Thread: My DC set up, Jet 3HP Cyclone and 6" duct.

Originally Posted by Jack E

I know there will be many here who will happily offer advice as to how this set up could be improved

Sorry, Jack. It is no good. There is nothing that you could do to improve it, It just wont work. I tell you what, I can do you a deal, pack it all up and send it to me and I will dispose of it safely for you. Pm me for delivery details.

Doug

Jack, your setup is not untypical of what I have seen around the traps. It's a pity you did not seek some advice here before you put all that effort in.

Originally Posted by Jack E

The main issue is static, as yet the ducting is not grounded, suggestions?
When running the joiner or thicknesser I don't notice any static, possibly because they create chips, not dust.

Partially Correct.

The table saw is a different story, which may be due to the inadequate prior extraction

No it's due to current poor extraction - using a 4" duct means you will always have very poor extraction - see below.
Extracting just from a TS cabinet is also ineffective. I note you have no overhead blade guard duct - lots of dust will be emitted from the top part of a table saw.

The second issue is the bends and junctions very close to the cyclone inlet, but I am very restricted by shed size and where the cyclone could be located.

Yep it's a bit of mess.

Mostly 6" pvc pipe.

Your 6" pipe which is capable of carrying 1250 cfm is totally wasted because you have nothing directly connected to it using 6" ducting, or machines with 6" ports.

Stepped down to 5" at the 20" thicknesser as that is the size of the point on the machine.

A 5" duct can only carry a maximum of 900 CFM but that assumes the thicknesser can even breathe to accept this. But 900 cfm is at least close enough to the 1000 CFM minimum that Bill Pentz recommends for grabbing fine dust and is also why you see less static with this machine.

Stepped down to 4" for the 8" jointer and table saw until I upgrade the points on the machine.
One branch is stepped own to a 4" blast gate as that is all I had left This branch will eventually run to the band saws.

Static is caused by trying to force too much air through too narrow a duct like the 4" duct. A 4" duct can only draw 400 cfm almost irrespective of wht size DC it is connected to. As I said above, your 6" ducting is wasted. What is happening is that these low air flows results in insufficient fine dust being grabbed where it is created, which in turn means your shed will fill with fine dust most of which you cannot see until it eventually settles out.

BTW unfortunately that cyclone and other like it will simply not pull 1450 cfm, even "when the moon is in the 7th house". That CFM figure is for the impeller alone but the cyclone is poorly designed so it creates a significant back pressure on the whole system which uses up much of its 12" of water pressure that the impeller generates. This ends up generating poorer airflow than a 3HP DC with twin air bags. Most home made cyclones and chip catchers do the same thing. Cyclones need to be very well designed otherwise they place too much back pressure, especially on a small system, The way industry deals with this is to use something like a 20HP motor so it does not matter too much if their cyclones are inefficient. Unfortunately these old designs translate poorly to small workshops where 3-4 HP is the max size motor that can be used.

If you want to connect to a machine with 4" ports using 4" ducting you need three 4" (3 x 400 cfm) independent ducts to make it equal to one 6" duct (~1200 cfm) so machines like band saws with 4" ports will require 3 separate 4" hoses/ducting. If a machine only has one 4" post then either it has to be enlarged or 2 other 4" hoses can be placed/fixed/arrange nearby. This will create a slight vacuum bubble around that machine and capture a significant amount of fine dust.

Thanks Bob.

I did a bit of research here, and to be honest it wasn't all that much effort to install
Once I enlarge the ports on some machines it should be better, not perfect but better.

Unfortunately the CNC will more than likely be a lengthy (2.5 - 3m) 4" flex duct as it needs to be suspended on a track so it can follow the router.
Given your point on static being caused by too much air flow in a small duct perhaps I could open a point elsewhere on the 6" main duct when the CNC is running to reduce some of the airflow.

The main issue with the table saw, or the duct running to it is the static, not the collection, as I am unable to test it, although I do concede it won't be perfect.
I understand your point on the 4" duct running to that machine and as I said, it is temporary until I can upgrade the outlet.
There is no overhead guard as yet but I do have the equipment necessary to install one, unfortunately it will probably be 4" but by then the cabinet connection point will be 6"

The connection to the jointer is almost exactly the same as that of the table saw but there is no static when running it.

As for the 6" duct being wasted, some of my machines will be changed to 6" outlets, but I am guessing even then they won't be fully effective if there are not enough gaps or points for air to enter the machines which are equivalent to the 6" ducting.

For example the 20" thicknesser which has a 5" outlet.
My 6" duct is run all the way to that outlet but I can see no way to increase the size of the dust shroud on the machine, and as you said the machine itself may not permit sufficient air flow.

Again, as for for the 6" duct being a waste, from what I can gather and what you have said, considering a 4" port on a machine, it is only necessary to run 4" duct for the entire length.
I would agree if that run was perfectly straight.
What about losses due to bends, blast gates etc?
Wouldn't increasing the diameter partially allow for these restrictions and get you somewhere back towards the ideal 4" straight/uninterrupted run?

I agree the cfm rating would be inaccurate.
Even without knowing too much about dust extraction, it is a given that most companies will publish the best figures they can to sell a machine

Part of the reason I bought this one was because it acts as a separator and allows the dust to be captured in a plastic bag for dust free removal and easy disposal.
Low shed height also limited my options.

I'm not sure of the age of Jet's cyclone design given it is a newish machine.
I haven't gone to the effort of comparing it to the specs given by the gurus
I can only compare it to a 2HP bag type DC with a 6" inlet and while I had that running with no restrictions I would estimate the airflow to be less than half that of the new cyclone.

Regarding back pressure of the cyclone, if static is caused by too much air being forced through a small duct, and the smallest duct I have is 4", and I am getting a lot of static, wouldn't that say that the back pressure is not so much of an issue and the cyclone is effective at a duct size larger than 4"?
Would I be correct in assuming it creates too much airflow for 4" duct or have I misread something?

What I can say is that at the end of the 6" duct it moves a tremendous amount of air
As a test I held up one of my Clearvue mini cyclone buckets which was full of dust, it was emptied in seconds and sucked up to the blast gate and held there, not that this proves anything but it was pretty cool

Jack since you have limitations to what you can do with the 4" duct on the CNC unless you can change the dust shroud surrounding the spindle to work with a 6" line, I suggest you enclose the machine to limit the dust from escaping that area to the rest of the shop. What I had in mind rather than hard walls is to enclose it with curtains (clear plastic/vinyl) that you can pull back to access the machine and to have the dust pipe open in the enclosure to catch the dust, including the invisible stuff, not picked up buy the 4" at the spindle. BobL can tell you if it would be better to have a single opening and it's size or if two 4" openings a distance apart would work better. You will need to keep the dust collector running for a while after the CNC stops to scrub the air in the enclosure of the invisible dust. I assume the CNC is in the corner of the shop so one curtain coming straight out from each of the two walls to meet each other would be simple and the one coming across the ducts can be filled above it with a hard wall for the pipes to come through. There will be enough makeup air coming in from below the curtain to keep it from pulling in towards the CNC........well I think there should be anyway. Clear as mud eh?

Pete

Jack,

You have hit a perennial problem ... undersized machine ports. I gnashed my teeth for some time about the ports fitted by manufacturers, but expanding all of them was not at all difficult, except for the thicknesses/planer, which you have identified as a troublemaker.

I liked Pete's idea for the CNC machine, and look forward to BobL's response. If you have a 4" line to the machine, you could have two more 4" lines scrubbing the air overhead.

You might get a few ideas for opening up machine ports from here. https://www.woodworkforums.com/f200/m...chines-161166/

Originally Posted by Jack E

Once I enlarge the ports on some machines it should be better, not perfect but better.

Yes it should improve things quite a bit. You should also run the DC for 10-20 minutes after the last dust making activity even if you just make one cut with the TS. Most people don't like doing this because of the noise but that's the way it is.

Unfortunately the CNC will more than likely be a lengthy (2.5 - 3m) 4" flex duct as it needs to be suspended on a track so it can follow the router. Given your point on static being caused by too much air flow in a small duct perhaps I could open a point elsewhere on the 6" main duct when the CNC is running to reduce some of the airflow.

Yes that is good idea - preferably open a 6" duct right above the CNC. If you open it elsewhere in the system this creates a slight pressure drop in that direction which will set up a preferential air flow in that direction and scatter fine dust along that path.
Sorry, it's only a bit more flow that is needed to cause the static ie it might only go from 380 to 420 cfm, but this increase is enough to start to generate static inside the pipe. Any static generate immediately transfers itself to the outside of the pipe - the laws of physics say there can be none inside so don't be worried about it from a safety perspective. My guess is you are also seeing a lot of dust settling on the outside of the pipes. This is because the dust is not being removed at source

There's lots more tricks for a CNC you could consider.
One is an extraction hood above the whole thing to capture fine dust, or better still as QC mention, enclose the whole unit.
The other is a bristle guard surround around the cutter like this https://www.woodworkforums.com/f200/b...guards-165892/

The main issue with the table saw, or the duct running to it is the static, not the collection, as I am unable to test it, although I do concede it won't be perfect. I understand your point on the 4" duct running to that machine and as I said, it is temporary until I can upgrade the outlet.
There is no overhead guard as yet but I do have the equipment necessary to install one, unfortunately it will probably be 4" but by then the cabinet connection point will be 6"

6" on the cabinet and 6" on the guard is ideal, but 4" on the guard is better than nothing. I only have 4" on my guard and combined with the bristle guard it works fine.

The connection to the jointer is almost exactly the same as that of the table saw but there is no static when running it.

That's because the jointer will make mostly chips or shavings. Also take a closer look - perhaps the jointer does not breathe quite as well as the TS - less flow means less static.

As for the 6" duct being wasted, some of my machines will be changed to 6" outlets, but I am guessing even then they won't be fully effective if there are not enough gaps or points for air to enter the machines which are equivalent to the 6" ducting.

Correct.

For example the 20" thicknesser which has a 5" outlet.
My 6" duct is run all the way to that outlet but I can see no way to increase the size of the dust shroud on the machine, and as you said the machine itself may not permit sufficient air flow.

In some cases some radical surgery is needed, maybe even the whole part part that contains the port needs to be remade. I can fully understand the reluctance to do this but that is the way it is.

Again, as for for the 6" duct being a waste, from what I can gather and what you have said, considering a 4" port on a machine, it is only necessary to run 4" duct for the entire length. I would agree if that run was perfectly straight. What about losses due to bends, blast gates etc?
Wouldn't increasing the diameter partially allow for these restrictions and get you somewhere back towards the ideal 4" straight/uninterrupted run?

Sorry I was not clearer. You are correct it will definitely be worse if you do that. My suggestion is where you have a 4" port on a machine, setup 2 or 3 short 4" connections to the nearest 6" line - connect one 4" to the machine and just leave the others free sucking until you get round to adding the others to the machine or modifying the 4" port on the machine to a 6" port. A 3 way connector or 2 Wyes are needed.

I agree the cfm rating would be inaccurate. Even without knowing too much about dust extraction, it is a given that most companies will publish the best figures they can to sell a machine

Yep, unfortunately this leads to consumers assuming that they will be safe when the picture is much more complicated.

Part of the reason I bought this one was because it acts as a separator and allows the dust to be captured in a plastic bag for dust free removal and easy disposal.Low shed height also limited my options.

Yes I understand the appeal of cyclones for this reason but unless they are well designed like a Cleavue they can create other problems like poor fine dust removal due to reduced air flow. You would have been better off with a Clearvue for a number of reasons.

I'm not sure of the age of Jet's cyclone design given it is a newish machine.
I haven't gone to the effort of comparing it to the specs given by the gurus

It's easy to see that it is an old design as it has a straight side entry into the cyclone. The newer designs have an angled entry. More expensive to make but works much better.air

I can only compare it to a 2HP bag type DC with a 6" inlet and while I had that running with no restrictions I would estimate the airflow to be less than half that of the new cyclone.

Unfortunately you can't tell by just looking. Air flow (cfm) is a strange thing. It is very easy to be fooled by a small increase in air speed (fpm) which is what picks up chips but it's the total flow (cfm) that grabs the fine dust.

Regarding back pressure of the cyclone, if static is caused by too much air being forced through a small duct, and the smallest duct I have is 4", and I am getting a lot of static, wouldn't that say that the back pressure is not so much of an issue and the cyclone is effective at a duct size larger than 4"?
Would I be correct in assuming it creates too much airflow for 4" duct or have I misread something?

See comments above about static.

What I can say is that at the end of the 6" duct it moves a tremendous amount of air
As a test I held up one of my Clearvue mini cyclone buckets which was full of dust, it was emptied in seconds and sucked up to the blast gate and held there, not that this proves anything but it was pretty cool

Yes a 6" duct can move a lot of air - that's the reason why it is recommended even for small workshops.

Picked up some more bits today, some more 6" fittings, very flexible 4" pipe and a track system for the CNC.

I ran out of time to see someone about having 6" ports made for some of my machines.

The CNC has a bristle type shroud, there is simply no room to enclose it whether by wall or curtain.
As yet it hasn't been hooked up to the cyclone and I have just been following it with a vac as it was cutting, hopefully it will be hooked up soon.

Just to clarify, even though the jointer and table saw are both connected to the 6" pipe by 4" flex, there is lots of static on the saw and none on the jointer.
do you think this is because the jointer starves the 4" of air while the table saw allows a lot of air to the pipe?

Either way, these should both 6" all the way soon.

I did open the 6" pipe near the CNC while the table saw was running and the static disappeared, I wonder though if having an unrestricted 6" opening while expecting another duct to extract from the table saw is effective?

Originally Posted by Jack E

. . . do you think this is because the jointer starves the 4" of air while the table saw allows a lot of air to the pipe?

This is likely because I'll bet all that the jointer has to draw air through is the slots around the knives whereas there are probably a few other air paths in the saw cabinet.

I did open the 6" pipe near the CNC while the table saw was running and the static disappeared, I wonder though if having an unrestricted 6" opening while expecting another duct to extract from the table saw is effective?

This supportd my idea of trying to force too much air through a 4" port. It won't be as effective as most of the air will be drawn through the 6" duct but let's wait and see what happens when you make the TS 6"

Hopefully that will solve the table saw.

The CNC will be another story as it will definitely be 4" but I will more than likely open another point as I did on the saw today.

Given that the CNC is just a router, 4" should be fine, especially with the brushed dust shroud attached, as long as I can eliminate any static if it is an issue.

Originally Posted by Jack E

Given that the CNC is just a router, 4" should be fine, especially with the brushed dust shroud attached, as long as I can eliminate any static if it is an issue.

Routers are one of the worst tools for fine dust. The 4" will pick up the chips but I would see if you can find a way to hook up a 6" duct.

Originally Posted by Jack E

The CNC will be another story as it will definitely be 4" but I will more than likely open another point as I did on the saw today.

Given that the CNC is just a router, 4" should be fine, especially with the brushed dust shroud attached, as long as I can eliminate any static if it is an issue.

Bearing in mind that you will need a rather long length if flexi hose to allow the CNC router to move around you would be likely to lose a lot of airflow as the flexi hose bends as well as just because it is a flexi hose. You put forward a very similar argument in your earlier post:

Originally Posted by Jack E

Again, as for for the 6" duct being a waste, from what I can gather and what you have said, considering a 4" port on a machine, it is only necessary to run 4" duct for the entire length.
I would agree if that run was perfectly straight.
What about losses due to bends, blast gates etc?
Wouldn't increasing the diameter partially allow for these restrictions and get you somewhere back towards the ideal 4" straight/uninterrupted run?

I have seen a few CNC routers being demonstrated and have been able to smell the airborne dust from quite a distance away. I would be inclined to get as much airflow as I could as close to the cutter as I could. I would think that a 4" port at the cutter and a 6" port open above the table is probably not going to be as effective as one 6" port close to the cutter and nothing else.

That is just my opinion, for which I have no proof. If anyone has any concrete data that contradicts this I will not mind.

But for that reason I would seriously consider getting as much airflow as close to the cutter as possible.

There was a CNC router being demonstrated at a wood show I attended where they were using no dust extraction and sweeping the visible dust off with a little brush. The router kept tracking through the dust already created and the air flow created by the router motor was kicking up any dust that had already settled. To make it worse, the workpieces they were carving patterns and pictures into were MDF. The air was thick with dust. I did not stay long.

The movement of the router over a 1500 x 2900 bed is a problem.
Usually a single duct fixed to the ceiling with some slack enables full range of travel.
My shed is quite low which is why I am installing a track system for the duct to travel on.
The 6" flex duct I have would not work as it is so big that the duct would nearly drag on the table, plus it would be asking a lot of flexible 6" duct to travel that well.

I am thinking there will need to be 2 or 3 half loops of duct, hopefully only 2.

Doug, the reason for my argument re the 6" duct not being wasted is relevant, that's why the 6" PVC duct will run as close as I can to the CNC but unfortunately I can't see a way around not having 4".

Jack, this is obviously shaping up to be a commercial operation. If you are successful, and I wish you well, you wont be operating out of the lawn locker for too long and will be setting up in more suitable premises where you can set things up with less limitations than you currently have. What you have already done is probably adequate for a short-term solution. Maybe just wear a dust mask or respirator to overcome the shortfall until you are up and running in more suitable premises. Good luck with the venture. Keep us posted with how it is going.

Cheers

Doug

Thanks Doug, I am in my last year at Uni, then I will have one more year here making some furniture and hopefully a reno' or two.
After that I will pack up the whole shebang and move back to the tropics, into a shed about 4 times the size

It is a relatively temporary set up but I want it to be as safe as possible without dust control becoming an obsession.
With a cyclone, 6" duct, 2 Festool vacs and another vac along with 3 Clearvue mini cyclones, some would say I have passed that point

I do wear a good quality mask when I think it is warranted.
A room filter is also on the cards.