Thread: Something different? Ducting a SHOP VAC – one happy chappy

Thanks for the reply Brett. I am hoping Bobl will indeed come in on this, and agree I understand fine dust needs high flow.

Hence my question is I guess how to match CTM capabilities (settings for different hose sizes) with the task (hand tool DE only here).

For the Domino and Festool router, the 27mm hose that came with the vac should fit straight into the tool; what do I team that with between cyclone and vac, and what setting for the vac?

For the non-Festool sanders, I presume I am better using a larger diameter hose (36/40mm) to cyclone; and do I team that with 36mm or 50mm to the vac?

In the end non-Festool hose and adaptors aren't that expensive, so I can always experiment.

Thanks Bob, our replies crossed.

So, if I understand correctly, basically the wider the hose, for as much as possible, the better. Therefore, 50mm hose up to the tool if possible.

Is that right?

Originally Posted by FenceFurniture

Hi Mark, I'm not sure if i can answer all of your question, but between vac and cyclone is 50mm hose which came with the cyclone. All the other hoses you can see are 27mm. I should be using a 36mm from the ducting outlet to the cyclone, but that's all I had then.

As far as hose diameters for various tools goes - Bobl would know more than I, but the hose dia depends on the tool/particle size, and how high the air velocity is required to be (I think the finer the dust the higher the velocity needs to be).

Air velocity is mainly important to prevent sawdust settling in hoses and ducting and to grab larger chips that are flung away from a tool/blade.

Fine dust behaves more like a gas so although it moves initially at the speed of blade/tool, within mm of leaving the tool/blade it slows down by the surrounding air to the air speed generated by the tool (this is not the same as the blade speed) and the DC system. Large chips are no so easily slowed and having more momentum will cut through the surrounding air more easily which is why it is easy to see them scatter around a machine. Fine dust behaves like a gas or a fart which forma a bubble that moves from areas of high concentration to low to eventually fill a shed. To over come this high volume flows (800-1000 cfm) are more important than local air speeds. Most quality power tools that use a quality VCs (which have high air speeds but <100 CFM) try to constrain the fine dust air bubble with mixed success because they cannot cater for every situation the tool is used in eg sanding edges etc.

Originally Posted by BobL

Fine dust behaves like a gas or a fart which forma a bubble that moves from areas of high concentration to low to eventually fill a shed.

Think I'm glad I don't live in Perth Bob - I'd be too tempted to come around and check out that fancy shed pair of yours. Can you really fill both of them?

Originally Posted by FenceFurniture

Think I'm glad I don't live in Perth Bob - I'd be too tempted to come around and check out that fancy shed pair of yours. Can you really fill both of them?

So now we know the REAL reason that BobL wants to have the dust extraction capacity to change over all the air in the shed so quickly. And its probably the real reason his filter bags clog up.

Doug

Originally Posted by FenceFurniture

Think I'm glad I don't live in Perth Bob - I'd be too tempted to come around and check out that fancy shed pair of yours. Can you really fill both of them?

Dang - I have been unmasked!

Originally Posted by BobL

Dang - I have been unmasked!

Deepest sympathies. Suggest replacing it with a 3M P2 disposable mask - first hand experience tells me that not even a fresh cat scat at dangerously close range can penetrate it (and let's face it, no man can top a cat or dog, although after a feed of Pacific oysters......a story for another day).

Thinking of enclosing my shop vac in a cabinet and venting it to my dust collection ductwork. My shop is "L" shaped and the vac is in the middle, so venting it to the outside is not possible ... and I want it where it is so the hose reaches the entire shop.

Also thought about a mini cyclone between the vac and the work ... but is it worthwhile? It would likely work when I vacuum the floor or chips from elsewhere, but I use the shop vac extensively with belt and orbital sanders. These produce fine dust and I wonder at the effectiveness of a mini cyclone at capturing this fine material.

I note that often the filter needs cleaning when there is only a small amount of material in the collector barrel.

Any advice appreciated.

Originally Posted by John Samuel

Thinking of enclosing my shop vac in a cabinet and venting it to my dust collection ductwork. My shop is "L" shaped and the vac is in the middle, so venting it to the outside is not possible ... and I want it where it is so the hose reaches the entire shop.

Also thought about a mini cyclone between the vac and the work ... but is it worthwhile? It would likely work when I vacuum the floor or chips from elsewhere, but I use the shop vac extensively with belt and orbital sanders. These produce fine dust and I wonder at the effectiveness of a mini cyclone at capturing this fine material.

Why muck around with a shop vacs and mini cyclones?
Have a look at my table in this post (BTW, the 1100 L/s should be 1100 L/min).

You already have a fantastic BIG cyclone (that vents outside) which you can hook up direct to your belt and orbital sanders that will out perform any VC.

Set yourself up with 2-3 m of 50 or 63 mm hose and 2-4-6" adapters and plug into any of your 6" ports.
I inserted several 6"-4" Y's (Screw cap on the 4" inlet) in my ducting specifically so that I can plug 2" hoses into these .
To maintain flow to the cyclone leave a 6" port partially open which will also remove any residual fine dust that escapes the sander..

When I work with a sander I loosely suspend my 50 mm hose from the ceiling with long occy straps - this works a treat.

We had a similar discussion a while ago, and I have already moved in this direction. Already have most of the parts to hook up a 50mm flexy to my ducting. Am in the process of building a blade guard/DC system for overhead the TS. When I go shopping for the remainder of those parts, I hope to pick up the final bits needed for the 50 mm DC system.

However, my problem is that unless I can hook up about 8 M of 50 mm hose (can I?) I'll still need the dirty old vac to clean up floors and when I am working of larger jobs parked away from my benches, like the one in the pic.
IMAG0134.jpg
This piece sits about 4-5 M away from a collection point. I used the shop vac when sanding back the sanding sealer etc, as the piece was beyond lifting onto the bench. Then there was the fine white over-spray from the lacquer that needed to be cleaned up. Again, the shop vac was used for this.

Nothing would give me more pleasure than to tear the vac off the wall. Where the air exits the machine it coats the wall with very fine dust, despite having a large fan inches away.

So, the big question is, "Can I use a long 50 mm hose with the cyclone?" I'd need about 8 M of hose to reach all parts of the workshop/garage.

Originally Posted by John Samuel

So, the big question is, "Can I use a long 50 mm hose with the cyclone?" I'd need about 8 M of hose to reach all parts of the workshop/garage.

I would suggest running a 6" duct from the cyclone closer to where you need it and then use 4" or 2" hose for sanders as needed from there. It sounds ungainly but it's fine provided the hose is supported from the roof.

I've stopped vacuuming the floor, I use a broom to sweep all the crap into the vicinity of my BS where I uncouple one of the 4" DC hoses and use to pick the crap. When sweeping up I run the DC and open all the gates.

Heeeeyy........Bob, your much earlier posts concerning using 50 or 60mm tube for the ducting have been eating away at me! Then there was using blast gates. Just down there now thinking about maybe a change or two, and it's still eatin' me - maybe a change on the way - hey, it's cheap and quick.

What I didn't quite get at the time was why using a larger main pipe would improve things (because air speed through the main pipe would be reduced, by default), but a thought just occurred to me. Is it to do with still having enough air speed in the main pipe to keep the fine particles in suspension, and giving less resistance to the system through the main pipe, but then increasing the air speed (ergo "pulling power") at the dust source (because it's a crevice nozzle or whatever)?

Some other related and interesting things that I've noted lately:

• Festool publicises using 27mm hose with the Kapex, but just read on these forums that 36mm works much better....
• Same deal with the TS55 Track Saw - everything says 27mm, and then I see with interest that when hooked up in a CMS table they use a duo hose and the 36mm part goes to where they normally put 27mm....
• So does this kinda relate to evrything or not?

Originally Posted by FenceFurniture

Heeeeyy........Bob, your much earlier posts concerning using 50 or 60mm tube for the ducting have been eating away at me! Then there was using blast gates. Just down there now thinking about maybe a change or two, and it's still eatin' me - maybe a change on the way - hey, it's cheap and quick.

What I didn't quite get at the time was why using a larger main pipe would improve things (because air speed through the main pipe would be reduced, by default), but a thought just occurred to me. Is it to do with still having enough air speed in the main pipe to keep the fine particles in suspension.

It's not the fine particles that need to be kept suspended but the big chips, fIne dust will stay suspended for hours. A larger pipe will only be of value if an air speed of 4000 fpm can be maintained, otherwise the bigger chips will start to fall out of suspension. This is why using a 6" pipe on a VC will be a waste of time.

Big chips also need high air speed to grab them at source before they get flung out of range of the VC/DC collection point. Fine dust capture also benefits from air speed at source but because fine dust billows around and out from sources like a gas and can even diffuse counter direction wise to a high speed air flow, volume flow is more significant in its capture. Using 50 instead of 27 mm hose on a DC should collect more fine dust and less chips - visually this probably looks worse but health-wise you would be better of.

Most VCs use high air speed to try to capture the bigger chips but because the motor is limited in its capacity (ie 1500W or two HP) it can only do this over a volume of a few cubic centimetres which is OK for some hand held power tools but usually insufficient for most machines.

BTW I have been using a TS75 Festool plung saw connected to a Festool Vac (27 mm hose) extensively over the last few days and it impressively collected two bags of sawdust but the saw must have sprayed at least an equivalent amount around the shed. Even though 1/2 of one of one long walls of the shed was opened up, &nbsp;next morning I noted some fine dust settling out in the shed, so it's still go a long way to go in terms of dust collection. I should have brought a dust particle counter with me to see what the dust levels were. Despite this, overall the TS75 is still a very fine tool and I would love to have one of my own.

Thanks Bob.

Just to clarify some points:

• the outlet at the far right of the ducting is only for drill press and general cleanup. The DP produces small quantities of small chips, although a Forstner produces larger quantities of larger chips (but they would still be defined as small chips). The general cleanup operation can sometimes include things remarkably similar to the size, shape, colour and bacterial infestation of a cockroach.
• perhaps on occasion I will use this outlet for a sander if i do it outside (it's right next to the door), but this would not be a significant consideration in the critical path
• The outlet in the middle of the bench (and middle of the ducting length) has so far been largely unused because I haven't had the hose to run off it. However, I will get some more hose shortly, and this outlet will be used for general cleanup, quite probably a sander (all dust of course), possibly a router (lots of small high speed chips), and definitely a track saw (justabout all dust)
• The outlet for the Kapex is about a metre of pipe away from the cyclone, plus about 750mm of hose to the cyclone intake, plus about 500mm of hose from outlet to Kapex (lots of dust, some tiny chips). Important to not that the pipe is all running downhill, so chips falling out of suspension is just not an issue. The very short hose from outlet to Kapex can be up/down/horizontal - whichever way the hose goes as I slide/drop the saw.
• for most general cleanup I run the hose direct into the cyclone, with the ducting disconnected

So, how does this sound for a plan:

• leave the Grey Water Diverter on the Drill Press end as it seems to work quite well and is great for varying the suck between the two hoses that I often run on the DP
• replace the GWD at the Kapex with a blast gate, and incorporate a couple of other blast gates (middle bench outlet)
• run 60mm pipe from cyclone to kapex outlet (this is the downhill part)
• use 50mm hose from the end of the ducting pipe to the cyclone (also downhill)
• use 36mm or even 50mm hose for the 500mm run to the Kapex from outlet (this is the up/down/horizontal hose)
• leave the 40mm pipe as is from immediately beyond the Kapex for the rest of the ducting (to keep airspeed up for the chip producers)
• use appropriate diameter hose for the machine in use from the middle outlet (using this outlet will mean that the hose runs upwards from the machine - a great ergonomic boost)

Cheers
Brett