Dust collection question

[aaron olson]

Hello, i have a small 20x20 shop using a harbor freight dust collector. I put in 4" pvc pipe that runs vertical along the ceiling to service both sides of the garage. The dust collector sits under the steps on the far side and pushes the fine dust outside and the rest in to a garbage can. I will try and post some pics of this stuff too.

My chop saw sits on the opposite side of the garage and is probably my biggest dust generator. When i try and run the dust collection however I find that very little is captured and part of my issue it seems is that the suction from the harbor freight unit isn't enough to push it vertically the 9 feet or so.

I have been using a shop vac which just doesn't collect enough dust so would like to try and improve what i have or put something better in place.

I don't think spending a ton on a new dust collector is wise but if you guys think otherwise say so.

A few options i have thought:

Idea 1 - and would be my first choice if it could work
I would love to utilize the harbor freight unit as I like that it extracts to the outside. Also, there is then only the one unit that i have to clean and maintain getting rid of dust. The idea here is could i but another harbor freight unit and install it on the far side of the garage and run them together. The idea being that the additional unit would aid in capturing and pushing the dust vertical and utilizing all that I have in place already. If that would stress the system to much what about a wall mounted 4" unit like the grizzly or wen?

Example:
https://www.homedepot.com/p/WEN-5-7-...+%7Bproduct%7D

Idea 2
Simply use a wall mounted unit and enclose it since I know that bag doesn't collect the fines and call it a day?

Any thoughts or ideas?

Thanks

Hopefully you can see a little of the piping in the first picture. the second (which i can't figure out how to rotate) is a continuation of the picture but of where the dust collector sits and extracts outside.

20180703_132144.jpg _temp_rotation.jpg

[Peter Christensen]

Aaron you have a few problems to deal with.

First is you have one of the more difficult machines to collect from far from the DC. Difficult at this stage to put it with the DC.

Second is the 4" pipes can only move a maximum of 425 cfm no matter what DC you have pulling. 6" pipes can move about 1200 cfm but there is a cost to upgrading.

Third is the length of the piping and number of elbows creates a lot of resistance to airflow, reducing what you can capture at the saw. Each elbow equals 10 feet of pipe. Here is a link to a calculator that will show you what kind of losses you get with different configurations.

Forth would be the DC is too small for what you are trying to do. If you try to put a second in line they may not play well together especially with the small pipe.

Putting a small dedicated DC would be the easiest to make work but the one you linked can't do much better with it's small impeller and half horse motor. The cfm numbers are not realistic. half would be closer to the truth.

Finding a 3hp collector on Craigslist or similar to replace the HF and upgrading to 6" pipe would be one way to solve your problem. Mount it like you have with the HF.

[Brice Rogers]

Aaron, I think that your idea of using two cheap DC is something worth trying. It is a cheap experiment. There are those that will tell you that you should spend a few thousand bucks and get a 3, 4 or 5 HP unit. There are HVAC devices that are put on furnace ductwork that boost the flow. So, it probably can be done. I suspect that the main DC suction unit is going to run with a slight positive "back pressure" (that is, it will run better than with no back pressure at all).

Peter's suggestions to go to 6" pipe and reducing elbows or making them more gradual are great ideas. And your DC is probably a bit on the small side.

I have a Harbor Fright 2 HP DC and ran 5" or 6" pipe but I suspended it only to about 7' above the floor rather than the 10' ceiling height. Like you, I run it through a separator and vent it outside. I also have a 1 HP HF DC and a spare Oneida separator - - so one of these days, I'm going to connect them is series and hook the 1 HP unit to the far side of my shop.

BTW, on your chop saw, make sure that you have a decent pickup - - I put a "big gulp" on my radial arm saw and it works very well. For straight cross-cuts, I think that about 95% of the sawdust is forced into the pickup without even the vacuum. Very little escapes with the DC turned on. On ripping cuts, I hook a 2" line to the saw and perhaps 80 plus percent gets caught.

[Matthew Curtis]

Sounds like you have an underpowered system with one of the worst machines to collect from way too far away from collector.

You may be better off using shop vac for chop saw.

[Rhys Hurcombe]

Bigger collector, bigger ducting. Or, move the DC closer to the miter saw. Or, get a second DC just for the miter saw. Peter did a good job of explaining the issues in the system. Dust collection is never perfect but improving it means you're improving your health.

[aaron olson]

Thanks everyone for the responses.

If i upgrade the piping to 6" how much of it do i need to upgrade? Only along the ceiling and then drops from there or do i need to make it 6" down the walls too? If i do this it feels to me like i would get less suction at the machine even when branching off the 6" to 4" at the machine is this true? Would it help if i mounted the actual motor half way up the wall do you think? I understand the 90's reduce the flow but how would i reduce them do in my setup?

I think eventually i would go with a bigger unit so the pipe upgrade seems like it would be a necessary evil at some point anyway and extracting the fines outside is what i want to do. The idea of putting a unit on that side of the building is just not as appealing when I have thought about it more. Another hole in the building to the outside and multiple units and bins to keep clean doesn't sound as appealing.

Health is a big thing for me with all of this. Second, i wear the mask so much it starts to detract from the enjoyment a bit. it is comfortable when it is on for hours it starts to suck.

Last any recommendations on a unit?

[Matthew Curtis]

I just worked my butt off in order to save the money for my last collector I plan on ever buying. To me it was worth saving up to by the right tool.

I pieced a poor dust collector together for ten years. It was not fun or good for my health.

I strongly recommend upgrading to something that can control fine dust at the distances you ate talking about. 4" runs will not be able to do that. You will need at least 6" runs and a collector less than 2 hp will probably not be able to move enough air through the larger ducting.

[Robert Engel]

Thanks everyone for the responses.

If i upgrade the piping to 6" how much of it do i need to upgrade? Only along the ceiling and then drops from there or do i need to make it 6" down the walls too? If i do this it feels to me like i would get less suction at the machine even when branching off the 6" to 4" at the machine is this true?

That's the way I did mine and it works fine.

Would it help if i mounted the actual motor half way up the wall do you think?

I'm no expert I'll tell what works for me. I would put the blower up high with the ceiling pipe running straight into it.

I understand the 90's reduce the flow but how would i reduce them do in my setup?

Two ways: use sweep fittings for 90's and Y fittings for branches (S&D fittings have both). You can also use 2-45's with a short length between.

I think eventually i would go with a bigger unit so the pipe upgrade seems like it would be a necessary evil at some point anyway and extracting the fines outside is what i want to do.

I've got a 1 1/2HP blower using 6" pipe and it works great.

Health is a big thing for me with all of this. Second, i wear the mask so much it starts to detract from the enjoyment a bit. it is comfortable when it is on for hours it starts to suck.

Smart. No DC will give you total dust control.

Last any recommendations on a unit?[/QUOTE]Lots of guys tout the Harbor Freight 2HP unit. Without knowing the whole layout and distances and machines, hard to say exactly.

[Peter Christensen]

Two ways: use sweep fittings for 90's and Y fittings for branches (S&D fittings have both). You can also use 2-45's with a short length between.

Here is a PDF that has a lot of info. On page 54 the Fitting Loss Charts show that 2-45's have more drag than a single 90. A 3 piece 90 (basically 2-45's) has about twice the drag as a smooth radius 90. A 2 piece 45' is about the same as a smooth 90 so a pair of 45's is double the smooth 90.

I've always assumed the information was for metal ducts and that PVC is a little smoother but the information from the chart would suggest that 2-45's have roughly twice the resistance as a single smooth 90, so unless someone has actually test data showing the 2-45's are indeed better than using a single 90 is the way to go. I doubt anyone has put together a few lengths, one with 45's and the other with 90's and tested them, but it would sure be informative if they did.

http://www.lorencook.com/PDFs/Catalo...ok_Catalog.pdf

Out of curiosity I played with the calculator I linked in post #2 and put in 6-90's and again with 12-45's and the results were about the same depending on whether it was done with ACFM or SCFM. I don't know what the difference is between them. With no advantage or a slight loss in the 2-45's and the extra work it would seem that just using 90's would be most appropriate.

http://www.freecalc.com/ductloss.htm

[John K Jordan]

I just worked my butt off in order to save the money for my last collector I plan on ever buying. To me it was worth saving up to by the right tool.
I pieced a poor dust collector together for ten years. It was not fun or good for my health.
I strongly recommend upgrading to something that can control fine dust at the distances you ate talking about. 4" runs will not be able to do that. You will need at least 6" runs and a collector less than 2 hp will probably not be able to move enough air through the larger ducting.

I agree. I spent a year reading and researching and up for a dust collector while building my shop. There are a lot of compromises I could have made for a lower performance and lower price. In the end I installed a 5hp ClearVue cyclone with 6" pvc ducts to 6" drops to the machines. This cyclone has so much suction I don't worry about any efficiency loss at 45s and 90s. It separates so well the bin gets even the flour-fines and almost nothing goes to the filters and the clean-out box below the filters.

The only downsided is it is extremely loud so I put it and the 5hp air compressor in a sound-insulated closet.

I am glad I didn't skimp on the dust collection.

JKJ

[Chris Parks]

Here is a PDF that has a lot of info. On page 54 the Fitting Loss Charts show that 2-45's have more drag than a single 90. A 3 piece 90 (basically 2-45's) has about twice the drag as a smooth radius 90. A 2 piece 45' is about the same as a smooth 90 so a pair of 45's is double the smooth 90.

I've always assumed the information was for metal ducts and that PVC is a little smoother but the information from the chart would suggest that 2-45's have roughly twice the resistance as a single smooth 90, so unless someone has actually test data showing the 2-45's are indeed better than using a single 90 is the way to go. I doubt anyone has put together a few lengths, one with 45's and the other with 90's and tested them, but it would sure be informative if they did.

http://www.lorencook.com/PDFs/Catalo...ok_Catalog.pdf

Out of curiosity I played with the calculator I linked in post #2 and put in 6-90's and again with 12-45's and the results were about the same depending on whether it was done with ACFM or SCFM. I don't know what the difference is between them. With no advantage or a slight loss in the 2-45's and the extra work it would seem that just using 90's would be most appropriate.

http://www.freecalc.com/ductloss.htm

This has been proven to be the case in tests done in Australia as well. One the biggest impediments to a lower powered dust extractor is the inlets which should be in the form of a bell mouth which fits into the cut pipe. 150mm/6'' pipe must be used all the way to the machine and the ports on the machine modified to the same size and the DE should be outside as the generic bag types all leak dust. Any separator put in the duct to catch bigger debris will also greatly reduce the air flow as well. The problem can be looked at two ways, a small less powerful system needs far better design and execution to detail to make it perform as well as it can. A larger and more expensive system needs less design detail as it has the capacity to overcome a few short comings so the larger one might actually be cheaper to install in both man hours and cost. People say it is only a small hobby workshop but the lungs in the individual do not see the difference unfortunately.

[Matthew Curtis]

. People say it is only a small hobby workshop but the lungs in the individual do not see the difference unfortunately.

As a Respiratory Therapist I can actually figure out who is a shop worker without them ever saying. Between the lung eggecys and hearing loss it is easy to tell.

I have been really trying to upgrade my systems as of late in both dust collection and hearing protection because of some of the things I see at work.

[Peter Christensen]

Matthew are you able to tell any other professions without being told? I worked in an aerospace machining shop and the air was filled with oil/cooling mist from the machining and the metal dust from the edge and surface grinding the metal finishers did. One machinist had to go on a compensation pension because of the damage to his breathing, like emphysema. I have sensitivity to dust, asthma like, from it too along with some hearing damage. Any suggestions for noise control in the shop aside from good ear muffs?

[glenn bradley]

Dust collection threads can wander far and wide. I will focus on one facet of you situation that could bring you some immediate relief. A vacuum is going to do a better job on your CMS than a DC. I have seen some enclosures and hoods that keep the bulk of the larger spoil contained so that a DC port can pull it in.

The fine dust still escapes into your breathing air similar to how spoil comes off a hand held circular saw or a router; its just moving too fast for the DC airflow to over come and capture. A shop vac with something like a Dust Deputy separator and some sort of shop made hood for overall containment would be my choice for the CMS. Although this worked well for me, the function of the CMS didn't earn the footprint it takes to operate one effectively. Mine lives out in the shed and I use it outdoors on the rare occasions that I need to cut very long thin stock.

It may be that by removing the CMS from your overall system via the dedicated vac your other stations will fare better.

[aaron olson]

Appreciate again all the feed back.

I have to say there are varied responses here for sure and works for one is very different from another. Nice to have options.

Is there a solution that doesn't require wearing a mask the full time one is in the shop? I am in here now for example and gut some wood 10 or so minutes ago with the mask and have it off and have a voice in my head saying I should be wearing it.

Also what is the consensus on an air cleaner? I have a jet model i run 75% of the time i would guess. I hope that does more than just stir things up but curious on what the group thinks of them?