I Hooked a Shop Vac to a Dust Collector and This Happened

[@buddythompson5284]

Justin Depew is brilliant. Check out his earlier videos where he set up a fully functioning woodworking shop in an apartment bedroom!

[@michaelmoster1382]

Great video.. A suggestion to eliminate your 2 remotes is to automate your blast gates to automatically start and stop your DC when they are opened or closed.... with a VERY easy and inexpensive setup with a low voltage relay and microswitches. Works on both 110 and 220 volt dust collectors. There are videos on youtube showing how to do it.

[@Katiebelly123]

Wow, thanks for the really articulate presentation and very clever design. Doing the measurements of both air flow, and pressure, added numbers to what is typically left to speculation!

[@quinn860]

I like the wooden valves and levers you have setup very nice

[@CALDues]

Love a new angle that is so well done! Thanks

[@mmezz5965]

Thanks for the video Justin Have you considered incorporating a venturi into your system? The small vacum airflow would then likely increase suction on the 4" line at the table saw.This may help with getting dust into the system but in the end I think you are right in that you will be limited by the max airflow through your large collector filter.

[@JohnMadeit]

It would be interesting to see what the results would be if you were to run the output of the small vac in to the large dust collector after the the motor. So basically both systems just feed in to the large filter. I suspect that you would keep the performance of the vac's has they was individually. .

[@Farm_fab]

A good source for used vacuum motors is any shop that routinely does pm on them. The voltage could be 24v or 36, but they are made by lamb electric. They likely would need bearings or brushes, or both. I have one that was to be scrapped, and it seems to be in good repair, but I've not tried it on 24v yet. The only draw back is a power supply to run it, but there might be a solution at your nearby scrap yard.

[@999erh]

Those dust collectors have a 5" intake, which is then reduced down to the 4" pvc. It happens to work out that a 4" and a 2.5" together have roughly the same surface area as a 5". I wonder how it would do with a dedicated 2.5" pipe running all the way back to the splitter at the intake...

[@WalnutAlley]

I experimented with connecting my shop vac to the opposite end of my main dust collector trunk line in the opposite way you did. The vac and dust collector were pulling against each other, and I had a very noticeable increase in suction at all tool ports.

[@joe-edward]

That's a great looking table saw, you should do a video on that build.

[@RossTheGenMan]

if you disconnected the mini dust collector from the larger system when the larger system wasn't running I believe you would get the same reading as you got with it connected and the big system running. it will go down without the big system running becuase when its off its basicly restricting the airflow out of the mini collector.

[@jayraysdiy852]

I’m wondering if the loss in CFM at the lower port is due to the way the exhaust from the small collector is entering the 4” pipe. it may be possible to make a smoother transition so the air is flowing the same direction and that may increase the air flow in both units. I’m not sure, but seems logical.

[@daveb5816]

Justin, I found your video to be very interesting. Thanks for running the tests and posting the results. However, I disagree with your conclusions. Discharging the mini dust collector into the large dust collector caused the air flow from the bottom of the saw to be reduced from a marginal flow rate to a very poor flow rate. According to date posted by Bill Pence, the OSHA requirement for dust collection from the bottom of a table saw is 440 cfm. The flow rate from the top of the saw should be at least 350 cfm. In my opinion, the mini dust collector should have its own filter, so that the flow rate from the bottom of your table saw is at least 440 cfm.

[@JustinDepew]

Thanks for the thoughts Dave. I had not hear the 440 CFM requirement. One other thought I've had is to exhaust the mini dust collector straight outside, still no filter.

[@paulruud5804]

Thanks, Justin. I enjoy all of your videos.

[@JustinDepew]

Thanks Paul!

[@neilf4128]

Wow man! It takes you a long time to put out videos. But whatever you share, is always amazing and innovative. I just love your channel. So glad to see you again. Here's to seeing you once more in another 6 months. Keep up the amazing content.

[@JustinDepew]

Thanks Neil. Too many projects, not enough free time!

[@tseckwr3783]

Thanks for the detailed video.

[@NMranchhand]

Fascinating test. I learned a lot. I’m dying to know what happened at some point downstream of the junction of the two flows to see if it affects the flow/pressure through the main separator. Also, I would want to try hooking in the shopvac output upstream of the table saw to see if it put a draw on the main line to the table saw undercarriage.

[@Craig-qx7uy]

Thanks for this! I’ve been thinking about doing the same thing. Now that you’ve done all the hard work for me I think I’ll run a parallel system (HI/LOW) to my dust collectors and activate both with relays as I’ve already got a iVAC switch for my High pressure DC. Cheers!

[@MD-en3zm]

Great video. I’ve been contemplating doing something like this as well. You saved me a lot of work testing this out. I have also been wondering if something even simpler - like an in-line fan - might be enough, but not sure if it would generate enough pressure.

[@placestosea]

interesting video, thanks for posting. it would be interesting to see how much power you are using compared to just upgrading to a larger main collector ( also noise as series/brush motors are often noisy)

[@ThomasZickell]

I previously owned a factory that produced cardboard cores like the ones found in paper towel tubes and other materials. The process of cutting all the paper created a lot of dust, which required a giant suction system similar to the one you have in your shop. I find the Cyclone system to be a great idea. I'm curious if you have installed a HEPA filter and completely sealed it. Currently, we are working with engineers from Miele and Fest Tool to develop a perfect solution. I would appreciate your input on this matter.

[@VulgrDisplay]

I would imagine a larger home run pipe going to the 2.5" and 4" connections would negate the loss as the larger pipe would have more volume.

[@musicbymark]

If you rebuilt your overhead dust collector today, would you still go with the smaller sized hose, or would you go with something larger, similar to the Excalibur and saw stop overhead desk collectors?

[@JustinDepew]

Good question. I think if I had a larger more powerful dust collector I would use a larger diameter. With my harbor freight unit now, I don't think there would be enough suction if I split the 4in line into 2 lines. I also like the small size of my over arm so that's another reason to keep it small.

[@joedance14]

Very interesting! Thanks!

[@donmeyers3090]

Dude!!! Wow!!!!!!!

[@kelseydepew]

Another great video! Bravo! 😃

[@Sehast]

Great video. I am considering doing something similar. Do you think you could eliminate the chip collector on the mini collection unit and just let the big dust collector pull everything to it? I want to reduce the footprint as much as possible and not have to service them mini collector at all.

[@JustinDepew]

Stephen - I don't think so. The dust and chips would have to go through the impellor. Unlike big dust collectors, the impellor on a shop vac is pretty small and flimsy. I imagine the chips would get stuck in the impellor and could cause damage. This is why I have the chip collector attached.

[@brandonbradford6317]

@@JustinDepew I probably don't know vacuum systems that well, but a theory might be could you place another junction connection to your main line but above where the shop vac is feeding its pressure to the main line and have that connected to your dust/ chip collector so that it pulls the separated dust/chips into the main line and doesn't go through the shop vac impeller? If the junction for that is above the exhaust of the shop vac wouldn't the pressure from the shop vac help draw that extra debris in the main line?

[@pnwgrown_360]

What product is that for Your remote to turn on those tools

[@TBizzell68]

Nice! I suspected that the mini would pressurize the main system and decrease it's efficiency more than it did. The fact that you showed the testing was a great addition. P.S. that filter on the main system is almost comically big, I can't imagine where you found it.

[@saritsotangkur2438]

Not sure I understand the conclusion. Why is gaining 1” of pressure on the shopvac worth losing all that CFM on the dust collector?

[@DG-vo8yc]

@JustinDepew Like @saritsotangkur2438 I also don't understand the conclusion or why other people aren't making the same point. The shopvac gained less than 3% in pressure while the dust collector dropped 27% in CFM. It's clearly better to run them separately. I love your channel in general though!

[@TildaAzrisk]

The connection to the big dust collection is for the filtration of fine dust, as the small unit isn't capable of filtering out fine dust on its own and requires a filter on its output before the air is returned to the room. Its explained at 2:37, though not very clearly. As far as I understand the collection system of the shop vac is there just to prevent big chips passing through the shop vac's blower and damaging it. And the airflow testing being done check that things are still working ok, given that it is a rather unusual configuration. The new system may or may not be at picking up dust, but having a centralized filter is was easy to set up and it means fewer filters to change.

[@neilspurr7149]

Nice to have you back (not sure where you have been for 8 months heard rumor's but I'm not interested in them just good honest shop work. ) Nice test comparison interesting results. >> Neil from South Australia

[@JustinDepew]

Thanks Neil. I have been busy with home a home renovation project.

[@chriss8206]

You could have just tapped the small hoseall the way back at the 4 inch take off by the dust collector.

[@dre7637]

Why’d you quit making videos? Been seven months! I hope you make more they’re great!

[@B.A.Bassangler]

Dood...you're a madman, truly 3D Chess thinking. I bought a manometer too, lol. Rather than doing stoopid math...it's easier to experiment with pipe diameter and measure air speed on your mains and drops.

[@kirkpowell6161]

Great idea, great video!

[@jessjulian9458]

The only test that matters is does it remove the dust from the table saw. I don't understand why you didn't try that. After all that is the point, isn't it?.

[@chchchscott1]

A good example of book knowledge vs experience. You did the engineering and math but didn’t actually do a real world test. CUT SOME WOOD AND SEE HOW THEY ACTUALLY PERFORM.