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Forum topic by KiwiDustmite posted 01-14-2017 02:56 AM 974 views 1 time favorited 8 replies Add to Favorites Watch
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KiwiDustmite

5 posts in 493 days


01-14-2017 02:56 AM

Hi folks, first time here although I have lurked in the shadows for some time:)

I’ve asked the following in another arena but thought I would throw the subject open to a wider cross section of woodies.
I sold my big woodworking gear and large dust extractor a couples of years back, in preparation for a move to a smaller workshop. Unfortunately the move never happened. Since then I have been replacing stuff as and when finances permit. To date all my machinery , Lathe, miter saw, table saw, router table and other smaller powertools all have either a 1-3/4 in ( 40 mm) or 2 inch (51 mm ) outlets.

Some time ago I built a Bill Pentz design cyclone for my powertools and it works extremely well, better than 98% collection with a filter change needed once every 18 months or so. Having trawled a few YouTube vids, it seems that most shop vac based systems are based on a 2 inch system.
However one thing I see is what appears to be a larger diameter shop-vac hose supplied in Northern Hemisphere shop vacs than ours here , which tend to run to 35 MM ID So to my first question; what is the average size hose ( I.D. ) on your shop vacs? and why do they use different hoses?

I have a choice of either 40 mm or 50 mm inexpensive waste pipe I can buy for the system and this leads to my second question; how much suction loss would there be using the larger pipe compared to the smaller diameter?
From what I’ve seen to date leads me to the conclusion that even with 50 mm (2 inch) pipe there still seems to be a pretty good level of suction on moderately long runs of 18 or 20 feet ( 6 or 7 meters ).
The three options I am looking at are the following.

Nilfisk medium ShopVac.

Arges Wet & Dry 30 L

Toolshed Pro Vacuum Cleaner

All three of the listed items come with the auto power function that is for me a least a major plus as I can set up power-points to each machine to auto start dust collection. All 3 units appear to have very good suction with the Nilfisk being the strongest of the three.

The Toolshed Vac is a cyclone system with 4 stage filtering which I think robs it of some of its efficiency, whereas the other two are a more standardized system.
One thing that was outstanding on all of them was how quiet they were when operating. None were more than 70db, I tested them with a decibel meter. In fact the background noise in the shop was 67 db and none of the vacs sounded like they were exceeding the ambient noise levels, which I have to say impressed me considerably. I’m currently using a bag-less household vacuum cleaner which when I tested it was running at 84 db and the shop vacs are way quieter than that which will be a welcome relief in the workshop.

And so to my third question; which shop vac would you choose and why.
Remember that filtration isn’t a major concern as I’m running the cyclone.


8 replies so far

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Andybb

964 posts in 598 days


#1 posted 01-14-2017 06:03 AM

My hose is 2” id. It’s a shopvac brand. Not sure of the size but it’s one of the bigger ones. 15 – 20 gal? It’s in an enclosed cabinet lined with carpet padding so it’s a pain to get at to check the exact size. It has a bag in it so the filter never gets dirty. I check the bag once a year or so but same bag for 2 years now. It is connected to a “cyclone” that is a 5 gal bucket with a 2 1/2 gal bucket hot glued on top of it mounted on the wall. It’ll suck the chrome off of a trailer hitch except really long 12” wide planer chips. Cost me $0 other than the $35 for the auto switch. In fact it will pack that 5 gal bucket so tightly before I really notice a reduction in suction that the sawdust comes out in the shape of the bucket. Inside the enclosure it runs well under 40db so i sometimes forget it’s on if there is music playing plus the wife can’t hear it when she’s upstairs trying to sleep. The enclosure is made of 3/4 ply and has wheels and is the stand for my drill press and jig saw and a little grinder.

I’m a yank so 50mm is Greek but I’m pretty sure that’s 2”. You would be more efficient with the larger hose. It’s a vacuum so the suction loss is non-existant and the shopvac would be happier with the larger hose. (imagine trying to take a deep breath through a straw) Mine would be more efficient with a 4” hose but like I said everything sucks fine and I don’t really have the space for a big dust collector. I have one of those Rockler hose kits so there is a combo of fittings for almost anything.

I think filtration is a concern because the 2% that gets by the cyclone is the really small stuff. By using a bag in the SV i’m 100 filtered.

The physics of a vacuum say that as long as there are no leaks the run could be any length with no suction loss.

Size matters. The bigger the motor the more air it can move and can help keep the motor cool as heat seems to be what kills them.

IMHO

-- Andy - Seattle USA

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KiwiDustmite

5 posts in 493 days


#2 posted 01-20-2017 11:32 PM

Thanks for that Andy. Has helped me to solidify how I’m going to approach the setup for the mid term at least.

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Lazyman

1938 posts in 1382 days


#3 posted 01-21-2017 02:49 AM

I am no expert but I think that a smaller hose gives you a higher velocity of the air stream. My understanding is that a higher velocity is needed, for example, if your pipe or hose run vertically upward so my assumption is that a smaller hose or pipe will do a better job of keeping particles suspended so that they make it all the way to your dust collector. Taking Andy’s straw example to the other extreme, if you try to suck through a 6” straw, you need a lot more airflow (CFM or LPM) to get enough velocity to pick up and carry the dust particles. The Nilfisk says it has an airflow of 3600 LPM which is about 127 CFM which should give enough velocity at either diameter for horizontal runs. If you are going to have vertical runs, it might be better to use the smaller diameter.

The Nilfisk specs say that it has nearly twice the airflow of the Toolshed Pro even though the suction is about the same. The Arges doesn’t list airflow but appears to be rated for fewer amps than the other two so unless it is more efficient somehow, it probably doesn’t have the airflow of the Nilfisk. Based upon the specs alone, Nilfisk is what I would choose.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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Andybb

964 posts in 598 days


#4 posted 01-21-2017 03:44 AM

Agreed. The only thing I would throw in is that the additional/loss of velocity with a smaller hose is negligible and doesn’t seem to make any difference. The trade off….. saw “dust” is not an issue, but when you are talking about shavings the small orifice will clog. That must be why all planers have 4” openings. That’s what I mean when I say that the difference in suction is negligible but the clogged hose is a deal breaker.

My shop vac is at floor level, the cyclone is mounted about 6’ high on the wall. To get to the table saw it has to run about 8’ horizontally overhead before dropping down to the saw. Again, the only issue I have is that for the planer with a 4” outlet the shavings clog at the restriction. I still use an adapter and connect the hose to the planer but that just gets the small stuff and keeps the dust from blowing all over the shop. I still have to take off the adapter and use the hose to suck out the shavings/chips every few minutes. Not an issue for me as I rarely use the planer.

Some dust will build up in the base of the table saw that I’ll suck out every few months but that too is negligible and not a concern compared to no dust coming off the blade up top because of the suction from below, if any of that makes any sense.

-- Andy - Seattle USA

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pintodeluxe

5654 posts in 2808 days


#5 posted 01-21-2017 05:08 AM

I only use a shop vac or dust extractor for three stations in my shop. Everything else is hard piped to my cyclone.

The router table does well with a 2-1/4” hose. The miter saw needs 1-7/8 or bigger to collect well. I tried it with a 1-1/4”, and a 1-1/2” hose and it didn’t work well.

For hand tools like sanders and routers I use a Dewalt dust extractor that works great.

Good luck with it.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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TungOil

927 posts in 490 days


#6 posted 01-21-2017 01:51 PM

You can find a lot of good information on designing dust collection systems here:

http://www.airhand.com/designing/

Having just finished up designing and installing my fourth shop (and hence my fourth dust collection system!) I can add a few thoughts for you to consider.

A “shop vacuum” based system will have a hard time servicing anything but the smallest floor machines and only if you keep them close together to minimize the amount of piping needed. The fluid mechanics behind designing these systems is surprisingly complex but the design guide available at the link above does a good job of explaining the practical aspects of it.

Some thoughts on how I might go about putting a system such as you are describing together:

1) your goal is to have as much flow (CFM) and velocity (FPM) at the entry point as possible to maximize the ability to collect dust and chips. try to cluster the equipment to minimize the amount of pipe needed to connect them, and especially minimize the number elbows and flex hose. Because there is flow, there is friction in the system. Each foot of pipe will have a pressure drop associated with it. Each elbow or fitting is equivalent to several feet of pipe regarding frictional pressure loss. Bigger pipe has less friction loss per foot, but also lower velocity so it’s a balancing act to size these systems correctly. Also minimize the amount of flex hose you use since the corrugations also introduce significant frictional pressure loss. The Nilfisk would be the only choice here in my mind.

2) you will benefit greatly from using blast gates at each machine so you can have just one open at a time. I have used this system for decades and it works well to keep pipe velocity up. You will need to maintain a minimum velocity or your chips will drop out of suspension at the elbows and plug your system.

3) consider expansion- what other machines might you buy and how will they impact your system? It would be disappointing to build a system around your current tools only to add a jointer or surface planer a year from now and find that it is not up to the task of collecting chips from these machines. Planers especially, and but also shapers and jointers produce a lot of chips really fast and have always been the most challenging in my shop to collect efficiently.

4) Try to position your dust collection entry points as close to the point of creation as possible. Some machines are nearly impossible to efficiently collect dust from, like miter saws. If your equipment does not have a built on dust port, study where the majority of the chips go and try to position the inlet to the system so the chips are “thrown” into your pipe.

In the end, seriously consider the main advantage of a shop vac based dust collection system- portability. You can save yourself a lot of work and expense if you just roll the vac over to the tool that’s you are using and hook it up. No piping to buy, install and have in your way and you minimize your pipe runs and maximize you flow. Complete flexibility on shop layout and redesign. This is less convenient than a dedicated collection system for sure, but a lot less work to set up. Rockler sells decent quick connects for the smaller 2-1/2” vacuum systems that might make this pretty painless but not sure if they are available in NZ.

One last thought on safety- if the pipe you are planning to use is PVC experts will say to run a bare copper conductor through the piping attached to a ground. The risk is that you will build up static charge and create an explosion hazard, especially with fine dust particles like those generated by a sander.

Good luck with this and post some pics of your finished system!

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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KiwiDustmite

5 posts in 493 days


#7 posted 01-21-2017 08:25 PM

I would agree with the thought that the Nilfisk was the brand to go for. I too had come to the same conclusion. Interestingly the “Toolshed” lists a smaller Nilfisk – “The Multi20” as having an even higher rate of air flow. I did think however that the it may well be less robust in its construction that its bigger brother, which may see it have a little less longevity long-term.

Future machinery plans do include a bandsaw and planer/thicknesser combo as well as a bigger tablesaw than my current home-built one.
As far as dust is concerned the planer combo could be used outside for most jobs, although I’m still debating whether a jointer is needed as I didnt use my 6”inch jointer much at all and it tended to gather dust. Either way thats the likely limit for the near future regarding larger machines. I had a 1hp dust extractor similar to this last time, but it didnt seem to perform particularly well given that it ran on one machine at a time.

However just to really put the cat among the pigeons I discovered this Sheppach dust collector which might just be the way to go and provide a little more future proofing. It also comes with the right sized connections for smaller tool dust extraction and the good thing is I already have all the piping from my original dust extractor. To top this off its a good deal more efficient than my old model.

Anyone familiar with the model or the brand?
The good thing is I hadn’t checked this site for a while and was pleasantly surprised that the prices were considerably better than I can get locally even with freight included.

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Lazyman

1938 posts in 1382 days


#8 posted 01-21-2017 11:14 PM

Sorry, those brands are not generally available in the US so I have no knowledge of them. Those both have significantly more CFM/LPM than the shop vacs you are looking at but have a bigger footprint. If you want to be able to use the dust collection with more than one or high volume chip generators like a jointer or planer, I would go with one of those if you have the space, though I am able to use my craftsman shopvac with my Dewalt planer with no problems, probably because it has a blower that expels the chips.

Of course if you want to really future proof, you could go with this one . Almost twice the CFM of the other 2 but only slightly more than the Nilfisk. Those prices are fairly reasonably compared to USD by the way.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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