Dust collection (yes, again...)

Add-ons & Modifications đź’¨ Dust
1

Does anyone know what the recommended CFM for dust extraction on the 4x8 is ? I know, I know, “how long is a piece of string ?” but most tools have some sort of guideline specification. I’m currently thinking that 1000 cfm is a “good-enough-for-government-work” target, and I was planning on dumping that as quickly as possible into a 6” conduit, taking that back to the Axminster AP145CE which will mate with 150mm (~6”) tubing.

My main concern isn’t picking up the sawdust (though that’s nice), it’s filtering out the sub-10-micron particulates in the air because I like my lungs, so I want high volume, low pressure, into a 1micron filter, and I’m not seeing too many of them around that (a) don’t break the bank, (b) work with 6” ducting and provide good flow into that size, and (c) aren’t unreasonably loud. Even the AP145CE is pretty loud at 84dB, and yes even if I’m wearing ear-protection, I still want it quiet because the garage is right next to my neighbours …

So, what do you all use that I’ve missed ? :slight_smile:

2

@SpacedCowboy

I don’t think I’ve ever seen any CFM recommendations. And there are a lot of discussions as to HVLP vs HPLV systems.

Not much help but FWIW, I have a Record Power CAMVAC dust extractor (HPLV) with 1 micron filters. The extractor is right next to my Altmill and there is zero airborne dust that I can detect. Depending on the placement of the dust shoe, it might not suck up all the wood chips but it does a good job with the particulates. I do need a better separator though.

3

Hello SpacedCowboy. I am just setting up my LongMill MK2.5. However, I have been using the King Canada KC 3109C for 4 years now. It is a 2hp, 220 unit,1200 CFM’s with a 1 micron canister. My main run is 6” pipe from the dust collector and then it steps down to 4” to hook to the machines. I use it in my shop as the central dust collection system. It is hooked up to my Chop Station station, Table Saw, Jointer, Planner and when needed I hook it to my 16/32 drum sander and haven’t had any issues with collecting dust or wood chips. I am impressed how it picks up the dust from the drum sander so I don’t foresee any issues with the LongMill. The KC 3109C is $899.00 CAD. They also have an KC 3105C and it can be either a 110 or 220V and it is rated a 1200 CFM’s. It is $699.00 CAD. Don’t matter what unit you get if it will mostly be noisy. However, I think you should really look into an Air Cleaner. I had my Delta for about 35 years and it is still going great. I would spend my money on a good quality air filter one with a timer so you can set it go off 2 or 3 hours after you leave the shop, and get a cheaper dust collector or shop vac to hook to the CNC. I used a cheaper dust collector until I could justify a better dust collector. Just what I have been doing for 35+ years. Pat

4

Thanks folks.

I was looking into an air cleaner as well - my “shop” is really the front half of my new garage and it’s 15.5m by 4.7m x 2.4m or ~175m^3. From reading, it seems like you’re supposed to turn over the air ~4-12x per hour in dust-heavy environments, so aiming for the middle of that, we’d need ~1400 m^3/hour rate, or ~825 CFM in non-metric terms. There’s a model by “lumberjack tools” that fits the bill and seems to be (relatively) quiet - it offers 945,1035 and 1675 on low/medium/high respectively. It also has dual 5-micron outer and 1-micron inner (washable) filters and has the timer feature for leaving it on for a while once the work is done.

So I think that’s definitely on the list :slight_smile:

With that helping out, I might be tempted to just go for the quieter 4”-inlet extractor - Charnwood do a reasonable 1HP one (W796CF) which is 73dB for £600, though they have the larger 2HP cyclone one (C300R) which is ~£1000 and operates at 77dB (about 1.2x to 1.3x as loud). This one has a 5” inlet. Both of those are a lot quieter than the Axminster one I linked above (which was 84dB, or roughly 2x as loud as the quieter Charnwood one).

It seems getting 5” tubing is a bit harder than 4” or 6” (even when you search in mm over here in the UK [grin]) but there are a few places. I’m guessing that putting a 5”→6” adaptor on the extractor and then running 6” ductwork to the machines is probably verboten, because the airflow in m/s rather than m^3/h might not be sufficient for larger chips to stay airborne. The Axminster one drops from 30-37 m/s via 100mm, down to 18-21 m/s via 150mm, for example. The C300R m^3/h at 125mm is roughly in the middle of the Axminster m^3/h rates (1080 m^3/h at 100mm, 1380 m^3/h at 150mm)

I think the combination of the 5” one and the air-cleaner would probably be sufficient for the new “shop”. Even taking into account up/down travel, the CNC will only be ~2 to 2.5m away from the extractor, and I’ll use blast gates to make sure I’m not losing suction to other stations.

5

@SpacedCowboy If you’re in the UK, take a look at the Record Power offerings. They are made in Britain.

I have this one. If you attach hoses to the outlets, the noise can drop down to about 68dB.

CGV386-5 Large Extractor

6

Thanks!

I think this particular series is a bit underpowered for the size of my “shop” but it’s always good to know about more suppliers :slight_smile:

The top-end one of these seems to run at 162 l/s, which is 580 m^3/h or ~340 CFM. I was aiming for about twice that - I suppose I could run two :slight_smile:

7

@SpacedCowboy Correct. They are high pressure low volume extractors. More like a Shop vac and a Festool than a dust collector with a high CFM.

They do have an air filter though, which you are also looking for.

1 Like
8

My Harvey gyro does a great job at its lowest setting with a 4"/100mm hose - more than enough suction and airflow when connected to an autodustboot (from FrancisCreation). I’d be more concerned with the spindle dragging around a bulky a 6" hose :slight_smile:

I’m “downgrading” to a 2 1/2" / 65mm hose to reduce the mass attached to the spindle, and don’t expect to have any issues.

The sealing and airflow qualities of the dust shoe probably have as much of an impact on total collection effectiveness as the rated CFM…

9

I’ve been reading a lot on Bill Pentz’ pages - given:

  • It’s my own health I’m protecting here
  • His opinion that a few hours in a typical home shop is as bad for you as many months in a commercial, inspected woodworking shop
  • You literally can’t see the stuff that’s bad for you, you need an air-quality monitor to tell you that there is danger because you don’t feel anything until it’s far too late, and the damage is done.
  • The small-size filters get ripped apart over a short time by the cleaning that you’re supposed to do, to the point where they’re just allowing the dangerous dust through again, but still providing the security blanket of seeing the visible dust get cleaned.

What’s not clear yet is whether a good dust-shoe on a CNC will prevent a lot of the fine dust (<10 micron) that he’s talking about from becoming a problem. It seems to me that this would be similar to the “properly designed shrouds” he talks about on hand-held and smaller machines.

From what I gather, the issue is that the 1000 CFM suction is more or less good enough to capture things escaping with an initial velocity away from the hose at about 50mph. The problem for fine dust collection is that the RPM of the tools are sufficiently high that fine dust can be accelerated away at closer to 100mph… putting a shroud around the tool lets you limit how far the dust can go, and lets it be then gathered up by the suction.

I’m not all the way through his site yet, it’s information-dense and there’s a fair amount of it, but fit does seem to be aimed at the more traditional tools in a shop, not a CNC in particular - of course it does mention the router table, which is one of the worst offenders :slight_smile:

On another note, the air cleaner is useful, but not as an immediate benefit - the filtering action is too slow (even at 12x per hour) to prevent fine dust from getting into your system at the point of creation, but it does circulate the air, and eventually will trap a lot of dust that did make it out of the capture-zone, so very useful to run overall.

A lot of the problems stem from us using systems that were designed on an industrial scale to vent fine particles outside being scaled down to sizes that fit into an 8’ ceiling, and losing a lot of their effectiveness as a result. To add insult to injury they then vent inside the shop because no-one at home has separate exterior venting set up. So fine dust that escapes (and it does because changing the filters suitably often is very expensive and time-consuming) just builds up and up over time.

Still reading the site but it’s fascinating (if a bit depressing) stuff.

To address your point though, the dust shoe that comes with the 2.2kW spindle (my current order for the 4x8 table includes this) is an 80mm (4”) outlet. There’s no real advantage if I immediately adapt that to a 6” since air does not compress at these low pressures, so the effects of a flow restriction remain in place throughout the air path. In fact, even a 6” pipe can only sustain 785 CFM with a standard 3hp collector, or a higher hp one if you’re using a cyclone since that reduces the air flow efficiency through the duct - energy is needed to accelerate the air in a circle) - you really need to go to 7” to get the 1000CFM that is better for fine dust…

I can’t tell what the outlet is on the new ATC spindle, but I expect it’ll be the same 4”. Both would need a redesign in Bill’s world. I guess I have a 3d printer…

10

Ummmmm …. speak for yourself. My dust collector is outside the house (can’t hear the motor inside) and vents to the outside. An interlinked window opens to allow for fresh air to enter the shop when the dust collector runs.

11

You’re correct, of course, and I misspoke, my apologies - I should have said “most”, not the all-encompassing “they”. The “nobody” part was supposed to be a bit hyperbolic though - like “nobody always obeys speed limits when driving”. I’m sure there are a minority of people that do, but it’s not my experience generally :slight_smile:

I’ve personally never seen anyone vent outside at home, though my sample-size is small :slight_smile: I’m wondering whether enclosing the extractor in its own area and having a fan blowing outside might work reasonably well…

1 Like
12

The concerns about dust shoe effectiveness lead some to fully enclose their machines and vent the whole enclosure through a filter / outside. Others also wear PPE while in the shop, ranging from masks through full face respirators, air shields and (if you have $4k to drop) the 3M PAPR :slight_smile:

As in all things, perfect often gets in the way of done. Not that I think you are, but don’t let the fear of dust keep you from getting enjoyment out of your woodworking shop!

My perspective is based on the diet plan my doctor recommended: The most important thing is to start. Pick any diet (ahem, dust control) you want, and use it, make it a habit, and keep track of how things change. Then, come back and let’s talk again about improving the things that aren’t working out the way you want, and maybe pick a better diet (dust elimination) plan.

13

Likely help would be from a company that produces vacuum systems

14

If you haven’t looked at the Grizzly offerings, it’s worth a look. I find Grizzly to be some of the best “bang for the buck” tools around. They aren’t really cheap, but good quality industrial type equipment. I have the G0777HEP dust collector which isn’t made any more, been very happy with it.

15

Dust collectors vary significantly with design and function. Many use a vacuum source that is adequate for the machines being adopted, with one, two or more centrifugal ( spinners causing a vortex and dumping the larger particles) in the catch bin. The final filter can be micron sized, but with consideration of air flow and surface area. In many cases a standalone HEPA filter and a portable vacuum is sufficient, some build a dynasty devices, other make do with less.

16

For some things a portable vacuum is sufficient. I have a big dust collector, but for things like a small orbital sander it’s too much. The port on my sander is 1” and it’s hard to throttle down my big dust collector for something that small. So I use a cheap cyclonic separator on top of a bucket and a shop vac for things like that.

Conversely, there isn’t a shop vac alive that will service my big cabinet table saw. It just needs too much air flow for any shop vac to provide. My big Grizzly dust collector is excellent for this. It has three stages, the separator collects about 95% of the sawdust and is easy to empty. The second stage collects to a bag about the size of a large garbage bag. In 5 years of operation I’ve yet to fill that bag up!! The final stage hepa filter is very robust and I’ve also never had to change those filters.

The CNC machine is somewhere in between. It creates more sawdust than a table saw, but it doesn’t need near the volume of air flow. My table saw has a 4” port on the cabinet and another 4” port on the “over blade” collector, so it needs a lot of air flow.

I’m also not running a commercial “all day, every day” operation. Just a home shop, but I do use it about 3 out of every 7 days on average. After years of getting by with a shop vac, I purchased a full dust collector and it was one of the best decisions I ever made. It was expensive, but well worth every penny.