Small shop dust collection.

[Matt Mackinnon]

break down the DC equation down into it's parts.

1. Unless the machine that you are connecting to allows for the proper flow of air to trap the fine dust particles at source as they are getting made, then you are wasting your time before you even begin.
2. The numbers are pretty well laid out by Bill Pentz as to what air flow and speed you need for a DC unit.
3. Unless you are venting outside and making it someone else's problem, you need to fiter what is sucked in, so it doesn't just get recirculated around the shop after spending so much time and effort to get it at the source.

Unless you are planning to do all three, then you are getting into a substandard option. Ian had spelled it out more eloquently that I ever could. Your choice is pay for it now with your dollars, or time and innovation, or pay for it later with your, or your families health. The bill will get paid at some point.

Matt.

[Kent Chasson]

.......

1. Unless the machine that you are connecting to allows for the proper flow of air to trap the fine dust particles at source as they are getting made, then you are wasting your time before you even begin.
.....

I agree that it's a huge improvement to own tools that are designed from the ground up with dust collection in mind but most tools that are poorly designed (which is to say, most tools) can be modified to work a lot better. Some just need a bigger port, some need more creative mods but I don't think it's at all futile.

[ian maybury]

I guess as I've been recently discovering and as you say Matt there is lots of equipment that's not that easily configured to make good use of a high CFM dust system - router tables for example. There's particularly the more budget floor machines out there too where the presumption that the owner will run a low CFM/small duct dust system leads to the fitting of hoods with small ports - if they fitted a large port and the owner sized his ducting accordingly a small system won't deliver the airspeed needed for effective transportation.

There are almost always routes around this though, and even a 4in or 5in ported machine performs so much better hooked up to a decent dust system - I had enough years of messing with a 1kWbag filter system that only seemed to collect chips right when the bags were freshly cleaned, and which anyway blew dust everywhere all the time...

ian

[David Hostetler]

I tried the shop vac as a DC route at first. Miserable failure, especially with the planer / jointer. It only seems to work well for me on handheld sanders, and even that is spotty...

I went with the HF 2HP DC / Wynn / Thien separator combo and have been very happy with the results... Bags from Highland would have kept my costs down more, but I wanted the added flow of the canister instead of a bag...

[Alan Wright]

I was fortunatae to get a 3HP Oneida Cyclone system for $150 at an estate sale. The gentleman woodworker had passed away and was meticulous about receipts. All told, the system had cost him $1,800. I guess that's gloat worthy.


What I really had a hard time with was sanding with my ROS. When I'm done building a project, I typically have 4-5 hours of sanding to do, depending on the size of the piece. I bought the Dewalt D279095 variable suction vac. I bought this one because I got a great deal (about $200 form tool king). However, it is very similar to the Festool and Fein units. I can now sand for an hour straight and not see ANY noticable dust in the air. I don't know how many microns, or microbes it catches or lets through. I just know I REALLY like the results.

[Greg Peterson]

When I have to sand inside (I try to save this task for outdoors), the down draft table comes out and the shop vac gets hooked up to the ROS. Even outside, the ROS gets hooked up to the vacuum as I feel it helps prevent clogging the sandpaper.

[ian maybury]

I guess sanding is one of the situations (although using something like an ROS with good dust collection has to help) where as is said in the car and bike worlds 'there ain't no substitute for cubes'. Turning is probably another.

It's tough in either case to arrange effective hooding short of something like a fume cabinet (the enclosed cabinets used in labs when working with materials giving off dust and/or vapours with an H&S risk), with the result that it becomes necessary to create a large low pressure volume.

This is where the typical dust system is going to fall short unless it's moving lots of CFM.

Fume hoods are a fair point of comparison when considering the sort of numbers Bill Pentz published for dust collection, I spent some years working in a lab environment. Bill suggests 50ft/min 'face' velocity around dust producing wood working operations. (the speed at which air is required to flow into the work volume from all directions to capture ambient/air borne dust - guards are needed on top of this to intercept dust thrown out at high speed from cutters etc).

From memory fume hoods are typically required to achieve about 60ft/min at rest, and 70 - 140ft/min (110ft/min average) in use with a maximum of 10% variation over the face/open area - so Bill's 50ft/min doesn't sound at all extreme. The inlet and exhaust fans have to be sized to maintain negative pressure inside of the cabinet too. (can't remember the number). The equivalent figure for a spray booth is around 100ft/min face velocity.

Say your work occupies a 4ft x 4ft x 2ft cube. That has a surface area of 64 sq ft. The CFM required to maintain 50ft/min inwards air flow over that = 50 x 64sq ft = 3,200CFM. Which is beyond the capability of most of our small shop dust systems. Luckily the numbers reduce rapidly as the work volume dimensions reduce - but the fact is that even one of the 'ginormous' to many minds 5HP Pentz type systems can at that only handle a cube of about 2ft x 2ft x 2ft = 24 sq ft = 24 x 50ft/min = 1,200 CFM.

This is possibly a strong argument for building some sort of say foldaway or collapsible fume hood/booth or cabinet like enclosure within which to do your sanding (maybe polyethylene film stapled to a hinged frame?) - that same 1,200 CFM will maintain 50ft/min over a 6ft x 4ft access opening (= 24sq ft) on one of the six sides of whatever reasonably sized cube/tent you might choose to use...

Here's another perspective. We're used to thinking of dust systems in terms of their sucking up the dust produced by woodworking operations. That's ideally true, but the fact is that if they are to do a really good job on this sort of work they actually need to start to do something of an air movement control and ambient air cleaning job too....

ian

[Neil Brooks]

I sand on my "assembly table" (a couple of sheets of OSB stacked on a pair of sawhorses).

At one end of my assembly table sits a 20" box fan. Strapped to that fan are two air filters. I leave the fan on high, when I sand. You can watch as the fines drift quickly toward the filters and fan.

I also wear my 3M 7500 while sanding.

My shop has a 2HP HF DC, a bit tricked out, a JDS air filtration unit, hanging from joists, and a roll-around, shop-built air-filtration unit. I run one filter while I'm working, and -- with a timer -- tend to turn the other one on, when I leave the shop.

Agreed: it's about space and money, but ... if you have both ... more dust collection -- IMHO -- is better than less.

[Rex Myers]

I started years ago with a basement shop. No dust control, saw dust all over the house. Next when we got an attached garage the shop moved out to the back of the garage. Still no dust control. Still dust all over the house, and cold as XZ#$C%$! Then I convinced my wife that a dedicated "shed" would accomodate the shop, and stop the saw dust. She was exstatic!

Enter my current shop. 14'x20' shed with 12/12 pitch roof. First thing on the agenda was dust control. After much research I built a Thien dust collection system. I used a 30 gallon trash can, a HF dust control blower and filter, and 4" drain pipe. The best investment I've made to the shop. Works wonderfully!
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[Jeff Hamilton Jr.]

I often don't reply on DC threads anymore because it sounds like I am on a campaign of some kind. ...be smart; get something decent and spend your money on good dust collection instead of on the doctor visits. Shoot for as close to HEPA compliant as you can get. A lot of it is just raw math; there's no magic here .

I too am going through the dizzying process of trying to upgrade my DC system. I'd love not to have to run a bunch of ducting, but do want to protect myself from "the fines." I have some larger equip - MM CU300 combo, 16 in. Bandsaw, lathe. No big drum sander.

Glenn, you mentioned elsewhere to try one of the new "rolls rounds." the Oneida 3 hp portable gorilla looks to have good CFM specs. Any opinions? Anybody have any experience with either that or the 2 hp unit?

Sorry to hijack, seemed to apply to the call of the OP's question which is why I didn't start a new thread.

[glenn bradley]

the Oneida 3 hp portable gorilla looks to have good CFM specs. Any opinions? Anybody have any experience with either that or the 2 hp unit?

I know we have Oneida V-series owners on here. Although this does apply to Jeff's original thread you may get better responses by starting a specific thread. I get good results when I start a thread with a title like "Oneida Dust Gorilla Portables - Owner's Opinions?" or something like that. There are thousands of members here and a wealth of info to be tapped. Good luck and good thinkin' about taking DC seriously.

[ian maybury]

There's differing views about on CFM Jeff, although the bottom line is that the only result that matters is air quality. A particle counter seems to be the practical means available to measure this.

There are hand tools and maybe some machines (with careful hood set up?) that seem to deliver decent collection at lower numbers. The gist of the situation on floor machines though seems to be that around 400cfm delivers good chip collection. How far you choose to go beyond that to make getting the fine dust easier depends on how you read the situation - risk vs. investment vs (longer term) benefit.

There's a view you can with careful machine and system set up do a decent job at the lower number, but equally there's many like myself that chose to go for the higher numbers.

Bill Pentz sets out the case for the higher numbers on his pages http://billpentz.com/woodworking/cyclone/DCBasics.cfm, and is quite definite that doing a good job on collection (as required to make possible delivery of the health based workplace air quality standards that are mandated in most countries) given the state of most machine hoods takes something more like a genuine (not manufacturers) 800 to 1000CFM in normal use. At this the system is doing a job very much like an air cleaner - as well as collecting chips it's creating a low pressure volume around the cutting operation that helps to pull fines in, and it's cleaning the room air too. Which on a typical LP fan means 6in ducting.

Unless you are exhausting all of the collected air, the second requirement he says is HEPA standard filtration. Without good quality filtration a dust system risks becoming a dust re-circulator. The knock on effect of using more expensive filter cartridges like this is that a cyclone or similar form of separation is advisable so that they don't blind up too quickly.

The above numbers seem to require about 3HP in the case of a cyclone system with very short ducting or hoses, or more like 4+ in a larger shop - see Bill's pages again.

ian

[Sam Murdoch]

Have been doing a lot of reading and thinking about dust collection, but coming away with more questions than answers. What better place to turn than the Creek? ;-)

Basic question: For a small shop (basement, single garage bay, etc) using primarily bench-sized power tools, do you need a cyclone or similar dust collector to achieve a high level of dust containment/control, or will a shop vacuum with an add-on dust separator be sufficient?

For what you are describing I am comfortable suggesting that a very good dust collector with HEPA capacity such as any FESTOOL vacuum system would be a great option for you. Big bucks but when attached to your power tools they keep the dust out of the air - period! You would need to adapt your hose fittings of course. For work with non bench tools that do not lend themselves to direct attachment to a Festool type vac I recommend the Rockler Dust Right wall mount dust collector. This is a small unit with a variety of lengths of flex hoses available and an assortment of connector ends. It works decent with a table saw, very well with a jointer and very well with a small thickness planer with a properly made hood to which you can attach the 4" hose connector. I was not happy with this unit with my small t-planer because it clogged up too fast. I decided to break out the "spokes" in the 2 chutes that are intended to protect the unit from sucking in high velocity big stuff. Since I don't use mine to vacuum the shop it is only collecting dust. I have had no issues with this solution and as I wrote the Dust Right now works very well to control dust from the jointer and t-planer. I also built a cowling around my compound sliding chop saw. The Dust Right is OK for this but not as good as a direct connection to the tool would be. My shop is small enough and I work alone so removing the hose end from one machine to the other is not a big deal for me. You could hook the hose end to be mounted under a work bench designed with holes for dust to pass through for other applications such as hand sanding. Worth a look?

[ian maybury]

Sorry to head off on a tangent, i was responding just now to Jeff H above and not Jeff S' original post. What's more - on Jeff S' original question i somehow read it as referring to smaller machines rather than power tools. The background on the need for effective dust collection and the sense that it's hard to avoid concluding that in most cases the more highly specified and hence (unless we get creative/lucky) more expensive solutions of whatever type stand - but high CFM dust systems clearly don't apply to power tools designed to run with a vacuum. There's others here with lots more work done in that area... Pardon me.

ian

[Jeff Hamilton Jr.]

Sorry to head off on a tangent, i was responding just now to Jeff H above and not Jeff S' original post. ..

ian

Thanks Ian, I appreciated the response! Jeff H