Cyclone for home shed CNC questions

[AvB]

Hi, I'm new to this forum, and apologies for not having read other relevant threads re: these questions. have a home CNC router - a very good quality, large table unit which I purchased from a professional manufacturer. I mainly use it to machine model aircraft moulds from Corian, Laminex Freestyle or other similar solid surface benchtop material. But it creates very fine dust. I have a Carbatec FM300 dust collector which originally had a dust bag but it leaked huge amounts of smokey dust, so I replaced it with their 1 micron cartridge filter. It's a lot better, but the finest dust still gets through it and it clogs fairly quickly (it has a winding flapper system that you use to knock the clogged dust off the insides of the cartridge flutes). The FM300 does have some cyclone action as the inlet enters at a tangent into the chamber creating a vortex, but I don't think it does much. So I'm very attracted to getting a proper cyclone to sit inline. However I am not an expert and don't know whether the cyclone would help with this ultra fine dust? I have spoken to some manufacturers who've said that cyclones are really more effective at eliminating larger debris. The FM300 is a 2hp blower and has 100mm ducting. I'm fairly handy, but when I've looked at some of the DIY threads on making a cyclone they seem beyond my expertise and time capacity. I'm just doing this in the suburbs and have to be careful not to offend my neighbors with noise etc, and I'm not keen to set up an external system, or spend too much on a big professional system. I'd really appreciate any advice - thanks, Andrew.

[BobL]

In general if the dust gets through pleated filters (PF) it will get through any cyclone.

If you really want to trap this dust you will need filters that are called" Nanofilters" or filters that have a high MERV rating but be aware that these will clog even faster than regular PFs

If you absolutely MUST trap all the dust you could consider staged filters - i.e. a set of regular PF filters, or a cyclone, followed by a set of Nanofilters - because the first set of PFs or cyclone should trap most of the dust then the second set (the Nanos) won't clog as quickly.

Despite using these filters ALL dust collectors (DCs) leak and so you will still contaminate your shed with fine dust.
An even greater issue is the dust you think you are seeing coming through the filters may not be the case.
What happens is if you are using 4" ducting you simply will not be collecting enough air and therefore not enough of the fine dust.
The dust that escapes collection will settle all over the shed, including on the filters themselves and that big puff of dust you see coming from what looks like the inside of the filters when you first turn your DC on is the dust from the shed hat has settled out onto the filters.
Remember this is only the dust you can see, the dust of greater concern is that which you cannot see and there will be a lot of this going uncaptured using 4" ducting.

This is why on this forum we advocate locating or venting DCs outside then leaky DCs and the quality of the final filter is much of an issue.
If you cannot locate your DC outside then at least locate it inside an air tight enclosure inside your shed and vent the enclosure outside the shed.
If you make the enclosure right you and your neighbours will benefit from reduced noise and most of the dust coming out will be invisible anyway so the neighbours won't see it.

If terms of cyclones, they all slow down air collection and that is the majority of most DIY dust problems. The least worse cyclones like the Bill Pent design are the way to go - just about all others slow the air flow down.

So in order of priority I would do the following
- move or enclose and vent the DC outside.
- upgrade to 6" ducting all the way including the machine port. - if your CNC only has a 4" port locate 2 other 4" ports or a 6" port above the machine itself.
- consider adding extra shed ventilation to vent the shed of fine dust.

[QC Inspector]

First off Andrew, welcome to the forum.

With your CNC you are in a good unique position to cut you own parts to make a cyclone should you decide to go in that direction. The Bill Pentz design Bob mentioned is described in detail on his site. The ClearVue cyclone design is licensed from Bill if you want to see what a plastic one would look like. If you went the cyclone route you would also want to also upgrade to a more powerful motor and fan too. All of which needs more electrical power and the cash that goes with it. Dust collection isn't for the faint of wallet.

Bob didn't mention it but he has a thread on modifying a dusty like yours to increase its performance. The past threads in the forum have a lot of useful information that you should take the time to read.

[John Samuel]

Andrew,

I have a ClearVue 1800 cyclone (Bill Pentz design) and a 6" ducted system. The cyclone is inside my shed and it is ducted outside with two layers of HVAC flexible insulated air con duct (6" duct inside bigger duct).

No dusty captures ALL the dust, but a Bill Pentz cyclone does a remarkably good job. I regularly cut MDF panels for laminating, and am impressed with the dust collection. MDF creates very fine and dangerous dust. My tests for MDF dust and sander dust indicate that my cyclone does an excellent job. Not all cyclones are created equal. As BobL suggested, the Bill Pentz design is far superior to anything else out there. So far as I am aware, there is nothing better for the home workshop. My shop was a dust trap until I installed the cyclone, now I clean windowsills and etc about every one or two years.

Under BobL's guidance I worked hard at getting good hoods/shrouds and good airflow into and through my machines (mission critical). That helped a lot.

Because my system is vented outside (strongly recommended) I have no filters to clean or to restrict air flow. I dislike filters, mainly because I am too lazy to want to clean/maintain them, but also because I don't trust them and don't want ANY of the dust collected returned to my shed. Because the system works well and is ducted outside, I don't need any other shed ventilation. These videos indicate how well the system works ... https://www.youtube.com/watch?v=X5WE5t-9MqA
and https://www.youtube.com/watch?v=mT-AefqC-nQ and finally ... https://www.youtube.com/watch?v=p2tHtOyOIrY

If you build a cyclone, please ensure you instal a very good impeller and enough HP to drive the system. The ClearVue 1800 system uses a 3 kW motor. I run mine at 60 Hz through a VFD which gives me 20% more air flow over a 50 Hz system. I think Clearvue will sell you an impeller and housing.

I am much impressed with the performance of the cyclone. However, if I had my time again I would instal a CearVue Max and 8" main lines to the ducting. There are two reasons for this. First, a Max creates the same airflow at 50 Hz as the 1800 does at 60 Hz. The noise levels double from 50 to 60 Hz, so most of the time you could run at 50 Hz and keep the shed much quieter. Second, when doing work where it is difficult to capture all the dust at the source, you can switch the VFD to 60 Hz and open another vent overhead and that will help to keep the air in your shed clean ... or you can run two machines simultaneously. The only negative is that 8" ducting is expensive compared with 6" ducting.

So, in summary ... there is nothing better than a Bill Pentz cyclone for a home workshop dust collection system ... if noise is an issue, park it inside your shed and vent it outside (like mine). It has a very small footprint and takes up almost negligible space ... consider getting a MAX type system so you can run it at 50 Hz most of the time (and halve the noise). I live in surburbia, and my system does not bother my neighbours.

A ducted cyclone system is not cheap ... in particular 8" ducting is expensive. But if you make the cyclone yourself you can contain costs. Another approach is to get a metalworker to make up the body of the cyclone for you and to source your own impeller, motor and VFD. The cheapest place to buy ducting (stormwater PVC) is Eden Gardens at Strathpine. The plumbing supplies places charge like wounded buffalo.

Finally, you simply must, as BobL suggested, use a 6" system to get enough airflow to do decent dust collection. If the cyclone/ducting approach is above budget, the next best solution is a two-bag 3 HP dusty, but then you are venting inside and as BobL so often says, they all leak. The question is by how much. The cheapest solution is BobL's optimised 2 HP system connected to your machine with a short length of flexy. It is not in the same league as a Bill Pentz cyclone, but I like it because it puts reasonable dust collection within the reach of nearly all woodies (see the Generic 2 HP dusty sticky).

I live 30 minutes away from you. Feel free to drop in and look at my system if that helps.

Cheerio!

John

[AvB]

Thanks very much for all the advice chaps, and I will need to do some more digesting of the info. John, I may take you up on the offer of checking out your system. I'm sure I'd learn a lot.

It actually sounds to me from what you guys are saying, that I don't have such a big problem. My spindle has a flange which holds a brush fence around the cutter, so when the vacuum is running, it pulls vacuum really hard from the cutter area and I don't get dust spreading around the shed at all. Cutting Corian isn't terribly dusty - not like MDF. When I'm roughing I use the vacuum but when I get to the finishing cuts I usually do them with no vacuum as the vacuum makes far more noise than the cutter when it's only taking off a tiny amount and these cuts take many hours, so I can do them without upsetting the neighbors ... and while doing so, there's no noticeable dust in the shed - the light debris is quite localized around the job.

My main dust problem is not coming from around the cutter when it's running - it comes from the filter when I unclog it. I have some offcuts of high density insulation (like 50mm thick black nylon wool batts) which I have tied around the whole cartridge filter and body, mostly to cut the noise back. I also often throw some old blankets over the whole thing to dull the noise too. It works fine that way, and every 45 mins or so I shut the vacuum off and use the flute flapper/ vibrator to knock the dust down from the inside of the cartridge flutes. When I do that, clouds of dust billow out of the insulation, and you can see that quite a lot of ultra fine dust has worked through the filter element and deposited around it sitting in the insulation and blankets, and it becomes airborne when disturbed. That's the main source of dust getting into the shed. I usually open the shed doors, take a deep breath and don't breathe while doing it!

I should visit John to learn a bit more about this, but I am reluctant to scale things up a lot due to 1) not being sure whether I'll be keeping the machine long-term, so I don't want to overcapitalize on it, and 2) concerns about noise, and 3) power (I only have 10A in the shed). I just thought putting a cyclone into my existing 4" system might cut down on the dust that gets through the cartridge.

[BobL]

Thanks very much for all the advice chaps, and I will need to do some more digesting of the info. John, I may take you up on the offer of checking out your system. I'm sure I'd learn a lot.
It actually sounds to me from what you guys are saying, that I don't have such a big problem.

Anyone who uses a DC or VC inside a shed has a problem - that you may or may not see.
Have you seen this photo?
That's 270 mg of dust in that cool drink bottle top.
CoolDrinktopdust.jpg
That is sufficient dust to contaminate the air inside 4 medium size sheds above recommended occupational health and safety limits.
Does this means that virtually 100% of wood workers have a dust problem- yep especially if they spend long periods of time their shed.

... and while doing so, there's no noticeable dust in the shed - the light debris is quite localized around the job.

The light debris is probably harmless but you are only fooling yourself - taking very fine cuts probably makes more invisible dust than visible dust so you won't see it
I'ts the invisible dust that we need to concern ourselves with.

Adding stuff to the outside of the dust collector filter simply is counter productive as it will just slow down the air flow so even less dust will be collected by the DC.

You are trying to do things visually - this is largely a waste of time.
Holding your breath while fiddling with the filters is a complete waste of time the invisible dust is being scattered all over the shed and takes hours or even days to scavenge out of a shed - this is why extra ventilation is

Short of purchasing very extensive test gear the best you can do is meet the recommended airflow specs for dusty gear.

[AvB]

Thanks. Having started to look into this, I'm coming to grips with the realization that my air ducting and blower are under-sized for a good system, when previously I thought it was a on the overkill side.

I don't use the machine very often - the CNC is a spinoff from my RC glider hobby. I might use it on and off for a couple of weeks and then rarely for months. And I have other hobbies and have a big family situation, disabled daughter to care for and we run our own business ... no need to drag out the violins, but what I'm saying is that I'm not keen to try to research and decipher this obviously complex science of dust extraction, or embark on a major project to make my own system.

And shifting the motor outside, or having a noisier unit, is not an option for my situation.

Stephen is calling me next week to talk about it so I'll see where I go from there.