[SML] Dust collection

[Duncan Mahoney]

Bill Potter states:

>We?re FINALLY adding dust collection to our scene shop and I thought I?d check in and see what folks like.

>At this point, I think we?d like to go with one overhead general ambient filter (with a remote) for general dust collection from the air and individual vacs for each stationary power tool. Any specific brands that >you like (or ones to avoid) would be great to hear about.

My first response when anyone asks about dust collection is to direct them to Bill Pentz's website.  Read all of it, your head won't explode.  Bill tends to repeat himself a lot, pretty soon you'll get the hang of gleaning the new information on each page while skimming over the old

I've been fighting the dust collection battle for about 2 decades now, and I've learned a lot of lessons the hard way. If I could have read Bill's website before I began, I could have bypassed quite a bit of the expensive experience.

The first step might be to contact the PTB and AHJ, there may be some local regulations about what a dust collection system can or can't be.  Unfortunately, most such regulations tend to favor expensive central systems with fire dampers, explosion vents, spark mitigation systems, etc.

OTOH, going without dust collection is a serious health risk.

I would save the money on the ambient filter and spend it on better collection at the machines.  Dust in the air is dust you are already breathing, and the filters in the vast majority of ambient filters are not sufficient to remove the harmful small particles.  Spend $200 of the money you save on a Dylos meter, so you can see if your efforts are making the air better or worse.

If by "vacs" you mean individual dust collection systems for each machine, that's how we are set up.  Each stationary machine (table saw, radial arm saw, panel saw,...) has a 2Hp dedicated cyclone dust collector.  We have a 5Hp unit that serves a cluster of machines.  Yes, in some cases the dust collector costs as much or more as the machine it serves.  I ended up doing this because when I tried to hook up a few machines to a 2 Hp collector, assuming we could use all the machines at the same time, this did not capture the fine dust. I learned that it really does take about 1,000 CFM coming through a 6" duct or equivalent cross sectional areas, to collect the fine dust coming off almost any stationary machine.  We've gotten fairly good at designing dust hoods and cutting bigger ports in our machines.

When we are only using 1 machine we don't have to start a huge motor on a central dust collection system.  The other advantage to using individual smaller systems is that you can add them as funds permit.

The first money I wasted on dust collection was spent on bag type dust collectors, and then more was wasted on better custom made filter bags.  Unless you are venting the air outside, bags are worthless.  The fine dust, clouds of it that you can see, just goes right through.  Then I bought some cyclones with cartridge filters that weren't much better...

If you are returning the air to the shop any filter with a MERV rating below 15 is a waste of money.  Protect that expensive filter with a cyclone to keep most of the dust out of the filter.  I buy filters from Wynn Envionmental

As to systems, arguably Penn State Industries cyclone systems offer the best "bang for the buck".  They come with MERV 15 filters and a pretty good "air to paper" ratio.  The cyclone is a simple design but the separation is very good, not much dust makes it to the filters.  A fair amount of assembly is required, but that's pretty typical.  We have 3 in the shop.  Unfortunately, their freight costs doubled recently.

ClearVue is probably the most efficient cyclone design you can buy, and their systems come with MERV 15 filters.  I can't get past the MDF and PETG construction though...

Grizzly cyclones are a weird combination of good and bad aerodynamic design.  Price is reasonable, but not so much after you buy replacement filters.  The separation efficiency is about as good as Penn State in my experience.  The impellers are steel, which is why I just bought 2 more for use in the metal area.  But the stock filters are not worth the money it costs to ship them.  Grizzly won't ship the systems without the filters.  Grizzly also has some systems with HEPA filters (MERV 17), but IMO the filters are not large enough for the airflow through them.  All of our systems pass 4 CFM or less per square foot of filter material.

We have one older system from Oneida, separation efficiency is not as good as Grizzly or Penn State, but it's an old design so YMMV.  Oneida has some available systems with HEPA filters, but IMO the filters are small for the airflow

How do we keep the roar of the dust collectors from being deafening?  There is a muffler on the outlet of each one.  The first few mufflers I bought, but they are simple to make, and I can use up the leftover stock of flame retardant acoustical felt.

Is all this worth it?  When we are running stationary wood working equipment in the shop with the dust collection going we have fewer particles in the shop air than are in the air outside the shop.  Now this is Los Angeles, so maybe that's not such an achievement.  We still have some issues when using portable tools and metal working tools, those are the current targets for mitigation.

Now if by "vacs" you meant a dedicated shop vac for each machine, well that may get the sawdust, but they won't move enough air to protect your lungs from the small dust.  Shop vacs have their place though, they are just the ticket for portable tools with small dust ports.  I am a fan of the HEPA vacs that have self-cleaning filters.  If you don't need variable power the best "bang for the buck" will probably go to the 8 gallon Dewalt, but we have not had it long enough for a real evaluation.  The Dewalt DWV 012 works well and the self-cleaning feature works fairly well to maintain suction power.  We use little plastic cyclones on 10 gallon drums to keep most of the dust out of the vacs.  I have not noticed any significant difference in performance between the "name brand" cyclone and the cheap one from EBAY.  One note about shop vacs, don't expect any vac hose, even from the same tool manufacturer, to fit any tool without an adaptor.  Talk about an industry where standardization is needed

HTH

Duncan Mahoney
Director of Technical Direction
Associate Professor of Theatre Practice
University of Southern California School of Dramatic Arts

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