of worked, but some of the paint kind of leaked through so it wasn't very accurate to be honest.
I then drilled a series of small pilot holes around the perimeter of the circle.  The correct tool to use for this would have been some kind of metal cutting holesaw, but I don't have any of those, so it's one of those situations where you do the best with what you've got to hand.
Once those holes were drilled, I could out the drill bit in to each hole and wriggle it from side to side to try and join the gaps.  I also tried using a hacksaw blade to cut away some of the remaining material, which again probably isn't the ideal tool to use for this, but again, whatever works.
And eventually I could kind of peel away the waste with a pair of pliers.  Then it was just a case of using a round file to smooth over the edges to refine the shape of the opening until the cyclone fitted in their snugly.
After the failure of my spray paint idea, I decided to just use a marker pen to mark up the holes to mount the cyclone to the lid more accurately.
And then I punched a centre hole using an awl, which creates a small divot which will help me locate my drill bit without it skidding around.
And I drilled out the holes with a 4mm bit.
I could then add the rubber gasket, and the bolts.  I turned the lid upside down ready to add the washers and nuts, and I'm just re-using the ones that came with it.
I got them all finger tight, and then nipped them all tight with a spanner.
Finally, I sanded away the worst of the loose rust on the underside of the lid around where the cyclone was fitted, and I added a bead of silicone around the opening.  This probably wasn't necessary because I'm sure the gasket will seal things off perfectly well enough, but I'm going for a belt and braces approach here.
And that was the cyclone all done!
I've been using it now for a couple of weeks, so now it's time to see how effective it's been, ideally I want to find lots of dust in the cyclone separator, and not a lot of dust in the extractor itself... Let's find out!