Thein baffle vs Dust Deputy

**BobL** · 18th February 2020, 02:01 PM

Originally Posted by jon542

Hi BobL, I'm not running anything large, all handyman size stuff. Biggest dust/shavings producer is a 13" thicknesser. 10 " bandsaw, Triton sawbench and router bench, 10" sliding mitre saw. Not all at once of course, and my reticulation is 90 mm poly pipe, all running off the DC2. Worked after a fashion but the inlet screen on the DC2 always clogged with shavings when I was putting pine through the thicknesser, and there was too much loose dust. I've just moved to another property, semi rural to suburban, so I have the opportunity to build a better system.
Jon

Thanks for the info.

One of the very first things I did on my DC2 was remove that inlet screen. Not long after I got it I measured the flow of air (and of course fine dust) and I was shocked at how much below spec it was (nearly all DCs are like this).
The next most important thing I did was locate it outside the shed.
Enclosure.jpg

However, on your system the most serious restriction will be the 90 mm ducting as this is only going to allow enough air flow to catch about 1/4 to 1/3rd of the fine dust generate by even your smaller machines. Adding any sort of chip capture to that system is only going to further reduce air flow and fine dust collection - it's basically all headed down hill. Using 100mm would be better but it will still be below safe requirements.

Provided the ducting is suitably positioned ie vertically downwards and no loose flexy is laying on the ground where it can suck up anything nearby, there should be no need for any sort of screen except in situation like this.
DRAFT Ducting Recommendations-bsandernew-jpg

DRAFT Ducting Recommendations-bsandernew-jpg

This screen is not there to protect the impeller but so's not to lose the workpiece and having it minced by the impeller - I have lost a few things this way. Placing a screen across the wider mouth of the hood also doesn't impact the flow anywhere near as much as the narrow section of the ducting. The difference is surprising. That screen only blocks about 1% of the flow where those inlet to impeller screen block up to 20% of the flow.

Even small impellers can usually easily handle shavings and small blocks of wood, and with only 90 mm pipe in use nothing really big except for maybe a rag is going to get down there. Large ducting usually means larger impellers that can handle bigger things. a few years back y system sucked up an 8m Stanley tape measure and minced it into small pieces and I could not even detect a scratch on the impeller.

Getting back to your setup, if you are not interested in upgrading to a more powerful DC then I would suggest directing any spare $$ on improved forced ventilation rather than trying to get a skyskerrickrim more air of a small DC. Not sure how big your workshop is but a start would be a couple of bath room exhaust fans or similar high up on a wall on the downwind side of the workshop and install some large vents on the opposite wall. The target is 20 room changes per hour but any venting is better than none. 10 room changes per hours will really make a difference. If you look up the fan specs of ventilation fans you will need to basically divide them by 2 (same for DCs) to get a more accurate working flow rate.

Running the ventilation fans from the moment you start making dust and then leave them on till you leave the shed, or leave them running over lunch/coffee will help remove the fine dust - which of course is the dust that is most likely to impact health.

**Lappa** · 18th February 2020, 04:38 PM

Originally Posted by BobL

FWIW Bill Pentz doesn’t think much of any separator..

i wonder why

**BobL** · 18th February 2020, 04:55 PM

Originally Posted by Lappa

i wonder why

Bill has has subjected separators to fairly rigorous test and the separators came out as considerably more restrictive in high flow applications.
I don't think there would be much different between separators and cyclones not specifically designed to be paired to vanilla/third party impellers.

**Lappa** · 18th February 2020, 05:02 PM

Originally Posted by BobL

Bill has has subjected separators to fairly rigorous test and the separators came out as considerably more restrictive in high flow applications.
I don't think there would be much different between separators and cyclones not specifically designed to be paired to vanilla/third party impellers.

Which is what the vast majority of hobby woodworkers have.

**jon542** · 18th February 2020, 05:18 PM

Hi BobL, thanks for the input. From the looks of it a complete redesign and new build will be the best option. The DC2 will handle one machine at a time, as long as it's connected with a couple of metres of 4" hose. The 90mm downpipes were a trial, worked to a certain extent but not as effective as I would have liked, hence the decision to upgrade. Unsure at this moment whether to go for the Dust Deputy or the Super. Super will require a larger blower but I think I'm up for that anyway. My projected shop is going to be around 7 metres long, with 4 maybe 5 offtakes. Only one offtake at a time in use, biggest user will be the lathe, followed by the thicknesser. Any suggestions on lightweight 100mm plastic piping? I could use sewer but it would be heavy. Jon

**poundy** · 18th February 2020, 08:02 PM

I think you overestimate the DC2's capabilities. Especially when you start talking about running long ducts and only talking 4". Plus, ignoring dust is a decision you've now consciously made... everyone here is kind of saying that you're destined to fail and ignoring the facts as presented...

**jack620** · 18th February 2020, 09:11 PM

I think some posters may have missed this:

Originally Posted by jon542

Other limiting factor is finances. Age pension stretches just so far ......

Jon came here looking for help with upgrading his current system. He's acknowledged he will need to upgrade his blower to 2HP or more.

Jon,
I wouldn't bother rebuilding the impeller. My take on the Wandel impeller is that he got an increase in static pressure but not CFM. That's why his modified 3/4HP blower was able to "overpower" his 2HP dust extractor.

You mentioned the Dust Deputy and Super DD. I would get the 5" Super Dust Deputy over the 4" Dust Deputy (finances permitting) as the latter will be too small if you upgrade to 2HP or bigger. But the 5" SDD is very expensive in Oz (I bought mine in the US), so a well designed Thien baffle might be a better option if you have a tight budget.

**aldav** · 18th February 2020, 09:24 PM

Everybody will make their own decision on dust extraction and for many of us cost will be a major consideration. jon542 is 77 years old and without knowing the general state of his health and how long he expects to enjoy his hobby we've really got no idea if he should have any health concerns re. dust. He has certainly made us aware of his financial constraints. Like most here I agree that for the duct length he is proposing he needs to go to a more powerful DE and he has acknowledged that he is 'up for that anyway'. With what he's proposing a move to 6" duct makes sense, but if he can't afford it there's little point in ear bashing him about it.

Have a look around the local builders demolition yards jon, amazing what you can find sometimes.

**jon542** · 18th February 2020, 10:16 PM

Originally Posted by aldav

Everybody will make their own decision on dust extraction and for many of us cost will be a major consideration. jon542 is 77 years old and without knowing the general state of his health and how long he expects to enjoy his hobby we've really got no idea if he should have any health concerns re. dust. He has certainly made us aware of his financial constraints. Like most here I agree that for the duct length he is proposing he needs to go to a more powerful DE and he has acknowledged that he is 'up for that anyway'. With what he's proposing a move to 6" duct makes sense, but if he can't afford it there's little point in ear bashing him about it.

Have a look around the local builders demolition yards jon, amazing what you can find sometimes.

Hi aldav,
Thanks for your kind remarks, I have a fairly thick hide, so the remarks about my relative ignorance are water off a duck's back. At the moment I'm not too mobile having just had an operation to fuse L3-L4-L5 which is going to take 12 months to recover from, so I'm doing a lot of forward planning - and saving! As to my vocational background, by trade I was an industrial Instrument technician, but have a goodly smattering of a lot of other trade and engineering disciplines, so I'm a fairly competent jack of a lot of trades. Figuring prominently are carpentry and wood turning, which I took up a couple of years ago. I expect to enjoy puttering with wood for another decade or so.

To put things financial into perspective, I have a budget for the job, and I'm trying to maximise the bang for the buck. The SDD is a known cost, and for the exercise I've chosen the Sherwood FM-400, which I can pipe directly to the SDD outlet, after taking out the crude screen on the fan inlet and substituting a wire screen.

What is giving me a headache is the reticulation. I am trying too find out what is available at what cost. If I use the SDD, ideally I should be using 125mm OD tubing which would bring the ID back to around 118mm, so the step down into the SDD isn't too drastic. That's an approximation, I don't have any specs-yet. I have to go consult a poly pipe supplier to find out what is available.

Fortunately I have a large stock of various timbers and ply accumulated over years of carpentry projects, including some wooden boat renovation,so wood shouldn't be a problem. I think I have a pretty fair idea where I'm going with this now so now I have to sort the details. And we all know the Devil is in the details!
Cheers,
Jon

**jack620** · 18th February 2020, 10:36 PM

Jon,
which SDD are you talking about? The 4” or 5” version?

**Chris Parks** · 19th February 2020, 09:03 AM

I don't know if 125mm PVC can be had in Australia and if it can be I doubt it would be classed as cheap. Ezi Duct might have it in metal, certainly 120mm is available in metal because I measured some yesterday.

**aldav** · 19th February 2020, 09:38 AM

Originally Posted by jack620

Jon,
which SDD are you talking about? The 4” or 5” version?

Is the 4" version even available in Australia? I suspect he's talking about the 5" SDD and the 6" XL SSD. 6" PVC stormwater pipe will work fine with either of those cyclones. I wouldn't be using any kind of screen on the fan inlet, the cyclone/thein baffle makes the need for such a screen totally redundant.

**QC Inspector** · 19th February 2020, 10:48 AM

One needs to keep in mind those screens are there to keep fingers out of the machine and not chunks of wood. People are not known for their brilliance and unfortunately so are some of their offspring. They were added for liability reasons. I had a 4 bagger, basically a DC-7 that came without the screens when I bought it in the early 90's. If you look at any of the cyclone setups being sold by Oneida, Clear Vue, Grizzly, Jet etc., none of them have screens but the single stage DC's do.

Pete

**BobL** · 19th February 2020, 12:53 PM

Those screen are notorious for getting choked up with shavings. At the men’s shed their dc3 was constantly getting block and members carried on using it even when dust was not bing collected. I removed the screen and the unbeknownst to me another member locked the motor switch in the on position. Some time later the dc sucked up a rag that wrapped itself around the impeller and a member duly turned off the DC at the expander board (already populated with many plugs) but does not remove the plug and stuck his arm onto the impeller to clear the rag. Meanwhile another member with a power tool already pugged into (but not switched on) the same expander board comes over and looks at the expander and turns on what he thinks is the right switch but it turns out to be the DC! By sheer good luck the other member happened to have his hand clear of the impeller opening. The guard/ screen is vital if flexies and connections are going to constantly be removed and reattached at the impeller opening as even a small dc can suck in a nearby hand. The screen can be removed if a length of ducting or flex longer or narrower than an arm is permanently attached.

**jon542** · 19th February 2020, 02:50 PM

Hi jack620,
The 4" one. If I go for the 5" one it's a couple of hundred dollars dearer and the reticulation will be proportionately dearer. I don't NEED a system that big, none of my machines are heavy chip/shaving/dust producers as they are all handyman scale, but I do want a system that will get me as close to a dust free environment as possible.

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