Follow-up: Central Shop Vac System

[Peter Aeschliman]

Sorry all, photobucket changed its rules on embedding photos on other sites. They want me to pay $400/year, which ain't gonna happen. I killed an hour trying to figure out how to embed photos from google drive and google photos to no avail. So I settled for uploading the files to SMC, which results in super small images. But hopefully you get the idea. Apologies.

Edit: looks like you can get the bigger images by just clicking on the thumbnails.


Hi All,

Way back in December 2014 (wow, time flies!) I posted this thread:

http://sawmillcreek.org/showthread.php?224757-Central-Shop-Vac-System&highlight=

I've finally gotten to the place where I can put some of the things I learned from that thread into practice and wanted to pay the forum back with a follow-up. We bought a new (old) house and I've been working to convert the basement into a shop.

Since the shop is small, I'm looking to ditch my shop vac/dust deputy cart in favor of a central vacuum system. I'm pretty sick of rolling that cart around... Note that I already have a cyclone with 6" ducting for my dust collection, so this is just for small tools (sanders, routers, TS and RT blade guard, and vacuuming up the shop floor). I definitely understand the difference between high volume low pressure and low volume high pressure... hence why i'm using both systems together.

What I learned is that most shop vacs are under-powered for a plumbed system. So on the advice I received, I looked into the power units used for home vacuum systems. I decided that I basically wanted to build a scaled-down version of a cyclone dust collector... Meaning, an motor and impeller sitting on top of a dust deputy.

I learned that the type of motor and impeller I needed is called a "tangential bypass motor". This is essentially the same concept as the big motor/impeller units on a cyclone dust collector. The impeller is sealed off from the motor, so the motor uses the ambient air in the room for cooling (kind of like the "totally enclosed, fan cooled" (aka TEFC) motors on dust collectors). Shop vacs use the vacuum air for cooling, which is why it has to pull the dusty air through a filter before the motor. That approach doesn't work for this kind of system, which is why you end up with a bulky cart when you adapt your shop vac for use with a cyclone. Nothing wrong with that, just a trade off.

I bought this motor/impeller. It's a 3 stage tangential bypass motor:

https://www.thinkvacuums.com/ametek-lamb-117500-12-central-vacuum-motor.html


Please excuse the disaster in the shop- I'm still setting it up, so I have no storage yet.

Here it is, sitting on top of an unadulterated steel dust deputy:

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The pipe on top was in the way, so I cut it off and added the foam gasket that I bought separately for this motor:

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Then I added some threaded rod to hold it together:

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Those with a keen eye will notice that the rotation directions of the cyclone and the impeller are opposite. This isn't ideal, and I was bummed out when I realized it. But when I fired it up for a test and felt the terrifying suction, I realized that it is going to work out just fine. haha. It pulls my skin hard enough for it to be moderately painful. In fact, this might be too much suction for my ROS, so I'll likely have to leave the blast gates half open.

I still have to install it and plumb the lines, so maybe I'll update this thread when I get around to it.

Anyway, hope this helps somebody somewhere at some point.

[Mike Henderson]

Looks like a good arrangement. What are you going to do on the exhaust side? Are you going to exhaust outside? Or through a filter?

Mike

[Peter Christensen]

I assume the cyclone doesn't have an inlet guide ramp. So you could carefully cut the inlet off and flip it over and weld it to the other side. The old hole can be patched over and you will have the cyclone and the impeller turning in the same directions. You might be able to find a friend to do the welding if you can't.

The website for the vacuum doesn't give the amperage draw or voltage. Do you remember seeing the information on the assembly?

[Peter Aeschliman]

Looks like a good arrangement. What are you going to do on the exhaust side? Are you going to exhaust outside? Or through a filter?

Mike

I plan to exhaust it outside, but still need to figure out how it will exit the house.

[Peter Aeschliman]

I assume the cyclone doesn't have an inlet guide ramp. So you could carefully cut the inlet off and flip it over and weld it to the other side. The old hole can be patched over and you will have the cyclone and the impeller turning in the same directions. You might be able to find a friend to do the welding if you can't.

The website for the vacuum doesn't give the amperage draw or voltage. Do you remember seeing the information on the assembly?

I have a MIG welder, so I could probably do that if I was so inclined. I'll give it a shot as-is and see how it goes.

As for the amp draw, have a look at page two of the manual:

https://www.thinkvacuums.com/media/pdfs/specs/117500-datasheet.pdf

I didn't measure the orafice opening unfortunately and i'm too lazy to disassemble it to do so. haha. But I would guess it's in the 1.5 - 1.75" range, since it was noticeably smaller than the 2" opening in the cyclone, which would mean it will draw around 14.2 amps. I have it on a dedicated 20 amp circuit.

[Carl Kona]

Peter,

Thanks for sharing your setup. I like the idea of a central vac - shop setup. As far as moving the port, that will only work if the motor is reversible AND the blades are straight (not angled for the current motor direction). A much simpler approach would be to add a simple air straightener between the vac and DD. 6-10" with a X vane down the center would work. What has been proven on dust collectors/ separators with this backwards flow configuration is it causes turbulence in the separator. That turbulence created a noticeable rise in noise level and a reduction in air flow and separation performance. I remember reading 'Retired2' posts in the Thien forum about the issue (someone else reported similar findings but I can't remember where)

Hope that helps. Thanks again.

Carl

[Keith Outten]

Your vac looks very similar to mine. Oneida sells a rack to wall mount their Cobra's that might work with yours.

[Peter Aeschliman]

Peter,

Thanks for sharing your setup. I like the idea of a central vac - shop setup. As far as moving the port, that will only work if the motor is reversible AND the blades are straight (not angled for the current motor direction). A much simpler approach would be to add a simple air straightener between the vac and DD. 6-10" with a X vane down the center would work. What has been proven on dust collectors/ separators with this backwards flow configuration is it causes turbulence in the separator. That turbulence created a noticeable rise in noise level and a reduction in air flow and separation performance. I remember reading 'Retired2' posts in the Thien forum about the issue (someone else reported similar findings but I can't remember where)

Hope that helps. Thanks again.

Carl

Makes sense. I'm installing the unit in my soundproofed dust collector closet, and unfortunately I only have about an inch of headroom in the space (hard to explain the configuration). So I wouldn't have room for an air straightener. Fingers crossed that it performs well as-is. I think it will judging by my unscientific "hand over the inlet" test. It nearly removed the skin from my body. lol



Your vac looks very similar to mine. Oneida sells a rack to wall mount their Cobra's that might work with yours.

I didn't realize Oneida had those units. Interesting. Luckily i'm saved from buyer's remorse since I spent about a the price for the dust cobra, although mine doesn't have filters and may not perform as well (who knows).

[Keith Outten]

The Dust Cobra pulls 90" of water column, it doesn't leave anything behind :)

[Peter Aeschliman]

Here's the chart for my unit.

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I have no idea what my CFM is, so I'm not really sure where the actual performance will fall on this curve, especially given that I've added a cyclone to it and will plumbing it around the shop.

All I know is that it has massively more suction than any shop vac I've ever owned and will likely be too powerful for sanding without choking it down.

[Peter Aeschliman]

Quick follow-up to my follow-up. ;)

I plumbed the central vac over the weekend with 2" schedule 40 PVC. I glued every joint and used off the shelf 2.5" aluminum blast gates. I'm disappointed actually. I think the suction will be good enough for sanding and for my Sawstop blade guard's dust pick up. But it's not quite enough suction for vacuuming up the shop I don't think (because the corrugated vac hoses rob a lot of suction).

Before I installed the blast gates, as a quick experiment, I duct taped all of the openings shut except one, and was pleased with the suction. The aluminum blast gates leak quite a lot... I think a high CFM system like my central dust collector can tolerate those kinds of leaks, but it's pretty amazing how quickly the static pressure drops off in a central vacuum system. So my new plan is to make my own blast gates that completely seal when closed (i.e., have some kind of gasket material).

If that's not enough, then I will revisit the topic of air rotation at the cyclone, covered previously in this thread. And if that doesn't work, I'll have to deal with it. :)

[Sean Nagle]

I've read many posts where people have made use of an older central vacuum unit for a centrally plumbed workshop system. I've never seen a post where someone bought a new central vacuum power unit for the same purpose. I ran across this vacuum when searching for central vacuum systems for a new house.

http://www.centralvacuumstores.com/central-vacuum/powerunits/power-units/imperium-garage-system-package-cv3200

They seem to be selling the power unit and numerous accessories for garage/workshop use. What's attractive about this system is the performance. It has 142" of suction and 117 CFM flow. For comparison, the current Fein and Festool vacuums have from 96"-98" suction and 137-151 CFM flow.

I have a centrally plumbed system in my shop using 2" central vacuum pipe and have been using an old Fein Turbo I with a Dust Deputy (I also have a separate Dust Gorilla plumbed to my stationary machinery for dust collection). Performance of my vacuum system has been good to just OK depending on how much dust/chips my portable power tools produce. I'm considering changing out the Fein/DD with this Imperium central vacuum unit or getting a Festool vacuum and just going back to using the vacuum next to my workbench.

I'm looking for any insight from others who have tried using a central system rather than a bench-side vacuum.

[Charles Lent]

I use a repaired and re-purposed Beam Central Vacuum that I acquired from the neighbor's house when they did a major remodel. I installed it in my shop with an Oneida Dust Deputy ahead of the vacuum unit and all of the pipes and inlets of the original central vacuum system were installed in the shop much like it would be in a home. I use the unit to collect dust from two scroll saws, two sanders, 2 drill presses, a miter saw, and the portable sanders at my workbench. I also have an inlet port in the outside wall next to the shop entrance door for vacuuming my cars and trucks. Only one inlet port is ever used at a time and for one tool at a time. I have large ceiling hooks placed in critical locations so I can route the vacuum hose from each tool to the nearest vacuum inlet port to keep it off the floor as much as possible. I don't even try to use it with my planer, jointer, band saw, or Unisaw, but I do vacuum the shop floor with it. My shop is quite small with no room for a large dust collector to handle these high volume chip producers. Fortunately, most of the waste from these is large chips and lest fine dust. In three years of use I have never found anything more than a trace of very fine dust in the bottom container of the vacuum unit. The Dust Deputy is catching it all, and I am considering the removal of the fabric filter in the central vacuum, because it seems to be doing nothing, except maybe reducing the air flow. The exhaust of the vacuum unit is piped to the outside just under the roof soffit, so nothing ever gets back into my shop. I've been very pleased with how well this all works for me. It was a very low budget idea that has done very well for me.

The vacuum unit, all of the piping, 4 inlet ports, and the 25' hose, and attachments were free. I had to replace the 24 volt transformer in the vacuum unit to get it running again. Price for the transformer was $14



I bought -

4 lengths of pipe and 26 fittings for $56 from the local vacuum store. The rest of the pipe, fittings and inlet ports came from the neighbors.

A used Dust Deputy from a friends commercial shop $35

The 20 gallon metal grease barrel was free - my son found it for me.

2 24" squares of 3/4" cabinet ply - Free from the scrap bin. This was for making the barrel cover/Dust Deputy mount.

So, for $105 and a day and a half of installation I have a small shop dust collector that exceeds any Shop Vac that I've ever used, and none of it uses any shop floor space. The Dust Deputy, barrel, and Central Vacuum unit are in my shop attic and the pipes are all in my shop walls and ceiling.

Sorry - The first picture is sideways and I've tried to delete it without success. The upright second picture is my central vacuum unit as it is installed in my shop attic.

Charley

[Jim Dwight]

I put a central vacuum into our last house but didn't use it in the shop. Actually I had the builder put the 2 inch pipe in the walls and then I put the power unit in later. It was a powerful vacuum, more powerful than even a Dyson vacuum. But it is designed to pull hard through 2 inch pipe. Shop vacuums pull pretty hard through 2.5 inch hose. I can tell you don't love shop vacuums but they will move more air, although not suck quite as hard, as a whole house vacuum. I use a 10 amp, so called 6 hp, Rigid on a dust deputy. I have a 20 foot 2.5 inch hose I use for my small table saw, router table, and to clean up. I use a Bosch 5meter hose to my track saw, sanders, and miter saw. The tools plug into a power strip that plugs into a switch that triggers the vacuum. The vacuum stays in one spot, the hoses reach to the tools in my small shop. So I move the hose but don't have to plug and unplug the tools. Works well for me. Just emptied the 4.5 gallon bucket under the cyclone last night (again). Debris from the planner and jointer get swept up but the shop vac gets most of the rest.

I don't think your whole house vacuum is without it's advantages but I respectfully submit a shop vac is a better idea for a shop. One reason is CFM. You need to move more air to clean up a shop than it takes to dust a house.

[Charles Lent]

Jim, I agree with you. A central vacuum unit isn't ideal for many shops, but neither is a Shop Vac. I had my Dust Deputy mounted on a 5 gal plastic bucket and connected to my Shop Vac when I first got the Dust Deputy, and it worked quite well, but was very loud and required significant shop space, space that I don't have available in my small shop. The combination worked well as far as collecting saw dust and separating it, but the noise and space requirements of it were not acceptable. I never collapsed the plastic bucket under the Dust Deputy with the Shop Vac either.

I was given the central vacuum unit, the pipe, hose, and accessories for it, and decided that if I installed it in my shop's attic that it would give me back the shop floor space that I was loosing with the Shop Vac and Dust Deputy located within the shop. In reality, there doesn't seem to be much operating difference in how well they work when compared with each other, but when the central vacuum unit was first installed along with the Dust Deputy I only had the 5 gal plastic bucket under the Dust Deputy to collect the saw dust. This bucket imploded within the first minute of use. I then replaced the plastic bucket with the strongest one that I could find, a recycled pickle bucket from Firehouse Subs. It too imploded about 3 minutes into it's first use. I then realized that these pickle buckets have ribs on the top third of their height that makes the top portion of the bucket very strong, so I stacked three of these buckets together, tripling the top bucket's effective thickness and putting ribs the full length of the top bucket. I had no more bucket implosions after doing this, but still only had 5 gal of capacity. Then my son found me a metal 20 gal barrel and I switched to using it under the Dust Deputy. This combination has been working very well since the change. I now have the strength to avoid implosions, plus 4X the original capacity, and it is a small enough diameter to be able to remove it from the attic when dumping is necessary, which will likely not be needed for several years. (remember, I'm only collecting very fine dust and cleaning the floor with this unit).

A true shop dust collector uses much larger pipe with more cfm capacity than either a Shop Vac or a central vacuum unit and I don't argue this point, but I don't have the space for one of these systems in my small shop. Mostly what I am collecting saw dust from are low, but fine dust producers, my scroll saws, drill presses, sanders, etc. and vacuuming my cars and trucks. The central vacuum and Dust Deputy combination have serviced this need very well. It occupies no shop floor space, is very quiet when compared to other dust collectors, and exhausts the micron sized dust not caught by the Dust Deputy and central vacuum fabric filter, to the outdoors, so none of even the smallest dust particles ever get back into my shop and lungs. I don't try to collect the saw dust and chips from my Unisaw, Jointer, Planer, etc. with this vacuum system. Most of the dust from these is in the form of larger chips that would be too large for the pipes of my system anyway, but I believe that my central vacuum/Dust Deputy system is keeping the most unhealthy dust out of my lungs without creating excessive noise levels or using any shop space. It has been a significant solution for my needs, but I'm certain that it isn't for others with larger shops.

Charley

[Sean Nagle]

Charles is contributing an interesting data point with the collapsing dist bin. I suspect central vacuum power units might offer the greatest amount of suction of the three options: (1) central vacuum; (2) "inexpensive" shop vac; (3) Festool/Fein vac. From my experience, I think suction is far more important than flow for a vacuum solution that's used primarily for handheld power tools and general shop cleanup. Given my arrangement with central vac plumbing, Dust Deputy and Fein vacuum, if I did not have enough volume, my plumbing would start to clog. What I think I'm lacking is enough suction for the tools producing the most "dust".

Have a look at the following reviews of vacuums where the reviewer uses a water column gauge to measure suction of the Festool vacuum compared to cheaper shop vacs.
https://www.youtube.com/watch?v=1y1GUH83N1s
https://www.youtube.com/watch?v=LOI_Ia55ULs

The Festool vac does produce more suction on the gauge. If published specs of some central vacuums are accurate, they produce even more suction than the Festool vacuum.

The other variable in this equation is the Dust Deputy. I suspect it is significantly contributing to suction loss. Maybe cyclones experience considerably more inches of water lift loss than CFM loss. I'm thinking of getting hold of a water column gauge to test this myself. Has anyone run across any articles or videos on the web that quantify Dust Deputy suction losses? Central vacuum plumbing also contributes to suction loss. Between the central vac plumbing and the Dust Deputy, I might be losing too many inches of water lift to effectively use a shop vac, even the most powerful ones available.

[Charles Lent]

Sean, the central vacuum plumbing does reduce the flow, but without a water column measurement of the suction at the vacuum unit as well as at the machine I can't provide a good digital comparison. With no flow the water column measurement in all locations of the piping should be the same, but when a port is open and there is flow, the plumbing most certainly affects the vacuum level at different points. With an open port at or near the vacuum I think one of these central vacuum units could suck your shorts right off of you under the right conditions.

When I first got my central vacuum unit repaired and running, I tried connecting my hand held DeWalt ROS direct to it. The vacuum was very effective at collecting the dust, for a few minutes, and then the fabric filter in the vacuum began clogging. In about 10 minutes, the flow was so bad that it was leaving sanding dust on the board being sanded. That's when I decided to get a Dust Deputy to use with the vacuum and not depend on the filter in the vacuum at all. On receiving the Dust Deputy I first had it hooked up to my Shop Vac with a white 5 gal plastic bucket from Lowes under the Dust Deputy mostly so I could test how well the Dust Deputy separated the saw and sanding dust from the air. The combination worked quite well and I was impressed with how well the Dust Deputy separated the dust and put it in the 5 gal bucket. The bucket didn't collapse either, until I decided that this Shop Vac/Dust Deputy arrangement was always in my way in my small shop. That's when I decided to install the central vacuum and Dust Deputy in the attic of my shop and the central vacuum plumbing in the walls and ceiling of my shop. After completion and the first time that I used it is when I had the imploding bucket problems, not with a free flow through the hose and pipes, but when the first large wood chip partially plugged the end of the hose while vacuuming the shop floor.

Again, this isn't a perfect solution and not a true wood shop dust collector, but it works very well for collecting the workbench sanding, 6" bel/12" disk sanding, scroll saws, drill presses, band saw, and floor vacuuming in my small shop where I don't have the room for a real wood shop dust collector in my small shop. Since this central vacuum has been working so well for collecting from these fine dust producers in my shop I think that if I ever have a larger shop I will still have my central vacuum/Dust Deputy combination installed for the smaller saw dust producers just like I have now, as well as a large dust collector for the high volume chip producing machines like the Unisaw, jointer, planer and wide belt sander (if I ever get one).

Charley

[Jim Dwight]

Charley,
It seems you have a great setup for you. That iss what we all try to get to. No criticism intended by my previous post or this one, just thoughts and other experiences. I appreciate you sharing yours. I get good suction with my Rigid shop vac dust deputy combination, even through my 20 foot and 5 meter hoses. I don't know what the inches of mecury or water is for this combo but I know it picks up the chips and dust well which is what counts. I was not sure I would with a 20 foot long flexible 2.5 inch hose (available for about $20 at home depot) but it works. My shop is only 14x24 so I am tight on space which is why I sold my DC. I have the vac/cyclone on a little cart that has been modified several times. The current configuration has the vacuum under the cyclone and is about 20 inches wide and 2 feet deep. It sits along the wall where I crosscut and have lumber storage. The tall part is close enough to the wall that it does not impede CMS or RAS use. So I found space for it. I agree it is loud but it isn't as loud as most of the tools it gets hooked up to. So I am wearing muffs anyway and the noise is not an issue.
I'd like to not have to empty the drywall bucket as often but I do not have space for a larger container in the shop. The space above the shop is a bedroom. So my setup is a compromise too but one that is working fine for me.
My biggest related issue was the use of my old Rockwell speed block. That sander was offered as a Porter Cable last time I looked but mine is before that switch occurred. I rarely use it now because it does not have provisions for dust pickup. I was sanding some panels with a cove cut on them, however, and the soft pad of the speed block works well for that. I had forgotten how much dust this creates, however. It made my appreciate my normal setup more. While a compromise, it really helps keeps the dust down.
Jim