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15th December 2017, 11:10 AM #1Novice
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Dust collection advice for my workshop.
Hi guys,
I would love your thoughts on my dust collection options for my workshop. My workshop if a fairly large double garage, in a rented property making it dificult to place my DC outside. I have the following tools:
- Table Saw
- Router Table
- Band Saw
I also have a number of hand tools, however I do most of my sanding outside so I mainly need to control dust from the tools listed above.
I currently have a 1HP Carba-Tec Dust Collector with cloth bags (model no. is SDC-2041S, not sold by Carba-Tec anymore but seems identical to this) which I move around and attached to each piece of equipment via very short ducting. The cloth bags don't really filter much and seem to just blow the fine particle back into the air (doing more harm than good?). I was planning on replacing the bag with Pleated Filter Cartridges from Timbecon which apparently filter down to 1 micron.
I have the following questions for those more knowledgeable than myself:
1. Is my dust collector underpowered to the point that its useless or should it be sufficient considering I only connect to 1 machine at a time and have less than 2m of ducting total?
2. Will the Pleated Filter Cartridges from Timbecon sufficiently filter out dangerous particles or do I really need to move my DC outside somehow?
3. What is the best way to clean the (thick) layer of dust currently residing on every surface of my workshop (shop vac?)
Thanks for reading!
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15th December 2017, 12:00 PM #2SENIOR MEMBER
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Hi I'm just regurgitating what I've read through the forums BobL is the dust guru around here so he can give you a more detailed explanation.
1) Not useless but if you want to collect fine dust yep useless. I have a 2hp dusty with about 1.5m of 6" ducting and it was struggling (especially at router table and table saw), moving it outside (best move ever) made it worse.
2) Pleated filters will still spew fine dust (the stuff that is most likely going to cause you grief), I have one on my 2hp dusty and every time i start it up it'll emit a visible cloud of dust, this may be due to dust settling on it over night, but either way its dust that wasn't captured at source. Plus depending on your setup i find that the metal straps that come with most dusty collectors to hold the collection bags don't seal very well so you end up with leaks somewhere. So even if pleated filters are perfect you'll end up with a leak somewhere so still best to move the dusty outside.
3) I have a ducted system that vents outside and what I do is connect a long peice of 4" flexy and go around and suck up as much as i can see. Once thats done i open up all the vents and get the garden blower out and try and blow as much out the shed door as i can. Leave the system on for about 20-30minutes and repeat the following day. I do this between projects.
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15th December 2017, 12:39 PM #3.
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Short answer is yes. They are basically not a dust but a chip collector.
My testing shows that 1HP DCs only collect about 300 cubic ft per minute (CFM) when connected to most machines and less than that for others
Adequate dust collection starts with a real 1000 CFM.
[START BROKEN RECORD]
There's nothing magical about the 1000 CFM - it's just a figure that is less likely to leave uncaptured dust inside a shed where it accumulates and falls out of the air making a mess.
Manufacturers claims for DC are for the impeller only, ie no ducting, filter/collection bags or machines. Their tests are based on a so called "industry standard test" that serious over estimates the flow. A closer real CFM figure is to halve the values claimed.
To achieve 1000 CFM it's essential to use 6" ducting for all the machines you mention. 4" ducting is usually sufficient for slower speed, less dusty machines like a drill press, scroll saws. It also works for most power tools with internal fans.
More than 1000 CFM may be needed on large sanders.
You'll need at least a 3HP DC to achieve 1000 CFM and even then that is for shortish ducting runs - should be OK for a double garage but less so for larger sheds..
[END BROKEN RECORD]
2. Will the Pleated Filter Cartridges from Timbecon sufficiently filter out dangerous particles or do I really need to move my DC outside somehow?
However, PF have a larger surface are so take longer to "clog up". Overall they have ~10% increased flow for up to twice as long as needlefelt.
3. What is the best way to clean the (thick) layer of dust currently residing on every surface of my workshop (shop vac?)
I used such a setup when I was re-surfacing and sealing a short flight of stairs inside my house.
In front of the shop vac I had 4m of vac hose connected to various sanders
IMG_2710.jpg
On the outlet side of the hose I had 5m of 2" hose that went through the laundry and then a doggie door to the back veranda.
IMG_2711.jpg
This setup was reasonably effective (as shown by dust sensor readings) for cleaning up and when connected to the ROS sanders (Festool 6" and Ryobi Mouse) but less effective for a 100 mm Makita Belt sander.
BTW the Belt sander works better using a DC connection with 50 mm flexy hose than using a shop vac.
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15th December 2017, 01:43 PM #4Woodworking mechanic
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I have a pleated filter on a 2hp system and its in its own metal shed. I do not get a cloud of dust everytime I start it up and in fact the inside of the small tin shed is remarkably clean. Then again, all connections are duct taped and regularly checked.
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15th December 2017, 04:51 PM #5Novice
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Thanks for all the responses guys, i really appreciate it!
BobL, you said "PF are about as efficient at removing dust as needlefelt bags". In your opinion is this suficient to protect my lungs if I have the DC in my workshop, or do i really need to find a way to get it outside (or at least in a sealed compartment that vents outside)?
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15th December 2017, 07:59 PM #6.
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No I don't think its sufficient and a sealed compartment that vents outside is a good idea.
[START BROKEN RECORD]
This is not because the filters themselves are usually a problem as they can even scrub shed air (make the air cleaner than it is), even without any sawdust being produced
The problem is all DCs eventually leak.
They usually ALL leak around the filter and collection bag seal.
The sawdust constantly swirling chips and pieces around inside the collection bags also caused these bags to develop pin price leaks.
The more clogged up the filters get the greater the back pressure and the greater amount of dust escapes from the leaks.
The dust that get's out of these leaks is invisible so you don't know its leaking - eventually (2-3 weeks later) a small powdery stain will appear at the leaks but by then the dust that has escaped from those leaks has filled you shed.
Many of these leaks are so small the amount of fine dust that escapes is low and maybe your DC can vent keep up with the leaks but without a particle counter you will never know what your dust levels are.
This brings me to ventilation.
There is understandably a large focus on chip and dust collection but for small sheds and small DIY operations it may be more cost effective to beefy up ventilation and only use a DC and a vac to collect chips. To do this you will need lots of air going through your shed and you cannot rely on natural ventilation to do this. Ideally 20 room changes per hour but even 10 room changes per hour may be enough.
On a 6 x 6 x 2.7m shed thats about 100 m^3 or for 20 room changes per hour that's 2000 m^3 per hour, or 33 m^3 per minute, or 1200 CFM.
That' in theory - but in practice it takes about twice as much "theoretical" air to affect a room change - this is why 10 room changes is sometimes used.
The difference between 1200 CFM on a DC and 1200 CFM though a window or door is the resistance though a DC duct is way higher than the resistance through a window/door. Thus you need a much more powerful (higher pressure) fan and more electricity and $$ to drive 1200 cfm through a 6" duct than you do for low pressure fan to drive 1200 CFM through a door or window.
Thanks to our friends in the "grow your own" brigade there are low cost, efficient, low power consumption and very quiet fans than can get close to this.
eg https://www.ebay.com.au/itm/INLINE-C...d29AsgeLTLp9dA
Forced ventilation with a single fan works more effectively in a long narrow shed - a square style shed may need 2 or 3 fans, these should preferably be arranged to vent opposite the largest opening in the shed eg the door or large window.
[END of broken record]
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17th December 2017, 07:24 PM #7Novice
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Thanks BobL, I really cant thank you enough for your input. This has completely changed my plans! Before I pull the trigger on some fans could I ask your thoughts on my final plan.
- 1HP dust collector connected to each machine as required to collect chips.
- Shop vac for clean up (vented outside).
- 2 x 8" exhaust fans from you link (giving around 2000m^3/hr airflow which is approaching 20 room changes on my 6.5m x 6m x 2.9m shed).
As I rent I cannot readily modify the shed to install the fans, as such my plan to to install them in some MDF panels/frames which I can fit into the base of the roller door opening. The idea being these panels will have the same width as the roller doors and the doors will only be opened to the exact height of the panels (to avoid any blow back). Does this sound feasible? With this plan the fans will be close(ish) to the floor, do you see any major problem with this?
Thanks again, it is much appreciated!
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17th December 2017, 08:10 PM #8.
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That's theoretical room air changes - in practice you will get around half that - and that assumes you have a decent size opening on the wall opposite the roller door - see below,.
Other than that it sounds reasonable.
As I rent I cannot readily modify the shed to install the fans, as such my plan to to install them in some MDF panels/frames which I can fit into the base of the roller door opening. The idea being these panels will have the same width as the roller doors and the doors will only be opened to the exact height of the panels (to avoid any blow back). Does this sound feasible? With this plan the fans will be close(ish) to the floor, do you see any major problem with this?
Is there a way for air to get into the shed via a moderately unrestricted opening or openings that are on the opposite side of the shed from the fan location?
If not you may end up recycling the fine dust back into the shed.
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17th December 2017, 08:25 PM #9Novice
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OK, so if I up it to 2 x 10" I'll get theoretical 2400 m^3/hr (~22 room changes per hr), call actual around half of that (~11 room changes per hour). From my understanding of your first post on ventilation 10 room changes per hour is around what I need, but 20 is targeted to make up for losses/inefficiencies. As such if my actual room changes are ~11 per hour that should suffice? Or should I really be targeting 20 actual (so ruffly 40 theoretical)?
Yep, I can leave the door and 2 large windows open on the opposite wall of the shed which should provide good airflow in.
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17th December 2017, 10:38 PM #10.
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17th December 2017, 10:59 PM #11Novice
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18th December 2017, 02:24 AM #12GOLD MEMBER
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Bob would it be better for MFH to put the fans in a panel, placed in the open window/s and open the garage door a little for the make up air? The air the fans pull will be higher where the fine dust is floating.
Pete
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18th December 2017, 07:52 AM #13Novice
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Hi QC Inspector,
There are two reasons I would prefer to vent out the garage doors instead of the windows:
1. The windows don't open all the way (typical winding type) and so the exhaust path would not be as free, and may be more likely to result in dust re-entering the shed.
2. I would prefer to exhaust fine dust into the uninhabited back ally the roller doors open onto rather than my back yard (my dog will be particularly grateful for this).
If elevation is a problem, perhaps I could rig up some ducting (although I worry that will be at the cost of CFM)?
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18th December 2017, 08:14 AM #14GOLD MEMBER
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No sweat. Each person has their reasons for doing things that the rest of us don't know until we respond. I bet your dog would head straight to a dust pile in the yard and roll in it if it was there.
Pete
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19th December 2017, 08:14 AM #15Novice
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