Steve's workshop - Painting the outside walls

[Graham Orm]

It's a big area Steve, you could get a nice sized workshop on there. :mrgreen:

 

[Steve Maskery]

Debris in the workshop is the bane of my life. I have several shopvacs, from cheap and nasty to top-of-the-range Festool, but all of them require emptying with monotonous regularity. Sometimes I can use a bag more than once, but emptying it is unpleasant and the bags themselves are pricey. And it's not just the bags. The shopvac has a filter which needs to be cleaned. When it gets clogged up, the machine cannot suck as well as it did before, and efficiency drops.

I've long wanted a dust separator, which sits between the machine making the mess and my shopvac which cleans it up.

The separator works because debris remains airborne only when the air is moving quickly When the air is slow or still, all the debris falls under gravity. It's just the same as leaves on a windy autumn day. They blow about until the wind drops, then so do they.

Air in the hose is travelling fast, but as it enters the oil drum, it slows down dramatically because it is the same volume of air moving though a much bigger space. As the air slows, the dust falls into the drum and once is is down there it cannot be sucked back up as it is too far away and there is a baffle in the way, too. So the only air going into the shopvac itself is clean air. So the bag doesn't fill and the filter stays clean, keeping the efficiency of the system high.

And finally, the oil drum is bigger than the shopvac bag, so doesn't need to be emptied as often.

I've seen several designs on YouTube and they seem straightforward to build. One day, a few months ago, I was driving round an industrial estate looking for a warehouse when I spotted a sign - “Oil Drums”. The guy who ran it wouldn't let me in, because of “hazardous substances”, which was fine by me, actually, but he was very helpful and 10 minutes later I was in possession of a rather tatty but undamaged oil drum with a well-fitting lid. It had contained mercury thermometers, but he assured me that it had been industrially cleaned, and indeed, apart from the rust, it did look OK.

Since then I've been collecting a few hoses from dead vacuum cleaners so now it is time to get cracking on the separator.

I started with the baffle. This is a piece of 6mm plywood. Its shape is made from two concentric circles. Part of the outside shape is the inside radius of the drum, in this case about 175mm, and the larger section is a smaller radius, in this case about 140mm. Although I do have a very nice router circle-cutting jig, it was made for my Elu and I need to re-make it for my Festool, but for now I rigged up a makeshift jig. It is simply a length of plywood 25mm hole and a panel pin for the centre. My router can be fitted with a 25mm bush so the router just drops in. Having routed about half way though, I changed the radius and cut the rest.

Then over to the bandsaw to rough-cut to the groove and finish on the router table with a flush-trim bit to get my finished baffle.

Actually, I have since modified it from the photographs to bring the leading edge of the full rim back to meet the shoe, because I didn't get the position of the baffle quite right with respect to the inlet.

 

[Steve Maskery]

Next it's some metalwork. There needs to be two holes in the lid, one for the debris-laden air to enter, and another for the clean air to be sucked out. One of the bits and pieces that I had collected was a spigot off a Henry and one end of it is just the right size for all my shopvacs to fit. It is moulded to fit the curve of a Henry machine, but if I turn it over the flange is flat, which is what I need. So I measured it at 57mm. Hmm, that's not very convenient, is it? And this hole needs to be cut in the steel lid of the oil drum.

I rang a couple of mates to see if they have an adjustable tank cutter, but no joy. So I marked out on the drum and resigned myself to drilling lots and lots of small holes and finishing it off with a file. Actually it was neither as difficult nor time-consuming as I feared and I ended up with a nice neat hole. A nice neat hole of exactly the wrong size... I'd failed to notice that there was a second flange underneath the main one. But is was done now, and it was actually a very good, neat job, so I've left it. It is sitting on a flange, just not the main wide one I'd intended. I've filled the resulting groove around it with roof sealant, so it is completely airtight.

The second hole is for the dirty air to enter, and for this I need to fit a piece of bent tube. My friend Doug recommended 50mm drainpipe fittings, which are easily found at Screwfix. So I bought a drainpipe shoe and a collar.

The collar is 46mm at one end, and the closest drill I have is a 45mm Forstner bit. Close enough and with a bit of sanding, it fits perfectly.

The hoses themselves are all different, but each is fitted with a nozzle, some are hard and rigid, some, like the Festool, are soft and pliable. I really like the Festool one, and it needs to be pliable for the oval dust port on my router. So I was trying to find a way of connecting that hose to the separator so that I could still use it, whilst using one of my salvaged hoses between the shopvac and the separator. To cut a long story short, I cut the collar in half so that the small end went into the big end, gaffer-taped a few other bits of piping together, and ended up with hoses which can be swapped around between my router table, SCMS and hand-held power tools all going through the separator before the shopvac itself.

 

[Steve Maskery]

Finally, I screwed four corner blocks to a square of OSB and fitted a set of castors underneath, so that the separator can be wheeled around the workshop easily.

So the big question is, “Does it work?”. I emptied the bag of my Lidl shopvac onto the floor and piled on as much other debris I could. I weighed brand new bag (72g) and installed it in the machine, then vacuumed up the pile of dirt.

When I had finished, that same bag weighed 148g, so 76g of dust had got through. The contents of the drum weighed 2834g, so the total comes to almost exactly 3kg of workshop dust, of which about 2.5% got through. That means that the bags will last 40x as long as they would otherwise and I won't have to empty them as often either.

The unkind would say it is all cobbled together. I prefer the term ”evolving engineering”.

 

[NickWelford]

Would a cyclone have been more efficient?

 

[Steve Maskery]

Quite possibly. But considerably more difficult to make.

 

[sploo]

Quite possibly. But considerably more difficult to make.

Indeed. What you have there is a form of Thien separator (http://www.jpthien.com/cy.htm).

Cyclones (of the form designed by Bill Pentz) are amazing, but much more work to build.

 

[Steve Maskery]

I meant to post the cost of this.

Oil drum (although it had never contained oil, AFAIAA), - £2
All-thread I was given - £0
Nuts and washers - I went to local supplier and asked for a bag of nuts and bolts. I have enough to last me the rest of my life, they cost me a tenner.
Plastic guttering fixings - £3.34
Hose bits and pieces cadged from friends - £0

 

[Steve Maskery]

Quite possibly. But considerably more difficult to make.

Indeed. What you have there is a form of Thien separator (http://www.jpthien.com/cy.htm).

Cyclones (of the form designed by Bill Pentz) are amazing, but much more work to build.

You are quite right, it's pretty much a copy of Phil Thien's. I did not mean to imply that any of this was my original design, it isn't.

I don't know if Mr. Thien invented this or if he simply popularised it on YT, but either way, I do owe him a debt of gratitude.

S

 

[sploo]

Quite possibly. But considerably more difficult to make.

Indeed. What you have there is a form of Thien separator (http://www.jpthien.com/cy.htm).

Cyclones (of the form designed by Bill Pentz) are amazing, but much more work to build.

You are quite right, it's pretty much a copy of Phil Thien's. I did not mean to imply that any of this was my original design, it isn't.

I don't know if Mr. Thien invented this or if he simply popularised it on YT, but either way, I do owe him a debt of gratitude.

S

Steve - take a look at his forum. He seems to be both a rather smart, and also pretty humble, guy (in the sense that he makes few grand claims about his inventions).

It looks as though a top hat design (side inlet) is now the preferred layout, and I've been meaning to build one for a while as I don't have the height for a Pentz style cyclone.

BTW For the Festool vac the Oneida Ultimate Dust Deputy does seem to work pretty well. It's not cheap though.

 

[Halo Jones]

Steve, from what I have read you should play about with a tube reaching down from the clean air outlet towards the baffle. It seems there should only be a gap of about half the diameter of the tube between the tube and baffle. I assume this description is clear as mud so you might want to look here:
https://woodgears.ca/reader/hector/shopvac.html

This should hopefully prevent even less dust making it to your vacum bags.

H.

 

[Halo Jones]

Looking again at the position of your baffle. Shouldn't it be moved around by 120 degrees so the incoming air hits the baffle for a bit longer?

 

[Wizard9999]

A jolly cost effective solution Steve. I wondered if you noticed any meaningful reduction in suction using the separator?

Terry.

 

[Steve Maskery]

Looking again at the position of your baffle. Shouldn't it be moved around by 120 degrees so the incoming air hits the baffle for a bit longer?

I don't think so. In fact I've cut the baffle back right to the tip of the inlet. I want as little dust as possible on the top side of that baffle.

In actual fact, I think it would work just as well with a simple circular disk, rather than the two-radius one I'm really not sure what it is supposed to achieve, it's just how the original was.

I like the idea of having the outlet down close to the baffle, I'll see if I can arrange that.

Terry - The system is very well sealed now that I've used the roof sealant and there is no noticeable drop in suction. The only hitch is that debris can get trapped at the hose ends where they fit into other bits of plastic, but it's not a major problem.

 

[sploo]

Looking again at the position of your baffle. Shouldn't it be moved around by 120 degrees so the incoming air hits the baffle for a bit longer?

That's a good spot - yes; I believe there are aero reasons for having the incoming air hug the baffle before dropping down the slot (possibly https://en.wikipedia.org/wiki/Coand%C4%83_effect). It also reduces the propensity of the incoming air stream to lift material from the bucket (scrubbing).

See the layout at: http://www.jpthien.com/cy.htm

 

[Steve Maskery]

That's an interesting Wiki, Sploo, thanks.
As regards the air sticking to hard surfaces, that does make sense. I'm no aerodynamics engineer, but I did used to teach Physics and have a reasonable general knowledge. I reckon, though, that the side of the drum itself will serve the same purpose. Maybe I should add a chute off the baffle drooping downwards.
But I still maintain that the less dust that touches the top side of the baffle, the better. Or am I missing something?

 

[sploo]

That's an interesting Wiki, Sploo, thanks.
As regards the air sticking to hard surfaces, that does make sense. I'm no aerodynamics engineer, but I did used to teach Physics and have a reasonable general knowledge. I reckon, though, that the side of the drum itself will serve the same purpose. Maybe I should add a chute off the baffle drooping downwards.
But I still maintain that the less dust that touches the top side of the baffle, the better. Or am I missing something?

AFAIU The air/dust will hug the outside wall due to the velocity/angle of the incoming stream, but gravity is what's getting the larger chips to fall through the baffle. I believe the main rationale for the angular placement of the baffle slot is that it reduces scrubbing - i.e. it prevents the inlet air from interfering with the dust already in the drum/can. I'm pretty certain there's relevant discussion on the Thien forum, but I'm afraid I don't have a link to hand (it's been a while since I last read through some of the articles).

 

[brianhabby]

I purchased a plastic dustbin lid some years ago that has two holes in the top for exactly the application you have described and it works perfectly being especially effective for the masses of chipping when planing. I am sure I bought it from Axminster but having rummaged through their catalogue, I can find no trace of it. It just sits on top of a regular plastic dustbin and has a foam strip around the interior of the lid which makes a seal between the lid and the bin.

I accept this is no good to you now Steve and your oil drum will hold much more debris than a regular dustbin but it may be of interest to others. I'll take a photo and post if anyone is interested.

regards

Brian

 

[sploo]

I purchased a plastic dustbin lid some years ago that has two holes in the top for exactly the application you have described and it works perfectly being especially effective for the masses of chipping when planing. I am sure I bought it from Axminster but having rummaged through their catalogue, I can find no trace of it. It just sits on top of a regular plastic dustbin and has a foam strip around the interior of the lid which makes a seal between the lid and the bin.

I accept this is no good to you now Steve and your oil drum will hold much more debris than a regular dustbin but it may be of interest to others. I'll take a photo and post if anyone is interested.

regards

Brian

Those bin lid separators are perfectly good, but the Thien baffle helps to reduce scrubbing. Whether it also makes the system more efficient (less turbulence) I don't know. The ultimate is obviously a well designed cyclone; but a poorly designed one won't be great either.

The best systems will leave almost no visible dust coming into your extractor - so you can use very high quality fine filters for your health, but obviously avoid sandblasting them. If the primary goal is to just reduce the amount of material hitting your shop vac bag then obviously something that sophisticated isn't a must. All separators will of course rob you of some pressure/suction, so it's important to not kill the airflow so much that you're then struggling to collect the dust at source.

 

[flying haggis]

I purchased a plastic dustbin lid some years ago that has two holes in the top for exactly the application you have described and it works perfectly being especially effective for the masses of chipping when planing. I am sure I bought it from Axminster but having rummaged through their catalogue, I can find no trace of it. It just sits on top of a regular plastic dustbin and has a foam strip around the interior of the lid which makes a seal between the lid and the bin.

I accept this is no good to you now Steve and your oil drum will hold much more debris than a regular dustbin but it may be of interest to others. I'll take a photo and post if anyone is interested.

regards

Brian

just googled "dust seperator lid" and this appeared

http://www.google.co.uk/url?url=http:// ... 7s0MZ2Xsjg

is this what you mean?