Instructables

DIY Shop Vac Dust Collector

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Like a lot of people, after retirement I built a woodworking shop.  I looked at the commercial dust collection systems, and did not like the look of the 4" hose laying all over the shop.  I also did not think I needed the capability of running several machines at once since it's just a hobby shop.   I decided to look at the possibility of using a smaller diameter wall mounted piping system using PVC.  My logic here was that a smaller diameter with adequate CFM resulted in higher velocity, hopefully resulting in similiar performance using one machine at a time.
I also wanted to use my existing shop-vac, knowing from experience that the 5.0(peak) HP unit was more than adequate for the machines I have, as i have used it on each, manually changing the hose.
The last requirement was it had to turn on automatically, I was getting tired of "aw crap", forgot to start shop-vac first!

With all the above, the photos pretty much explain where I went from there.  1-1/2" PVC water pipe with 1-1/2" electrical conduit wall brackets made it easy to setup.  I opted for ball valves instead of blast gates, mainly because it was going to take more work to match fittings for the blast gate.  The standard 2-1/2" vacuum hose did not quite match up to the outside diamater of the PVC, but as always, the "handyman's secret weapon" duct tape, provided the solution.  I wrapped duct tape on the PVC pipe end to the size where I could use a hair dryer to expand the vacuum hose and slide the hose over the duct tape.  When the hose cooled, it made a perfect fit.

I decided early on to use the Dust Deputy cyclone and capture most of the dust and chips before they made it to the shop-vac so that I would not have to clean so often.  The other driving factor was that this allowed me to put the shop-vac above the ceiling.  More floor space and less noise.  The unit mounted easily on the drum lid with six 1/4" metal screws(not included).   I have to say, at $40 I was buying a bit of a pig-in-a-poke, but it truly  works as advertized.  I have half filled the 30 gallon drum with sawdust and have yet to empty the shop-vac or clean the filter.

I decided to anchor the PVC pipe going through the ceiling by using a floor flange for electrical conduit and drilling a clearance hole for the PVC, then gluing the PVC in place.  I also used a pipe clamp above the ceiling on the PVC.

I looked at a few commercial current sensing products to automatically turn on the shop-vac when I started one of the machines, but the cost was about $50 per machine for the remote nodes, plus the controller itself.  I, luckily, have all 5 of the machines I use the shop-vac on, on one circuit, which simplified the automation requirements as I just had to monitor one point.

I settled on a design that did not limit the current in case I did try to run multiple machines, using an Aprilaire 51 current sensing relay that is normally used for humidifier circuits triggered from the furnace fan motor current.  It is only rated for 50 watts so I used it to drive a relay.  When I first prototyped the circuit, the relay was energizing immediately.  After a replacement current sensor gave the same result, I started experimenting with loading, and determined that although the specs said 50 watt max, it should have also said 10 watt minimum load.  The particular relay I used only draws 10ma and measures 5k ohms resistive load, so I added a 2k ohm 20 watt wirewound resistor in parallel with the relay coil to increase the load and keep the relay from a false start.
 

The system has been running about a month, and works to my expectations, with more than enough vacuum and velocity.  One gotcha in my system is my paper barrel.   I closed all of the valves with the shop-vac on and it imploded.  Nice ad for Shop-vac I suppose.

I'm not good at writing conclusions, or writing at all for that matter, so I end here I guess.  I'd be happy to answer any questions.

Thanks,
Steve


Update - 10/30/2012
I was still having trouble after 3 months with occasional false triggers from my garage door opener.  I modified the circuit by replacing the original relay with a single contact relay and replaced the 2000 ohm resistor with a 40 watt light bulb.  It has ran well since then, with no false triggers, but I have procrastinated updating this site.

I also added a wall switch directly across the Aprilaire current sensor to aid in shop cleanup.  The switch energizes the relay to start the vacuum directly, so I can connect a 20ft hose to clean the floor.

Thanks,
Steve
spstewart (author) 3 months ago

The ball valves work well as a vacuum seal, but once in a while they get stiff and hard to close completely. WD40 loosens them back up. Probably fine dust on the ball is the culprit. How do the costs compare?

Thank you for responding.

The 2" PVC pipe and fittings (elbows, wyes, couplings, etc.) seem to be less than 50% of the cost of similar components for 2.5" dust collection systems (from Rockler & similar vendors). The PVC ball valves do cost about 25% more than the "better" 2.5" blast gates (which still aren't very good). Total cost of a PVC system would be less, and the components are available at any home improvement store.

A common complaint of the 2.5" systems is that they tend to leak, as the pieces don't fit together nearly as snug as with PVC. The 2.5" pipe is expensive and comes in 3' sections, so there are likely to be more joints to leak. (I will say that it is kind of neat to be able to see dust moving through the clear 2.5" pipe.)

In my opinion, it appears that the advantages of PVC (stronger, seals better, easier to find parts for, less expensive, available in longer lengths) are enough that it makes sense for me to go forward with PVC.

welincoln3 months ago

Thank you for writing this instructable! I am in the planning stage of building a basement workshop. I have a few pieces of the clear 2.5" pipe and fittings from a small setup that I used at my previous home and initially planned on expanding on this system. However, the more I research and think about it, it seems that using 2" PVC would be better and probably less expensive.

How well do the ball valves work for dust collection? The commercially available 2.5" blast gates seem to be almost universally disliked, and the PVC ball valves seem like a much better option in theory. Thank you!

Gantman4eva10 months ago
Could u give some more info on the dust collecting chamber itself? What did u use to put it together are there any baffles inside?
spstewart (author)  Gantman4eva10 months ago
If you are referring to the barrel where the sawdust ends up, it is just a 30 gallon paper barrel with a metal lid that lifts off. There are no baffles inside at all. I suppose most people would use a metal barrel but I had this one and it is much lighter.
spstewart (author) 10 months ago
If you are referring to the barrel where the sawdust ends up, it is just a 30 gallon paper barrel with a metal lid that lifts off. There are no baffles inside at all. I suppose most people would use a metal barrel but I had this one and it is much lighter.
RangerJ1 year ago
Really outstanding. I have never gotten around to much beyond building a DIY cyclone thing, but I have every intention of getting on it when it gets warmer...

Thanks
frozedog1 year ago
Steve,
How much did the AutoSwitch cost to build?
spstewart (author)  frozedog1 year ago
Most of the stuff was in my junk box. The Aprilaire 51 current sensing relay was on ebay, think $15 or so, same with the RIBU1C(ebay). I could have built cheaper by not using the heavy electrical box(Menards- don't remember the cost). But I don't think I have over $60 in it.
edalquist1 year ago
Could you list the make/model/part number for the vacuum relay? I'm looking to built the automatic vacuum toggle part of this project and want to make sure I'm looking at the right parts.

Thanks!
spstewart (author)  edalquist1 year ago
Sorry for the procrastination. Look over the schematic and pics again, I had updated the circuit but didn't get around to updating this website. I think the relay you want is the R1BU1C, I'm sure I got it off of ebay.
Steve
spstewart (author)  spstewart1 year ago
Make that RIBU1C from Functional Devices.
http://www.energysavingcontrols.com/Functional-Devices-RIBU1C-RIB-Relay-Enclosed-10-amp-SPDT.html
Awesome, thanks for the info. The best pre-made relay I could find for a reasonable price only handles tools up to 12A so this setup using a current sensor will be perfect!

I'll try to make a specific set of instructions for the relay when I build it and link back here to yours.
kryptoman2 years ago
Cyclones are great, but note that shop vac is not going to give you anywhere near enough airflow for the equipment you have it hooked up to, if you want to remove the fine dust that is dangerous to your lungs. I recommend anyone looking at dust extraction for woodwork equipment do a google on Bill Pentz and check out his web page on how to build an adequate system and why you absolutely need it.
spstewart (author)  kryptoman2 years ago
Yes, I looked at Pentz's material in my research, and for a full time shop, it makes sense. but if my shop vac ran 30 minutes a day i would be suprised. This is just for occasional use. (Too many other hobbies).
Makedo2 years ago
I have made a dust collection system from shop vacs. The major problem is to prevent fire you need to find a vac with a ball bearing motor. Because the cheap ones will catch fire if used all day. the lack of bearings will allow the motor to wear the plastic bushings and will cause miss-alinement of the brushes and cause over heating. For safety you should use a timer in line . also place a smoke alarm over the motor so when you turn it off . it will sound off if there is a problem. just set it on top when your done. I have burned up about 8 vacs. and have never burned up a vac with a ball bearing motor.
pfred22 years ago
Have you had any issues with static electricity and your plastic piping? I've heard tales both ways, anywhere from it doesn't matter to it'll knock you across the room.
kentdvm pfred22 years ago
My 2 cents .... I have a cyclone dust collector and about 40' of 6" plastic pipe running around my shop. I've not had any problem with static electricity during the 6 years since I installed it. So my vote is in the "doesn't matter" category but I agree there are a lot of stories and theories out there.
pfred2 kentdvm2 years ago
There are a lot of things you have to get right, er, wrong, to make a PVC vacuum system into a decent static generator. The potential is there, realizing it isn't always easy though. Running higher CFM and more drier and finer dust with drier air and you may be onto something with your 40' 6" system, then again maybe not.

What certainly doesn't matter is the static sparks cause fires nonsense. If you're running hard enough to create ignition sparks you're running too hard to support combustion. It is just like trying to light a candle in the wind. Though I believe some extremely poorly designed systems have been known to make little explosions inside them. They literally blow themselves out when they happen though.
kentdvm pfred22 years ago
I agree. My system pulls 4400 CFM so I'm not sure a spark would matter much. What I am concerned about is if metal hits my impeller and lights my collection of dust on fire. For my dust can I'm using a metal trash can and lid to help prevent a shop fire. That's a much greater risk than static sparks, however, I don't think it's as great a risk using a shop vac. Always something to keep in mind though.
pfred2 kentdvm2 years ago
What I wonder is why can't impellers be screened off? Nothing that would block air flow, but something that would stop larger chunks from hitting the blades. That is how shop vacs are. Their impellers are behind the filters. But I'm not saying put the filters on larger dust collectors in front of the blowers, but put something there.
spstewart (author)  pfred22 years ago
I read things on the web like that also, but so far, no trouble. I left the end cap unglued so that I can run a ground wire in the future if I need to, but thought I'd wait and see.
Now that I've given it a little more thought you're likely running too low velocity and volume to make much of a charge. All running a wire inside PVC will do for you is give debris a place to lodge. That has to do with the fact that PVC is an excellent insulator, how long sparks do you think you're going to be making? You'd have to be making several inch long ones in the pipe you have for the wire to work. Victor Frankenstein would have set a cot up in your shop long before then! If you say it's alive one more time ...

If you haven't felt anything I wouldn't worry about it. I don't think you should either. But keep that cap free, you might want to expand your system someday.
temper2 years ago
Great stuff Steve, any info on the ball valves?
spstewart (author)  temper2 years ago
The ball valves are regular water PVC 1 1/2" off the Menard's shelf. They open the full dimension.
Cheers.