Improving HF dust-spreader with 4" PVC ducts: Pentz cyclone or Thien baffle?

[Jon Singer]

Hello, first post. Looking for some basic DC guidance. I've been doing a lot of reading (Bill Pentz's website) and everything I'm seeing says that I probably should be bigger than 4" ducts and that the HF motor/unit I have is garbage. I bought the HF unit a few years ago (used on CL) but it did come with the upgraded Rikon impeller. I've got a 25x25 2-car garage/shop with 2 bandsaws, ts, two RAS, planer, jointer, router table, etc. I also have a couple welders and some metal working stuff that's not part of the DC issue but I'll mention it because I've got a metal brake and can weld so fabrication isn't an issue at all. I think I've got a typical homeowner shop. Every once in a while she's out in the shop with me doing a project or maybe I've got a friend over and two machines get used at same time. That said, 99.9% of the time it's just me, one machine at a time and two dogs sitting at attention waiting for the off-cuts to fall to the floor.



My biggest concern is my health. My allergist told me to wear a respirator and get an air filtration system in place. Second to that, space/footprint and noise are the two other things I worry about. Reading Bill Pentz's website wasn't very encouraging that I could get what I want by modifying the HF unit --but also I wonder if modifying what I have will be night/day over what I've been using and therefore it'll make a difference.


Venting outside is not an option. Or, I REALLY don't want to vent outside. My garage is fully finished and insulated. I had issues with a single-vent rolling air conditioning unit and I know that I'd have big issues venting a DC outside. In addition to that, I'd like to add a vent hood over my welding table and put a HEPA filter on the back end of the DC so I can try and double-dip using it as DC as well as air filter when woodworking machines aren't on.


With all that said, I'm trying to decide if I want to fabricate a Pentz cyclone or if a Thien baffle will be just as good. Thanks.

[Andrew More]

Bill Pentz is a bit alarmist, so take what he says with a grain of salt. If it's also not clear from his site, he wrote it a number of years ago, and things have moved on a bit. Finally he's got a dust allergy, which may or may not be something that also effects you.

In this case "safety" is likely going to be pretty expensive, and not guaranteed. Even if you install one of those clearvue-cyclones with the 5 HP motor, perfect ducting, and the best shrouds available you're still going to generate saw dust that isn't captured by the dust collector. Not to say you should just give up, it's a matter of making trade-offs, and accepting that no solution is perfect.

If you want to spend as little as possible, and still get some safety, best solution is to put a Wynn environment filter that captures submicron dust onto the HF unit. Working with a 3M dust mask with organic filters is another excellent solution.

A cyclone or thien baffle really is about convience. Generally what they do is pull the sawdust out better than the 1 stage HF, but they're not necessarily any better at protecting your health.

[Jon Singer]

Bill Pentz is a bit alarmist, so take what he says with a grain of salt. If it's also not clear from his site, he wrote it a number of years ago, and things have moved on a bit. Finally he's got a dust allergy, which may or may not be something that also effects you.

In this case "safety" is likely going to be pretty expensive, and not guaranteed. Even if you install one of those clearvue-cyclones with the 5 HP motor, perfect ducting, and the best shrouds available you're still going to generate saw dust that isn't captured by the dust collector. Not to say you should just give up, it's a matter of making trade-offs, and accepting that no solution is perfect.

If you want to spend as little as possible, and still get some safety, best solution is to put a Wynn environment filter that captures submicron dust onto the HF unit. Working with a 3M dust mask with organic filters is another excellent solution.

A cyclone or thien baffle really is about convience. Generally what they do is pull the sawdust out better than the 1 stage HF, but they're not necessarily any better at protecting your health.

Thanks. Yes, I did gather that he did his research several years ago and I do understand that no solution is perfect. I'm not looking for "clean room" clean, just better than a 1 stage HF unit. I've never had allergies (ever in my life) but over the past several years that I've really started doing more woodworking it seems like a constant sinus infection, nasal issues, always stuffed up, coughing, hacking, etc. Zero DC started it and then I'm not sure that the stock HF dust distributor helped much. I weld a bunch so I am clean shaven (for good seal on respirator, ever notice how firemen are all clean shaven) but respirator is not an ideal solution. We have a newborn, attached garage, two dogs, etc. I don't want everyone breathing my sawdust.


Budget is flexible. I'm not spending $3,500 on the latest and greatest simply because I don't have room for it. I'd like to find a way to modify the HF unit into something 2-stage-ish and put as much of it as I can up on the wall vs. taking up floor space. I wouldn't mind the Wynn filter and the HF motor up on the wall with a pipe doing down to a Thien baffle over a 55-gal drum.


Looking for a reality check: How much will that really help? I'm fine spending the money but I want it to work and make a difference. Thanks again.

[Larry Frank]

If your health is an issue, perhaps spending the money for a really good dust collector will save you money. One trip to the ER because of an allergy attack or pneumonia would pay for an excellent dust collector.

[Jon Singer]

If your health is an issue, perhaps spending the money for a really good dust collector will save you money. One trip to the ER because of an allergy attack or pneumonia would pay for an excellent dust collector.

Not since Obamacare. Maybe I could get Obamacare to buy me a dust collection system as preventative maintenance? It's not that bad. Just that I've been sucking down sawdust for too long without a decent DC. I'm not really worried about the money, just wondering what people are using and what works for them. When the kid starts walking I'd like to give mom a break and have some company in the shop.

[Andrew More]

The problem with a two stage DC from the HF unit is that you're likely going to find that the velocity drops below that necessary to collect the fine dust. It might also make chip collection less effective. I'm not sure what the performance cost is, and YMMV, but 20-40% reduction in CFM and equivalent air speed seem likely.

OTOH, it's a relatively cheap project, so maybe it's worth the gamble of $50-100 + an air speed meter.

If your intention is to protect your health cheaply, the cyclone or thein baffle won't effective it, just the filter, which is probably inadequte on any bag filter, though once again YMMV. There's another thread on air quality meters, you can get one pretty cheap on Amazon, and it would answer your questions about what's floating around, and how bad it gets.

One interesting note with regard to Bill's claims: Mathias Wandel got a air quality meter, and determined that yes, there was stuff in the air after various wood working operations, but at the same time, there were problems with the air quality in general just going outside on some days.

https://woodgears.ca/dust/dylos.html

FWIW, I bought the Grizzly G0443, which most people will tell you is underpowered by Bill's calculations (1 1/2 HP vs 5 HP motor), but works amazingly well in my small 2 car garage shop. Probably a bit of overkill, truth to tell. Unfortunately Grizzly has since discontinued the model, not sure why.

[Carl Beckett]

First - mine is just another opinion and there is no exact answer to DC. Hence the zillions of posts on the topic similar to yours.

From your post it sounds like you are showing signs of respiratory sensitivities. And have exposure in your job on top of it. And a young child and others to consider. And like to work inside (with the doors and windows closed for climate control)

I do not think upgrading the HF is a great solution. My own personal experience was a series of band aids and upgrades until I landed on a 5hp clearvue (there are other options), after much wasted time and expense. But even this current system is lacking in some areas around collection at the source.

So I recommend bumping up the capability to a larger system.

An air quality meter would be a good addition and would answer your questions with data...

[Jon Singer]

First - mine is just another opinion and there is no exact answer to DC. Hence the zillions of posts on the topic similar to yours.

From your post it sounds like you are showing signs of respiratory sensitivities. And have exposure in your job on top of it. And a young child and others to consider. And like to work inside (with the doors and windows closed for climate control)

I do not think upgrading the HF is a great solution. My own personal experience was a series of band aids and upgrades until I landed on a 5hp clearvue (there are other options), after much wasted time and expense. But even this current system is lacking in some areas around collection at the source.

So I recommend bumping up the capability to a larger system.

An air quality meter would be a good addition and would answer your questions with data...

Thanks. I'm looking to buy an air quality meter (probably today on Amazon). Strange that you hit the nail on the head about me. I used to live in a city and wear a tie to work. Then I met her. Now I work from home part-time and have been fortunate enough to try a few new things. Over the past few years I've done a lot of work on our home (total gut/reno, addition, Hardie siding). I also purchased a home with the intent to fix/flip it but circumstances changed and a family member now lives there. I look at it as more of a hobby but my 9-5 over the last few years has been doing construction/jobsite work. Everything from framing & drywall to building cabinets and furniture. I went from 0-100 with woodworking and a shop. So the "exposure in my job" comment is very accurate. At night when I was working in my home shop, most days I had already spent 8-10 hours in "jobsite conditions" (no PPE, DC, etc.).

Having a kid changed everything. Once the houses were done I started making furniture, crib, etc. and whatever else she finds on Pinterest so still doing a lot of woodworking (and a moderate amount of welding). I feel like working with hardwoods (or anything other than dimensional) made the fine dust/particles much worse and I think it's really starting to take its toll on me.


I think now what I'm trying to balance is what I did previously over last few years vs. what the next few years of my life is going to be like: more kids, less time in shop, etc. Maybe I'll start cheap/easy, buy an air quality meter, build a Thien baffle + buy a cartridge filter and start taking measurements. At least that way I can establish a baseline and go from there. There are also a few other considerations on my end: We are going to move at some point. We are building a new house on a property with a 40x90 barn. The perfect solution for a 25x25 shop won't be close to what I need in the new place. I'm not looking for a band-aid, I'd like a reasonable fix but I also don't want to spend a bunch of money that will be useless to me in a year.


Thanks.

[Gerry Grzadzinski]

You can get 20% more airflow from your HF collector by changing the impeller.

https://www.youtube.com/watch?v=2NOZTlwHe3A

https://www.toolcenter.com/60-200-22.html

[Frank Drackman]

He already stated that his collector has an upgraded Rikon impeller

[Curt Harms]

I was in a similar situation to Jon and didn't want to invest a lot because I don't use dust producers very much. I did first install a Wynn cartridge filter and it clogged too fast for my tastes. I got one that I could wash out with a garden hose which did help on the cleaning front. I then read about the Thien baffle and decided to make one of those. The baffle cut down on the amount of material getting to the filter by quite a lot, virtually no chips and not much dust. If I were doing it again I'd use a thinner material or at least round over either end of the slot to cut down on air turbulence in the slot. Some pics:

[Robert Engel]

Well one thing you've realized on point is regardless of the efficiency of your DC, wearing a respirator.

I whole heartedly agree 4" ducts are woefully undersized for that blower.

Just a suggestion: rather than ducting to all those machines, just do the tablesaw, planer, jointer & maybe, the bandsaws. I say this because, for example, my smaller 12" bandsaw is definitely not worth collecting. I do collect my big bandsaw but truthfully I rarely use it. I'd go so far to say collecting a bandsaw may not be worth the effort.

Keep in mind planer and jointers produce shavings, hence a cyclone is definitely the best way to go.

The biggest duct producers are the most dangerous healthwise. I respirator is in order as well as an air filtration unit when using these machines. They are also require higer CFM's and therefore are the hardest to collect. I have an air filtration unit mounted directly over my tablesaw. I do not do overarm collecting.

I would forgo trying to duct to collect the other tools. IMO, a shop vac unit with a cyclone is the best way to collect routers, sanders, miter saws, etc. and gives you some mobility, too.

I use a run of the mill shop vac with a mini cyclone mounted on a cart. This seconds as my shop cleanup vac, too.

Hope this helps!

[Matthew Springer]

IANAD

Any DC is a huge improvement over no dust collector. I had noticeable respiratory issues the day or so after I'd been in my shop for an extended period. (I've had allergies/asthma my whole life). My shop is an exterior two car garage, so this was even with the large garage door open.

Three things:
1) respirators are still great/necessary especially for things like routers.

2) The thing that seemed to help me the most was the ambient Rikon dust /air filter (the kind you hand from the ceiling). Noticeably better. These are cheap. get one. YMMV, but I highly recommend one. Even the cheap one works well.

3) Use any dust collector even if it's suboptimal.

I rigged up a delta + cyclone + aftermarket filter to tide me over until I get setup for a "real" cyclone, but I'm glad I made the time investment in getting even temporary DC up over living with piles of sawdust.

On the HF DC you already have: Hot rodding HF dust collectors could be it's own subforum. There's LOTS of prior art.

There isn't a "proper" size, there's a balance of flow velocity (which keeps things suspended in the stream and increases as the duct size is smaller) and volume(which gets higher percentages of the dust and increases as the duct size is bigger). Velocity needs to be greater than a certain threshold to keep the fine dust suspended in the stream, volume needs to be larger than a number to get the lion's share of the dust/chips produced at the source.

For the HF, the stock inlet on it is actually 120mm, which is basically 5". The HF + your rikon impeller would fit really well with 5" ducting and a Super Dust Deputy (the 5" model would work great). You'll need a retrofit cannister filter; highly recommended over the bags. Wynn makes one as do a couple other sources. You can find 5" PVC, but 4 and 6 are much more common, hence easier to find and cheaper. Again,it's a trade off of big enough for the CFM, but not so big you drop your velocity below the suspension threshold.

Your original question was Thien vs Cyclone. Thien baffles are easy to build and it's not that cyclone manufacturers didn't know about the design, it's that the design has a high airflow resistance so if you can use a cyclone, you can get the separation plus you don't lose too much airflow.

Note that the purpose of either the cyclone or the Thien is to keep your HEPA style filter from getting clogged by diverting material before it hits the post-impeller filter. Ducting is great is (like me) you're too lazy or floor space constrained to roll around a portable cart style unit. If you're like me and you also sucks up handplane shavings, it helps keep the impeller itself free and clear also.

Fun fact: cherry shavings seems to clog impellers the best, followed by fir.

[michael langman]

I bought a harbor freight dust collector and bought the wynn filter and built a thien baffle right from the start. I made it mobile and hook it up to each machine as I use it. In my cellar work shop I find the collector satisfactory for my needs while wood working and can wear a respirator when cutting mdf .
I open the garage door and run a fan over my welding projects. A diy person also needs a good respirator if doing alot of renovaion around the house.

[Bill Jobe]

IANAD
For the HF, the stock inlet on it is actually 120mm, which is basically 5". The HF + your rikon impeller would fit really well with 5" ducting and a Super Dust Deputy (the 5" model would work great). You'll need a retrofit cannister filter; highly recommended over the bags. Wynn makes one as do a couple other sources. You can find 5" PVC, but 4 and 6 are much more common, hence easier to find and cheaper. Again,it's a trade off of big enough for the CFM, but not so big you drop your velocity below the suspension threshold.

Mathew, there are a couple of things you wrote I'm not so sure about.
First off, the intake on the HF unit may be 5', but the grill over the inlet reduces that a bit.
Secondly, since it also has a 4" outlet, it doesn't seem to me that upgrading to 5" duct would help....in fact it might make it less effecient, might it not?
Or perhaps you also mean that the exhaust port would need to be upgraded to accept 5' ducting.

I was using mine for a while as-is, but routed the blower exhaust ductwork directly outside.